CN103124914B - The micro spectrometer of complex function diffraction optical element is focused on based on dispersion - Google Patents

Abstract

What the implementing of the present invention provided that one is referred to as " G Fresnel " can realize striated pattern and the device of Fresnel lens function simultaneously.We use PDMS Soft lithograph technology to be made for G Fresnel device.This device checks its quality by three-dimensional surface profile algoscopy.We confirm this device also by optical characteristics sign and focus on the dual-use function with dispersion simultaneously.This G Fresnel device may be used for developing micro spectrometer and the application of emerging various light fluids.We also provide with this diffraction optical device make miniature spectrometer implement design.Theoretical modeling result shows, the spectral resolution of the G Fresnel device of grade size can reach about 1 nanometer.Experiment has turned out a Proof of Concept G Fresnel spectrogrph and can reach the spectral resolution of Subnano-class.

Description

The micro spectrometer of complex function diffraction optical element is focused on based on dispersion

See related application

It is hereby stated that this application claims the priority of United States of America's NO.61/373,501 temporary patent application.This faces Time patent application submit on August 13rd, 2010, and be included into the application by quoting.

Research or the statement of technological development about federal funding

The present invention is supported by National Science Foundation No.DBI0649866, ECCS0547475 by government.Make negative phenanthrene The Fresnel lens of alunite ear mold is provided by OIDA Photonics Technology Access Program.OIDA PTAP It is to be subsidized by National Science Foundation and national defence forward position research project mechanism.According to the National Science Foundation cooperation with Cornell University Agreement No.0335765, country's nanosecond science and technology infrastructure network, related optical contour curve is measured at Pennsylvania State University's material Material institute nanometer processing laboratory is carried out.This invention is enjoyed certain right by government.

Background of invention

Inventive technique field

The instantiation of the present invention relates to having the diffraction optical element focused on dispersion incident illumination dual-use function, and multiple Make the mold components of this diffraction optical element, and miniature spectrometer based on this element.

Description of Related Art

Spectrogrph be one of most important and most widely used instrument in modern science and engineering (with reference to J.James, Spectrograph Design Fundamentals, Cambridge University Press, Cambridge, 2007). Its extensive application is had in various fields such as Materials Measurement, chemical detection and biomedical diagnostics.Working as in view of spectroscopy Critical role in the field that modern many develops rapidly and the portable electronic piece industry (mobile phone, notebook computer etc.) of prosperity are right The demand of the economical micro spectrometer that may be integrated in mobile electronic terminal future increases.

Although the performance of spectrogrph improves constantly, but separate optical element (collimating and collect curved mirror, diffraction grating) Use is the main cause causing conventional spectrometers heavy and expensive.Multiple trial has been carried out for this problem scientific research personnel, Single matrix grating is such as utilized collimation and the acquisition function of concave mirror to be combined with diffraction grating function (with reference to C.Palmer, and E.Loewen, Diffraction grating handbook (Newport Corporation, 2005)).Another kind goes out recently Existing method is volume holographic spectrogrph, it utilize volume holographic instead of into optical slits, optically focused Qu Jing and grating (with reference to C.Hsieh, O.Momtahan, A.Karbaschi, andA.Adibi, Appl.Phys.B91,1 (2008)).Other trials include waveguide optical grating With methods such as integrated micro-mechanical systems.

Invention brief introduction

(such as Fresnel is saturating by high numerical aperture lens function for diffraction optical element involved by the instantiation of the present invention Mirror) and diffraction grating integrate.This element can be bending or planar structure.We combine grating and phenanthrene by this The element of alunite ear lens is referred to as G-Fresnel parts, it is also possible to is referred to as G-Fresnel lens, or is simply referred as G- Fresnel.Other implementation methods can utilize other diffraction light device, such as, but is not limited only to, monoplanar surface structure or novel G-Fresnel device needed for micro spectrometer.

Further, the present invention relates to polydimethylsiloxane (polydimethylsiloxane, PDMS) Soft lithograph Process this device.The function of grating and Fresnel lens is integrated in a multiple device by PDMS printing.Saturating compared to tradition Mirror and concave mirror, the f-number (f/#) of G-Fresnel lens is less so that it is potential make less than application conventional art Spectrogrph.It addition, the surface texture properties of G-Fresnel makes by replicating the low cost large-scale production of template, become can Energy.

Accompanying drawing explanation

Fig. 1 illustrates the focusing dispersion complex function of transmission-type G-Fresnel (T-G-Fresnel).

Fig. 2 is G-Fresnel Making programme figure, wherein: PDMS prepolymer is poured on Fresnel lens surface by (a)；(b) warp Cross in-situ solidifying form negative Fresnel lens die and can take off；C PDMS prepolymer is clipped in negative Fresnel lens die by () And between grating；Transmission-type G-Fresnel is formed after (d) solidification；E () is by anti-in the plating of transmission-type G-Fresnel grating side Penetrate film and can obtain reflection-type G-Fresnel；F () bears Fresnel lens die finished product photo；G () transmission-type G-Fresnel becomes Product photo；(h) reflection-type G-Fresnel finished product photo (grating is towards upper).

Fig. 3 is given by negative Fresnel mould and the Fresnel of transmission-type G-Fresnel device that optical profilometer is measured The surface profile of mirror one side.A () and (b) is negative Fresnel mould and the Fresenl mirror one of transmission-type G-Fresnel device respectively The surface profile 3-D view of face mid portion；C () and (d) is negative Fresnel mould and transmission-type G-Fresnel device respectively Fresenl mirror one side marginal portion surface profile 3-D view；(e) mould and transmission-type G-Fresnel device mid portion Radial direction apparent height contrasts；(f) mould and transmission-type G-Fresnel device marginal portion radial direction apparent height pair Ratio.

Fig. 4 provides optical characteristic test result: (a) experimental provision schematic diagram；B () collimation super continuous spectrums light passes through T-G- The focusing diffraction pattern produced after Fresnel；C diffraction pattern that () grating produces；The intensity obtained under (d) several exemplary wavelength Scattergram (486.0nm, 525.3nm, 564.7nm, 604.1nm, 643.5nm and682.8nm).

Fig. 5 illustrates the demonstration spectrometer design containing transmission-type G-Fresnel or reflection-type G-Fresnel device Figure.

Fig. 6 is that computer generates (a) double side micro G-Fresnel surface texture side view (mid portion) and (b) list Face miniature G-Fresnel surface texture sectional view.

Fig. 7 (a) schematic diagram gives the geometry used by simulation.Fig. 7 (b) display three kinds of exemplary wavelength (490nm, 500nm, 510nm) under calculate the First order diffraction pattern intensity distributions of gained；Focal position can matching by a dotted line.Fig. 7 (c) Show and optimize the multiple wavelength placed on gained position received by an inclination virtual detector according to Fig. 8 (c) experimental result (496nm-504nm) point spread function result of calculation.

Fig. 8 (a) is G-Fresnel spectrometer architecture schematic diagram.Fig. 8 (b) illustrates the G-Fresnel fixed is installed Device.Fig. 8 (c) gives the argon laser part light measured respectively by G-Fresnel spectrogrph and commercial spectroanalysis instrument Spectrum.Pixel-wavelength relationship after Fig. 8 (d) calibration.

Fig. 9 shows the transmitted spectrum by (a) laser rays light filter with (b) long wave light filter measuring gained.

The concrete introduction of invention

The instantiation of the present invention provides has grating and the G-Fresnel device of Fresnel lens dual-use function.I Prove that G-Fresnel can separate different spectral component therein while to point source imaging by theory analysis.Two-sided Transmission and reflection-type G-Fresnel device can pass through PDMS Soft lithograph fabrication techniques.We utilize 3D surface profile bent simultaneously The quality of inspection finished product measured by line.The focusing dispersion dual-use function of this device is demonstrated finally by optical characteristic measurement experiment. The potential duplication by surface texture of the present invention carries out large-scale production, and reaches the least f/#, and this makes G-Fresnel open Open the new direction of economic minitype portable spectrogrph development.

The optical element that instantiation of the present invention provides, by the Fresenl mirror side being made up of cutting of much warbling with one heart, is carved Separation is from inside outwards gradually reduced.This element also includes the grating side being made up of a large amount of line style cuttings.In general these Cutting is parallel to each other.

In some instantiations, this element needs one side or double-sided coating or surface to process.At a preferred example In can grating side plate reflectance coating.Other kind film transmissive characteristic frequency light.Plated film is it may be that but be not limited only to, such as Metallic film, liquid metal film and dielectric substance plated film.

This type of spectrogrph can be applied to scientific research field or as consumer electronics product.Such as, when someone has dinner Can detect with it and whether food contains the anaphylactic composition of meeting.This product can also grind with space science for astronomy The polytype miniaturization spectral instrument of offer is provided.This device can also be used in the authenticity of file and bank note, chemistry Material detects, and the field such as biomedicine.

Light stream device based on PDMS Soft lithograph technology can be integrated into easily in view of this device (G-Fresnel) On, it is believed that G-Fresnel can find infusive application (about light fluid at the emerging field of light stream device research Discussion, with reference to Y.Fainman, L.P.Lee, D.Psaltis and C.Yang, Optofluidics-Fundamentals, Devices and Applications (McGraw-Hill, 2010)), such as chip spectrum analysis.

Other examples provide the method manufacturing diffraction optics components and parts, including, prepolymer is copied in Fresnel lens table Face, solidification the first prepolymer described, thus make a negative Fresnel lens die.Solidification can be carried out in position.Then Two kinds of prepolymers are positioned between this negative Fresnel lens die and a grating, described the second prepolymer cures and form one and spread out Penetrate optics.

Selection for prepolymer has many clocks option.Such as, the first prepolymer can be polydimethylsiloxane, the Two kinds of prepolymers can be polydimethylsiloxane.The constituent material of G-Fresnel can also be other solid-state materials, such as Glass, plastics or other polymer such as SU8, PMMA.It also can be made up of biopolymer, such as silk (reference F.G.Omenetto and D.L.Kaplan, " New Opportunities for an Ancient Material, " Science329,528-531 (2010) .).It can also be by the liquid adjustable, dynamic in optical flow systems structure or stream Body material is constituted.

This invention is particularly suitable for the application in light fluid field.Such as can be by said method in G-Fresnel device Fresnel face and grating face add a cavity.Such as this can by by negative Fresnel lens die and negative grating mold it Between be implemented separately by space.Another one method is to synthesize Fresnel lens device and grating device at G-Fresnel device The same side of part, and the opposite side of this device is plane.A cavity can be formed between two faces of this optics.

This cavity can fill various fluid after being formed wherein, including sky gas and water, ethanol, gas recombination thing or element, Or other any fluids may selected by those skilled in the art.By this way, the attribute of single G-Fresnel is permissible Therefore the optical path changed by this optical element by changing fluid composition is conditioned, to meet the need of specific application Want.

In the further embodiment of the present invention, optical element can include multiple space.For example, this optical element Fresnel assembly, opposite side may be had in side to have grating assembly, and these two parts are separated by a space, this space can be entered One step is divided into two separate spaces, and one contacts with Fresnel face, and another contacts with grating face.This permission is right The fluid of optical element not homonymy carries out separate adjustment.

The realization of this invention (but need not necessarily) can provide many advantages.For example, such device can by focus on, The multi-functional of dispersion and collection is integrated on a thin-film device.Second, such device can have the least f/#, thus Realize miniaturized system.3rd, such device can be realized by picture on surface, thus low for replicate based on main mould Cost production in enormous quantities provides possibility.Certainly, unless claims requirement, need not necessarily realize all in certain device These advantages.

In order to make it have the dual-use function of lens and grating, transmission (or reflection) coefficient of this diffraction optical device should This be

$t(x,y)\∝\mathrm{\η}\left(\mathrm{\λ}\right)e^{-j\frac{\mathrm{\π}}{\mathrm{\λF}}(x^2+y^2)}{e}^{j\frac{2\mathrm{\π}}{\mathrm{\Λ}}x}---\left(1\right)$

Wherein λ is wavelength, and F corresponds to the focal length of this wavelength X, and Λ is screen periods, and η represents the diffraction efficiency of device. Owing to formula (1) contains Fresnel lens transmission coefficient and the product of striated pattern transmission coefficient, this diffraction optical element will be Description below is referred to as G-Fresnel.Consider one now and be positioned at (x₀, y₀,-d) and the point source of (such as Fig. 1 (a)).Paraxial Under approximation, the field distribution after G-Frenel can be calculated by following means of Fresnel diffraction (with reference to J.W.Goodman, Fourier optics introduction, Roberts&Company, Englewood, Colorado, 1996):

$f(x,y,z)\∝\∫\∫e^{j\frac{\mathrm{\π}}{\mathrm{\λd}}[{(x^{\′}-x_0)}^2+{(y^{\′}-y_0)}^2]}p(x^{\′},y^{\′})e^{-j\frac{\mathrm{\π}}{\mathrm{\λF}}(x^{\′2}+y^{\′2})}{e}^{j\frac{2\mathrm{\π}}{\mathrm{\Λ}}{x}^{\′}}{e}^{j\frac{\mathrm{\π}}{\mathrm{\λz}}[{(x-x^{\′})}^2+{(y-y^{\′})}^2]}{\mathrm{dx}}^{\′}{\mathrm{dy}}^{\′}$

$\∝\∫\∫e^{j\frac{\mathrm{\π}}{\mathrm{\λ}}(\frac{1}{d}-\frac{1}{F}+\frac{1}{z})(x^{\′2}+y^{\′2})}p(x^{\′},y^{\′})e^{-j2\mathrm{\π}[(\frac{x_0}{\mathrm{\λd}}-\frac{1}{\mathrm{\Λ}}+\frac{x}{\mathrm{\λz}})x^{\′}+(\frac{y_0}{\mathrm{\λd}}+\frac{y}{\mathrm{\λz}})y^{\′}]}{\mathrm{dx}}^{\′}{\mathrm{dy}}^{\′}---\left(2\right)$

Wherein (x y) is the pupil function of G-Fresnel to p.May certify that, the geometry imaging of point source will be positioned at x_i, y_i, And coordinate meets relation L),

$x_i=-\frac{L}{d}{x}_0+L\frac{\mathrm{\λ}}{\mathrm{\Λ}},$ $y_i=-\frac{L}{d}{y}_0,$ $L=\frac{\mathrm{Fd}}{d-F}=\frac{d}{\mathrm{\λd}/{\mathrm{\λ}}_0{F}_0-1}$ (3)

λ₀And F₀It is respectively design wavelength and the design focal length (note: λ F=λ of G-Fresnel₀F₀；With reference to Francis T.S.Yu, An Introduction to Diffraction, Information Processing, and Holography (The MIT Press, 1973)；K.Shi, Supercontinuum Imaging and Spectroscopy, Penn State Doctoral Dissertation, 2007.).Therefore, a G-Fresnel can be right while to a point source imaging Its different wavelength components carries out dispersion.Following x is understood from formula (3)_iAnd the linear relationship establishment between L:

$L=\frac{\mathrm{\Λd}}{{\mathrm{\λ}}_0{F}_0-x_0\mathrm{\Λ}}{x}_i-\frac{{\mathrm{\λ}}_0{F}_{0}d}{{\mathrm{\λ}}_0{F}_0-x_0\mathrm{\Λ}}$ (4)

In other words, the focus of different wave length is all distributed in a slope and isStraight line on.

Noticing that formula (1) is rewritable is

$t(x,y)\∝\mathrm{\η}\left(\mathrm{\λ}\right)e^{j\frac{\mathrm{\π}}{\mathrm{\λF}}{x}_c^2}{e}^{-j\frac{\mathrm{\π}}{\mathrm{\λF}}[{(x-x_c)}^2+y^2]}$ (5)

Wherein x_c=λ F/ Λ.In other words, a G-Fresnel device is equivalent to an axle center and is moved to (x_c, 0) from Axle Fresnel lens.But due to the circular grating cycle of Fresnel lens be warble and be inversely proportional to from lens centre away from From, work as x_cWhen value is the biggest, the making of this off-axis Fresnel lens just becomes more difficult.Such as, it is contemplated that a grating week Phase Λ～λ, active centre displacement is x_c～F, this is accomplished by a big Fresnel lens with sub-wavelength details.One G- Fresnel device can also be interpreted by a diverging spherical reference wave and a thin holography assembling signal wave record, Can be expressed as following formula:

$t_H\∝{|e^{j\frac{\mathrm{\π}}{\mathrm{\λl}}(x^2+y^2)}+e^{-j\frac{\mathrm{\π}}{\mathrm{\λl}}[{(x-x_c)}^2+y^2]}|}^2=2+\{e^{-j\frac{\mathrm{\π}}{\mathrm{\λl}}(x^2+y^2)}{e}^{-j\frac{\mathrm{\π}}{\mathrm{\λl}}[{(x-x_c)}^2+y^2]}+c.c.\}$

$=2+[e^{-j\frac{\mathrm{\π}}{\mathrm{\λl}}{x}_c^2}{e}^{-j\frac{2\mathrm{\π}}{\mathrm{\λl}}(x^2+y^2)}{e}^{j\frac{2\mathrm{\π}}{\mathrm{\λl}/x_c}x}+c.c.]$ (6)

In formula (6) bracket, Section 1 (the second row) is at F=l/2 and Λ=λ //x_cUnder conditions of be a G-Fresnel device Part.But, a thin holography contains conjugation item (formula (6)) equally, and has limited diffraction effect under normal circumstances Rate.

Device fabrication and sign

Example 1 PDMS Soft lithograph makes

In this example, a straightforward procedure being made G-Fresnel device by PDMS Soft lithograph is we described. About " J.A.Rogers, R.G.Nuzzo, " Recent progress in soft seen from the general discussion of Soft lithograph Lithography, " Materials Today, 8,2,50-56 (2005) ".Making step is shown in Fig. 2. briefly, first uses PDMS pre-polymer mixture (Dow Corning, Sylgard-184PDMS, gum base: curing additive part by weight is 10: 1) waters Cover on the surface of a Fresnel lens (as shown in Fig. 2 (a), Fresnel lens is in lower section).This prepolymer is at room temperature put After putting two days in-situ solidifyings, a negative Fresnel lens die with regard to molding and can be stripped (such as Fig. 2 (b)).Fig. 2 (f) Illustrate the negative Fresnel mould that this kind of method of a use makes.

Next PDMS prepolymer is clipped in negative Fresnel mould and grating (Newport, a 300lines/ by us Mm) (such as Fig. 2 (c)) between.This grating is placed on a linear moving platform by fixing, so can adjust between two moulds The thickness of distance, i.e. device.After in room temperature two solidify, a transmission-type G-Fresnel (T-G-can be produced Fresnel) device (such as Fig. 2 (d)).Fig. 2 g is the photo of the T-G-Fresnel device made by the method.Reflection-type G- Fresnel (R-G-Fresnel) device can make, such as Fig. 2 by T-G-Fresnel grating face is plated one layer of thin reflectance coating Shown in (e).Fig. 2-h illustrates the photo of R-G-Fresnel, and its grating face uses sputter coating system (Kurt Lesker CMS-18/RF) the thick golden film of one layer of 50nm has been plated.

Any plated film can be used, as long as it can be attached at PDMS, (or other make G-Fresnel's Material) and light can be reflected at applicable wave band.These are thin including, but not limited to such as metallic film, liquid metals and dielectric Film etc..Plated film needs can be reflection-type, transmission-type or partially reflective/transmission-type according to different application.This plated film is same Filter function can be provided.At not coplanar or diverse location, a G-Fresnel may have the different of two or more Plated film.

Although demonstration provided herein is the manufacture method with compacting prepolymer, G-Fresnel can be by a lot of method systems Make.These methods include but are not limited to etching (such as, Soft lithograph, focused particle beam etching, photoetching or electron beam lithography), gold Hard rock turning, rapid laser carving, holography, liquid G-Fresnel based on light fluid method make and use impressing or Nano printing method carries out mass production.

In order to check the G-Fresnel device quality made by PDMS Soft lithograph, we used profilograph (WYKONT1100) three-dimensional surface profile in Fresnel face in negative Fresnel mould and T-G-Fresnel device is measured.Measure Result is showed in Fig. 3.Wherein (a) and (b) corresponds respectively to negative norm tool core and (G-Fresnel device) Fresnel The typical three-dimensional surface profile in face.C () and (d) then corresponds respectively to marginal portion.Fig. 3 (e) and (f) show further two The center and peripheral part of individual device surface height profile in axial direction.For ease of comparing, these figure lines are carried out Suitably translation is to be mutually aligned.As would be expected, the height in the Fresnel face of negative Fresnel mould and T-G-Fresnel device Profile demonstrates anti-correlation.It is obvious that we obtain the high-quality pattern copy from mould to G-Fresnel device.

It has to be noted that G-Fresnel has the advantage of many Fresnel lenses and grating, but it is only never Both simple combination.On the contrary, a G-Fresnel can be realized by monoplanar surface relief fabric, and this one side rises Volt distribution is both unlike a Fresnel lens, also unlike a grating.The realization of this design is also low one-tenth based on single mold This batch production provides probability.

Realize after the key request of an optical spectrometer is to be mapped to dispersion before a diverging wave being derived from slit Convergent wave before and detect.In order to realize miniature spectrometer, need single diffraction optical element to complete these functions.I The G-Fresnel that proposes combine the character of grating and Fresnel lens, it is provided that the simplest method completes this Task.Although grating has been widely used in spectral instrument, but the use of Fresnel lens is the rarest.In order to research and develop A kind of high-resolution miniature spectrometer, should keep grating diaphragm size to reduce the longitudinal size of system as far as possible simultaneously.We carry In the design gone out, G-Fresnel provides large-numerical aperture and little f/#, is therefore especially suitable for this purpose.

It addition, we utilize by femto-second laser pulse high non-linear photon crystal optical fiber (with reference to J.C.Knight, T.A.Birks, P.S.Russell and D.M.Atkin, " All-silica single-mode optical fiber With photonic crystal cladding, " Opt.Lett, 21,1547-1549 (1996)) in produce super continuous in vain Spectrum is (with reference to J.K.Ranka, R.S.Windeler andA.J.Stentz, " Visible continuum generation in air-silica microstructure optical fibers with anomalous dispersion At800nm, " Opt.Lett.25,25-27 (2000)), the optical property to T-G-Fresnel type device (as shown in Fig. 2 (g)) Characterized.Fig. 4 (a) is the schematic diagram of this experimental system.Briefly, the super continuum light bundle (diameter :～10 of a branch of collimation Millimeter) incide on T-G-Fresnel.Diffraction terms at different levels is contained after the light beam of T-G-Fresnel transmission focuses on, as Shown in Fig. 4 (b).The speck that center focuses on is corresponding to Zero-order diffractive, and the light beam being i.e. directed through, the rainbow band on both sides is the most right Should in high-order diffraction (± 1, ± 2 ..., etc.).In contrast, if this collimated super continuum light bundle is directly incident on grating, It is only capable of producing unfocused diffraction pattern, as shown in Fig. 4 (c).

In order to study the focusing dispersion double grading of this device deeper into ground, we use multimode fibre as probe.Should After probe is placed on T-G-Fresnel, and under the control of motorized translation platform, carry out two-dimensional scan (the most vertically with a certain Laterally, as shown in Fig. 4 (a)).Scanning area is 4mm (laterally) × 25mm (axially).The signal of multimode fibre output is by spectrogrph Detection (PI/Acton SpectraPro2500: the ccd detector PI/Acton Spec-10 equipped with cooling down through liquid nitrogen).Fig. 4 D () shows the intensity distributions measuring multiple wavelength component.This figure illustrates that the component of different wave length is through T-G-Fresnel device Part focuses on and propagates in different directions.Fig. 5 is an example of spectrogrph based on the present invention, its main optical element Include an entrance slit, a G-Fresnel device and a line style detector array.The G-Fresnel of reflection-type Device can realize greater compactness of spectrometer design.

We test result indicate that, this G-Fresnel device has the character of grating and Fresnel lens simultaneously, therefore Light can be carried out dispersion and focusing simultaneously.Note, according to formula (4), when using the super continuum light of quasi-value (d → ∞), different The focal track of wavelength is parallel to optical axis (z), and this is consistent with the measurement result shown in Fig. 4 (d).

Example 2 theoretical resolution

In example 2, it is contemplated that an imaginary transmission-type G-Fresnel diffraction optical element.In order to realize dispersion and The dual-use function focused on, transmitance can be by formula T (x, y)=T_G(x, y) T_F(x y) expresses, wherein T_G(x, y), T_F(x, y) respectively Represent the grating assembly in this device and the transmitance of Fresnel lens assembly.Grating and Fresnel lens all can be by surface undulations Pattern realizes.Their transmitance expression formula is given by:

$T_i(x,y)=e^{j\frac{2\mathrm{\π}}{\mathrm{\λ}}(n-1)h_i(x,y)}$ (i=GorF) (7)

Wherein λ is wavelength, and n is backing material specific refractivity, h_GAnd h_FFor respective apparent height distribution function.This G-Fresnel device can be realized by following two mode: grating is individually positioned in the both sides that device is relative with Fresnel lens (double-flanged end)；Or, they superpositions are placed on the same side (single side type) of device.It is bilateral that Fig. 6 shows that computer produces Type G-Fresnel structure (Fig. 6 (a)) and the single side type structure (surface profile of Fig. 6 (b) core.Wherein single side type is tied Structure, its apparent height is grating and the superposition of Fresnel lens each apparent height, i.e. h (x, y)=h_G(x, y)+h_F(x, y).

In the simulation of this example calculates, the profile function h of grating_G(x y) is set to every millimeter (mm) and has 200 quarters The preiodic type sawtooth of groove is wavy.Fresnel lens assembly in the structure shown here has continuous topography.In design wavelength lambda₀= During 500nm, its focal length is f₀=1cm.Its a diameter of 4.096mm (corresponding f/#～2.4).The one of this G-Fresnel device Individual important advantage is that can realize little f/# in thin-film component, and the realization for microminiature spectrogrph provides possibility.Fei Nie The apparent height distribution of ear lens subassembly is given by

$h_F(x,y)=\frac{m{\mathrm{\λ}}_0-(\sqrt{x^2+y^2+f_0^2}-f_0)}{n-1}$

$((m-1){\mathrm{\&lambda;}}_0\&le;\sqrt{x^2+y^2+f_0^2}-f_0<m{\mathrm{\&lambda;}}_0)$ (8)

Wherein, m=1,2,3...M, number for Fresnel zone.

For the accessible spectral resolution of qualitative assessment, our imagination has a single color point light source to be placed on from G- (i.e. 2f at Fresnel device 2cm₀), see Fig. 7 (a).Light field U of (z=0) after G-Fresnel₀(x y) is given by

$U_0(x,y)\&Proportional;\frac{\exp \left(\mathrm{jkr}\right)}{r}P(x,y)T(x,y)$ (9)

$r=\sqrt{{\left({2f}_0\right)}^2+x^2+y^2}$ (10)

Wherein (x y) is pupil function to P.Light field U after G-Fresnel₁(x, y, z) can be former according to Huygens's Fresnel Reason is calculated.

$U_1(x,y,z)\&Proportional;\frac{1}{\mathrm{j\&lambda;}}\underset{\mathrm{\&Sigma;}}{\&Integral;\&Integral;}{U}_0(\mathrm{\&xi;},\mathrm{\&eta;})\frac{\exp \left({\mathrm{jkr}}_{01}\right)}{r_{01}}\cos \mathrm{\&theta;d\&xi;d\&eta;}$ (11)

$r=\sqrt{{(x-\mathrm{\&xi;})}^2+{(y-\mathrm{\&eta;})}^2+z^2}$ (12)

$\cos \mathrm{\&theta;}=z/r_{01}$ (13)

We first calculate this point source several picture peripheral region light distribution (1.9mm≤x≤2.1mm and 18.7mm≤z≤21.3mm, is shown in the rectangle of labelling in Fig. 7 (a)).Fig. 7 (b) gives three different wave lengths (490nm, 500nm And 510nm) the first-order diffraction pattern (superposition of y direction) at place.We can be clearly seen that focusing and the color of designed G-Fresnel Dissipate double grading.It is dx/dz=λ that the focus that different wave length is corresponding falls at slope₀f₀On one oblique line of/(Λ d)=0.5, wherein D=2f₀, Λ is screen periods.

Assuming that a detector array (pel spacing is 5 μm) is placed along this oblique line, as shown in Fig. 7 (b).Keep slope not While change, intercept is done and optimizes, can be calculated be positioned on the detector of hypothesis multiple wavelength (from 496nm to 504nm, Be divided into 1nm) point spread function, and be plotted in Fig. 7 (c).It can be seen that this G-Fresnel achieves close to 1nm from Fig. 7 (c) Spectral resolution.It should be pointed out that, that similar analysis can apply to reflection-type G-Fresnel device, this device can be rolled over Fold light path and obtain greater compactness of design.

Example 3 miniature spectrometer

Example 3 report concept prove experimental studies results, to prove spectrogrph based on G-Fresnel feasibility and Function.In this instance, we utilize PDMS Soft lithograph to prepare bilateral transmission-type G-Fresnel device prototype.PDMS prepolymer Mixture is poured into (diameter 2in. (5cm) on Fresnel lens；At design wavelength 821nm, focal length is 100mm).Pass through After solidification, obtain Fresnel minus lens mould.Then, we PDMS pre-polymer mixture is clipped in Fresnel minus lens mould and Between one diffraction grating (THORLABS GR25-0310, every millimeter of 300 lines).At the room temperature in-situ solidifying of lower 48 hours Reason, just prepared a bilateral transmission-type G-Fresnel device, as shown in Fig. 8 (b), device area be about 1in. × 1in.(2.54cm×2.54cm)。

It is structured on optical table after the spectrogrph of one conceptual proof, as shown in Fig. 8 (a).This device includes One entrance slit, G-Fresnel device (see Fig. 8 (b)), and a CMOS line style imageing sensor being obliquely installed (HamamatsuS8378) to adapt to the position of different wave length focus.Incident illumination, after slit, is received by G-Fresnel device Collection, dispersion and focusing, and form spectral distribution on the image sensor.Then, by the data acquisition equipment of periphery component interconnection (National Instruments, PCI-6251) carries out numeral conversion to detectable signal, and through National Instruments LabVIEW software is analyzed.For calibration spectrum, by the argon laser (Melles of a branch of multi-wavelength Griot532-GS-A01) focus to the entrance slit of this device, and its spectrum is measured.

By comparing respectively by this G-Fresnel type spectrogrph (see Fig. 8 (c)) and Tianwan businessman's spectroanalysis instrument The normalization spectrum that (ANDOAQ-6315E, spectral resolution is 0.5nm) obtains, calibrates four shown in Fig. 8 (c) peak, The calibration of pixel wavelength relationship can be realized.This relation can be by cubic polynomial Function Fitting (see Fig. 8 (d)).It is worth note Meaning, the full width at half maximum (FWHM) from Fig. 8 (c) is it can be seen that this spectrogrph has the spectral resolution of sub-nanometer scale.

Afterwards, we utilize this calibrated G-Fresnel type spectrogrph to characterize laser line filter (THORLABSFL488-10, CWL=488 ± 2nm, FWHM=10 ± 2nm) and long pass filter (CHROMAHQ485LP). To this end, we irradiate optical filter with beam of white light light source (ROI150Illuminator).It is focused in entrance narrow through light Seam.Fig. 9 (blue curve) is the normalization transmission spectrum of laser line filter and the long pass filter recorded through this spectrogrph.With Time, as a comparison, we also use commercial high-resolution spectrometer (PI/Acton SpectraPro2500, spectral resolution: 0.09nm) record filter plate through spectrum (red curve), the CCD camera that this spectrogrph cools down equipped with liquid nitrogen.Measured knot Fruit meets preferably from each other, except the point spread function that recorded by this G-Fresnel type spectrogrph has one slow at long wave The afterbody (see Fig. 8 (c)) of decay.The afterbody of this slow-decay result in some obvious errors, as shown in Figure 9.This is likely to It is to introduce aberration due to this G-Fresnel and the possible flaw that manufactures causes.We can be by improving the accuracy of manufacture Process with later data and reduce this error.

The above-mentioned any file quoted all passes through to quote to include in this.Including in of they can not illustrate that they are to the present invention Important or any relevant prior art.

Claims (18)

1. a diffraction optical device, comprises:

Fresnel lens side: multiple cannelure of warbling with one heart is carved with in this face, and cutting spacing is outwards successively decreased by center；And

Grating side: multiple linear cutting is carved with in this face；

The phase function of this diffraction optical device comprises a radial second PHASE DISTRIBUTION item and an one-dimensional linear PHASE DISTRIBUTION , described diffraction optical device has focusing incident light wave and the double grading of dispersion different wave length simultaneously；It is a diameter of 4.096mm。

Diffraction optical device the most according to claim 1, there is plated film described grating side.

Diffraction optical device the most according to claim 1, there is plated film described Fresnel lens side.

Diffraction optical device the most according to claim 3, the plated film of described Fresnel lens side is metal coating.

Diffraction optical device the most according to claim 1, its side is coated with liquid metal film, so that this device becomes anti- Emitting diffraction optical device.

Diffraction optical device the most according to claim 1, wherein between Fresnel lens side and grating side at least Close isolation space for one, and each is closed and optionally contains a kind of fluent material in isolation space, changes at least a part of which The character of a kind of fluent material or fluent material all can make the performance of this diffraction optical device change.

Diffraction optical device the most according to claim 6, containing a kind of fluent material in described closing isolation space.

8. a spectrogrph, comprises a slit, a diffraction optical device, and a detector array, wherein, described diffraction Optics comprises:

Fresnel lens side: multiple cannelure of warbling with one heart is carved with in this face, and cutting spacing is outwards successively decreased by center；And

Grating side: multiple linear cutting is carved with in this face；

The phase function of this diffraction optical device comprises a radial second PHASE DISTRIBUTION item and an one-dimensional linear PHASE DISTRIBUTION , described diffraction optical device has focusing incident light wave and the double grading of dispersion different wave length simultaneously；It is a diameter of 4.096mm；

Incident illumination is after slit, by the collection of described diffraction optical device, dispersion and focusing, then by being arranged on the different ripple of adaptation The detector array detection of long focal position.

Spectrogrph the most according to claim 8, its diffraction optical device does not plate reflectance coating, the diverging light sent from slit By dispersion and focusing while that ripple being after this diffraction optical device, thus different wave length separately and is gathered along different wave length then The detector array detection that burnt track is placed.

Spectrogrph the most according to claim 8, the grating side of its diffraction optical device is coated with reflectance coating, sends out from slit Go out dissipates light wave after diffraction optical device reflects simultaneously by dispersion and focusing, thus different wave length by separately and then by Detector array detection along the track placement that different wave length focuses on.

11. spectrogrphs according to claim 8, this spectrogrph is by by diffraction optical device and at least one portable smooth device Part or electronic installation are integrated and realize miniaturization.

The manufacture method of diffraction optical device described in 12. claim 1, comprises:

A) the first prepolymer is poured on the surface of a Fresnel lens；

B) make the first prepolymer above-mentioned solidify in position, thus form a negative Fresnel lens die；

C) the second prepolymer is placed between negative Fresnel lens die and a grating；And

D) by above-mentioned the second prepolymer cures, thus a diffraction optical device is formed.

13. manufacture methods according to claim 12, the first prepolymer used in it is polydimethylsiloxane.

14. manufacture methods according to claim 12, the second prepolymer used in it is polydimethylsiloxane.

15. manufacture methods according to claim 12, the first prepolymer and the second prepolymer used in it are equal For polydimethylsiloxane.

16. 1 kinds of diffraction optical devices, its diffraction grating and fresnel structure on the same side, comprise:

First side and the second side, above-mentioned first side comprises multiple Fresnel and warbles with one heart cannelure, wherein cutting spacing by The heart outwards successively decreases, and the multiple linear cutting of raster pattern；Above-mentioned second side is plane；

The phase function of this diffraction optical device comprises a radial second PHASE DISTRIBUTION item and an one-dimensional linear PHASE DISTRIBUTION , this diffraction optical device has focusing incident light wave and the double grading of dispersion different wave length simultaneously；It is a diameter of 4.096mm。

17. diffraction optical devices according to claim 16, in its first side and the second side, at least there is plated film side.

18. 1 kinds of spectrogrphs, comprise: a slit, a diffraction optical device, and a detector array, wherein, described in spread out Penetrate optics to comprise:

First side and the second side, above-mentioned first side comprises multiple Fresnel and warbles with one heart cannelure, wherein cutting spacing by The heart outwards successively decreases, and the multiple linear cutting of raster pattern；Above-mentioned second side is plane；

The phase function of this diffraction optical device comprises a radial second PHASE DISTRIBUTION item and an one-dimensional linear PHASE DISTRIBUTION , this diffraction optical device has focusing incident light wave and the double grading of dispersion different wave length simultaneously；It is a diameter of 4.096mm；

Incident illumination is after slit, by the collection of described diffraction optical device, dispersion and focusing, then by being arranged on the different ripple of adaptation The detector array detection of long focal position.