US20050243425A1 - Optical film with sharpened bandedge - Google Patents
Optical film with sharpened bandedge Download PDFInfo
- Publication number
- US20050243425A1 US20050243425A1 US11/173,663 US17366305A US2005243425A1 US 20050243425 A1 US20050243425 A1 US 20050243425A1 US 17366305 A US17366305 A US 17366305A US 2005243425 A1 US2005243425 A1 US 2005243425A1
- Authority
- US
- United States
- Prior art keywords
- optical
- thickness
- layers
- repeating unit
- multilayer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000012788 optical film Substances 0.000 title description 6
- 230000003287 optical effect Effects 0.000 claims abstract description 234
- 229920000642 polymer Polymers 0.000 claims description 22
- 230000007423 decrease Effects 0.000 claims description 15
- 238000001228 spectrum Methods 0.000 abstract description 30
- 239000010410 layer Substances 0.000 description 178
- 239000010408 film Substances 0.000 description 107
- 230000005540 biological transmission Effects 0.000 description 42
- 239000000463 material Substances 0.000 description 30
- 239000013047 polymeric layer Substances 0.000 description 21
- -1 polyethylene terephthalate Polymers 0.000 description 19
- 101100274508 Oryza sativa subsp. japonica CKI1 gene Proteins 0.000 description 17
- 238000009826 distribution Methods 0.000 description 13
- 230000002441 reversible effect Effects 0.000 description 9
- 229920001577 copolymer Polymers 0.000 description 8
- 150000002148 esters Chemical class 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 238000001125 extrusion Methods 0.000 description 7
- 230000006872 improvement Effects 0.000 description 7
- 238000000576 coating method Methods 0.000 description 6
- IBQMGZLNUJDKJY-OODJPBEGSA-N (5s,6r,7e,9e,11z,14z)-6-(2-carboxy-2-oxoethyl)sulfanyl-5-hydroxyicosa-7,9,11,14-tetraenoic acid Chemical compound CCCCC\C=C/C\C=C/C=C/C=C/[C@@H](SCC(=O)C(O)=O)[C@@H](O)CCCC(O)=O IBQMGZLNUJDKJY-OODJPBEGSA-N 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 238000010276 construction Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000011112 polyethylene naphthalate Substances 0.000 description 5
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 description 4
- 238000002310 reflectometry Methods 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- 239000004793 Polystyrene Substances 0.000 description 3
- 101100152436 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) TAT2 gene Proteins 0.000 description 3
- 229920010524 Syndiotactic polystyrene Polymers 0.000 description 3
- 238000013459 approach Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229920002313 fluoropolymer Polymers 0.000 description 3
- 238000012886 linear function Methods 0.000 description 3
- 229920003207 poly(ethylene-2,6-naphthalate) Polymers 0.000 description 3
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 3
- 229920000139 polyethylene terephthalate Polymers 0.000 description 3
- 239000005020 polyethylene terephthalate Substances 0.000 description 3
- 229920006254 polymer film Polymers 0.000 description 3
- 239000004926 polymethyl methacrylate Substances 0.000 description 3
- 229920002223 polystyrene Polymers 0.000 description 3
- 229920001283 Polyalkylene terephthalate Polymers 0.000 description 2
- 230000003667 anti-reflective effect Effects 0.000 description 2
- 230000008033 biological extinction Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000004040 coloring Methods 0.000 description 2
- 239000002178 crystalline material Substances 0.000 description 2
- QYQADNCHXSEGJT-UHFFFAOYSA-N cyclohexane-1,1-dicarboxylate;hydron Chemical compound OC(=O)C1(C(O)=O)CCCCC1 QYQADNCHXSEGJT-UHFFFAOYSA-N 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 239000000975 dye Substances 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 239000004811 fluoropolymer Substances 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229920000620 organic polymer Polymers 0.000 description 2
- 239000000049 pigment Substances 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 238000001429 visible spectrum Methods 0.000 description 2
- NEQFBGHQPUXOFH-UHFFFAOYSA-N 4-(4-carboxyphenyl)benzoic acid Chemical compound C1=CC(C(=O)O)=CC=C1C1=CC=C(C(O)=O)C=C1 NEQFBGHQPUXOFH-UHFFFAOYSA-N 0.000 description 1
- 241000282461 Canis lupus Species 0.000 description 1
- DQEFEBPAPFSJLV-UHFFFAOYSA-N Cellulose propionate Chemical compound CCC(=O)OCC1OC(OC(=O)CC)C(OC(=O)CC)C(OC(=O)CC)C1OC1C(OC(=O)CC)C(OC(=O)CC)C(OC(=O)CC)C(COC(=O)CC)O1 DQEFEBPAPFSJLV-UHFFFAOYSA-N 0.000 description 1
- 229920001634 Copolyester Polymers 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 239000004812 Fluorinated ethylene propylene Substances 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 229920001774 Perfluoroether Polymers 0.000 description 1
- 229920002319 Poly(methyl acrylate) Polymers 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000005062 Polybutadiene Substances 0.000 description 1
- 229920002614 Polyether block amide Polymers 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 229920002367 Polyisobutene Polymers 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 1
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Natural products C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 1
- FJWGYAHXMCUOOM-QHOUIDNNSA-N [(2s,3r,4s,5r,6r)-2-[(2r,3r,4s,5r,6s)-4,5-dinitrooxy-2-(nitrooxymethyl)-6-[(2r,3r,4s,5r,6s)-4,5,6-trinitrooxy-2-(nitrooxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-3,5-dinitrooxy-6-(nitrooxymethyl)oxan-4-yl] nitrate Chemical compound O([C@@H]1O[C@@H]([C@H]([C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O)O[C@H]1[C@@H]([C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@@H](CO[N+]([O-])=O)O1)O[N+]([O-])=O)CO[N+](=O)[O-])[C@@H]1[C@@H](CO[N+]([O-])=O)O[C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O FJWGYAHXMCUOOM-QHOUIDNNSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 239000002671 adjuvant Substances 0.000 description 1
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 description 1
- 229920006125 amorphous polymer Polymers 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 229920006217 cellulose acetate butyrate Polymers 0.000 description 1
- 229920006218 cellulose propionate Polymers 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- IXMINUYYYUZPRX-UHFFFAOYSA-N cyclohexane;methanediol Chemical compound OCO.OCO.C1CCCCC1 IXMINUYYYUZPRX-UHFFFAOYSA-N 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000004313 glare Effects 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 238000009998 heat setting Methods 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 150000003949 imides Chemical class 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- KYTZHLUVELPASH-UHFFFAOYSA-N naphthalene-1,2-dicarboxylic acid Chemical compound C1=CC=CC2=C(C(O)=O)C(C(=O)O)=CC=C21 KYTZHLUVELPASH-UHFFFAOYSA-N 0.000 description 1
- KHARCSTZAGNHOT-UHFFFAOYSA-N naphthalene-2,3-dicarboxylic acid Chemical compound C1=CC=C2C=C(C(O)=O)C(C(=O)O)=CC2=C1 KHARCSTZAGNHOT-UHFFFAOYSA-N 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 1
- 229920009441 perflouroethylene propylene Polymers 0.000 description 1
- 229920001485 poly(butyl acrylate) polymer Polymers 0.000 description 1
- 229920001084 poly(chloroprene) Polymers 0.000 description 1
- 229920002493 poly(chlorotrifluoroethylene) Polymers 0.000 description 1
- 229920001483 poly(ethyl methacrylate) polymer Polymers 0.000 description 1
- 229920000205 poly(isobutyl methacrylate) Polymers 0.000 description 1
- 229920002285 poly(styrene-co-acrylonitrile) Polymers 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920001281 polyalkylene Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920002857 polybutadiene Polymers 0.000 description 1
- 229920001748 polybutylene Polymers 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000005023 polychlorotrifluoroethylene (PCTFE) polymer Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920006393 polyether sulfone Polymers 0.000 description 1
- 229920001601 polyetherimide Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920001195 polyisoprene Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002689 polyvinyl acetate Polymers 0.000 description 1
- 239000011118 polyvinyl acetate Substances 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000005033 polyvinylidene chloride Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000012260 resinous material Substances 0.000 description 1
- 238000000518 rheometry Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229920006126 semicrystalline polymer Polymers 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000000992 sputter etching Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- KKEYFWRCBNTPAC-UHFFFAOYSA-L terephthalate(2-) Chemical compound [O-]C(=O)C1=CC=C(C([O-])=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-L 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000012815 thermoplastic material Substances 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 238000000411 transmission spectrum Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/28—Interference filters
- G02B5/281—Interference filters designed for the infrared light
- G02B5/282—Interference filters designed for the infrared light reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/28—Interference filters
- G02B5/285—Interference filters comprising deposited thin solid films
- G02B5/287—Interference filters comprising deposited thin solid films comprising at least one layer of organic material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/0074—Production of other optical elements not provided for in B29D11/00009- B29D11/0073
- B29D11/00788—Producing optical films
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
- G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
- G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
Definitions
- the present invention relates generally to multilayer optical bodies, and in particular to multilayer films exhibiting a sharpened reflective bandedge.
- multilayer reflective films comprising alternating layers of two or more polymers to reflect light is known and is described, for example, in U.S. Pat. No. 3,711,176 (Alfrey, Jr. et al.), U.S. Pat. No. 5,103,337 (Schrenk et al.), WO 96/19347, and WO 95/17303.
- the reflection and transmission spectra of a particular multilayer film depends primarily on the optical thickness of the individual layers, which is defined as the product of the actual thickness of a layer times its refractive index.
- a multilayer film can be designed that reflects light over a broad band of wavelengths. This band is commonly referred to as the reflection band or stop band.
- a reflection band it is desirable for a reflection band to have a sharp spectral edge at the long wavelength (red) and/or short wavelength (blue) side.
- the reflective films known to the art that contain an optical repeating unit of varying optical thickness typically have moderately sloped bandedges which cause reflections outside of the desired wavelengths of interest.
- a reflective film is designed to reflect infrared light while being transparent over the visible spectrum, a sloped edge on the blue side of the reflection band may encroach into the visible region of the spectrum, thereby resulting in unwanted coloring of the infrared reflective film body.
- Such coloring can be avoided by designing the infrared film such that the infrared reflection band is moved further into the infrared region, but this results in substantial transmission of infrared light near the visible region of the spectrum.
- a reflective film or other optical body that reflects light over a selected range in the visible region of the spectrum, e.g., a reflective film that reflects only green light. In such a case, it may be desirable to have sharp edges at both the red and blue sides of the reflection band.
- Optical bodies of the present invention can comprise of reflective films having a plurality of optical repeating units having an optical thickness profile that defines a curve, the curve having substantially no discontinuities in its first derivative and shaped so that it, in order, monotonically decreases from an initial optical thickness to a minimum optical thickness, remains substantially constant at the minimum optical thickness, monotonically increases from the minimum optical thickness to a maximum optical thickness, remains substantially constant at the maximum optical thickness, and monotonically decreases from the maximum optical thickness to an end optical thickness, wherein the optical repeating units monotonically increasing from the minimum optical thickness to the maximum optical thickness form a reflection band.
- FIGS. 1 a to 1 e show the optical thickness variation of the optical repeating units R 1 and R 2 in multilayer stacks M 1 and M 2 to obtain bandedge sharpening at the red or blue edge of the reflection band;
- FIG. 2 shows the optical thickness variation of the optical repeating units R 1 , R 2 and R 3 in multilayer films M 1 , M 2 and M 3 to obtain bandedge sharpening at the blue and red edges of the reflection band;
- FIG. 3 shows the optical thickness variation of the optical repeating units R 1 , R 2 and R 3 in multilayer films M 1 , M 2 and M 3 in which M 1 and M 3 have continuously changing slopes;
- FIGS. 4 a and 4 b are schematic diagrams of a multilayer film consisting of two alternating polymeric layers
- FIG. 5 is a 3-dimensional schematic diagram of an optical repeating unit consisting of two alternating layers of polymeric materials
- FIG. 6 is a 3-dimensional schematic diagram of an optical repeating unit consisting of polymeric layers A, B and C arranged in an ABCB pattern;
- FIG. 7 a is a layer thickness gradient profile showing a combined layer thickness gradient of LTG1 and LTG2;
- FIG. 7 b is a computed spectrum illustrating the short wavelength bandedge for the reflectance band created by layer thickness gradient LTG1 and the effect of adding the reverse gradient LTG2;
- FIG. 8 a is a layer thickness gradient profile of a stack design having a reverse gradient with an f-ratio deviation
- FIG. 8 b is a computational spectrum illustrating the improvement in bandedge sharpness afforded by the combination of LTG1 and LTG3;
- FIG. 9 a is a layer thickness gradient profile for the combined stacks LTG1 and LTG4;
- FIG. 9 b is a computational spectrum illustrating the improvement observed with the layer thickness gradient of FIG. 9 a compared to the LTG1 case;
- FIG. 10 a is a the layer thickness gradient profile in which the low index layer is linear for the entire stack for LTG1 and LTG5, but the high index component undergoes a gradient reversal in the LTG5 section;
- FIG. 10 b is a computational spectrum illustrating the improvement seen with the gradient of FIG. 10 a vs. the LTG1 case;
- FIG. 11 a is a layer thickness gradient profile for a simple band pass filter made by introducing a step discontinuity in the layer thickness profile of a broad band reflecting stack;
- FIG. 11 b is the calculated spectrum for the gradient of FIG. 11 a;
- FIG. 12 a is a layer thickness gradient profile made with two graded linear thickness distributions and an additional non-graded quarter wave stack;
- FIG. 12 b is the calculated spectrum for the gradient of FIG. 12 a;
- FIG. 13 a is a layer thickness gradient profile illustrating a curved layer thickness profile
- FIG. 13 b is the calculated spectrum for the gradient of FIG. 13 a.
- Desired part of the spectrum any continuous range of wavelengths between 400 nm and 2500 nm, also called desired reflection band.
- Optical repeating unit a stack of layers arranged in a particular order, which arrangement is repeated across the thickness of a multilayer film; the stack of layers have a first order reflection at a wavelength according to Formula (I) above.
- Intrinsic bandwidth, or optical repeating unit (ORU) bandwidth The bandwidth that an infinite stack of ORU's of identical thickness would exhibit, which is readily calculated from the matrix elements of the characteristic matrix M as defined by Born and Wolf, “Principles of Optics”, Edition 5, page 67. For a quarterwave stack of two materials with an index differential less than about 0.3, it is given, to a good approximation, by the absolute value of the Fresnel reflection coefficient for that interface.
- Stopband A reflectance band is defined in general as a spectral band of reflection bounded on either side by wavelength regions of low reflection. With dielectric stacks, the absorption is typically low enough to be ignored for many applications, and the definition is given in terms of transmission. In those terms, a reflectance band or stop band is defined in general as a region of low transmission bounded on both sides by regions of high transmission.
- a single reflectance band or stop band for p-polarized light has a continuous spectrum between any two successive wavelengths at which the transmission is greater than 50 percent, and including such successive wavelengths as endpoints, and where the average transmission from one endpoint to the other is less than 20 percent.
- Such preferred reflectance band or stop band is described in the same way for unpolarized light and light of normal incidence.
- the transmission values in the preceding description are calculated in a way that excludes the portion of light reflected by an air interface with the stack or the stack's skin layers or coatings.
- the bandwidth is defined to be the distance, in nm, between the two wavelengths within the band which are nearest each 50 percent transmission point, at which the transmission is 10 percent. In commonly used terms, the bandwidths are defined by the 10 percent transmission points.
- the respective blue and red (i.e., short and long wavelength) bandedges are then taken to be the wavelength at the above defined 10% transmission points.
- the transmission of the preferred stop band is taken to be the average transmission between the 10 percent transmission points. If a reflectance band does not have high enough reflectivity to satisfy the definitions of bandwidth and bandedge slope for the preferred embodiment, then the bandwidth may be taken simply to be the full width at half maximum (FWHM), where the maximum is the peak reflectance value.
- FWHM full width at half maximum
- Bandedge slope of stop band The slope of a band edge as described in the preceding paragraph is taken from the 50 percent and 10 percent transmission/wavelength points, and is given in units of percent transmission per nm.
- Pass band A pass band is defined in general as a spectral transmitting band bounded by spectral regions of relatively low transmission. With the multilayer color shifting film, the passband is bounded by reflective stopbands. The width of the pass band is the Full Width at Half Maximum Transmission (FWHM) value.
- FWHM Full Width at Half Maximum Transmission
- Bandedge slope of pass band Band edge slopes are calculated from the two points on a given bandedge nearest the maximum transmission point, the transmission values of which are 50 and 10 percent of the maximum transmission value.
- the passband has low transmission regions on both sides of the transmission peak with transmission minima of 10 percent or less of the transmission value of the peak transmission point.
- a pass band having a 50 percent transmission maximum would be bounded on both sides by reflectance bands having 5 percent or lower transmission minima. More preferably, the transmission minima on both sides of the passband are less than 5 percent of the peak transmission value of the passband.
- Edge filter reflectance filter having only one bandedge within the wavelength range of interest.
- Multilayer film a film comprising an optical repeating unit designed to reflect light over a particular range of wavelengths.
- the multilayer film may contain additional layers between the optical repeating units and which additional layers may or may not be repeated throughout the multilayer film.
- Monotonically varying layer thickness of an optical repeating unit along a multilayer film the thickness of the optical repeating unit either shows a consistent trend of decreasing or increasing along the thickness of the multilayer film (e.g., the thickness of the optical repeating unit does not show an increasing trend along part of the thickness of the multilayer film and a decreasing trend along another part of the multilayer film thickness).
- These trends are independent of layer-to-layer thickness errors, which may have a statistical variance with a 1-sigma value as large as 5% or more.
- a local variation in the optical repeating unit may cause ripples in the layer thickness profile which is not strictly monotonic by the mathematical definition, but the ripple should be relatively small compared to the thickness difference between first and last optical repeating unit.
- Maximum optical thickness of an optical repeating unit the maximum of a statistical curve fit to the actual layer distribution containing random errors in layer thickness.
- Minimum optical thickness of an optical repeating unit the minimum of a statistical curve fit to the actual layer distribution containing random errors in layer thickness.
- In-plane axes two mutually perpendicular axes that are in the plane of the reflective film. For the sake of convenience, they are denoted as the x-axis and the y-axis.
- Transverse axis an axis that is perpendicular to the plane of the reflective film. For sake of convenience, this axis is denoted the z-axis.
- n i An index of refraction along a particular axis is referred to as n i , wherein i indicates the particular axis, for example, n x indicates an index of refraction along the x-axis.
- Negative birefringence the index of refraction along the transverse axis is less than or equal to the index of refraction along both in-plane axes (n z ⁇ n x and n y )
- the index of refraction along the transverse axis is greater than the index of refraction along both in-plane axes (n z >n x and n y ).
- the optical thickness ratio of polymeric layer k along an optical axis j is denoted as f jk and is defined as above, but with replacement of n k with the refractive index of polymer material k along axis j ().
- Skin layer a layer that is provided as an outermost layer typically having a thickness between 10% and 20% of the sum the physical thickness of all optical repeating units.
- multilayer films in accordance with the present invention can be used in a variety of ways to obtain bandedge sharpening at the red or blue side of the band or on both sides.
- a multilayer stack M 1 having an optical repeating unit R 1 is combined with a multilayer stack M 2 having an optical repeating unit R 2 .
- Both multilayer stacks are designed to have a first order reflection band in a desired region of the spectrum, e.g., in the infrared region. It is possible to produce a film or other optical body having a first order reflection band in a particular region of the spectrum by selecting polymeric materials with appropriate indices of refraction and by manipulating the physical thickness of each of the individual polymeric layers of an optical repeating unit such that the optical thickness of the optical repeating unit appears at the desired wavelength as predicted by Formula (I) above.
- the desired reflection over a particular range in the spectrum can be obtained.
- the optical repeating unit R 1 of multilayer stack M 1 is monotonically varied in optical thickness such that the desired reflection band is obtained.
- the optical thickness of optical repeating unit R 1 preferably increases monotonically along the thickness of multilayer stack M 1 .
- Multilayer stack M 2 may comprise an optical repeating unit R 2 that is substantially constant in optical thickness or the optical thickness of optical repeating unit R 2 may decrease monotonically along the thickness of multilayer stack M 2 . If the optical thickness of optical repeating unit R 2 is substantially constant, the optical thickness thereof should be approximately equal to the minimum optical thickness of optical repeating unit R 1 along the thickness of multilayer stack M 1 . Preferably in this embodiment, the optical thickness of optical repeating unit R 2 is substantially equal to the minimum optical thickness of optical repeating unit R 1 .
- FIG. 1 a depicts this embodiment and shows a plot of the optical thickness of optical repeating units R 1 and R 2 versus the optical repeating unit number in a reflective film made in connection with the present invention.
- multilayer stack M 1 comprises optical repeating unit R 1 of increasing optical thickness
- multilayer stack M 2 comprises optical repeating unit R 2 of substantially constant optical thickness.
- a reflective film designed in accordance with FIG. 1 a will have a sharpened bandedge on the blue side of the reflection band.
- FIG. 1 b depicts another embodiment of the present invention that also leads to sharpening of the reflection band on the blue side.
- multilayer stack M 2 in this embodiment comprises an optical repeating unit R 2 that decreases monotonically in optical thickness along the thickness of multilayer stack M 2 .
- the minimum optical thickness of optical repeating unit R 2 in this embodiment is such that it is substantially equal to the minimum optical thickness of optical repeating unit R 1 along multilayer stack M 1 .
- a multilayer stack M 1 having an optical repeating unit R 1 is combined with a multilayer stack M 2 having an optical repeating unit R 2 .
- Both multilayer films are designed to have a first order reflection in a desired portion of the spectrum, e.g., a reflection band in the green part of the visible spectrum.
- the optical thickness of optical repeating unit R 1 preferably increases monotonically along the thickness of multilayer stack M 1 .
- Multilayer stack M 2 may comprise an optical repeating unit R 2 that is substantially constant in optical thickness, or else the optical thickness of optical repeating unit R 2 may decrease monotonically along the thickness of multilayer stack M 2 . If the optical thickness of optical repeating unit R 2 is substantially constant, the optical thickness thereof should be equal to the maximum optical thickness of optical repeating unit R 1 along the thickness of multilayer stack M 1 . Preferably in this embodiment, the optical thickness of optical repeating unit R 2 is substantially equal to the maximum optical thickness of optical repeating unit R 1 .
- FIG. 1 c depicts this embodiment and shows a plot of the optical thickness of optical repeating units R 1 and R 2 versus the optical repeating unit number in a reflective film body in connection with the present invention.
- multilayer stack M 1 comprises optical repeating unit R 1 of increasing optical thickness
- multilayer stack M 2 comprises optical repeating units R 2 of substantially constant optical thickness.
- a reflective film body designed in accordance with FIG. 1 c will exhibit a sharpened bandedge at the red end of the reflection band.
- FIG. 1 d depicts another embodiment of the present invention that also leads to sharpening of the reflection band on the red side.
- multilayer stack M 2 now comprises an optical repeating unit R 2 that decreases monotonically in optical thickness along the thickness of multilayer stack M 2 .
- the maximum optical thickness of optical repeating unit R 2 in this embodiment is such that it is substantially equal to the maximum optical thickness of optical repeating unit R 1 along multilayer stack M 1 .
- multilayer stack M 1 comprises an optical repeating unit R 1 that monotonically increases along the thickness of multilayer stack M 1 .
- multilayer stack M 1 is combined with multilayer stack M 2 that comprises optical repeating unit R 2 having a constant optical thickness.
- the optical thickness of R 2 is either substantially equal (as shown in FIG. 2 ) or is less than the minimum optical thickness of optical repeating unit R 1 .
- optical repeating unit R 2 can also decrease monotonically along the thickness of multilayer stack M 2 .
- optical repeating unit R 3 At the end of the stack where optical repeating unit R 1 has its maximum optical thickness, there is combined a multilayer film M 3 comprising an optical repeating unit R 3 that has a substantially constant optical thickness. As shown in FIG. 2 , the optical thickness of R 3 is equal to the maximum optical thickness of optical repeating unit R 1 . As already described above for obtaining bandedge sharpening at the red end, optical repeating unit R 3 can also decrease monotonically along the thickness of multilayer film M 3 .
- the multilayer stacks M 1 and M 2 and, optionally, M 3 have been described as being physically next to each other in the reflective film.
- the multilayer stacks may be spaced away from each other in the reflective film body by additional multilayer stacks and/or additional layers such as, for example, a layer which improves the adherence between the multilayer stacks.
- multilayer stack M 2 in FIG. 1 a could equally well be present at the other end of multilayer stack M 1 as shown in FIG. 1 e .
- the positions of multilayer stacks M 2 and M 3 in FIG. 2 can be interchanged as well.
- the preferred spatial positions of the multilayer stacks M 1 , M 2 and, optionally, M 3 relative to each other is that they join together such that adjacent layers are of approximately equal optical thickness as illustrated in FIGS. 1 a - 1 d and 2 , with no intervening material layers or spaces.
- Bandedge sharpening can be obtained even if the multilayer stacks M 1 , M 2 , and M 3 are not adjacent or in the order illustrated in FIG. 1 e .
- the materials and their indices may even be different in each of the three multilayer stacks.
- the most efficient use of optical layers will occur when repeat units of the same or similar optical thickness (multilayer stacks having overlapping reflection bands) are optically coupled to enhance constructive interference between those layers.
- This constraint also provides a guideline for the range of useful thicknesses of repeat units R 1 , R 2 and R 3 in multilayer stacks M 1 , M 2 and M 3 . For example, in FIG.
- the optical coupling for constructive interference is progressively weakened between those layers at the extremities. If the minimum thickness repeat unit of M 2 is of optical thickness d that is outside of the intrinsic bandwidth of the maximum thickness repeat unit in M 1 , then that minimum thickness unit will not contribute appreciably to bandedge sharpening on the red side of the reflection band of multilayer M 1 .
- a reflective film or other optical body made in accordance with the present invention can be manufactured, for example, by multilayer co-extrusion as described in more detail below.
- the multilayer stacks forming the reflective films or other optical bodies of the present invention may be manufactured separately from each other (e.g., as separate, free-standing films) and then laminated together to form the final reflective film.
- Layer thickness distributions for extended reflection bands may take the form of a variety of exponentially or linearly increasing functional forms. Such optical stacks create an extended reflection band of pre-determined bandwidth and extinction. If the same functional form is maintained from beginning to end (first to last layer), then the slopes of the bandedges may not be as steep as desired. To increase the slope of either the left or right bandedge, the functional form of the layer thickness distribution may change near the end points of the primary stack distribution such that the slope of the layer thickness distribution approaches zero.
- multilayer optical stacks M 1 , M 2 , and M 3 can be constructed as shown in FIG. 3 in which there are no discontinuities in the first derivative of the (statistically averaged) layer thickness profile.
- M 2 itself has a slight band sharpening profile in that the slope at the beginning and end of M 2 is equal to zero.
- Stacks M 1 and M 2 are designed such that they also have zero slopes where they join M 2 .
- the slopes of both M 1 and M 3 change continuously until, at their endpoints, their slopes are equal and opposite to that of the main stack M 2 .
- M 1 consists of repeat units 1 to 10 , M 2 of units 10 to 90 , and M 3 of units 90 to 105 .
- M 2 itself consists of 3 regions: M 21 , M 22 , and M 23 , similar to the profile in FIG. 2 .
- M 21 consists of units 10 to 20 , M 22 from 20 to 80 , and M 23 from 80 to 90 .
- M 22 is a linear thickness profile.
- the combined distribution curve M 1 +M 2 +M 3 may be part of a larger optical stack and can be in an interior or on the exterior position of a larger stack.
- films and other optical bodies can be made in accordance with the present invention whose total constructions contain multiple reflecting bands created by multiple sets of layer thickness gradients, all with their respective bandedge sharpening layer groups.
- the optical thickness variation of an optical repeating unit in accordance with the present invention can be obtained by varying the physical thickness of the polymeric layers of the optical repeating unit.
- the optical thickness of a repeat unit is selected according to the wavelengths selected to be reflected. Any range of wavelengths outside of the intrinsic bandwidth of the optical repeating unit can be selected by addition of optical repeating units having the appropriate range of optical thicknesses.
- the physical thickness of all polymeric layers constituting the optical repeating unit is varied at the same rate. For example, all polymeric layers of the optical repeating unit may be varied in thickness according to the same linear function.
- the physical thickness of the polymeric layers of the optical repeating unit may be varied differently. This is particularly preferred where it is desirable to obtain an optical thickness variation of the optical repeating unit R 2 or R 3 of multilayer films M 2 and M 3 , respectively.
- the optical thickness of an optical repeating unit consisting of two alternating polymeric layers may be monotonically varied in accordance with the present invention by keeping the physical thickness of one of the layers substantially constant while varying the physical thickness of the other layer in accordance with, for example, a linear function.
- both layers can be varied in physical thickness but in accordance with different functions, e.g., different linear functions or different subtile power law functions.
- FIG. 7 a An example of a reverse gradient is shown in FIG. 7 a .
- This figure shows the combined layer thickness gradient of LTG1 and LTG2.
- the bandedge sharpening gradient, LTG2 consists of 20 layers of alternating high and low index materials, both of which increase in thickness to maintain an f-ratio of 0.5 from the first to last layer pair.
- FIG. 7 b Another example of a reverse layer gradient is shown in FIG. 7 b .
- This figure shows the short wavelength bandedge for the reflectance band created by layer thickness gradient LTG1 and the effect of adding the reverse gradient LTG2.
- the addition of LTG2 results in an increase to the edge slope.
- the bandedge slope without the addition of LTG 2 is 1.1 percent/nm.
- LTG 2 is added, the slope increases to 1.9 percent/nm.
- the layer thickness profiles are shown in FIG. 7 a.
- FIG. 8 a An example of a stack design having a reverse gradient with an f-ratio deviation is shown in FIG. 8 a .
- This figure shows a film stack design of only one material component with a reverse thickness gradient while the other has a zero gradient in the added band sharpening stack of LTG 3.
- This combination of LTG1 and LTG3 also shows an improvement in bandedge sharpness over the LTG1 case as seen in FIG. 8 b below.
- the bandedge slope with LTG 3 added is 7.3 percent/nm.
- This example demonstrates bandedge sharpening for the case of zero gradient stacks LTG4 for both materials.
- the stack design of this example also produces a much sharper bandedge than LTG1 alone.
- the bandedge slope in this case is 3.6 percent/nm.
- FIG. 9 a shows the layer thickness gradient for the combined stacks LTG1 and LTG4.
- LTG4 has a zero thickness gradient for both materials, and maintains a constant ratio of thickness between the high and low index layers.
- FIG. 9 b substantial improvement is seen compared to the LTG1 case, with a bandedge slope of 3.6 percent/nm compared to the value of 1.1 percent per nm for LTG 1.
- the layer gradient for the low index layer is linear for the entire stack for LTG1 and LTG5, but the high index component undergoes a gradient reversal in the LTG5 section, as shown in FIG. 10 a below.
- the resulting spectra are shown in FIG. 10 b , and a substantial improvement is seen vs. the LTG1 case, with the bandedge slope increasing from 1.1 percent/nm to 3.6 percent/nm.
- narrow bandpass transmission filters sometimes referred to as notch filters
- notch filters can be made by using two broad reflection bands which cover most of the appropriate spectrum except for a very narrow band between their adjacent bandedges. If the band pass filter is to be of both narrow band and high transmission, then nearly vertical bandedges are required.
- Typical design techniques of the prior art in which individual layer thicknesses of each layer in the stack is assigned a unique value, may be impractical for polymeric stacks involving hundreds of layers. The edge sharpening techniques described herein are particularly useful in this case.
- One preferred embodiment involves the use of band sharpening stacks having continuously varying gradients.
- the resulting band pass filters have a higher transmission than filters made with linear (constant gradient) layer thickness distributions.
- the following computer modeled examples illustrate this improvement.
- FIG. 11 a A simple band pass filter can be made by introducing a step discontinuity in the layer thickness profile of a broad band reflecting stack, as illustrated in FIG. 11 a .
- the calculated spectrum of such a notch filter, made with the two simple linear thickness distributions of FIG. 11 a is shown in FIG. 11 b .
- the bandedge slopes are not high enough to make a narrow band notch filter.
- the bandedges slopes are about 1.2 percent/nm and 1.4 percent/nm for the blue and red edges, respectively.
- the Bandwidth is 54 nm and the peak transmission value is 62 percent.
- a notch filter can be made with two graded linear thickness distributions and additional non-graded quarter wave stacks as shown in FIG. 12 a .
- the flat (zero gradient) sections are useful for sharpening the respective bandedges of the adjacent reflecting bands. With the additional layers concentrated at the two thickness values on either side of the notch wavelength, a much sharper transmission band can be made.
- the calculated spectrum for the illustrated stack is given in FIG. 12 b .
- the steepness of the bandedges of the notch filter spectrum of FIG. 12 b will increase with the number of layers included in the band sharpening feature of the stack, as illustrated in FIG. 12 a .
- the bandedge slopes are about 9 percent/nm for both the blue and red edges.
- the Bandwidth is 13.8 nm and the peak transmission value is 55.9 percent.
- the curved layer thickness profile of FIG. 13 a was created to improve upon a deficiency of the stack design and spectrum of FIG. 12 a and 12 b .
- the side band ripples of the layer thickness profiles of FIG. 12 a overlap and limit the transmission of a notch filter. Note that the peak transmission of the notch band in FIG. 12 b is only about 50%.
- the bandedge slopes are about 12 percent/nm and 14 percent/nm for the blue and red edges, respectively.
- the Bandwidth is 11 nm and the peak transmission value is 76 percent. Note that, although the bandwidth is narrower than in FIG. 12 b , the maximum transmission is significantly higher.
- the number of layers in the band sharpening portion of the stack is 60 on each side of the thickness gap, which is the same number of layers used in the zero gradient sections of the layer distribution of FIG. 12 a.
- the curved profile can follow any number of functional forms.
- the main purpose of the form is to break the exact repetition of thickness present in a quarter wave stack with layers tuned to only a single wavelength.
- the particular function used here was an additive function of a linear profile (the same as used on the remainder of the reflectance band) and a sinusoidal function to curve the profile with the appropriate negative or positive second derivative.
- An important feature is that the second derivative of the layer thickness profile is positive for the red bandedge of a reflectance stack and negative for the blue bandedge of a reflectance stack. Note that the opposite sign is required if one refers to the red and blue bandedges of a notch band.
- Other embodiments of the same principle include layer profiles that have multiple points with a zero value of the first derivative. In all cases here, the derivatives refer to those of a best fit curve fitted through the actual layer thickness profile which can contain small statistical errors of less than 10% one sigma standard deviation in layer thickness values.
- the band sharpening profiles that are added to the layer thickness distribution can have significant effects on the slope of the bandedges, for one or both edges of a reflectance band, and for the edges of a pass band.
- Sharp bandedges and high extinction are desirable in obtaining color filters having saturated colors of high purity.
- the slopes of the bandedges are at least about 1 percent per nm, more preferably greater than about 2 percent per nm, and even more preferably greater than about 4 percent per nm.
- the same slopes are preferred for bandpass filters having a bandwidth greater than or about 50 nm.
- the edges are preferably greater than about 2 percent per nm, more preferably greater than about 5 percent per nm, and even more preferably, greater than about 10 percent per nm.
- the polymeric layers of an optical repeating unit in accordance with the present invention can be isotropic or anisotropic.
- An isotropic polymeric layer is a layer wherein the index of refraction of the polymeric layer is the same independent of the direction in the layer, whereas in case of an anisotropic polymeric layer, the index of refraction will differ along at least two different directions.
- the latter type of polymeric layer is also called a birefringent layer.
- an anisotropic polymeric layer an orthogonal set of axes x, y and z is used as set out above in the definition section.
- an anisotropic polymeric layer will have at least two of the indices of refraction n x , n y and n z different from each other.
- optical repeating units R 1 , R 2 and/or R 3 consists of two alternating isotropic polymeric layers that have an index of refraction differing from each other, preferably by at least about 0.05 and more preferably by at least about 0.1. More preferably, however, at least one of the two alternating polymeric layers is a birefringent layer wherein at least one of the in-plane indices n x and n y differs by at least 0.05 from the corresponding in-plane index of refraction of the other layer.
- the index of refraction along the transverse axes (n z ) of both layers is substantially matched, i.e., the difference of the index of refraction along the z-axes between both layers is preferably less than about 0.05.
- Optical repeating units of this type are particularly suitable for reflecting light in the visible region of the spectrum, but may also be used for reflecting light in the infrared region of the spectrum. Optical repeating units and multilayer films having this feature have been described in detail in WO 96/19347 and WO 95/17303, which are incorporated herein by reference.
- the transverse index of the polymer layer having the highest in-plane index is lower than the in-plane indices of the other polymer. This feature is also described in the above-cited references.
- FIGS. 4 a and 4 b illustrate these embodiments and show a multilayer film 10 comprising an optical repeating unit consisting of two alternating polymeric layers 12 and 14 .
- at least one of the materials has the property of stress induced birefringence, such that the index of refraction (n) of the material is affected by the stretching process.
- FIG. 4 a shows an exemplary multilayer film before the stretching process in which both materials have the same index of refraction.
- Light ray 13 experiences relatively little change in index of refraction and passes through the film.
- FIG. 4 b the same film has been stretched, thus increasing the index of refraction of material 12 in the stretch direction (or directions). The difference in refractive index at each boundary between layers will cause part of ray 15 to be reflected.
- the multilayer film can thus be made useful as reflective polarizers or mirrors. If stretched biaxially, the sheet can be stretched asymmetrically along orthogonal in-plane axes or symmetrically along orthogonal in-plane axes to obtain desired polarizing and reflecting properties.
- FIG. 5 shows an optical repeating unit consisting of two polymeric layers, and indicates the three-dimensional indices of refraction for each layer.
- the indices of refraction are n 1 x, n 1 y, and n 1 z for layer 102 , and n 2 x, n 2 y, and n 2 z for layer 104 , respectively.
- the relationships between the indices of refraction in each film layer to each other and to those of the other layers in the film stack determine the reflectance behavior of the multilayer stack at any angle of incidence, from any azimuthal direction.
- an optical repeating unit of a multilayer film in accordance with the present invention comprises polymeric layers A, B and C having different indices of refraction.
- Such type of repeating unit is particularly suitable for designing an infrared reflective multilayer film.
- an infrared reflective film can be designed for which at least two successive higher order reflections are suppressed, thus allowing the design of an infrared reflective film that is substantially transparent in the visible.
- a multilayer film of this type is described in detail in, e.g., U.S. Pat. No. 5,103,337, which is also incorporated herein by reference.
- the optical thickness ratio f a of first material A is 1/3
- the optical thickness ratio f b of second material B is 1/6
- the optical thickness ratio f c of third material C is 1/3
- the index of refraction of polymeric layer B equals the square root of the product of the index of refraction of polymeric layers A and C.
- the above multilayer film having an optical repeating unit comprising polymeric layers A, B and C arranged in an ABCB order can be designed using an anisotropic layer for at least one of polymeric layers A, B and C.
- a multilayer film that reflects light in the infrared region of the spectrum while transmitting light in the visible region of the spectrum may comprise an optical repeating unit comprising polymeric layers A, B and C arranged in an ABCB order, the polymeric layer A having refractive indices n x a and n y a along in-plane axes x and y, respectively, the polymeric layer B having refractive indices n x b and n y b along in-plane axes x and y, respectively, the polymeric layer C having refractive indices n x c and n y c along in-plane axes x and y, respectively, polymeric layers A, B and C having a refractive index n z a , n z b and n z c , respectively, along a transverse axis z perpendicular to the in-plane axes,
- the optical repeating unit By designing the optical repeating unit such that at least one of the differences n z a -n z b and n z b -n z c is less than 0 and preferably less than ⁇ 0.05, or such that both said differences are substantially 0, and while setting the index relationship along the in-plane axis between the layers as set out above, at least second and third higher order reflections can be suppressed without a substantial decrease of the infrared reflection with angle of incidence of the infrared light.
- the polymeric layers A, B and C of the optical repeating unit preferably form an ABCB optical repeating unit.
- a schematic drawing of such a repeating unit is shown in FIG. 6 .
- the difference of the index of refraction between layers A and B along the z-axis (n z a -n z b ) and/or the difference of the index of refraction between layers B and C along the z-axis (n z b -n z c ) is preferably negative, i.e., has a value less than 0, more preferably less or equal to ⁇ 0.05, and most preferably less than or equal to ⁇ 0.1.
- the optical repeating unit such that one of the differences is less than 0, more preferably less than or equal to ⁇ 0.05, and the other difference is either equal to 0 or less than 0. Most preferably, both difference are less than 0.
- one of the differences in refraction index between layers A and B across the z-axis is of opposite in sign to the difference of the refraction index between layers B and C across the z-axis.
- the difference that is less than 0 has the largest absolute value or that the absolute value of both differences is substantially equal.
- the optical thickness ratios along the particular in-plane axis that has the index of refraction for polymeric layer B intermediate that of polymeric layer A and polymeric layer C at least two higher order reflections for infrared light having its plane of polarization parallel to that particular in-plane axis can be suppressed. It is, however, preferred that the index of refraction for polymeric layer B is intermediate that of polymeric layers A and C along both in-plane axes, and by adjusting the optical thickness ratios along both in-plane axes, an infrared reflective mirror can be obtained for which at least two successive higher order reflections are suppressed. Such an infrared reflective mirror will be substantially clear in the visible region and will be free of color.
- Such an embodiment is capable of suppressing second, third and fourth order reflections.
- An infrared reflective multilayer film designed according to this embodiment can be used to reflect infrared light up to about 2000nm without introducing reflections in the visible part of the spectrum.
- an optical repeating unit comprising polymeric layers A, B and C has, along an in-plane axis, refractive indices of polymers A, B and C different by at least 0.05.
- n x a , n x b and n x c differ from each other by at least 0.05 and/or that n y a , n y b and n y c differ from each other by at least 0.05.
- multilayer films comprising optical repeating units of different design can be used in combination for forming a reflective film body in accordance with the present invention.
- a multilayer film comprising an optical repeating unit consisting of only two polymeric layers can be combined with a multilayer film comprising an optical repeating unit comprising polymeric layers A, B and C arranged in an ABC order in particular in an ABCB pattern.
- the desired refractive index relationships can be achieved in a variety of ways, including stretching during or after film formation (e.g., in the case of organic polymers), extruding (e.g., in the case of liquid crystalline materials), or coating.
- the two materials have similar Theological properties (e.g., melt viscosities) so that they can be co-extruded.
- crystalline, semi-crystalline, or liquid crystalline material or amorphous polymer.
- crystalline or semi-crystalline polymers refer to those polymers that are not amorphous and includes any of those materials commonly referred to as crystalline, partially crystalline, semi-crystalline, etc.
- suitable materials for usew in the present invention include polyethylene naphthalate (PEN) and isomers thereof (e.g., 2,6-, 1,4-, 1,5-, 2,7-, and 2,3-PEN), polyalkylene terephthalates (e.g., polyethylene terephthalate, polybutylene terephthalate, and poly-1,4-cyclohexanedimethylene terephthalate), polyimides (e.g., polyacrylic imides), polyetherimides, atactic polystyrene, polycarbonates, polymethacrylates (e.g., polyisobutyl methacrylate, polypropylmethacrylate, polyethylmethacrylate, and polymethylmethacrylate), polyacrylates (e.g., polybutylacrylate and polymethylacrylate), syndiotactic polystyrene (sPS), syndiotactic poly-alpha-methyl styrene, syndiotact
- copolymers e.g., copolymers of PEN (e.g., copolymers of 2,6-, 1,4-, 1,5-, 2,7-, and/or 2,3-naphthalene dicarboxylic acid, or esters thereof, with (a) terephthalic acid, or esters thereof; (b) isophthalic acid, or esters thereof; (c) phthalic acid, or esters thereof; (d) alkane glycols; (e) cycloalkane glycols (e.g., cyclohexane dimethanol diol); (f) alkane dicarboxylic acids; and/or (g) cycloalkane dicarboxylic acids (e.g., cyclohexane dicarboxylic acid)), copolymers of polyalkylene terephthalates (e.g., copolymers of terephthalic acid, or esters thereof, with (a) naphthalene dicar
- Particularly preferred birefringent polymeric layers for use in the present invention include layers containing a crystalline or semi-crystalline polyethylenenaphthalate (PEN), inclusive of its isomers (e.g. 2,6-; 1,4-; 1,5-; 2,7; and 2,3-PEN).
- PEN crystalline or semi-crystalline polyethylenenaphthalate
- a particularly preferred isotropic polymeric layer for use in connection with this invention is a layer containing a polymethylmethacrylate, and in particular, polymethylmethacrylate itself.
- each of the polymeric layers may be composed of blends of two or more polymeric materials to obtain desired properties for a specific layer.
- the films and other optical devices made in accordance with the invention may also include one or more anti-reflective layers or coatings, such as, for example, conventional vacuum coated dielectric metal oxide or metal/metal oxide optical films, silica sol gel coatings, and coated or coextruded antireflective layers such as those derived from low index fluoropolymers such as THV, an extrudable fluoropolymer available from 3M Company (St. Paul, Minn.).
- Such layers or coatings which may or may not be polarization sensitive, serve to increase transmission and to reduce reflective glare, and may be imparted to the films and optical devices of the present invention through appropriate surface treatment, such as coating or sputter etching.
- Both visible and near IR dyes and pigments are contemplated for use in the films and other optical bodies of the present invention, and include, for example, optical brighteners such as dyes that absorb in the UV and fluoresce in the visible region of the color spectrum.
- optical brighteners such as dyes that absorb in the UV and fluoresce in the visible region of the color spectrum.
- Other additional layers that may be added to alter the appearance of the optical film include, for example, opacifying (black) layers, diffusing layers, holographic images or holographic diffusers, and metal layers. Each of these may be applied directly to one or both surfaces of the optical film, or may be a component of a second film or foil construction that is laminated to the optical film. Alternately, some components such as opacifying or diffusing agents, or colored pigments, may be included in an adhesive layer which is used to laminate the optical film to another surface.
- the polymers have compatible rheologies for coextrusion. That is, as a preferred method of forming the reflective film bodies is the use of coextrusion techniques, the melt viscosities of the polymers are preferably reasonably matched to prevent layer instability or non-uniformity.
- the polymers used also preferably have sufficient interfacial adhesion so that the films will not delaminate.
- the multilayer reflective film bodies of the present invention can be readily manufactured in a cost effective way, and they can be formed and shaped into a variety of useful configurations after coextrusion.
- Multilayer reflective film bodies in accordance with the present invention are most advantageously prepared by employing a multilayered coextrusion device such as those described in U.S. Pat. Nos. 3,773,882 and 3,884,606, the disclosures of which are incorporated herein by reference.
- Such devices provide a method for preparing multilayered, simultaneously extruded thermoplastic materials, each of which are of a substantially uniform layer thickness.
- a series of layer multiplying means as are described in U.S. Pat. No. 3,759,647, the disclosure of which is incorporated herein by reference, may be employed.
- the feedblock of the coextrusion device receives streams of the diverse thermoplastic polymeric materials from a source such as a heat plastifying extruder.
- the streams of resinous materials are passed to a mechanical manipulating section within the feedblock. This section serves to rearrange the original streams into a multilayered stream having the number of layers desired in the final body.
- this multilayered stream may be subsequently passed through a series of layer multiplying means in order to further increase the number of layers in the final body.
- the multilayered stream is then passed into an extrusion die which is so constructed and arranged that stream-lined flow is maintained therein.
- an extrusion die which is so constructed and arranged that stream-lined flow is maintained therein.
- Such an extrusion device is described in U.S. Pat. No. 3,557,265, the disclosure of which is incorporated by reference herein.
- the resultant product is extruded to form a multilayered body in which each layer is generally parallel to the major surface of adjacent layers.
- the configuration of the extrusion die can vary and can be such as to reduce the thickness and dimensions of each of the layers.
- the precise degree of reduction in thickness of the layers delivered from the mechanical orienting section, the configuration of the die, and the amount of mechanical working of the body after extrusion are all factors which affect the thickness of the individual layers in the final body.
- the number of layers in the reflective film body can be selected to achieve the desired optical properties using the minimum number of layers for reasons of film thickness, flexibility and economy.
- the number of layers is preferably less than about 10,000, more preferably less than about 5,000, and (even more preferably) less than about 2,000.
- the desired relationship between refractive indices of polymeric layers as desired in this invention can be achieved by selection of appropriate processing conditions used to prepare the reflective film body.
- the multilayer films are generally prepared by co-extruding the individual polymers to form a multilayer film (e.g., as set out above) and then orienting the reflective film body by stretching at a selected temperature, optionally followed by heat-setting at a selected temperature. Alternatively, the extrusion and orientation steps may be performed simultaneously.
- the desired extent of birefringence (negative or positive) is set in those polymeric layers that comprise a polymer that can exhibit birefringence.
- Negative birefringence is obtained with polymers that show a negative optical stress coefficient, i.e., polymers for which the in-plane indices will decrease with orientation, whereas positive birefringence is obtained with polymers having a positive optical stress coefficient.
- This terminology in the art of film orientation conflicts somewhat with the standard optical definition of positive and negative birefringence.
- a uniaxially positive birefringent film or layer is one in which the z-index of refraction is higher than the in-plane index.
- a biaxially stretched polymer film such as PET will have high in-plane indices, e.g., 1.65, and a low out-of-plane or z-axis index of 1.50.
- a material such as PET is said to be positively birefringent because the index increases in the stretch direction, but in the art of optics, the same material, after biaxially stretching to film, is said to have uniaxial negative birefringence because the z-index is lower than the in-plane indices which are substantially equal.
- the term “positive birefringence” for a material as used herein will be that of the polymer film art, and will mean that the index of refraction increases in the stretch direction.
- the term “negative birefringence” for a material will mean that the index of refraction of a film decreases in the direction of stretch.
- the terms “uniaxially positive” or “uniaxially negative”, when used in reference to a birefringent layer, will be taken to have the meaning in the optics sense.
- the reflective film body is stretched substantially in one direction (uniaxial orientation), while in the case of mirrors the film can be stretched substantially in two directions (biaxial orientation).
- the stretching may be asymmetric to introduce specially desired features, but is preferably symmetric.
- the reflective film body may be allowed to dimensionally relax in the cross-stretch direction from the natural reduction in cross-stretch (equal to the square root of the stretch ratio) or may be constrained (i.e., no substantial change in cross-stretch dimensions).
- the reflective film body may be stretched in the machine direction, as with a length orienter, and/or in width using a tenter.
- the pre-stretch temperature, stretch temperature, stretch rate, stretch ratio, heat set temperature, heat set time, heat set relaxation, and cross-stretch relaxation are selected to yield a multilayer device having the desired refractive index relationship.
- These variables are inter-dependent; thus, for example, a relatively low stretch rate could be used if coupled with, e.g., a relatively low stretch temperature. It will be apparent to one skilled in the art how to select the appropriate combination of these variables to achieve the desired multilayer device.
- a stretch ratio in the range from about 1:2 to about 1:10 (more preferably about 1:3 to about 1:7) in the stretch direction and from about 1:0.2 to about 1:10 (more preferably from about 1:0.2 to about 1:7) orthogonal to the stretch direction is preferred.
- Orientation of the extruded film can be accomplished by stretching individual sheets of the material in heated air.
- stretching may be accomplished on a continuous basis in a standard length orienter, tenter oven, or both.
- economies of scale and line speeds of standard polymer film production may be achieved, thereby achieving manufacturing costs that are substantially lower than costs associated with commercially available absorptive polarizers.
- Two or more multilayer films may also be laminated together to obtain a reflective film body in accordance with the present invention.
- Amorphous copolyesters such as VITEL Brand 3000 and 3300 from the Goodyear Tire and Rubber Co. of Akron, Ohio, are useful as laminating materials.
- the choice of laminating material is broad, with adhesion to the multilayer films, optical clarity and exclusion of air being the primary guiding principles.
- inorganic or organic adjuvants such as an antioxidant, extrusion aid, heat stabilizer, ultraviolet ray absorber, nucleator, surface projection forming agent, and the like in normal quantities so long as the addition does not substantially interfere with the performance of the present invention.
Abstract
The present invention provides reflective films and other optical bodies which exhibit sharp bandedges on one or both sides of the main reflection bands. The optical bodies comprise multilayer stacks M1 and M2, each having first order reflections in a desired part of the spectrum and comprising optical repeating units R1 and R2, respectively. At least one of the optical repeating units R1 and R2 varies monotonically in optical thickness along the thickness of the associated multilayer stack.
Description
- This application is a continuation of U.S. Ser. No. 09/634319, filed Aug. 9, 2000, which is a continuation of U.S. Ser. No. 09/006085, filed Jan. 13, 1998, now U.S. Pat. No. 6,157,490.
- The present invention relates generally to multilayer optical bodies, and in particular to multilayer films exhibiting a sharpened reflective bandedge.
- The use of multilayer reflective films comprising alternating layers of two or more polymers to reflect light is known and is described, for example, in U.S. Pat. No. 3,711,176 (Alfrey, Jr. et al.), U.S. Pat. No. 5,103,337 (Schrenk et al.), WO 96/19347, and WO 95/17303. The reflection and transmission spectra of a particular multilayer film depends primarily on the optical thickness of the individual layers, which is defined as the product of the actual thickness of a layer times its refractive index. Accordingly, films can be designed to reflect infrared, visible or ultraviolet wavelengths λM of light by choice of the appropriate optical thickness of the layers in accordance with the following formula:
λM=(2/M)·D r (Formula I)
wherein M is an integer representing the particular order of the reflected light and Dr is the optical thickness of an optical repeating unit (also called a multilayer stack) comprising two or more polymeric layers. Accordingly, Dr is the sum of the optical thicknesses of the individual polymer layers that make up the optical repeating unit. Dr is always one half lambda in thickness, where lambda is the wavelength of the first order reflection peak. By varying the optical thickness of an optical repeating unit along the thickness of the multilayer film, a multilayer film can be designed that reflects light over a broad band of wavelengths. This band is commonly referred to as the reflection band or stop band. - It is desirable for a reflection band to have a sharp spectral edge at the long wavelength (red) and/or short wavelength (blue) side. However, the reflective films known to the art that contain an optical repeating unit of varying optical thickness typically have moderately sloped bandedges which cause reflections outside of the desired wavelengths of interest. For example, if a reflective film is designed to reflect infrared light while being transparent over the visible spectrum, a sloped edge on the blue side of the reflection band may encroach into the visible region of the spectrum, thereby resulting in unwanted coloring of the infrared reflective film body. Such coloring can be avoided by designing the infrared film such that the infrared reflection band is moved further into the infrared region, but this results in substantial transmission of infrared light near the visible region of the spectrum.
- In other situations, it may be desirable to design a reflective film or other optical body that reflects light over a selected range in the visible region of the spectrum, e.g., a reflective film that reflects only green light. In such a case, it may be desirable to have sharp edges at both the red and blue sides of the reflection band.
- Many prior art reflective films comprising multilayer stacks also show a number of small reflection peaks near the reflection band. This so-called “ringing” also may introduce unwanted reflections. It has been suggested in the art that, for multilayer films that consist of an optical repeating unit of constant optical thickness, such ringing might be suppressed by adding a number of optical repeating units having an optical thickness of half that of the other optical repeating units responsible for the reflection band. However, while this approach may eliminate ringing, it does not improve bandedge sharpness and, in fact, may worsen it. Furthermore, this approach requires the presence of strippable skins on multilayer extruded films, since it permits only thin layers of specific optical thickness on the surface.
- There is thus a need in the art for a reflective film, and a method of making the same, that exhibits a sharp bandedge on one or both sides of the main reflection band, and that avoids the presence of ringing and other undesirable reflections. These and other needs are met by the present invention, as hereinafter described.
- The present invention provides reflective films and other optical bodies that exhibit sharp bandedges on one or both sides of the main reflection bands. Optical bodies of the present invention can comprise of reflective films having a plurality of optical repeating units having an optical thickness profile that defines a curve, the curve having substantially no discontinuities in its first derivative and shaped so that it, in order, monotonically decreases from an initial optical thickness to a minimum optical thickness, remains substantially constant at the minimum optical thickness, monotonically increases from the minimum optical thickness to a maximum optical thickness, remains substantially constant at the maximum optical thickness, and monotonically decreases from the maximum optical thickness to an end optical thickness, wherein the optical repeating units monotonically increasing from the minimum optical thickness to the maximum optical thickness form a reflection band.
- The present invention is described in detail by reference to the following drawings, without, however, the intention to limit the invention thereto:
-
FIGS. 1 a to 1 e show the optical thickness variation of the optical repeating units R1 and R2 in multilayer stacks M1 and M2 to obtain bandedge sharpening at the red or blue edge of the reflection band; -
FIG. 2 shows the optical thickness variation of the optical repeating units R1, R2 and R3 in multilayer films M1, M2 and M3 to obtain bandedge sharpening at the blue and red edges of the reflection band; -
FIG. 3 shows the optical thickness variation of the optical repeating units R1, R2 and R3 in multilayer films M1, M2 and M3 in which M1 and M3 have continuously changing slopes; -
FIGS. 4 a and 4 b are schematic diagrams of a multilayer film consisting of two alternating polymeric layers; -
FIG. 5 is a 3-dimensional schematic diagram of an optical repeating unit consisting of two alternating layers of polymeric materials; -
FIG. 6 is a 3-dimensional schematic diagram of an optical repeating unit consisting of polymeric layers A, B and C arranged in an ABCB pattern; -
FIG. 7 a is a layer thickness gradient profile showing a combined layer thickness gradient of LTG1 and LTG2; -
FIG. 7 b is a computed spectrum illustrating the short wavelength bandedge for the reflectance band created by layer thickness gradient LTG1 and the effect of adding the reverse gradient LTG2; -
FIG. 8 a is a layer thickness gradient profile of a stack design having a reverse gradient with an f-ratio deviation; -
FIG. 8 b is a computational spectrum illustrating the improvement in bandedge sharpness afforded by the combination of LTG1 and LTG3; -
FIG. 9 a is a layer thickness gradient profile for the combined stacks LTG1 and LTG4; -
FIG. 9 b is a computational spectrum illustrating the improvement observed with the layer thickness gradient ofFIG. 9 a compared to the LTG1 case; -
FIG. 10 a is a the layer thickness gradient profile in which the low index layer is linear for the entire stack for LTG1 and LTG5, but the high index component undergoes a gradient reversal in the LTG5 section; -
FIG. 10 b is a computational spectrum illustrating the improvement seen with the gradient ofFIG. 10 a vs. the LTG1 case; -
FIG. 11 a is a layer thickness gradient profile for a simple band pass filter made by introducing a step discontinuity in the layer thickness profile of a broad band reflecting stack; -
FIG. 11 b is the calculated spectrum for the gradient ofFIG. 11 a; -
FIG. 12 a is a layer thickness gradient profile made with two graded linear thickness distributions and an additional non-graded quarter wave stack; -
FIG. 12 b is the calculated spectrum for the gradient ofFIG. 12 a; -
FIG. 13 a is a layer thickness gradient profile illustrating a curved layer thickness profile; and -
FIG. 13 b is the calculated spectrum for the gradient ofFIG. 13 a. - The following definitions and conventions are used throughout the disclosure:
- Desired part of the spectrum: any continuous range of wavelengths between 400 nm and 2500 nm, also called desired reflection band.
- Optical repeating unit (ORU): a stack of layers arranged in a particular order, which arrangement is repeated across the thickness of a multilayer film; the stack of layers have a first order reflection at a wavelength according to Formula (I) above.
- Intrinsic bandwidth, or optical repeating unit (ORU) bandwidth: The bandwidth that an infinite stack of ORU's of identical thickness would exhibit, which is readily calculated from the matrix elements of the characteristic matrix M as defined by Born and Wolf, “Principles of Optics”, Edition 5, page 67. For a quarterwave stack of two materials with an index differential less than about 0.3, it is given, to a good approximation, by the absolute value of the Fresnel reflection coefficient for that interface. Stopband: A reflectance band is defined in general as a spectral band of reflection bounded on either side by wavelength regions of low reflection. With dielectric stacks, the absorption is typically low enough to be ignored for many applications, and the definition is given in terms of transmission. In those terms, a reflectance band or stop band is defined in general as a region of low transmission bounded on both sides by regions of high transmission.
- In one preferred embodiment, a single reflectance band or stop band for p-polarized light has a continuous spectrum between any two successive wavelengths at which the transmission is greater than 50 percent, and including such successive wavelengths as endpoints, and where the average transmission from one endpoint to the other is less than 20 percent. Such preferred reflectance band or stop band is described in the same way for unpolarized light and light of normal incidence. For s-polarized light, however, the transmission values in the preceding description are calculated in a way that excludes the portion of light reflected by an air interface with the stack or the stack's skin layers or coatings.
- Bandwidth of stop band: For such a preferred embodiment as described in the preceding paragraph, the bandwidth is defined to be the distance, in nm, between the two wavelengths within the band which are nearest each 50 percent transmission point, at which the transmission is 10 percent. In commonly used terms, the bandwidths are defined by the 10 percent transmission points. The respective blue and red (i.e., short and long wavelength) bandedges are then taken to be the wavelength at the above defined 10% transmission points. The transmission of the preferred stop band is taken to be the average transmission between the 10 percent transmission points. If a reflectance band does not have high enough reflectivity to satisfy the definitions of bandwidth and bandedge slope for the preferred embodiment, then the bandwidth may be taken simply to be the full width at half maximum (FWHM), where the maximum is the peak reflectance value.
- Bandedge slope of stop band: The slope of a band edge as described in the preceding paragraph is taken from the 50 percent and 10 percent transmission/wavelength points, and is given in units of percent transmission per nm.
- Pass band: A pass band is defined in general as a spectral transmitting band bounded by spectral regions of relatively low transmission. With the multilayer color shifting film, the passband is bounded by reflective stopbands. The width of the pass band is the Full Width at Half Maximum Transmission (FWHM) value.
- Bandedge slope of pass band: Band edge slopes are calculated from the two points on a given bandedge nearest the maximum transmission point, the transmission values of which are 50 and 10 percent of the maximum transmission value. In one preferred embodiment, the passband has low transmission regions on both sides of the transmission peak with transmission minima of 10 percent or less of the transmission value of the peak transmission point. For example, in this preferred embodiment, a pass band having a 50 percent transmission maximum, would be bounded on both sides by reflectance bands having 5 percent or lower transmission minima. More preferably, the transmission minima on both sides of the passband are less than 5 percent of the peak transmission value of the passband.
- Edge filter: reflectance filter having only one bandedge within the wavelength range of interest.
- Multilayer film: a film comprising an optical repeating unit designed to reflect light over a particular range of wavelengths. The multilayer film may contain additional layers between the optical repeating units and which additional layers may or may not be repeated throughout the multilayer film.
- Monotonically varying layer thickness of an optical repeating unit along a multilayer film: the thickness of the optical repeating unit either shows a consistent trend of decreasing or increasing along the thickness of the multilayer film (e.g., the thickness of the optical repeating unit does not show an increasing trend along part of the thickness of the multilayer film and a decreasing trend along another part of the multilayer film thickness). These trends are independent of layer-to-layer thickness errors, which may have a statistical variance with a 1-sigma value as large as 5% or more. In addition, a local variation in the optical repeating unit may cause ripples in the layer thickness profile which is not strictly monotonic by the mathematical definition, but the ripple should be relatively small compared to the thickness difference between first and last optical repeating unit.
- Maximum optical thickness of an optical repeating unit: the maximum of a statistical curve fit to the actual layer distribution containing random errors in layer thickness.
- Minimum optical thickness of an optical repeating unit: the minimum of a statistical curve fit to the actual layer distribution containing random errors in layer thickness.
- In-plane axes: two mutually perpendicular axes that are in the plane of the reflective film. For the sake of convenience, they are denoted as the x-axis and the y-axis.
- Transverse axis: an axis that is perpendicular to the plane of the reflective film. For sake of convenience, this axis is denoted the z-axis.
- An index of refraction along a particular axis is referred to as ni, wherein i indicates the particular axis, for example, nx indicates an index of refraction along the x-axis.
- Negative birefringence: the index of refraction along the transverse axis is less than or equal to the index of refraction along both in-plane axes (nz<nx and ny)
- Positive birefringence: the index of refraction along the transverse axis is greater than the index of refraction along both in-plane axes (nz>nx and ny).
- Isotropic: the indices of refraction along x, y and z-axes are substantially equal (e.g., nx=ny=nz)
- Infrared region: 700 nm to 2500 nm
- Visible region: 400 nm to 700 nm
- The f-ratio is defined as:
wherein fk is the optical thickness of polymeric layer k, 1 is the number of layers in the optical repeating unit, nk is the refractive index of polymeric layer k, and dk is the thickness of polymeric layer k. The optical thickness ratio of polymeric layer k along an optical axis j is denoted as fjk and is defined as above, but with replacement of nk with the refractive index of polymer material k along axis j (). - Skin layer: a layer that is provided as an outermost layer typically having a thickness between 10% and 20% of the sum the physical thickness of all optical repeating units.
- The construction of multilayer films in accordance with the present invention can be used in a variety of ways to obtain bandedge sharpening at the red or blue side of the band or on both sides.
- Bandedge Sharpening—Blue Edge
- To obtain bandedge sharpening in accordance with the present invention at the blue edge of the reflection band, a multilayer stack M1 having an optical repeating unit R1 is combined with a multilayer stack M2 having an optical repeating unit R2. Both multilayer stacks are designed to have a first order reflection band in a desired region of the spectrum, e.g., in the infrared region. It is possible to produce a film or other optical body having a first order reflection band in a particular region of the spectrum by selecting polymeric materials with appropriate indices of refraction and by manipulating the physical thickness of each of the individual polymeric layers of an optical repeating unit such that the optical thickness of the optical repeating unit appears at the desired wavelength as predicted by Formula (I) above. By varying the optical thickness of the optical repeating unit in the multilayer film, the desired reflection over a particular range in the spectrum can be obtained. Preferably, the optical repeating unit R1 of multilayer stack M1 is monotonically varied in optical thickness such that the desired reflection band is obtained. However, it is also possible to use several multilayer stacks comprising different optical repeating units to cover a desired reflection band.
- The optical thickness of optical repeating unit R1 preferably increases monotonically along the thickness of multilayer stack M1. Multilayer stack M2 may comprise an optical repeating unit R2 that is substantially constant in optical thickness or the optical thickness of optical repeating unit R2 may decrease monotonically along the thickness of multilayer stack M2. If the optical thickness of optical repeating unit R2 is substantially constant, the optical thickness thereof should be approximately equal to the minimum optical thickness of optical repeating unit R1 along the thickness of multilayer stack M1. Preferably in this embodiment, the optical thickness of optical repeating unit R2 is substantially equal to the minimum optical thickness of optical repeating unit R1.
-
FIG. 1 a depicts this embodiment and shows a plot of the optical thickness of optical repeating units R1 and R2 versus the optical repeating unit number in a reflective film made in connection with the present invention. InFIG. 1 a, multilayer stack M1 comprises optical repeating unit R1 of increasing optical thickness, and multilayer stack M2 comprises optical repeating unit R2 of substantially constant optical thickness. A reflective film designed in accordance withFIG. 1 a will have a sharpened bandedge on the blue side of the reflection band. -
FIG. 1 b depicts another embodiment of the present invention that also leads to sharpening of the reflection band on the blue side. As shown inFIG. 1 b, multilayer stack M2 in this embodiment comprises an optical repeating unit R2 that decreases monotonically in optical thickness along the thickness of multilayer stack M2. The minimum optical thickness of optical repeating unit R2 in this embodiment is such that it is substantially equal to the minimum optical thickness of optical repeating unit R1 along multilayer stack M1. - Bandedge Sharpening—Red Edge
- To obtain bandedge sharpening in accordance with the present invention at the red end of the reflection band, a multilayer stack M1 having an optical repeating unit R1 is combined with a multilayer stack M2 having an optical repeating unit R2. Both multilayer films are designed to have a first order reflection in a desired portion of the spectrum, e.g., a reflection band in the green part of the visible spectrum.
- The optical thickness of optical repeating unit R1 preferably increases monotonically along the thickness of multilayer stack M1. Multilayer stack M2 may comprise an optical repeating unit R2 that is substantially constant in optical thickness, or else the optical thickness of optical repeating unit R2 may decrease monotonically along the thickness of multilayer stack M2. If the optical thickness of optical repeating unit R2 is substantially constant, the optical thickness thereof should be equal to the maximum optical thickness of optical repeating unit R1 along the thickness of multilayer stack M1. Preferably in this embodiment, the optical thickness of optical repeating unit R2 is substantially equal to the maximum optical thickness of optical repeating unit R1.
-
FIG. 1 c depicts this embodiment and shows a plot of the optical thickness of optical repeating units R1 and R2 versus the optical repeating unit number in a reflective film body in connection with the present invention. InFIG. 1 c, multilayer stack M1 comprises optical repeating unit R1 of increasing optical thickness, and multilayer stack M2 comprises optical repeating units R2 of substantially constant optical thickness. A reflective film body designed in accordance withFIG. 1 c will exhibit a sharpened bandedge at the red end of the reflection band. -
FIG. 1 d depicts another embodiment of the present invention that also leads to sharpening of the reflection band on the red side. As shown inFIG. 1 d, multilayer stack M2 now comprises an optical repeating unit R2 that decreases monotonically in optical thickness along the thickness of multilayer stack M2. The maximum optical thickness of optical repeating unit R2 in this embodiment is such that it is substantially equal to the maximum optical thickness of optical repeating unit R1 along multilayer stack M1. - Bandedge Sharpening—Both Edges
- To obtain bandedge sharpening at both ends of the reflection band, three multilayer stacks M1, M2 and M3 can be combined as in the embodiment shown in
FIG. 2 . There, multilayer stack M1 comprises an optical repeating unit R1 that monotonically increases along the thickness of multilayer stack M1. At the end of the stack, where R1 has the minimum optical thickness, multilayer stack M1 is combined with multilayer stack M2 that comprises optical repeating unit R2 having a constant optical thickness. The optical thickness of R2 is either substantially equal (as shown inFIG. 2 ) or is less than the minimum optical thickness of optical repeating unit R1. As already described above for obtaining bandedge sharpening at the blue edge of the reflection band, optical repeating unit R2 can also decrease monotonically along the thickness of multilayer stack M2. - At the end of the stack where optical repeating unit R1 has its maximum optical thickness, there is combined a multilayer film M3 comprising an optical repeating unit R3 that has a substantially constant optical thickness. As shown in
FIG. 2 , the optical thickness of R3 is equal to the maximum optical thickness of optical repeating unit R1. As already described above for obtaining bandedge sharpening at the red end, optical repeating unit R3 can also decrease monotonically along the thickness of multilayer film M3. - In each of the above described embodiments, the multilayer stacks M1 and M2 and, optionally, M3 have been described as being physically next to each other in the reflective film. However, this is not a requirement. In particular, the multilayer stacks may be spaced away from each other in the reflective film body by additional multilayer stacks and/or additional layers such as, for example, a layer which improves the adherence between the multilayer stacks. For example, multilayer stack M2 in
FIG. 1 a could equally well be present at the other end of multilayer stack M1 as shown inFIG. 1 e. Similarly, the positions of multilayer stacks M2 and M3 inFIG. 2 can be interchanged as well. However, the preferred spatial positions of the multilayer stacks M1, M2 and, optionally, M3 relative to each other is that they join together such that adjacent layers are of approximately equal optical thickness as illustrated inFIGS. 1 a-1 d and 2, with no intervening material layers or spaces. - Bandedge sharpening can be obtained even if the multilayer stacks M1, M2, and M3 are not adjacent or in the order illustrated in
FIG. 1 e. The materials and their indices may even be different in each of the three multilayer stacks. However, the most efficient use of optical layers will occur when repeat units of the same or similar optical thickness (multilayer stacks having overlapping reflection bands) are optically coupled to enhance constructive interference between those layers. This constraint also provides a guideline for the range of useful thicknesses of repeat units R1, R2 and R3 in multilayer stacks M1, M2 and M3. For example, inFIG. 1 d, as the repeat units in multilayer stack M2 get progressively thinner to the right, with progressive deviation from the thickness of the maximum repeat unit of M1, the optical coupling for constructive interference is progressively weakened between those layers at the extremities. If the minimum thickness repeat unit of M2 is of optical thickness d that is outside of the intrinsic bandwidth of the maximum thickness repeat unit in M1, then that minimum thickness unit will not contribute appreciably to bandedge sharpening on the red side of the reflection band of multilayer M1. - A reflective film or other optical body made in accordance with the present invention can be manufactured, for example, by multilayer co-extrusion as described in more detail below. Alternatively, the multilayer stacks forming the reflective films or other optical bodies of the present invention may be manufactured separately from each other (e.g., as separate, free-standing films) and then laminated together to form the final reflective film.
- Optical Stack Designs
- Layer thickness distributions for extended reflection bands may take the form of a variety of exponentially or linearly increasing functional forms. Such optical stacks create an extended reflection band of pre-determined bandwidth and extinction. If the same functional form is maintained from beginning to end (first to last layer), then the slopes of the bandedges may not be as steep as desired. To increase the slope of either the left or right bandedge, the functional form of the layer thickness distribution may change near the end points of the primary stack distribution such that the slope of the layer thickness distribution approaches zero.
- To further sharpen the bandedges, additional layers with zero or opposite sign slopes may be added. For example, combined multilayer optical stacks M1, M2, and M3 can be constructed as shown in
FIG. 3 in which there are no discontinuities in the first derivative of the (statistically averaged) layer thickness profile. InFIG. 3 , M2 itself has a slight band sharpening profile in that the slope at the beginning and end of M2 is equal to zero. Stacks M1 and M2 are designed such that they also have zero slopes where they join M2. The slopes of both M1 and M3 change continuously until, at their endpoints, their slopes are equal and opposite to that of the main stack M2. InFIG. 3 , M1 consists ofrepeat units 1 to 10, M2 of units 10 to 90, and M3 ofunits 90 to 105. M2 itself consists of 3 regions: M21, M22, and M23, similar to the profile inFIG. 2 . M21 consists of units 10 to 20, M22 from 20 to 80, and M23 from 80 to 90. M22 is a linear thickness profile. - Furthermore, the combined distribution curve M1+M2+M3 may be part of a larger optical stack and can be in an interior or on the exterior position of a larger stack. Thus, films and other optical bodies can be made in accordance with the present invention whose total constructions contain multiple reflecting bands created by multiple sets of layer thickness gradients, all with their respective bandedge sharpening layer groups.
- Typically, the optical thickness variation of an optical repeating unit in accordance with the present invention can be obtained by varying the physical thickness of the polymeric layers of the optical repeating unit. The optical thickness of a repeat unit is selected according to the wavelengths selected to be reflected. Any range of wavelengths outside of the intrinsic bandwidth of the optical repeating unit can be selected by addition of optical repeating units having the appropriate range of optical thicknesses. According to one particular embodiment in connection with the present invention, the physical thickness of all polymeric layers constituting the optical repeating unit is varied at the same rate. For example, all polymeric layers of the optical repeating unit may be varied in thickness according to the same linear function.
- In an alternative embodiment of the present invention, the physical thickness of the polymeric layers of the optical repeating unit may be varied differently. This is particularly preferred where it is desirable to obtain an optical thickness variation of the optical repeating unit R2 or R3 of multilayer films M2 and M3, respectively. For example, the optical thickness of an optical repeating unit consisting of two alternating polymeric layers may be monotonically varied in accordance with the present invention by keeping the physical thickness of one of the layers substantially constant while varying the physical thickness of the other layer in accordance with, for example, a linear function. Alternatively, both layers can be varied in physical thickness but in accordance with different functions, e.g., different linear functions or different subtile power law functions.
- Several preferred embodiments of the present invention are illustrated in Table I and in the examples which follow. Table I lists four separate layer thickness gradients. Each gradient is comprised of repeating quarter wave layers of a high index material (n=1.75) and a low index polymer (n=1.50). The starting thickness and the thickness increment for each successive layer is provided. A computer modeling program was used to investigate the effect of several combinations of gradients on the bandedge steepness of the primary reflectance band.
TABLE I LTG1 LTG2 LTG3 LTG4 LTG5 Total number 170 30 30 30 30 of layers High index 154.6 112.4 112.4 112.4 112.4 beginning layer thickness (nm) High index −0.4965 0.726 0.726 0 0.726 layer thickness increment (nm) Low index 183.3 133.3 133.3 133.3 133.3 beginning layer thickness (nm) High index −0.5882 0.8608 0 0 −0.5882 layer thickness increment (nm) - An example of a reverse gradient is shown in
FIG. 7 a. This figure shows the combined layer thickness gradient of LTG1 and LTG2. In this case, the bandedge sharpening gradient, LTG2, consists of 20 layers of alternating high and low index materials, both of which increase in thickness to maintain an f-ratio of 0.5 from the first to last layer pair. - Another example of a reverse layer gradient is shown in
FIG. 7 b. This figure shows the short wavelength bandedge for the reflectance band created by layer thickness gradient LTG1 and the effect of adding the reverse gradient LTG2. The addition of LTG2 results in an increase to the edge slope. The bandedge slope without the addition of LTG 2 is 1.1 percent/nm. When LTG 2 is added, the slope increases to 1.9 percent/nm. The layer thickness profiles are shown inFIG. 7 a. - An example of a stack design having a reverse gradient with an f-ratio deviation is shown in
FIG. 8 a. This figure shows a film stack design of only one material component with a reverse thickness gradient while the other has a zero gradient in the added band sharpening stack of LTG 3. This combination of LTG1 and LTG3 also shows an improvement in bandedge sharpness over the LTG1 case as seen inFIG. 8 b below. The bandedge slope with LTG 3 added is 7.3 percent/nm. - This example demonstrates bandedge sharpening for the case of zero gradient stacks LTG4 for both materials. The stack design of this example also produces a much sharper bandedge than LTG1 alone. The bandedge slope in this case is 3.6 percent/nm.
-
FIG. 9 a shows the layer thickness gradient for the combined stacks LTG1 and LTG4. LTG4 has a zero thickness gradient for both materials, and maintains a constant ratio of thickness between the high and low index layers. Again, as shown inFIG. 9 b, substantial improvement is seen compared to the LTG1 case, with a bandedge slope of 3.6 percent/nm compared to the value of 1.1 percent per nm forLTG 1. - In this case, the layer gradient for the low index layer is linear for the entire stack for LTG1 and LTG5, but the high index component undergoes a gradient reversal in the LTG5 section, as shown in
FIG. 10 a below. The resulting spectra are shown inFIG. 10 b, and a substantial improvement is seen vs. the LTG1 case, with the bandedge slope increasing from 1.1 percent/nm to 3.6 percent/nm. - Band Pass Filters
- The fabrication of narrow bandpass transmission filters, sometimes referred to as notch filters, can be made by using two broad reflection bands which cover most of the appropriate spectrum except for a very narrow band between their adjacent bandedges. If the band pass filter is to be of both narrow band and high transmission, then nearly vertical bandedges are required. Typical design techniques of the prior art, in which individual layer thicknesses of each layer in the stack is assigned a unique value, may be impractical for polymeric stacks involving hundreds of layers. The edge sharpening techniques described herein are particularly useful in this case.
- One preferred embodiment involves the use of band sharpening stacks having continuously varying gradients. The resulting band pass filters have a higher transmission than filters made with linear (constant gradient) layer thickness distributions. The following computer modeled examples illustrate this improvement.
-
FIG. 11 a. A simple band pass filter can be made by introducing a step discontinuity in the layer thickness profile of a broad band reflecting stack, as illustrated inFIG. 11 a. The calculated spectrum of such a notch filter, made with the two simple linear thickness distributions ofFIG. 11 a, is shown inFIG. 11 b. Without the band sharpening techniques described above, the bandedge slopes are not high enough to make a narrow band notch filter. The bandedges slopes are about 1.2 percent/nm and 1.4 percent/nm for the blue and red edges, respectively. The Bandwidth is 54 nm and the peak transmission value is 62 percent. - A notch filter can be made with two graded linear thickness distributions and additional non-graded quarter wave stacks as shown in
FIG. 12 a. The flat (zero gradient) sections are useful for sharpening the respective bandedges of the adjacent reflecting bands. With the additional layers concentrated at the two thickness values on either side of the notch wavelength, a much sharper transmission band can be made. The calculated spectrum for the illustrated stack is given inFIG. 12 b. The steepness of the bandedges of the notch filter spectrum ofFIG. 12 b will increase with the number of layers included in the band sharpening feature of the stack, as illustrated inFIG. 12 a. The bandedge slopes are about 9 percent/nm for both the blue and red edges. The Bandwidth is 13.8 nm and the peak transmission value is 55.9 percent. - The curved layer thickness profile of
FIG. 13 a was created to improve upon a deficiency of the stack design and spectrum ofFIG. 12 a and 12 b. The side band ripples of the layer thickness profiles ofFIG. 12 a overlap and limit the transmission of a notch filter. Note that the peak transmission of the notch band inFIG. 12 b is only about 50%. By introducing a curvature to the band sharpening stack thickness profile, the ringing at the edge of the spectrum of such a stack is reduced. Combining two such stacks will then make a notch filter with steeper bandedges and higher peak transmission, as illustrated by the results shown inFIG. 13 b. The bandedge slopes are about 12 percent/nm and 14 percent/nm for the blue and red edges, respectively. The Bandwidth is 11 nm and the peak transmission value is 76 percent. Note that, although the bandwidth is narrower than inFIG. 12 b, the maximum transmission is significantly higher. The number of layers in the band sharpening portion of the stack is 60 on each side of the thickness gap, which is the same number of layers used in the zero gradient sections of the layer distribution ofFIG. 12 a. - The curved profile can follow any number of functional forms. The main purpose of the form is to break the exact repetition of thickness present in a quarter wave stack with layers tuned to only a single wavelength. The particular function used here was an additive function of a linear profile (the same as used on the remainder of the reflectance band) and a sinusoidal function to curve the profile with the appropriate negative or positive second derivative. An important feature is that the second derivative of the layer thickness profile is positive for the red bandedge of a reflectance stack and negative for the blue bandedge of a reflectance stack. Note that the opposite sign is required if one refers to the red and blue bandedges of a notch band. Other embodiments of the same principle include layer profiles that have multiple points with a zero value of the first derivative. In all cases here, the derivatives refer to those of a best fit curve fitted through the actual layer thickness profile which can contain small statistical errors of less than 10% one sigma standard deviation in layer thickness values.
- As illustrated by the above examples, the band sharpening profiles that are added to the layer thickness distribution can have significant effects on the slope of the bandedges, for one or both edges of a reflectance band, and for the edges of a pass band. Sharp bandedges and high extinction are desirable in obtaining color filters having saturated colors of high purity. Preferably for reflectance bands, the slopes of the bandedges are at least about 1 percent per nm, more preferably greater than about 2 percent per nm, and even more preferably greater than about 4 percent per nm. The same slopes are preferred for bandpass filters having a bandwidth greater than or about 50 nm. For pass band filters with a bandwidth of less than or about 50 nm, the edges are preferably greater than about 2 percent per nm, more preferably greater than about 5 percent per nm, and even more preferably, greater than about 10 percent per nm.
- Design of the Optical Repeating Units
- The polymeric layers of an optical repeating unit in accordance with the present invention can be isotropic or anisotropic. An isotropic polymeric layer is a layer wherein the index of refraction of the polymeric layer is the same independent of the direction in the layer, whereas in case of an anisotropic polymeric layer, the index of refraction will differ along at least two different directions. The latter type of polymeric layer is also called a birefringent layer. To describe an anisotropic polymeric layer, an orthogonal set of axes x, y and z is used as set out above in the definition section. Thus, an anisotropic polymeric layer will have at least two of the indices of refraction nx, ny and nz different from each other.
- In one embodiment of the present invention, optical repeating units R1, R2 and/or R3 consists of two alternating isotropic polymeric layers that have an index of refraction differing from each other, preferably by at least about 0.05 and more preferably by at least about 0.1. More preferably, however, at least one of the two alternating polymeric layers is a birefringent layer wherein at least one of the in-plane indices nx and ny differs by at least 0.05 from the corresponding in-plane index of refraction of the other layer. According to a particular preferred embodiment in connection with the present invention, the index of refraction along the transverse axes (nz) of both layers is substantially matched, i.e., the difference of the index of refraction along the z-axes between both layers is preferably less than about 0.05. Optical repeating units of this type are particularly suitable for reflecting light in the visible region of the spectrum, but may also be used for reflecting light in the infrared region of the spectrum. Optical repeating units and multilayer films having this feature have been described in detail in WO 96/19347 and WO 95/17303, which are incorporated herein by reference. In another preferred embodiment of the present invention, the transverse index of the polymer layer having the highest in-plane index is lower than the in-plane indices of the other polymer. This feature is also described in the above-cited references.
-
FIGS. 4 a and 4 b illustrate these embodiments and show a multilayer film 10 comprising an optical repeating unit consisting of two alternatingpolymeric layers -
FIG. 4 a shows an exemplary multilayer film before the stretching process in which both materials have the same index of refraction.Light ray 13 experiences relatively little change in index of refraction and passes through the film. InFIG. 4 b, the same film has been stretched, thus increasing the index of refraction ofmaterial 12 in the stretch direction (or directions). The difference in refractive index at each boundary between layers will cause part ofray 15 to be reflected. By stretching the multilayer stack over a range of uniaxial to biaxial orientation, a film is created with a range of reflectivities for differently oriented plane-polarized incident light. The multilayer film can thus be made useful as reflective polarizers or mirrors. If stretched biaxially, the sheet can be stretched asymmetrically along orthogonal in-plane axes or symmetrically along orthogonal in-plane axes to obtain desired polarizing and reflecting properties. - The optical properties and design considerations of multilayer stacks comprising two alternating polymeric layers is described most completely in copending and commonly assigned U.S. patent application Ser. No. 08/402,041, filed on Mar. 10, 1995, the disclosure of which is hereby incorporated herein by reference. Very briefly, that application describes the construction of multilayer films (mirrors and polarizers) for which the Brewster angle (the angle at which reflectance goes to zero) is very large or is nonexistent for the polymer layer interfaces. This feature allows for the construction of mirrors and polarizers whose reflectivity for p-polarized light decreases slowly with angle of incidence, is independent of angle of incidence, or increases with angle of incidence away from normality. As a result, multilayer films having high reflectivity for both s- and p-polarized light over a wide bandwidth, and over a wide range of angles, can be achieved.
-
FIG. 5 shows an optical repeating unit consisting of two polymeric layers, and indicates the three-dimensional indices of refraction for each layer. The indices of refraction are n1x, n1y, and n1z forlayer 102, and n2x, n2y, and n2z forlayer 104, respectively. The relationships between the indices of refraction in each film layer to each other and to those of the other layers in the film stack determine the reflectance behavior of the multilayer stack at any angle of incidence, from any azimuthal direction. - The principles and design considerations described in U.S. patent application Ser. No. 08/402,041 can be applied to create multilayer films having the desired optical effects for a wide variety of circumstances and applications. The indices of refraction of the layers in the multilayer stack can be manipulated and tailored to produce devices having the desired optical properties. Many useful devices, such as mirrors and polarizers having a wide range of performance characteristics, can be designed and fabricated using the principles described therein.
- In accordance with another embodiment of the present invention, an optical repeating unit of a multilayer film in accordance with the present invention comprises polymeric layers A, B and C having different indices of refraction. Such type of repeating unit is particularly suitable for designing an infrared reflective multilayer film. In particular, by selecting polymeric layers A, B and C such that polymeric layer B has an index of refraction intermediate that of polymeric layers A and C, an infrared reflective film can be designed for which at least two successive higher order reflections are suppressed, thus allowing the design of an infrared reflective film that is substantially transparent in the visible. A multilayer film of this type is described in detail in, e.g., U.S. Pat. No. 5,103,337, which is also incorporated herein by reference.
- In accordance with this embodiment of the invention, multiple alternating substantially transparent polymeric layers A, B and C having different indices of refraction niare arranged in the order ABC. Additionally, the refractive index of polymeric layer B is intermediate the respective refractive indices of the polymeric layers A and C. In a particularly preferred embodiment having an optical repeating unit comprising polymeric layers A, B and C arranged in a pattern ABCB, and where multiple successive higher order reflections are suppressed, the optical thickness ratio fa of first material A is 1/3, the optical thickness ratio fb of second material B is 1/6, the optical thickness ratio fc of third material C is 1/3, and the index of refraction of polymeric layer B equals the square root of the product of the index of refraction of polymeric layers A and C. This particular type of optical repeating unit can be used to design a multilayer film in which reflections for the second, third, and fourth order wavelengths will be suppressed.
- In accordance with a further embodiment of the present invention, the above multilayer film having an optical repeating unit comprising polymeric layers A, B and C arranged in an ABCB order can be designed using an anisotropic layer for at least one of polymeric layers A, B and C. Thus, in accordance with one embodiment of the present invention, a multilayer film that reflects light in the infrared region of the spectrum while transmitting light in the visible region of the spectrum may comprise an optical repeating unit comprising polymeric layers A, B and C arranged in an ABCB order, the polymeric layer A having refractive indices nx a and ny a along in-plane axes x and y, respectively, the polymeric layer B having refractive indices nx b and ny b along in-plane axes x and y, respectively, the polymeric layer C having refractive indices nx c and ny c along in-plane axes x and y, respectively, polymeric layers A, B and C having a refractive index nz a, nz b and nz c, respectively, along a transverse axis z perpendicular to the in-plane axes, wherein nx b is intermediate nx a and nx c, with nx a being larger than nx c and/or ny b is intermediate to ny a and ny c with ny a being larger than ny c and wherein preferably at least one of the differences nz a-nz b and nz b-nz c is less than 0 or both said differences are substantially equal to 0.
- By designing the optical repeating unit such that at least one of the differences nz a-nz b and nz b-nz c is less than 0 and preferably less than −0.05, or such that both said differences are substantially 0, and while setting the index relationship along the in-plane axis between the layers as set out above, at least second and third higher order reflections can be suppressed without a substantial decrease of the infrared reflection with angle of incidence of the infrared light.
- The polymeric layers A, B and C of the optical repeating unit preferably form an ABCB optical repeating unit. A schematic drawing of such a repeating unit is shown in
FIG. 6 . According to this embodiment, the difference of the index of refraction between layers A and B along the z-axis (nz a-nz b) and/or the difference of the index of refraction between layers B and C along the z-axis (nz b-nz c) is preferably negative, i.e., has a value less than 0, more preferably less or equal to −0.05, and most preferably less than or equal to −0.1. It is particularly preferred to design the optical repeating unit such that one of the differences is less than 0, more preferably less than or equal to −0.05, and the other difference is either equal to 0 or less than 0. Most preferably, both difference are less than 0. Such designs, wherein one of the difference is less than 0 and the other is 0 or less than 0, yield an increase of the reflection with the angle of incidence. - It is also possible to design an optical repeating unit in accordance with the present embodiment wherein both differences are substantially 0, i.e., wherein the absolute value of the differences is preferably less than 0.03. When both differences are substantially 0, there will be little or no decrease in the infrared reflection with the angle of incidence.
- According to a still further species of the present embodiment, one of the differences in refraction index between layers A and B across the z-axis is of opposite in sign to the difference of the refraction index between layers B and C across the z-axis. In the latter case, it is preferred that the difference that is less than 0 has the largest absolute value or that the absolute value of both differences is substantially equal.
- By adjusting the optical thickness ratios along the particular in-plane axis that has the index of refraction for polymeric layer B intermediate that of polymeric layer A and polymeric layer C, at least two higher order reflections for infrared light having its plane of polarization parallel to that particular in-plane axis can be suppressed. It is, however, preferred that the index of refraction for polymeric layer B is intermediate that of polymeric layers A and C along both in-plane axes, and by adjusting the optical thickness ratios along both in-plane axes, an infrared reflective mirror can be obtained for which at least two successive higher order reflections are suppressed. Such an infrared reflective mirror will be substantially clear in the visible region and will be free of color.
- A particularly preferred optical repeating unit for designing an infrared reflecting multilayer film in accordance with the present invention comprises polymeric layers A, B and C arranged in an ABCB pattern, with the refractive indices for polymeric layers A, B and C such that nx b=(nx anx c)1/2 and/or ny b=(ny any c)1/2 while keeping the following optical thickness ratios: fx a=1/3, fx b=1/6 and fx c=1/3 and/or fy a=1/3, fy b=1/6 and fy c=1/3. Such an embodiment is capable of suppressing second, third and fourth order reflections. An infrared reflective multilayer film designed according to this embodiment can be used to reflect infrared light up to about 2000nm without introducing reflections in the visible part of the spectrum.
- Preferably, an optical repeating unit comprising polymeric layers A, B and C has, along an in-plane axis, refractive indices of polymers A, B and C different by at least 0.05. Thus, it is preferred that nx a, nx b and nx c differ from each other by at least 0.05 and/or that ny a, ny b and ny c differ from each other by at least 0.05.
- The above various embodiments describing different possible designs of optical repeating units for use in the multilayer films in accordance with the present invention is not intended to be limiting to this invention. In particular, other designs of optical repeating units can be used as well. Furthermore, multilayer films comprising optical repeating units of different design can be used in combination for forming a reflective film body in accordance with the present invention. For example, a multilayer film comprising an optical repeating unit consisting of only two polymeric layers can be combined with a multilayer film comprising an optical repeating unit comprising polymeric layers A, B and C arranged in an ABC order in particular in an ABCB pattern.
- One skilled in the art will readily appreciate that a wide variety of materials can be used to form (infrared) mirrors or polarizers according to the present invention when processed under conditions selected to yield the desired refractive index relationships. The desired refractive index relationships can be achieved in a variety of ways, including stretching during or after film formation (e.g., in the case of organic polymers), extruding (e.g., in the case of liquid crystalline materials), or coating. In addition, it is preferred that the two materials have similar Theological properties (e.g., melt viscosities) so that they can be co-extruded.
- In general, appropriate combinations may be achieved by selecting, for each of the layers, a crystalline, semi-crystalline, or liquid crystalline material, or amorphous polymer. It should be understood that, in the polymer art, it is generally recognized that polymers are typically not entirely crystalline, and therefore in the context of the present invention, crystalline or semi-crystalline polymers refer to those polymers that are not amorphous and includes any of those materials commonly referred to as crystalline, partially crystalline, semi-crystalline, etc.
- Specific examples of suitable materials for usew in the present invention include polyethylene naphthalate (PEN) and isomers thereof (e.g., 2,6-, 1,4-, 1,5-, 2,7-, and 2,3-PEN), polyalkylene terephthalates (e.g., polyethylene terephthalate, polybutylene terephthalate, and poly-1,4-cyclohexanedimethylene terephthalate), polyimides (e.g., polyacrylic imides), polyetherimides, atactic polystyrene, polycarbonates, polymethacrylates (e.g., polyisobutyl methacrylate, polypropylmethacrylate, polyethylmethacrylate, and polymethylmethacrylate), polyacrylates (e.g., polybutylacrylate and polymethylacrylate), syndiotactic polystyrene (sPS), syndiotactic poly-alpha-methyl styrene, syndiotactic polydichlorostyrene, copolymers and blends of any of these polystyrenes, cellulose derivatives (e.g., ethyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, and cellulose nitrate), polyalkylene polymers (e.g., polyethylene, polypropylene, polybutylene, polyisobutylene, and poly(4-methyl)pentene), fluorinated polymers (e.g., perfluoroalkoxy resins, polytetrafluoroethylene, fluorinated ethylene-propylene copolymers, polyvinylidene fluoride, and polychlorotrifluoroethylene), chlorinated polymers (e.g., polyvinylidene chloride and polyvinylchloride), polysulfones, polyethersulfones, polyacrylonitrile, polyamides, silicone resins, epoxy resins, polyvinylacetate, polyether-amides, ionomeric resins, elastomers (e.g., polybutadiene, polyisoprene, and neoprene), and polyurethanes. Also suitable are copolymers, e.g., copolymers of PEN (e.g., copolymers of 2,6-, 1,4-, 1,5-, 2,7-, and/or 2,3-naphthalene dicarboxylic acid, or esters thereof, with (a) terephthalic acid, or esters thereof; (b) isophthalic acid, or esters thereof; (c) phthalic acid, or esters thereof; (d) alkane glycols; (e) cycloalkane glycols (e.g., cyclohexane dimethanol diol); (f) alkane dicarboxylic acids; and/or (g) cycloalkane dicarboxylic acids (e.g., cyclohexane dicarboxylic acid)), copolymers of polyalkylene terephthalates (e.g., copolymers of terephthalic acid, or esters thereof, with (a) naphthalene dicarboxylic acid, or esters thereof; (b) isophthalic acid, or esters thereof; (c) phthalic acid, or esters thereof; (d) alkane glycols; (e) cycloalkane glycols (e.g., cyclohexane dimethane diol); (f) alkane dicarboxylic acids; and/or (g) cycloalkane dicarboxylic acids (e.g., cyclohexane dicarboxylic acid)), and styrene copolymers (e.g., styrene-butadiene copolymers and styrene-acrylonitrile copolymers), 4,4′-bibenzoic acid and ethylene glycol. In addition, each individual layer may include blends of two or more of the above-described polymers or copolymers (e.g., blends of SPS and atactic polystyrene).
- Particularly preferred birefringent polymeric layers for use in the present invention include layers containing a crystalline or semi-crystalline polyethylenenaphthalate (PEN), inclusive of its isomers (e.g. 2,6-; 1,4-; 1,5-; 2,7; and 2,3-PEN). A particularly preferred isotropic polymeric layer for use in connection with this invention is a layer containing a polymethylmethacrylate, and in particular, polymethylmethacrylate itself.
- It will further be understood by one skilled in the art that each of the polymeric layers may be composed of blends of two or more polymeric materials to obtain desired properties for a specific layer.
- The films and other optical devices made in accordance with the invention may also include one or more anti-reflective layers or coatings, such as, for example, conventional vacuum coated dielectric metal oxide or metal/metal oxide optical films, silica sol gel coatings, and coated or coextruded antireflective layers such as those derived from low index fluoropolymers such as THV, an extrudable fluoropolymer available from 3M Company (St. Paul, Minn.). Such layers or coatings, which may or may not be polarization sensitive, serve to increase transmission and to reduce reflective glare, and may be imparted to the films and optical devices of the present invention through appropriate surface treatment, such as coating or sputter etching.
- Both visible and near IR dyes and pigments are contemplated for use in the films and other optical bodies of the present invention, and include, for example, optical brighteners such as dyes that absorb in the UV and fluoresce in the visible region of the color spectrum. Other additional layers that may be added to alter the appearance of the optical film include, for example, opacifying (black) layers, diffusing layers, holographic images or holographic diffusers, and metal layers. Each of these may be applied directly to one or both surfaces of the optical film, or may be a component of a second film or foil construction that is laminated to the optical film. Alternately, some components such as opacifying or diffusing agents, or colored pigments, may be included in an adhesive layer which is used to laminate the optical film to another surface.
- It is preferred that the polymers have compatible rheologies for coextrusion. That is, as a preferred method of forming the reflective film bodies is the use of coextrusion techniques, the melt viscosities of the polymers are preferably reasonably matched to prevent layer instability or non-uniformity. The polymers used also preferably have sufficient interfacial adhesion so that the films will not delaminate.
- The multilayer reflective film bodies of the present invention can be readily manufactured in a cost effective way, and they can be formed and shaped into a variety of useful configurations after coextrusion. Multilayer reflective film bodies in accordance with the present invention are most advantageously prepared by employing a multilayered coextrusion device such as those described in U.S. Pat. Nos. 3,773,882 and 3,884,606, the disclosures of which are incorporated herein by reference. Such devices provide a method for preparing multilayered, simultaneously extruded thermoplastic materials, each of which are of a substantially uniform layer thickness.
- Preferably, a series of layer multiplying means as are described in U.S. Pat. No. 3,759,647, the disclosure of which is incorporated herein by reference, may be employed. The feedblock of the coextrusion device receives streams of the diverse thermoplastic polymeric materials from a source such as a heat plastifying extruder. The streams of resinous materials are passed to a mechanical manipulating section within the feedblock. This section serves to rearrange the original streams into a multilayered stream having the number of layers desired in the final body. Optionally, this multilayered stream may be subsequently passed through a series of layer multiplying means in order to further increase the number of layers in the final body.
- The multilayered stream is then passed into an extrusion die which is so constructed and arranged that stream-lined flow is maintained therein. Such an extrusion device is described in U.S. Pat. No. 3,557,265, the disclosure of which is incorporated by reference herein. The resultant product is extruded to form a multilayered body in which each layer is generally parallel to the major surface of adjacent layers.
- The configuration of the extrusion die can vary and can be such as to reduce the thickness and dimensions of each of the layers. The precise degree of reduction in thickness of the layers delivered from the mechanical orienting section, the configuration of the die, and the amount of mechanical working of the body after extrusion are all factors which affect the thickness of the individual layers in the final body.
- The number of layers in the reflective film body can be selected to achieve the desired optical properties using the minimum number of layers for reasons of film thickness, flexibility and economy. In the case of both reflective polarizers and reflective mirrors, the number of layers is preferably less than about 10,000, more preferably less than about 5,000, and (even more preferably) less than about 2,000.
- The desired relationship between refractive indices of polymeric layers as desired in this invention can be achieved by selection of appropriate processing conditions used to prepare the reflective film body. In the case of organic polymers which can be oriented by stretching, the multilayer films are generally prepared by co-extruding the individual polymers to form a multilayer film (e.g., as set out above) and then orienting the reflective film body by stretching at a selected temperature, optionally followed by heat-setting at a selected temperature. Alternatively, the extrusion and orientation steps may be performed simultaneously. By the orientation, the desired extent of birefringence (negative or positive) is set in those polymeric layers that comprise a polymer that can exhibit birefringence. Negative birefringence is obtained with polymers that show a negative optical stress coefficient, i.e., polymers for which the in-plane indices will decrease with orientation, whereas positive birefringence is obtained with polymers having a positive optical stress coefficient. This terminology in the art of film orientation conflicts somewhat with the standard optical definition of positive and negative birefringence. In the art of optics, a uniaxially positive birefringent film or layer is one in which the z-index of refraction is higher than the in-plane index. A biaxially stretched polymer film such as PET will have high in-plane indices, e.g., 1.65, and a low out-of-plane or z-axis index of 1.50. In the film making art, a material such as PET is said to be positively birefringent because the index increases in the stretch direction, but in the art of optics, the same material, after biaxially stretching to film, is said to have uniaxial negative birefringence because the z-index is lower than the in-plane indices which are substantially equal. The term “positive birefringence” for a material as used herein will be that of the polymer film art, and will mean that the index of refraction increases in the stretch direction. Similarly, the term “negative birefringence” for a material will mean that the index of refraction of a film decreases in the direction of stretch. The terms “uniaxially positive” or “uniaxially negative”, when used in reference to a birefringent layer, will be taken to have the meaning in the optics sense.
- In the case of polarizers, the reflective film body is stretched substantially in one direction (uniaxial orientation), while in the case of mirrors the film can be stretched substantially in two directions (biaxial orientation). In the latter case, the stretching may be asymmetric to introduce specially desired features, but is preferably symmetric.
- The reflective film body may be allowed to dimensionally relax in the cross-stretch direction from the natural reduction in cross-stretch (equal to the square root of the stretch ratio) or may be constrained (i.e., no substantial change in cross-stretch dimensions). The reflective film body may be stretched in the machine direction, as with a length orienter, and/or in width using a tenter.
- The pre-stretch temperature, stretch temperature, stretch rate, stretch ratio, heat set temperature, heat set time, heat set relaxation, and cross-stretch relaxation are selected to yield a multilayer device having the desired refractive index relationship. These variables are inter-dependent; thus, for example, a relatively low stretch rate could be used if coupled with, e.g., a relatively low stretch temperature. It will be apparent to one skilled in the art how to select the appropriate combination of these variables to achieve the desired multilayer device. In general, however, a stretch ratio in the range from about 1:2 to about 1:10 (more preferably about 1:3 to about 1:7) in the stretch direction and from about 1:0.2 to about 1:10 (more preferably from about 1:0.2 to about 1:7) orthogonal to the stretch direction is preferred.
- Orientation of the extruded film can be accomplished by stretching individual sheets of the material in heated air. For economical production, stretching may be accomplished on a continuous basis in a standard length orienter, tenter oven, or both. Economies of scale and line speeds of standard polymer film production may be achieved, thereby achieving manufacturing costs that are substantially lower than costs associated with commercially available absorptive polarizers.
- Two or more multilayer films may also be laminated together to obtain a reflective film body in accordance with the present invention. Amorphous copolyesters, such as VITEL Brand 3000 and 3300 from the Goodyear Tire and Rubber Co. of Akron, Ohio, are useful as laminating materials. The choice of laminating material is broad, with adhesion to the multilayer films, optical clarity and exclusion of air being the primary guiding principles.
- It may be desirable to add to one or more of the layers, one or more inorganic or organic adjuvants such as an antioxidant, extrusion aid, heat stabilizer, ultraviolet ray absorber, nucleator, surface projection forming agent, and the like in normal quantities so long as the addition does not substantially interfere with the performance of the present invention.
- The preceding description of the present invention is merely illustrative, and is not intended to be limiting. Therefore, the scope of the present invention should be construed solely by reference to the appended claims.
Claims (9)
1. A reflective film comprising a plurality of optical repeating units having an optical thickness profile that defines a curve, the curve having substantially no discontinuities in its first derivative and shaped so that it, in order, monotonically decreases from an initial optical thickness to a minimum optical thickness, remains substantially constant at the minimum optical thickness, monotonically increases from the minimum optical thickness to a maximum optical thickness, remains substantially constant at the maximum optical thickness, and monotonically decreases from the maximum optical thickness to an end optical thickness, wherein the optical repeating units monotonically increasing from the minimum optical thickness to the maximum optical thickness form a reflection band.
2. The reflective film of claim 1 , wherein the reflection band includes visible light.
3. The reflective film of claim 1 , wherein the reflection band includes infrared light.
4. The reflective film of claim 1 , wherein the reflection band includes ultraviolet light.
5. The reflective film of claim 1 , wherein the optical repeating units comprise polymer layers.
6. The reflective film of claim 1 , wherein the optical repeating units comprise a plurality of layers.
7. The reflective film of claim 5 , wherein at least a portion of the optical repeating units comprise two layers.
8. The reflective film of claim 5 , wherein at least a portion of the optical repeating units comprise three layers A, B, and C arranged in an order ABC, the layers having respective indices of refraction na, nb, and nc that differ from each other, index nb being intermediate to indices na and nc.
9. The reflective film of claim 8 , wherein the three layers are arranged in an order ABCB.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/173,663 US20050243425A1 (en) | 1998-01-13 | 2005-07-01 | Optical film with sharpened bandedge |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/006,085 US6157490A (en) | 1998-01-13 | 1998-01-13 | Optical film with sharpened bandedge |
US09/634,319 US6967778B1 (en) | 1998-01-13 | 2000-08-09 | Optical film with sharpened bandedge |
US11/173,663 US20050243425A1 (en) | 1998-01-13 | 2005-07-01 | Optical film with sharpened bandedge |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/634,319 Continuation US6967778B1 (en) | 1998-01-13 | 2000-08-09 | Optical film with sharpened bandedge |
Publications (1)
Publication Number | Publication Date |
---|---|
US20050243425A1 true US20050243425A1 (en) | 2005-11-03 |
Family
ID=21719234
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/006,085 Expired - Lifetime US6157490A (en) | 1998-01-13 | 1998-01-13 | Optical film with sharpened bandedge |
US11/173,663 Abandoned US20050243425A1 (en) | 1998-01-13 | 2005-07-01 | Optical film with sharpened bandedge |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/006,085 Expired - Lifetime US6157490A (en) | 1998-01-13 | 1998-01-13 | Optical film with sharpened bandedge |
Country Status (9)
Country | Link |
---|---|
US (2) | US6157490A (en) |
EP (1) | EP1047963B1 (en) |
JP (1) | JP4399113B2 (en) |
KR (1) | KR100582973B1 (en) |
CN (1) | CN1141604C (en) |
AU (1) | AU2109699A (en) |
BR (1) | BR9906907A (en) |
DE (1) | DE69913102T2 (en) |
WO (1) | WO1999036809A1 (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014070450A1 (en) | 2012-11-01 | 2014-05-08 | 3M Innovative Properties Company | Above-deck roof venting article |
US20140268346A1 (en) * | 2011-10-20 | 2014-09-18 | 3M Innovative Properties Company | Apodized broadband partial reflectors having differing optical packets |
US8915022B2 (en) | 2011-06-07 | 2014-12-23 | 3M Innovative Properties Company | System and method for management of a roof |
WO2015048624A1 (en) * | 2013-09-30 | 2015-04-02 | 3M Innovative Properties Company | Polymeric multilayer optical film |
US9228356B2 (en) | 2011-12-22 | 2016-01-05 | 3M Innovative Properties Company | Above-deck roof venting article |
WO2016089695A1 (en) * | 2014-12-05 | 2016-06-09 | 3M Innovative Properties Company | Vision-protecting filter lens |
US9502477B2 (en) | 2013-07-18 | 2016-11-22 | Samsung Display Co., Ltd. | Display apparatus having color saturation filter with layers of different refractive indexes |
US9945127B2 (en) | 2010-09-08 | 2018-04-17 | 3M Innovative Properties Company | Above-deck roof venting article, system and methods |
WO2019073330A2 (en) | 2017-10-09 | 2019-04-18 | 3M Innovative Properties Company | Optical components and optical systems |
KR20200027968A (en) * | 2017-07-07 | 2020-03-13 | 도요보 필름 솔루션 가부시키가시야 | Multilayer laminated film |
EP4332640A1 (en) * | 2022-08-29 | 2024-03-06 | Meta Platforms Technologies, LLC | Reflective polarizer with integrated anti-reflective coating |
Families Citing this family (179)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE69435173D1 (en) | 1993-12-21 | 2009-01-15 | Minnesota Mining & Mfg | Multilayer optical film |
US6498683B2 (en) | 1999-11-22 | 2002-12-24 | 3M Innovative Properties Company | Multilayer optical bodies |
US6080467A (en) | 1995-06-26 | 2000-06-27 | 3M Innovative Properties Company | High efficiency optical devices |
US6486997B1 (en) | 1997-10-28 | 2002-11-26 | 3M Innovative Properties Company | Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter |
US7023602B2 (en) | 1999-05-17 | 2006-04-04 | 3M Innovative Properties Company | Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter and color separation and recombination prisms |
US6808658B2 (en) * | 1998-01-13 | 2004-10-26 | 3M Innovative Properties Company | Method for making texture multilayer optical films |
US6926952B1 (en) * | 1998-01-13 | 2005-08-09 | 3M Innovative Properties Company | Anti-reflective polymer constructions and method for producing same |
US6788463B2 (en) | 1998-01-13 | 2004-09-07 | 3M Innovative Properties Company | Post-formable multilayer optical films and methods of forming |
US6157490A (en) * | 1998-01-13 | 2000-12-05 | 3M Innovative Properties Company | Optical film with sharpened bandedge |
US6531230B1 (en) | 1998-01-13 | 2003-03-11 | 3M Innovative Properties Company | Color shifting film |
US6515785B1 (en) | 1999-04-22 | 2003-02-04 | 3M Innovative Properties Company | Optical devices using reflecting polarizing materials |
WO2001058681A1 (en) * | 2000-02-11 | 2001-08-16 | Denglas Technologies, Llc. | Antireflective uv blocking multilayer coatings wherin film has cerium oxide |
US6419483B1 (en) | 2000-03-01 | 2002-07-16 | 3M Innovative Properties Company | Method and apparatus for curling light-curable dental materials |
US6797396B1 (en) | 2000-06-09 | 2004-09-28 | 3M Innovative Properties Company | Wrinkle resistant infrared reflecting film and non-planar laminate articles made therefrom |
EP2316569A1 (en) | 2000-06-28 | 2011-05-04 | 3M Innovative Properties Company | Enhanced sample processing devices, systems and methods |
AU3486401A (en) | 2000-08-21 | 2002-03-04 | 3M Innovative Properties Co | Loss enhanced reflective optical filters |
US6767609B2 (en) | 2000-09-15 | 2004-07-27 | 3M Innovative Properties Company | Perforated film constructions for backlit signs |
KR100905142B1 (en) * | 2001-01-15 | 2009-06-29 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Multilayer Infrared Reflecting Film With High and Smooth Transmission in Visible Wavelength Region and Laminate Articles Made Therefrom |
US7052762B2 (en) | 2001-05-24 | 2006-05-30 | 3M Innovative Properties Company | Low Tg multilayer optical films |
US6521329B2 (en) * | 2001-06-18 | 2003-02-18 | Eastman Kodak Company | Radiographic phosphor panel having reflective polymeric supports |
US6611378B1 (en) | 2001-12-20 | 2003-08-26 | Semrock, Inc. | Thin-film interference filter with quarter-wavelength unit sub-layers arranged in a generalized pattern |
US7189447B2 (en) | 2002-01-04 | 2007-03-13 | 3M Innovative Properties Company | Laminates |
US6652996B2 (en) * | 2002-01-31 | 2003-11-25 | Eastman Kodak Company | Radiographic phosphor panel having improved speed and sharpness |
US6900450B2 (en) | 2002-03-09 | 2005-05-31 | Kimberly-Clark Worldwide, Inc. | Method and apparatus for inferring item position based on multiple data |
US6885451B2 (en) | 2002-03-09 | 2005-04-26 | Kimberly-Clark Worldwide, Inc. | Infrared detection of composite article components |
US6919965B2 (en) | 2002-03-09 | 2005-07-19 | Kimberly-Clark Worldwide, Inc. | Apparatus and method for making and inspecting pre-fastened articles |
US6927857B2 (en) | 2002-03-09 | 2005-08-09 | Kimberly-Clark Worldwide, Inc. | Process for the detection of marked components of a composite article using infrared blockers |
US6888143B2 (en) | 2002-03-09 | 2005-05-03 | Kimberly-Clark Worldwide, Inc. | Apparatus and method for inspecting pre-fastened articles |
US7396493B2 (en) * | 2002-05-21 | 2008-07-08 | 3M Innovative Properties Company | Multilayer optical film with melt zone to control delamination |
US20050041292A1 (en) * | 2002-05-21 | 2005-02-24 | Wheatley John A. | Visible wavelength detector systems and filters therefor |
US6991695B2 (en) * | 2002-05-21 | 2006-01-31 | 3M Innovative Properties Company | Method for subdividing multilayer optical film cleanly and rapidly |
US7095009B2 (en) * | 2002-05-21 | 2006-08-22 | 3M Innovative Properties Company | Photopic detector system and filter therefor |
AU2003248885A1 (en) * | 2002-07-10 | 2004-01-23 | Denglas Technologies, L.L.C. | Method of making stress-resistant anti-reflection multilayer coatings containing cerium oxide |
US7123765B2 (en) | 2002-07-31 | 2006-10-17 | Kimberly-Clark Worldwide, Inc. | Apparatus and method for inspecting articles |
US7215473B2 (en) | 2002-08-17 | 2007-05-08 | 3M Innovative Properties Company | Enhanced heat mirror films |
US7709095B2 (en) | 2002-11-05 | 2010-05-04 | Nv Bekaert Sa | Infra-red reflecting layered structure |
US7064897B2 (en) * | 2002-12-31 | 2006-06-20 | 3M Innovative Properties Company | Optical polarizing films with designed color shifts |
DE10319005A1 (en) * | 2003-04-25 | 2004-11-25 | Carl Zeiss Smt Ag | Reflective optical element, optical system and EUV lithography device |
US20040219338A1 (en) * | 2003-05-01 | 2004-11-04 | Hebrink Timothy J. | Materials, configurations, and methods for reducing warpage in optical films |
US20040227994A1 (en) * | 2003-05-16 | 2004-11-18 | Jiaying Ma | Polarizing beam splitter and projection systems using the polarizing beam splitter |
US6808394B1 (en) | 2003-06-23 | 2004-10-26 | American Polarizers, Inc. | System for demonstrating effects of polarized lens |
US8932701B2 (en) * | 2003-07-16 | 2015-01-13 | 3M Innovative Properties Company | Laminates and methods of making same |
US6859323B1 (en) | 2003-12-11 | 2005-02-22 | Optical Coating Laboratory, Inc. | Dichroic neutral density optical filter |
US7234816B2 (en) * | 2004-02-03 | 2007-06-26 | 3M Innovative Properties Company | Polarizing beam splitter assembly adhesive |
DE102004021494B4 (en) * | 2004-04-30 | 2006-04-06 | Man Roland Druckmaschinen Ag | Device for applying and removing a sleeve |
US7201497B2 (en) * | 2004-07-15 | 2007-04-10 | Lumination, Llc | Led lighting system with reflective board |
JP4578900B2 (en) * | 2004-09-07 | 2010-11-10 | 富士フイルム株式会社 | Optical film, polarizing plate and liquid crystal display device |
JP4986865B2 (en) * | 2005-02-16 | 2012-07-25 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Luminescent body and use thereof |
US20060221447A1 (en) * | 2005-03-31 | 2006-10-05 | 3M Innovative Properties Company | Stabilized polarizing beam splitter assembly |
US7315418B2 (en) * | 2005-03-31 | 2008-01-01 | 3M Innovative Properties Company | Polarizing beam splitter assembly having reduced stress |
US7733310B2 (en) | 2005-04-01 | 2010-06-08 | Prysm, Inc. | Display screens having optical fluorescent materials |
US7474286B2 (en) | 2005-04-01 | 2009-01-06 | Spudnik, Inc. | Laser displays using UV-excitable phosphors emitting visible colored light |
US7791561B2 (en) * | 2005-04-01 | 2010-09-07 | Prysm, Inc. | Display systems having screens with optical fluorescent materials |
US9709700B2 (en) | 2005-04-06 | 2017-07-18 | 3M Innovative Properties Company | Optical bodies including rough strippable boundary layers |
US20060227421A1 (en) | 2005-04-06 | 2006-10-12 | Stover Carl A | Optical bodies including strippable boundary layers |
JP4814312B2 (en) | 2005-04-06 | 2011-11-16 | スリーエム イノベイティブ プロパティズ カンパニー | Optical body including rough strippable boundary layer and asymmetric surface structure |
US7385763B2 (en) * | 2005-04-18 | 2008-06-10 | 3M Innovative Properties Company | Thick film multilayer reflector with tailored layer thickness profile |
US7994702B2 (en) | 2005-04-27 | 2011-08-09 | Prysm, Inc. | Scanning beams displays based on light-emitting screens having phosphors |
US8089425B2 (en) | 2006-03-03 | 2012-01-03 | Prysm, Inc. | Optical designs for scanning beam display systems using fluorescent screens |
US8000005B2 (en) | 2006-03-31 | 2011-08-16 | Prysm, Inc. | Multilayered fluorescent screens for scanning beam display systems |
US20070097509A1 (en) * | 2005-10-31 | 2007-05-03 | Nevitt Timothy J | Optical elements for high contrast applications |
US7884816B2 (en) | 2006-02-15 | 2011-02-08 | Prysm, Inc. | Correcting pyramidal error of polygon scanner in scanning beam display systems |
US8451195B2 (en) | 2006-02-15 | 2013-05-28 | Prysm, Inc. | Servo-assisted scanning beam display systems using fluorescent screens |
US20070242197A1 (en) * | 2006-04-12 | 2007-10-18 | 3M Innovative Properties Company | Transflective LC Display Having Backlight With Spatial Color Separation |
TW200809327A (en) * | 2006-04-19 | 2008-02-16 | 3M Innovative Properties Co | Transflective LC display having narrow band backlight and spectrally notched transflector |
US20080020186A1 (en) * | 2006-07-18 | 2008-01-24 | 3M Innovative Properties Company | Calendering process for making an optical film |
US20090251917A1 (en) * | 2006-08-01 | 2009-10-08 | Wollner Mark R | Illumination device |
US7773302B2 (en) * | 2006-09-01 | 2010-08-10 | Semrock, Inc. | Low cost filter for fluorescence systems |
US8525402B2 (en) | 2006-09-11 | 2013-09-03 | 3M Innovative Properties Company | Illumination devices and methods for making the same |
US8581393B2 (en) | 2006-09-21 | 2013-11-12 | 3M Innovative Properties Company | Thermally conductive LED assembly |
US20080085383A1 (en) * | 2006-10-06 | 2008-04-10 | 3M Innovative Properties Company | Processes for improved optical films |
US20080083998A1 (en) * | 2006-10-06 | 2008-04-10 | 3M Innovative Properties Company | Multiple draw gap length orientation process |
KR100809849B1 (en) * | 2006-11-10 | 2008-03-04 | 엘지.필립스 엘시디 주식회사 | Optical film and method for fabricating the same, liquid crystal display device having the same |
US8013506B2 (en) | 2006-12-12 | 2011-09-06 | Prysm, Inc. | Organic compounds for adjusting phosphor chromaticity |
US8471983B2 (en) * | 2006-12-27 | 2013-06-25 | Teijin Limited | Polarizing element and liquid crystal display device |
WO2008116123A1 (en) * | 2007-03-20 | 2008-09-25 | Spudnik, Inc. | Delivering and displaying advertisement or other application data to display systems |
US8169454B1 (en) | 2007-04-06 | 2012-05-01 | Prysm, Inc. | Patterning a surface using pre-objective and post-objective raster scanning systems |
US7697183B2 (en) | 2007-04-06 | 2010-04-13 | Prysm, Inc. | Post-objective scanning beam systems |
US9770611B2 (en) | 2007-05-03 | 2017-09-26 | 3M Innovative Properties Company | Maintenance-free anti-fog respirator |
US20080271739A1 (en) | 2007-05-03 | 2008-11-06 | 3M Innovative Properties Company | Maintenance-free respirator that has concave portions on opposing sides of mask top section |
RU2442197C2 (en) | 2007-05-17 | 2012-02-10 | Призм, Инк. | The multilayer screens with light emitting strips for the display system with a scan-off beam |
KR101519171B1 (en) | 2007-05-20 | 2015-05-11 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Semi-specular components in hollow cavity light recycling backlights |
EP2162785B1 (en) | 2007-05-20 | 2018-03-07 | 3M Innovative Properties Company | Design parameters for thin hollow cavity backlights of the light-recycling type |
EP2535766A3 (en) | 2007-05-20 | 2013-05-01 | 3M Innovative Properties Company | Asymmetric reflective film and backlight having a hollow cavity, which recycles the light |
TWI439641B (en) | 2007-05-20 | 2014-06-01 | 3M Innovative Properties Co | Collimating light injectors for edge-lit backlights |
US7878657B2 (en) | 2007-06-27 | 2011-02-01 | Prysm, Inc. | Servo feedback control based on invisible scanning servo beam in scanning beam display systems with light-emitting screens |
US8556430B2 (en) | 2007-06-27 | 2013-10-15 | Prysm, Inc. | Servo feedback control based on designated scanning servo beam in scanning beam display systems with light-emitting screens |
CN101452088B (en) * | 2007-12-07 | 2011-07-27 | 财团法人工业技术研究院 | Low or zero birefraction optical film and method for manufacturing same |
JP5702151B2 (en) | 2008-02-07 | 2015-04-15 | スリーエム イノベイティブ プロパティズ カンパニー | Hollow backlight with structured film |
EP2252828A1 (en) | 2008-02-22 | 2010-11-24 | 3M Innovative Properties Company | Backlights having selected output light flux distributions and display systems using same |
US9110245B2 (en) * | 2008-03-31 | 2015-08-18 | 3M Innovative Properties Company | Low layer count reflective polarizer with optimized gain |
JP2011516921A (en) * | 2008-03-31 | 2011-05-26 | スリーエム イノベイティブ プロパティズ カンパニー | Optical film |
BRPI0907685A2 (en) | 2008-04-30 | 2019-02-26 | 3M Innovative Properties Co | lighting system and light injection coupler for the same |
EP2297607B1 (en) | 2008-06-04 | 2014-04-23 | 3M Innovative Properties Company | Hollow backlight with tilted light source |
CN202188907U (en) * | 2008-06-05 | 2012-04-11 | 魄金莱默保健科学有限公司 | Optical device and system using same |
US7869112B2 (en) * | 2008-07-25 | 2011-01-11 | Prysm, Inc. | Beam scanning based on two-dimensional polygon scanner for display and other applications |
KR101696492B1 (en) | 2008-11-19 | 2017-01-13 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Multilayer Optical Film With Output Confinement in Both Polar and Azimuthal Directions and Related Constructions |
KR101703363B1 (en) * | 2008-11-19 | 2017-02-06 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Brewster Angle Film for Light Management in Luminaires and Other Lighting Systems |
JP5706332B2 (en) * | 2008-11-19 | 2015-04-22 | スリーエム イノベイティブ プロパティズ カンパニー | Reflective film combination with output limitations in both polar and azimuthal directions and related configurations |
US20110222263A1 (en) * | 2008-11-19 | 2011-09-15 | Weber Michael F | High transmission flux leveling multilayer optical film and related constructions |
WO2010075340A1 (en) | 2008-12-22 | 2010-07-01 | 3M Innovative Properties Company | Multilayer optical films having side-by-side mirror/polarizer zones |
CN102333998B (en) | 2008-12-30 | 2015-08-05 | 3M创新有限公司 | Broadband reflector, light collecting type solar power system and use their method |
US20100163759A1 (en) * | 2008-12-31 | 2010-07-01 | Stmicroelectronics S.R.L. | Radiation sensor with photodiodes being integrated on a semiconductor substrate and corresponding integration process |
IT1392502B1 (en) * | 2008-12-31 | 2012-03-09 | St Microelectronics Srl | SENSOR INCLUDING AT LEAST ONE DOUBLE-JOINT VERTICAL PHOTODIOD INTEGRATED ON A SEMICONDUCTIVE SUBSTRATE AND ITS INTEGRATION PROCESS |
WO2011012545A1 (en) | 2009-07-31 | 2011-02-03 | Technische Universiteit Eindhoven | Luminescent optical device and solar cell system with such luminescent optical device |
CN102576113B (en) * | 2009-10-24 | 2014-12-17 | 3M创新有限公司 | Immersed asymmetric reflector with reduced color |
WO2011050226A1 (en) | 2009-10-24 | 2011-04-28 | 3M Innovative Properties Company | Immersed reflective polarizer with angular confinement in selected planes of incidence |
EP2491445B1 (en) | 2009-10-24 | 2018-01-03 | 3M Innovative Properties Company | Light source and display system incorporating same |
EP2491443B1 (en) | 2009-10-24 | 2021-03-24 | 3M Innovative Properties Company | Immersed reflective polarizer with high off-axis reflectivity |
JP5869494B2 (en) | 2009-12-08 | 2016-02-24 | スリーエム イノベイティブ プロパティズ カンパニー | Optical structure incorporating light guide and low refractive index film |
EP2339382A1 (en) | 2009-12-22 | 2011-06-29 | 3M Innovative Properties Company | A light guide for a dental light device and a method of making the light guide |
WO2012003215A1 (en) | 2010-06-30 | 2012-01-05 | 3M Innovative Properties Company | Retarder film combinations with spatially selective birefringence reduction |
WO2012003213A1 (en) | 2010-06-30 | 2012-01-05 | 3M Innovative Properties Company | Diffuse reflective optical films with spatially selective birefringence reduction |
CN103038681B (en) | 2010-06-30 | 2016-09-28 | 3M创新有限公司 | Use the mask processing with the film that spatial selectivity birefringence reduces |
KR101926204B1 (en) | 2010-10-20 | 2018-12-06 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Wide Band Semi-Specular Mirror Film Incorporating Nanovoided Polymeric Layer |
KR101740603B1 (en) * | 2010-12-27 | 2017-05-29 | 에스케이씨 주식회사 | Infrared ray shielding multi-layer film |
SG10201602517RA (en) | 2010-12-30 | 2016-05-30 | 3M Innovative Properties Co | Laser cutting method and articles produced therewith |
EP2658674B1 (en) | 2010-12-30 | 2017-03-01 | 3M Innovative Properties Company | Apparatus for laser converting using a support member having a gold facing layer; method of laser converting a sheet material using such apparatus |
US9353930B2 (en) | 2011-04-08 | 2016-05-31 | 3M Innovative Properties Company | Light duct tee extractor |
CN103907035B (en) | 2011-10-20 | 2017-07-04 | 3M创新有限公司 | apodization broadband partial reflector |
KR102047286B1 (en) | 2011-10-20 | 2019-11-21 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Illumination systems with sloped transmission spectrum front reflector |
TWI474079B (en) * | 2012-03-14 | 2015-02-21 | Extend Optronics Corp | Reflection optical film and method of manufacturing the same, and imaging display |
TWI580994B (en) * | 2012-05-15 | 2017-05-01 | Dainippon Printing Co Ltd | A laminated substrate, a laminate, a laminate plate, a liquid crystal display panel, and an image display device |
US20130314788A1 (en) * | 2012-05-24 | 2013-11-28 | Extend Optronics Corp. | Reflective optical film and method of manufacturing the same, and image display device |
CN104412133A (en) * | 2012-06-28 | 2015-03-11 | 可隆工业株式会社 | Brightness enhancing film and backlight unit comprising the same |
US20140065397A1 (en) | 2012-08-28 | 2014-03-06 | 3M Innovative Properties Company | Coextruded polymer film configured for successive irreversible delamination |
EP2943824B1 (en) | 2013-01-14 | 2017-11-22 | 3M Innovative Properties Company | Filters to enhance color discrimination for color vision deficient individuals |
US9279921B2 (en) * | 2013-04-19 | 2016-03-08 | 3M Innovative Properties Company | Multilayer stack with overlapping harmonics for wide visible-infrared coverage |
EP4272840A1 (en) | 2013-07-15 | 2023-11-08 | 3M Innovative Properties Co. | Respirator having optically active exhalation valve |
USD746974S1 (en) | 2013-07-15 | 2016-01-05 | 3M Innovative Properties Company | Exhalation valve flap |
WO2015034910A1 (en) | 2013-09-05 | 2015-03-12 | 3M Innovative Properties Company | Patterned marking of multilayer optical film by thermal conduction |
EP3042226A1 (en) | 2013-09-06 | 2016-07-13 | 3M Innovative Properties Company | Multilayer reflective polarizer |
KR102259103B1 (en) * | 2013-09-06 | 2021-06-01 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Head mounted display with eye tracking |
US20150077873A1 (en) | 2013-09-16 | 2015-03-19 | 3M Innovative Properties Company | Adhesive articles containing light shielding film substrates, method of making thereof and articles therefrom |
CN105745559B (en) | 2013-11-19 | 2018-06-01 | 3M创新有限公司 | Multiple layer polymer reflector |
US9885885B2 (en) | 2013-11-27 | 2018-02-06 | 3M Innovative Properties Company | Blue edge filter optical lens |
KR20160105442A (en) | 2013-12-30 | 2016-09-06 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Optical film including collimating reflective polarizer |
US9841598B2 (en) | 2013-12-31 | 2017-12-12 | 3M Innovative Properties Company | Lens with embedded multilayer optical film for near-eye display systems |
US9739916B2 (en) | 2014-03-20 | 2017-08-22 | 3M Innovative Properties Company | Circadian rhythm optical film |
US10642044B2 (en) | 2014-04-09 | 2020-05-05 | 3M Innovative Properties Company | Near-eye display system having a pellicle as a combiner |
EP3180650A4 (en) | 2014-08-13 | 2018-08-08 | 3M Innovative Properties Company | Head-mounted display system and components |
MX2017008747A (en) | 2014-12-30 | 2018-03-15 | 3M Innovative Properties Co | Optical stack including reflective polarizer and compensation film. |
US10422941B2 (en) | 2015-02-27 | 2019-09-24 | 3M Innovative Properties Company | Optical film including collimating reflective polarizer and structured layer |
CN107407755B (en) * | 2015-03-17 | 2020-06-05 | 东丽株式会社 | Laminated film, liquid crystal display, touch panel, and organic EL display using the same |
GB201508114D0 (en) | 2015-05-12 | 2015-06-24 | 3M Innovative Properties Co | Respirator tab |
EP3317624B1 (en) | 2015-07-05 | 2019-08-07 | The Whollysee Ltd. | Optical identification and characterization system and tags |
WO2017019450A2 (en) | 2015-07-24 | 2017-02-02 | 3M Innovative Properties Company | Reflective stack with heat spreading layer |
CN108139613B (en) | 2015-10-02 | 2020-08-18 | 3M创新有限公司 | Optical filter |
JP2018537723A (en) | 2015-12-18 | 2018-12-20 | スリーエム イノベイティブ プロパティズ カンパニー | Broadband visible light reflector |
MX2018011502A (en) | 2016-03-21 | 2019-01-24 | Hubbell Inc | Light fixture with narrow light distribution. |
JP2019523442A (en) | 2016-07-13 | 2019-08-22 | スリーエム イノベイティブ プロパティズ カンパニー | Optical film |
WO2018052872A1 (en) * | 2016-09-13 | 2018-03-22 | 3M Innovative Properties Company | Single packet reflective polarizer with thickness profile tailored for low color at oblique angles |
WO2018160866A1 (en) | 2017-03-02 | 2018-09-07 | 3M Innovative Properties Company | Dynamic reflected color film with low optical caliper sensitivity |
WO2018165126A1 (en) | 2017-03-06 | 2018-09-13 | 3M Innovative Properties Company | Vehicle projection assembly |
US11813581B2 (en) | 2017-07-14 | 2023-11-14 | 3M Innovative Properties Company | Method and adapter for conveying plural liquid streams |
US11726245B2 (en) | 2017-10-02 | 2023-08-15 | 3M Innovative Properties Company | Partial reflector having stack of polymer layers for correcting color shift |
CN111164470A (en) * | 2017-10-03 | 2020-05-15 | 东丽株式会社 | Laminated film |
US11726246B2 (en) * | 2017-10-20 | 2023-08-15 | 3M Innovative Properties Company | Optical film and polarizing beam splitter |
JP2021504761A (en) * | 2017-12-01 | 2021-02-15 | スリーエム イノベイティブ プロパティズ カンパニー | Thin multilayer reflector with uniform left band edge |
US20200355859A1 (en) | 2018-01-26 | 2020-11-12 | 3M Innovative Properties Company | Multilayer Reflective Polarizer with Crystalline Low Index Layers |
US20210003757A1 (en) * | 2018-02-22 | 2021-01-07 | Toyobo Film Solutions Limited | Multilayer laminated film |
US10850595B2 (en) | 2018-03-07 | 2020-12-01 | Magna Electronics Inc. | Vehicular sensing system with attenuation of reflected-refracted light off of precipitation using light polarization |
WO2020016703A2 (en) | 2018-07-17 | 2020-01-23 | 3M Innovative Properties Company | Optical film including infrared reflector and multilayer reflective polarizer with crystalline low index layers |
CN112424650B (en) | 2018-07-20 | 2022-10-11 | 3M创新有限公司 | Optical film comprising polymeric optical reflector and discontinuous transparent coating |
EP3847488A1 (en) | 2018-09-06 | 2021-07-14 | 3M Innovative Properties Company | Multilayer reflective polarizer with crystalline low index layers |
CN112673290B (en) * | 2018-09-14 | 2023-08-01 | 3M创新有限公司 | Optical film |
KR102532479B1 (en) * | 2018-09-27 | 2023-05-16 | 도요보 가부시키가이샤 | multilayer laminated film |
WO2020066667A1 (en) * | 2018-09-27 | 2020-04-02 | 東洋紡フイルムソリューション株式会社 | Multilayer laminate film |
KR20210063353A (en) | 2018-09-27 | 2021-06-01 | 도요보 필름 솔루션 가부시키가시야 | multilayer laminated film |
CN109541736B (en) * | 2018-11-27 | 2021-01-05 | 河海大学 | Brewster angle polarizer based on multilayer gradient refractive index transparent film |
WO2020194146A1 (en) | 2019-03-26 | 2020-10-01 | 3M Innovative Properties Company | Sensor array spectrometer |
US20220146728A1 (en) | 2019-04-03 | 2022-05-12 | 3M Innovative Properties Company | Optical film and glass laminate |
JP2022527356A (en) | 2019-04-05 | 2022-06-01 | スリーエム イノベイティブ プロパティズ カンパニー | Sensor array spectrometer |
EP3963377A1 (en) | 2019-04-30 | 2022-03-09 | 3M Innovative Properties Company | Optical stack |
WO2020234808A1 (en) * | 2019-05-23 | 2020-11-26 | 3M Innovative Properties Company | Multilayer optical film |
JP2023524554A (en) * | 2020-05-08 | 2023-06-12 | スリーエム イノベイティブ プロパティズ カンパニー | optical film |
TWI747575B (en) * | 2020-10-26 | 2021-11-21 | 南亞塑膠工業股份有限公司 | Polymer film with laminated structure |
CN116745661A (en) * | 2020-12-21 | 2023-09-12 | 3M创新有限公司 | Two-factor authentication film |
WO2023099998A1 (en) * | 2021-12-01 | 2023-06-08 | 3M Innovative Properties Company | Multilayer optical film |
Citations (44)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US540768A (en) * | 1895-06-11 | Richard walsingham western | ||
US3124839A (en) * | 1964-03-17 | l yaich | ||
US3610729A (en) * | 1969-06-18 | 1971-10-05 | Polaroid Corp | Multilayered light polarizer |
US3711176A (en) * | 1971-01-14 | 1973-01-16 | Dow Chemical Co | Highly reflective thermoplastic bodies for infrared, visible or ultraviolet light |
US3860036A (en) * | 1970-11-02 | 1975-01-14 | Dow Chemical Co | Variable geometry feed block for multilayer extrusion |
US4446305A (en) * | 1981-03-02 | 1984-05-01 | Polaroid Corporation | Optical device including birefringent polymer |
US4520189A (en) * | 1981-03-02 | 1985-05-28 | Polaroid Corporation | Optical device including birefringent aromatic amino carboxylic acid polymer |
US4521588A (en) * | 1981-03-02 | 1985-06-04 | Polaroid Corporation | Optical device including birefringent polyhydrazide polymer |
US4525413A (en) * | 1981-03-02 | 1985-06-25 | Polaroid Corporation | Optical device including birefringent polymer |
US4720426A (en) * | 1986-06-30 | 1988-01-19 | General Electric Company | Reflective coating for solid-state scintillator bar |
US4747666A (en) * | 1985-06-25 | 1988-05-31 | Horiba, Ltd. | Multi-layer interference filter |
US4955692A (en) * | 1986-08-19 | 1990-09-11 | The University Of Michigan | Quasi-periodic layered structures |
US5103337A (en) * | 1990-07-24 | 1992-04-07 | The Dow Chemical Company | Infrared reflective optical interference film |
US5179468A (en) * | 1991-11-05 | 1993-01-12 | Gte Products Corporation | Interleaving of similar thin-film stacks for producing optical interference coatings |
US5188760A (en) * | 1990-04-06 | 1993-02-23 | U. S. Philips Corporation | Liquid crystalline material and display cell containing said material |
US5211878A (en) * | 1988-03-10 | 1993-05-18 | Merck Patent Gesellschaft Mit Beschrankter Haftung | Difluorobenzonitrile derivatives |
US5235443A (en) * | 1989-07-10 | 1993-08-10 | Hoffmann-La Roche Inc. | Polarizer device |
US5269995A (en) * | 1992-10-02 | 1993-12-14 | The Dow Chemical Company | Coextrusion of multilayer articles using protective boundary layers and apparatus therefor |
US5294657A (en) * | 1992-05-15 | 1994-03-15 | Melendy Peter S | Adhesive composition with decorative glitter |
US5315437A (en) * | 1989-03-13 | 1994-05-24 | Alfano Robert R | Protective device for selectively reflecting high-intensity light over a broad spectral bandwidth |
US5316703A (en) * | 1991-01-22 | 1994-05-31 | The Dow Chemical Company | Method of producing a lamellar polymeric body |
US5319478A (en) * | 1989-11-01 | 1994-06-07 | Hoffmann-La Roche Inc. | Light control systems with a circular polarizer and a twisted nematic liquid crystal having a minimum path difference of λ/2 |
US5360659A (en) * | 1993-05-24 | 1994-11-01 | The Dow Chemical Company | Two component infrared reflecting film |
US5389324A (en) * | 1993-06-07 | 1995-02-14 | The Dow Chemical Company | Layer thickness gradient control in multilayer polymeric bodies |
US5448404A (en) * | 1992-10-29 | 1995-09-05 | The Dow Chemical Company | Formable reflective multilayer body |
US5486935A (en) * | 1993-06-29 | 1996-01-23 | Kaiser Aerospace And Electronics Corporation | High efficiency chiral nematic liquid crystal rear polarizer for liquid crystal displays having a notch polarization bandwidth of 100 nm to 250 nm |
US5486949A (en) * | 1989-06-20 | 1996-01-23 | The Dow Chemical Company | Birefringent interference polarizer |
US5540978A (en) * | 1992-02-25 | 1996-07-30 | The Dow Chemical Compny | All-polymeric ultraviolet light reflecting film |
US5629055A (en) * | 1994-02-14 | 1997-05-13 | Pulp And Paper Research Institute Of Canada | Solidified liquid crystals of cellulose with optically variable properties |
US5686979A (en) * | 1995-06-26 | 1997-11-11 | Minnesota Mining And Manufacturing Company | Optical panel capable of switching between reflective and transmissive states |
US5699188A (en) * | 1995-06-26 | 1997-12-16 | Minnesota Mining And Manufacturing Co. | Metal-coated multilayer mirror |
US5721603A (en) * | 1993-01-11 | 1998-02-24 | U.S. Philips Corporation | Illumination system and display device including such a system |
US5744534A (en) * | 1992-08-10 | 1998-04-28 | Bridgestone Corporation | Light scattering material |
US5751388A (en) * | 1995-04-07 | 1998-05-12 | Honeywell Inc. | High efficiency polarized display |
US5767935A (en) * | 1995-08-31 | 1998-06-16 | Sumitomo Chemical Company, Limited | Light control sheet and liquid crystal display device comprising the same |
US5770306A (en) * | 1995-03-09 | 1998-06-23 | Dai Nippon Printing Co., Ltd. | Antireflection film containing ultrafine particles, polarizing plate and liquid crystal display device |
US5783120A (en) * | 1996-02-29 | 1998-07-21 | Minnesota Mining And Manufacturing Company | Method for making an optical film |
US5793456A (en) * | 1993-01-11 | 1998-08-11 | U.S. Philips Corporation | Cholesteric polarizer and the manufacture thereof |
US5808794A (en) * | 1996-07-31 | 1998-09-15 | Weber; Michael F. | Reflective polarizers having extended red band edge for controlled off axis color |
US5825543A (en) * | 1996-02-29 | 1998-10-20 | Minnesota Mining And Manufacturing Company | Diffusely reflecting polarizing element including a first birefringent phase and a second phase |
US5825542A (en) * | 1995-06-26 | 1998-10-20 | Minnesota Mining And Manufacturing Company | Diffusely reflecting multilayer polarizers and mirrors |
US5882774A (en) * | 1993-12-21 | 1999-03-16 | Minnesota Mining And Manufacturing Company | Optical film |
US5940149A (en) * | 1997-12-11 | 1999-08-17 | Minnesota Mining And Manufacturing Company | Planar polarizer for LCD projectors |
US6157490A (en) * | 1998-01-13 | 2000-12-05 | 3M Innovative Properties Company | Optical film with sharpened bandedge |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3124639A (en) * | 1964-03-10 | figure | ||
US34605A (en) * | 1862-03-04 | George westinghouse | ||
KR100344364B1 (en) * | 1993-12-21 | 2002-11-30 | 미네소타 마이닝 앤드 매뉴팩춰링 캄파니 | Optical Polarizers and Display Devices |
DE69435173D1 (en) * | 1993-12-21 | 2009-01-15 | Minnesota Mining & Mfg | Multilayer optical film |
KR100407210B1 (en) * | 1993-12-21 | 2004-05-31 | 미네소타 마이닝 앤드 매뉴팩춰링 캄파니 | Reflective Polarizer Display |
IL112071A0 (en) * | 1993-12-21 | 1995-03-15 | Minnesota Mining & Mfg | Reflective polarizer with brightness enhancement |
AU2242295A (en) * | 1994-04-06 | 1995-10-30 | Minnesota Mining And Manufacturing Company | Polarized light sources |
US6080467A (en) * | 1995-06-26 | 2000-06-27 | 3M Innovative Properties Company | High efficiency optical devices |
KR100468560B1 (en) * | 1995-06-26 | 2005-08-04 | 미네소타 마이닝 앤드 매뉴팩춰링 캄파니 | Multilayer polymer film with additional coatings or layers |
EP0883824B1 (en) * | 1996-02-29 | 2003-05-02 | Minnesota Mining And Manufacturing Company | Brightness enhancement film |
-
1998
- 1998-01-13 US US09/006,085 patent/US6157490A/en not_active Expired - Lifetime
-
1999
- 1999-01-08 AU AU21096/99A patent/AU2109699A/en not_active Abandoned
- 1999-01-08 WO PCT/US1999/000452 patent/WO1999036809A1/en active IP Right Grant
- 1999-01-08 JP JP2000540463A patent/JP4399113B2/en not_active Expired - Fee Related
- 1999-01-08 KR KR1020007007668A patent/KR100582973B1/en not_active IP Right Cessation
- 1999-01-08 BR BR9906907-5A patent/BR9906907A/en not_active Application Discontinuation
- 1999-01-08 EP EP99901387A patent/EP1047963B1/en not_active Expired - Lifetime
- 1999-01-08 CN CNB998021113A patent/CN1141604C/en not_active Expired - Lifetime
- 1999-01-08 DE DE69913102T patent/DE69913102T2/en not_active Expired - Lifetime
-
2005
- 2005-07-01 US US11/173,663 patent/US20050243425A1/en not_active Abandoned
Patent Citations (49)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US540768A (en) * | 1895-06-11 | Richard walsingham western | ||
US3124839A (en) * | 1964-03-17 | l yaich | ||
US3610729A (en) * | 1969-06-18 | 1971-10-05 | Polaroid Corp | Multilayered light polarizer |
US3860036A (en) * | 1970-11-02 | 1975-01-14 | Dow Chemical Co | Variable geometry feed block for multilayer extrusion |
US3711176A (en) * | 1971-01-14 | 1973-01-16 | Dow Chemical Co | Highly reflective thermoplastic bodies for infrared, visible or ultraviolet light |
US4525413A (en) * | 1981-03-02 | 1985-06-25 | Polaroid Corporation | Optical device including birefringent polymer |
US4521588A (en) * | 1981-03-02 | 1985-06-04 | Polaroid Corporation | Optical device including birefringent polyhydrazide polymer |
US4446305A (en) * | 1981-03-02 | 1984-05-01 | Polaroid Corporation | Optical device including birefringent polymer |
US4520189A (en) * | 1981-03-02 | 1985-05-28 | Polaroid Corporation | Optical device including birefringent aromatic amino carboxylic acid polymer |
US4747666A (en) * | 1985-06-25 | 1988-05-31 | Horiba, Ltd. | Multi-layer interference filter |
US4720426A (en) * | 1986-06-30 | 1988-01-19 | General Electric Company | Reflective coating for solid-state scintillator bar |
US4955692A (en) * | 1986-08-19 | 1990-09-11 | The University Of Michigan | Quasi-periodic layered structures |
US5211878A (en) * | 1988-03-10 | 1993-05-18 | Merck Patent Gesellschaft Mit Beschrankter Haftung | Difluorobenzonitrile derivatives |
US5315437A (en) * | 1989-03-13 | 1994-05-24 | Alfano Robert R | Protective device for selectively reflecting high-intensity light over a broad spectral bandwidth |
US5486949A (en) * | 1989-06-20 | 1996-01-23 | The Dow Chemical Company | Birefringent interference polarizer |
US5612820A (en) * | 1989-06-20 | 1997-03-18 | The Dow Chemical Company | Birefringent interference polarizer |
US5235443A (en) * | 1989-07-10 | 1993-08-10 | Hoffmann-La Roche Inc. | Polarizer device |
US5319478A (en) * | 1989-11-01 | 1994-06-07 | Hoffmann-La Roche Inc. | Light control systems with a circular polarizer and a twisted nematic liquid crystal having a minimum path difference of λ/2 |
US5188760A (en) * | 1990-04-06 | 1993-02-23 | U. S. Philips Corporation | Liquid crystalline material and display cell containing said material |
US5103337A (en) * | 1990-07-24 | 1992-04-07 | The Dow Chemical Company | Infrared reflective optical interference film |
USRE34605E (en) * | 1990-07-24 | 1994-05-10 | The Dow Chemical Company | Infrared reflective optical interference film |
US5316703A (en) * | 1991-01-22 | 1994-05-31 | The Dow Chemical Company | Method of producing a lamellar polymeric body |
US5179468A (en) * | 1991-11-05 | 1993-01-12 | Gte Products Corporation | Interleaving of similar thin-film stacks for producing optical interference coatings |
US5540978A (en) * | 1992-02-25 | 1996-07-30 | The Dow Chemical Compny | All-polymeric ultraviolet light reflecting film |
US5294657A (en) * | 1992-05-15 | 1994-03-15 | Melendy Peter S | Adhesive composition with decorative glitter |
US5744534A (en) * | 1992-08-10 | 1998-04-28 | Bridgestone Corporation | Light scattering material |
US5269995A (en) * | 1992-10-02 | 1993-12-14 | The Dow Chemical Company | Coextrusion of multilayer articles using protective boundary layers and apparatus therefor |
US5448404A (en) * | 1992-10-29 | 1995-09-05 | The Dow Chemical Company | Formable reflective multilayer body |
US5568316A (en) * | 1992-10-29 | 1996-10-22 | The Dow Chemical Company | Formable reflective multilayer body |
US5793456A (en) * | 1993-01-11 | 1998-08-11 | U.S. Philips Corporation | Cholesteric polarizer and the manufacture thereof |
US5721603A (en) * | 1993-01-11 | 1998-02-24 | U.S. Philips Corporation | Illumination system and display device including such a system |
US5360659A (en) * | 1993-05-24 | 1994-11-01 | The Dow Chemical Company | Two component infrared reflecting film |
US5389324A (en) * | 1993-06-07 | 1995-02-14 | The Dow Chemical Company | Layer thickness gradient control in multilayer polymeric bodies |
US5486935A (en) * | 1993-06-29 | 1996-01-23 | Kaiser Aerospace And Electronics Corporation | High efficiency chiral nematic liquid crystal rear polarizer for liquid crystal displays having a notch polarization bandwidth of 100 nm to 250 nm |
US5882774A (en) * | 1993-12-21 | 1999-03-16 | Minnesota Mining And Manufacturing Company | Optical film |
US5962114A (en) * | 1993-12-21 | 1999-10-05 | 3M Innovative Properties Company | Polarizing beam-splitting optical component |
US5965247A (en) * | 1993-12-21 | 1999-10-12 | 3M Innovative Properties Company | Process for forming reflective polarizer |
US5629055A (en) * | 1994-02-14 | 1997-05-13 | Pulp And Paper Research Institute Of Canada | Solidified liquid crystals of cellulose with optically variable properties |
US5770306A (en) * | 1995-03-09 | 1998-06-23 | Dai Nippon Printing Co., Ltd. | Antireflection film containing ultrafine particles, polarizing plate and liquid crystal display device |
US5751388A (en) * | 1995-04-07 | 1998-05-12 | Honeywell Inc. | High efficiency polarized display |
US5686979A (en) * | 1995-06-26 | 1997-11-11 | Minnesota Mining And Manufacturing Company | Optical panel capable of switching between reflective and transmissive states |
US5699188A (en) * | 1995-06-26 | 1997-12-16 | Minnesota Mining And Manufacturing Co. | Metal-coated multilayer mirror |
US5825542A (en) * | 1995-06-26 | 1998-10-20 | Minnesota Mining And Manufacturing Company | Diffusely reflecting multilayer polarizers and mirrors |
US5767935A (en) * | 1995-08-31 | 1998-06-16 | Sumitomo Chemical Company, Limited | Light control sheet and liquid crystal display device comprising the same |
US5783120A (en) * | 1996-02-29 | 1998-07-21 | Minnesota Mining And Manufacturing Company | Method for making an optical film |
US5825543A (en) * | 1996-02-29 | 1998-10-20 | Minnesota Mining And Manufacturing Company | Diffusely reflecting polarizing element including a first birefringent phase and a second phase |
US5808794A (en) * | 1996-07-31 | 1998-09-15 | Weber; Michael F. | Reflective polarizers having extended red band edge for controlled off axis color |
US5940149A (en) * | 1997-12-11 | 1999-08-17 | Minnesota Mining And Manufacturing Company | Planar polarizer for LCD projectors |
US6157490A (en) * | 1998-01-13 | 2000-12-05 | 3M Innovative Properties Company | Optical film with sharpened bandedge |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9945127B2 (en) | 2010-09-08 | 2018-04-17 | 3M Innovative Properties Company | Above-deck roof venting article, system and methods |
US8915022B2 (en) | 2011-06-07 | 2014-12-23 | 3M Innovative Properties Company | System and method for management of a roof |
US9551818B2 (en) * | 2011-10-20 | 2017-01-24 | 3M Innovative Properties Company | Apodized broadband partial reflectors having differing optical packets |
US20140268346A1 (en) * | 2011-10-20 | 2014-09-18 | 3M Innovative Properties Company | Apodized broadband partial reflectors having differing optical packets |
US9562996B2 (en) | 2011-10-20 | 2017-02-07 | 3M Innovative Properties Company | Multilayer stack combinations with interleaved overlapping harmonics for wide visible infrared coverage |
US9228356B2 (en) | 2011-12-22 | 2016-01-05 | 3M Innovative Properties Company | Above-deck roof venting article |
WO2014070450A1 (en) | 2012-11-01 | 2014-05-08 | 3M Innovative Properties Company | Above-deck roof venting article |
US9502477B2 (en) | 2013-07-18 | 2016-11-22 | Samsung Display Co., Ltd. | Display apparatus having color saturation filter with layers of different refractive indexes |
US10429558B2 (en) * | 2013-09-30 | 2019-10-01 | 3M Innovative Properties Company | Polymeric multilayer optical film |
CN105593716A (en) * | 2013-09-30 | 2016-05-18 | 3M创新有限公司 | Polymeric multilayer optical film |
US11009638B2 (en) | 2013-09-30 | 2021-05-18 | 3M Innovative Properties Company | Polymeric multilayer optical film |
WO2015048624A1 (en) * | 2013-09-30 | 2015-04-02 | 3M Innovative Properties Company | Polymeric multilayer optical film |
US10948745B2 (en) | 2014-12-05 | 2021-03-16 | 3M Innovative Properties Company | Vision-protecting filter lens having organic polymer multilayer and neutral-density optical filter |
WO2016089695A1 (en) * | 2014-12-05 | 2016-06-09 | 3M Innovative Properties Company | Vision-protecting filter lens |
AU2015355331B2 (en) * | 2014-12-05 | 2018-03-29 | 3M Innovative Properties Company | Vision-protecting filter lens |
KR20200027968A (en) * | 2017-07-07 | 2020-03-13 | 도요보 필름 솔루션 가부시키가시야 | Multilayer laminated film |
KR102644128B1 (en) | 2017-07-07 | 2024-03-07 | 도요보 가부시키가이샤 | multi-layer laminated film |
WO2019073330A2 (en) | 2017-10-09 | 2019-04-18 | 3M Innovative Properties Company | Optical components and optical systems |
EP4332640A1 (en) * | 2022-08-29 | 2024-03-06 | Meta Platforms Technologies, LLC | Reflective polarizer with integrated anti-reflective coating |
Also Published As
Publication number | Publication date |
---|---|
WO1999036809A1 (en) | 1999-07-22 |
US6157490A (en) | 2000-12-05 |
KR100582973B1 (en) | 2006-05-24 |
EP1047963B1 (en) | 2003-11-26 |
KR20010034059A (en) | 2001-04-25 |
CN1288520A (en) | 2001-03-21 |
DE69913102D1 (en) | 2004-01-08 |
AU2109699A (en) | 1999-08-02 |
EP1047963A1 (en) | 2000-11-02 |
JP2002509280A (en) | 2002-03-26 |
JP4399113B2 (en) | 2010-01-13 |
BR9906907A (en) | 2000-10-10 |
CN1141604C (en) | 2004-03-10 |
DE69913102T2 (en) | 2004-08-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6157490A (en) | Optical film with sharpened bandedge | |
US6967778B1 (en) | Optical film with sharpened bandedge | |
JP4091978B2 (en) | Reflective polarizer with enhanced brightness | |
US7297393B2 (en) | Optical film | |
JP4130836B2 (en) | Reflective polarizer display | |
EP1051649B1 (en) | Multicomponent optical body | |
JPH09506837A (en) | Multilayer optical film | |
WO1999036804A1 (en) | Anti-reflective polymer constructions and method for producing same | |
JPH11508380A (en) | Transparent multilayer device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |