WO2001006915A1 - A radiation probe and detecting tooth decay - Google Patents
A radiation probe and detecting tooth decay Download PDFInfo
- Publication number
- WO2001006915A1 WO2001006915A1 PCT/GB2000/002849 GB0002849W WO0106915A1 WO 2001006915 A1 WO2001006915 A1 WO 2001006915A1 GB 0002849 W GB0002849 W GB 0002849W WO 0106915 A1 WO0106915 A1 WO 0106915A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- radiation
- probe
- tooth
- thz
- assembly according
- Prior art date
Links
- 239000000523 sample Substances 0.000 title claims abstract description 319
- 230000005855 radiation Effects 0.000 title claims abstract description 296
- 208000002925 dental caries Diseases 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 57
- 238000006243 chemical reaction Methods 0.000 claims abstract description 36
- 238000003384 imaging method Methods 0.000 claims abstract description 29
- 208000028169 periodontal disease Diseases 0.000 claims abstract description 20
- 230000005670 electromagnetic radiation Effects 0.000 claims abstract description 9
- 230000004044 response Effects 0.000 claims abstract description 8
- 238000004891 communication Methods 0.000 claims abstract description 3
- 210000003298 dental enamel Anatomy 0.000 claims description 94
- 239000000835 fiber Substances 0.000 claims description 66
- 210000000988 bone and bone Anatomy 0.000 claims description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- 239000006185 dispersion Substances 0.000 claims description 27
- 239000013078 crystal Substances 0.000 claims description 24
- 230000000694 effects Effects 0.000 claims description 20
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims description 16
- 230000001678 irradiating effect Effects 0.000 claims description 16
- 238000012545 processing Methods 0.000 claims description 13
- 230000009021 linear effect Effects 0.000 claims description 12
- 241000894006 Bacteria Species 0.000 claims description 11
- 210000004369 blood Anatomy 0.000 claims description 10
- 239000008280 blood Substances 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 claims description 8
- 241001465754 Metazoa Species 0.000 claims description 7
- 230000017531 blood circulation Effects 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 239000010703 silicon Substances 0.000 claims description 5
- XTWYTFMLZFPYCI-KQYNXXCUSA-N 5'-adenylphosphoric acid Chemical compound C1=NC=2C(N)=NC=NC=2N1[C@@H]1O[C@H](COP(O)(=O)OP(O)(O)=O)[C@@H](O)[C@H]1O XTWYTFMLZFPYCI-KQYNXXCUSA-N 0.000 claims description 4
- 229910005540 GaP Inorganic materials 0.000 claims description 4
- 239000007836 KH2PO4 Substances 0.000 claims description 4
- 229910003327 LiNbO3 Inorganic materials 0.000 claims description 4
- 229910012463 LiTaO3 Inorganic materials 0.000 claims description 4
- 229910007709 ZnTe Inorganic materials 0.000 claims description 4
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 4
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 4
- 229910002113 barium titanate Inorganic materials 0.000 claims description 4
- 229910052980 cadmium sulfide Inorganic materials 0.000 claims description 4
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 claims description 4
- CSJLBAMHHLJAAS-UHFFFAOYSA-N diethylaminosulfur trifluoride Substances CCN(CC)S(F)(F)F CSJLBAMHHLJAAS-UHFFFAOYSA-N 0.000 claims description 4
- 229910000402 monopotassium phosphate Inorganic materials 0.000 claims description 4
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 claims description 4
- 229910052968 proustite Inorganic materials 0.000 claims description 4
- 239000010453 quartz Substances 0.000 claims description 4
- 229910052594 sapphire Inorganic materials 0.000 claims description 4
- 239000010980 sapphire Substances 0.000 claims description 4
- 229910052711 selenium Inorganic materials 0.000 claims description 4
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 claims description 4
- 229910052714 tellurium Inorganic materials 0.000 claims description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N zinc oxide Inorganic materials [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 4
- 238000001356 surgical procedure Methods 0.000 claims description 3
- 230000035559 beat frequency Effects 0.000 claims description 2
- 210000000515 tooth Anatomy 0.000 description 114
- 210000004268 dentin Anatomy 0.000 description 60
- 230000003287 optical effect Effects 0.000 description 51
- 239000000463 material Substances 0.000 description 48
- 238000001514 detection method Methods 0.000 description 47
- 230000005540 biological transmission Effects 0.000 description 27
- 230000008859 change Effects 0.000 description 21
- 210000001519 tissue Anatomy 0.000 description 19
- 238000005115 demineralization Methods 0.000 description 18
- 239000000126 substance Substances 0.000 description 17
- 229910052500 inorganic mineral Inorganic materials 0.000 description 14
- 239000011707 mineral Substances 0.000 description 14
- 239000012071 phase Substances 0.000 description 14
- 239000013307 optical fiber Substances 0.000 description 13
- 238000010521 absorption reaction Methods 0.000 description 12
- 210000005239 tubule Anatomy 0.000 description 12
- 230000003902 lesion Effects 0.000 description 11
- 238000012986 modification Methods 0.000 description 11
- 230000004048 modification Effects 0.000 description 11
- 230000001681 protective effect Effects 0.000 description 11
- 239000004065 semiconductor Substances 0.000 description 10
- 238000013461 design Methods 0.000 description 9
- 230000006870 function Effects 0.000 description 9
- 230000007246 mechanism Effects 0.000 description 8
- 230000002123 temporal effect Effects 0.000 description 8
- 238000004458 analytical method Methods 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 230000006378 damage Effects 0.000 description 5
- 201000010099 disease Diseases 0.000 description 5
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 5
- 229910052588 hydroxylapatite Inorganic materials 0.000 description 5
- XYJRXVWERLGGKC-UHFFFAOYSA-D pentacalcium;hydroxide;triphosphate Chemical compound [OH-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O XYJRXVWERLGGKC-UHFFFAOYSA-D 0.000 description 5
- 210000002966 serum Anatomy 0.000 description 5
- 230000005697 Pockels effect Effects 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 230000001419 dependent effect Effects 0.000 description 4
- 230000035515 penetration Effects 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 238000012216 screening Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 150000007513 acids Chemical class 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 210000004207 dermis Anatomy 0.000 description 3
- 150000002303 glucose derivatives Chemical class 0.000 description 3
- 239000004973 liquid crystal related substance Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 244000005700 microbiome Species 0.000 description 3
- 210000004416 odontoblast Anatomy 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 210000003491 skin Anatomy 0.000 description 3
- 102000004190 Enzymes Human genes 0.000 description 2
- 108090000790 Enzymes Proteins 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 208000010641 Tooth disease Diseases 0.000 description 2
- 244000309466 calf Species 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 238000007385 chemical modification Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 238000003745 diagnosis Methods 0.000 description 2
- 238000002405 diagnostic procedure Methods 0.000 description 2
- ZZEMEJKDTZOXOI-UHFFFAOYSA-N digallium;selenium(2-) Chemical compound [Ga+3].[Ga+3].[Se-2].[Se-2].[Se-2] ZZEMEJKDTZOXOI-UHFFFAOYSA-N 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 201000010840 enamel caries Diseases 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000009022 nonlinear effect Effects 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 238000002601 radiography Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 230000000391 smoking effect Effects 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 102000008186 Collagen Human genes 0.000 description 1
- 108010035532 Collagen Proteins 0.000 description 1
- 208000035473 Communicable disease Diseases 0.000 description 1
- 201000011180 Dental Pulp Calcification Diseases 0.000 description 1
- 206010013786 Dry skin Diseases 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 206010061218 Inflammation Diseases 0.000 description 1
- 208000034189 Sclerosis Diseases 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000006117 anti-reflective coating Substances 0.000 description 1
- 229910052586 apatite Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000001580 bacterial effect Effects 0.000 description 1
- 230000008952 bacterial invasion Effects 0.000 description 1
- 244000052616 bacterial pathogen Species 0.000 description 1
- 238000010009 beating Methods 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011111 cardboard Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 210000005056 cell body Anatomy 0.000 description 1
- 229920001436 collagen Polymers 0.000 description 1
- 210000001608 connective tissue cell Anatomy 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 210000000805 cytoplasm Anatomy 0.000 description 1
- 230000001086 cytosolic effect Effects 0.000 description 1
- 230000037123 dental health Effects 0.000 description 1
- 210000004262 dental pulp cavity Anatomy 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 206010012601 diabetes mellitus Diseases 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000037336 dry skin Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 210000002950 fibroblast Anatomy 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 208000015181 infectious disease Diseases 0.000 description 1
- 230000004054 inflammatory process Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000000944 nerve tissue Anatomy 0.000 description 1
- 230000000604 odontoblastic effect Effects 0.000 description 1
- 239000000382 optic material Substances 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000000123 paper Substances 0.000 description 1
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000001907 polarising light microscopy Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 210000004872 soft tissue Anatomy 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 210000002784 stomach Anatomy 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000002366 time-of-flight method Methods 0.000 description 1
- 230000036346 tooth eruption Effects 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0082—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes
- A61B5/0088—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes for oral or dental tissue
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/41—Detecting, measuring or recording for evaluating the immune or lymphatic systems
- A61B5/414—Evaluating particular organs or parts of the immune or lymphatic systems
- A61B5/417—Evaluating particular organs or parts of the immune or lymphatic systems the bone marrow
-
- A61B6/512—
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/59—Transmissivity
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
- A61B1/04—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor combined with photographic or television appliances
- A61B1/042—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor combined with photographic or television appliances characterised by a proximal camera, e.g. a CCD camera
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/0233—Special features of optical sensors or probes classified in A61B5/00
- A61B2562/0238—Optical sensor arrangements for performing transmission measurements on body tissue
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/08—Sensors provided with means for identification, e.g. barcodes or memory chips
- A61B2562/085—Sensors provided with means for identification, e.g. barcodes or memory chips combined with means for recording calibration data
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3577—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing liquids, e.g. polluted water
Definitions
- the present invention relates to probes which can be used to image or determine compositional information from structures using radiation with a frequency from
- the present invention also relates to a method for studying diseased teeth.
- THz radiation can be used for both imaging samples and obtaining spectra at each pixel in an image.
- THz radiation penetrates most dry, non-metallic and non-polar objects like plastic, paper, textiles, cardboard, semiconductors and non-polar organic substances. Therefore, THz radiation can be used instead of x-rays to look inside boxes, cases etc.
- THz has lower energy non ionising photons compared to x-rays, hence, the health risk of using THz radiation are expected to be vastly reduced compared to those using conventional x-rays.
- THz imaging for medical purposes has been suggested.
- the penetration depth of THz radiation might hinder imaging deep inside the human body.
- water is known to be a strong absorber of THz radiation, this will also affect the useful imaging depth which can be obtained using THz radiation.
- dehydrated tissue types such a dry skin have limited penetration depths. For example, at 2.0THz, ⁇ 35 cm " ' for moist dermis whereas ⁇ 29 cm " ' for dry dermis.
- the lmW average power levels suggest that only about 4mm of moist dermis could be probed using THz.
- the present invention relates to a probe assembly which has a probe which can be inserted into a human or animal body to image parts of the body or obtain spectra.
- the present invention could be used as a THz endoscope to probe inside the human or animal body.
- the probe could be inserted down the throat of a patient to examine the stomach or used in keyhole surgery.
- the probe could be used to exam external surfaces as well.
- the probe will be primarily discussed for medical applications, the probe could also be used for non medical applications.
- it could be used as a remote probe in liquid, gaseous or solid environments, or used as a safe means of delivering and detecting THz radiation to a specific part of an object under study. Remote sensing of this sort is also of particular importance in applications where imaging is required in the field or on a factory floor etc.
- a continuous or pulsed laser, electrical and/ or optical components which may used to generate or detect the THz are often sensitive to changes in temperature, vibration etc.
- the pulsed laser and/or other electronic/optical components can be placed in a controlled environment favourable to their operation that is also remote from the Terahertz measurement/imaging site.
- the present invention provides a probe assembly for examining a sample, the assembly comprising a probe, communicating means for communicating signals to and/or from the probe, an emitter for emitting radiation to irradiate the sample and an electro-magnetic radiation detector for detecting radiation which is transmitted or reflected from the sample, the emitter comprising a frequency conversion member which emits radiation in response to being irradiated input radiation with a different frequency to that of the emitted radiation, wherein at least one of the emitter or detector is located in the probe.
- the detector directly detects electro-magnetic radiation from the sample. It does not detect electro-magnetic radiation via a non direct method such as detecting a photo-current in the sample.
- both the emitter and the detector will be located in the probe. If the emitter is located in the probe, the commumcating means can be used to supply the input radiation for the frequency conversion member. It will be appreciated that only one of the emitter or detector could be located within the probe, for example the emitter could be provided within the probe and the detector could be a large fixed detector remote from the probe. Alternatively, the detector could be located within the probe and the emitter could be fixed remote from the probe.
- the probe is primarily intended to be a THz probe.
- the emitter will emit THz radiation.
- THz radiation is radiation within the range of 0.1 THz to 84 THz, more preferably in the range from 0.2 THz to 20THz.
- the emitter has a frequency conversion member for converting the radiation supplied to the probe into radiation with the desired frequency range.
- the probe may be configured so that the detector detects radiation which has been transmitted through the sample being examined by the probe.
- the probe may also be configured such that the detector detects radiation that has been reflected from the sample.
- the probe could also be configured to detect both reflected and transmitted radiation.
- the radiation may be supplied as continuous radiation or pulsed radiation.
- Pulsed radiation contains a plurality of frequencies.
- An image can be generated from the radiation and/or compositional information may be obtained by looking at which frequency components are more strongly absorbed, or examining the modification of the refractive index or the time of flight of the pulse as it passes through the object, or a combination of these mechanisms.
- pulsed radiation is advantageous in that it allows the sample to be imaged with a plurality of frequencies, pulsed laser diodes are more expensive and also it is difficult to send a pulse of radiation down an optical fibre. Therefore, it is also desirable to use continuous wave (CW) radiation.
- CW radiation can be supplied by CW laser diodes.
- CW input radiation of two different frequencies is provided as input radiation to the probe, the CW frequencies are then used to generate THz radiation using an optically non-linear member configured to generate radiation with a frequency which is substantially the difference of that of the two input frequencies.
- the two CW input frequencies could be used to generate THz radiation using a photoconductive antenna or any of the other methods referred to in this specification.
- the beam which has been transmitted through or reflected from the sample is compared with a reference beam to measure the change in a phase dependent quantity of the radiation as it passes through the sample.
- the reference beam is preferably derived from the input radiation and comprises all of the input radiation frequencies.
- CW radiation with just two frequencies is used to produce THz radiation having substantially a single frequency.
- a plurality of discreet frequencies can be provided by C W input radiation to produce THz radiation having a plurality of discreet frequencies.
- This CW radiation may be provided by a single source running in multimode or by a plurality of single frequency CW sources.
- three separate CW sources can be connected to the probe, each by its own fibre optic cable. If the emitter is configured to exhibit difference frequency generation, then two THz frequencies will irradiate the sample, these two frequencies can be selected to demonstrate particular contrast mechanisms in the sample which is being studied. As has been mentioned above, it is generally necessary to provide radiation to the emitter.
- this radiation will have a wavelength in the range from 600 nm to 2 ⁇ m.
- This radiation which will hereinafter be referred to as the 'probe radiation' is preferably provided to the probe via a fibre optic cable for example a Silicon based cable.
- the term probe pulse will be used to describe any radiation being supplied to the probe which is in the form of a pulse.
- the probe assembly comprises a means for compensating for the dispersion of the probe radiation.
- a dispersion shifting means in the emitter which has a negative dispersion effect on the radiation.
- the fibre itself will have a positive dispersion effect on the radiation.
- the communicating means itself (e.g. the fibre) may be provided with alternating sections which provide positive and negative dispersion effects. The negative dispersion effects could be produced using dispersion shifted fibre. This ensures that pulses of probe radiation remain compressed on arrival at the emitter.
- the frequency conversion member can comprise a material which possesses good nonlinear optical characteristics such that upon irradiation with radiation of a first frequency (the input radiation), it emits radiation (emitted radiation) with a frequency different to that of the first frequency.
- the frequency conversion member has a crystalline structure. The following are possible materials for the frequency conversion member:
- the frequency conversion member is configured to emit radiation with a frequency substantially equal to the difference of two frequencies of the input radiation.
- a photoconductive emitter comprises a photoconductive member having two electrodes. To emit THz radiation, the photoconductive member is illuminated with input radiation having at least two different frequencies, upon application of a suitable bias, radiation with a frequency which is substantially the difference of the at least two input frequencies is emitted. The input radiation can be selected such that THz radiation is emitted.
- the ability to supply additional power in the 25GHz-5THz part of the spectrum is important in endoscopic applications because most tissues have higher penetration depths (are more transmissive) at these frequencies compared to the 5THz-20THz band, where absorption by liquid water is more prevalent.
- An advantage of these photoconductive generators and detectors is their coverage of frequencies in the range 25GHz-500GHz, where the peak power from the emitters is typically centred near 300GHz-500GHz, and extends down to 25GHz; this can lead to large penetration depths at lower frequencies, less scattering at lower frequencies (longer wavelengths), etc.
- phonon-related absorption/dispersion, phase matching, or other propagation effects in the emitter and detector crystals are not as problematic as they can be in some configurations using difference frequency generation (DFG) in emission and electro-optic sampling in detection.
- DFG difference frequency generation
- Such effects can add unwanted structure to the Terahertz time domain and frequency domain waveforms. This unwanted structure can lead to ghosts in images and can mask reflections from interfaces with small refractive index contrast - e.g.
- the amount of optical pulse energy that can be transported down a fibre is limited due to non-linear effects.
- Conventional fibres will typically support 20-30mW average optical power per fibre with pulse energies in the lOpJ-nJ range and pulsewidths in the lOOfs-lps, although this can vary significantly with design, material type, laser pulse repetition rate, wavelength, etc.
- DFG difference frequency generation
- optical pulse energies ideally at the nJ- ⁇ J level or larger
- nJ levels suffice for photoconductive generation in antenna structures with small (1- lOO ⁇ m) gaps between adjacent surface electrodes, provided the average optical power is in the 10-30mW range with pulsewidths ⁇ 100fs-lps and laser pulse repetition rates 10- 100MHz.
- Terahertz power is derived primarily from the acceleration of photocharge due to the applied bias on the electrodes and not the optical field out of the end of the fibre as in the case of DFG. This makes photoconductive generators particularly well-suited to low pulse energy (and hence low average power) fibre delivery systems that are used in Terahertz endoscopes.
- a related advantage is that many endoscopes require compact design of not only the endoscope head, but also the near infrared/visible pulsed laser itself providing the optical radiation to the optical fibres.
- optical pulsed lasers are Erbium doped fibre lasers or C ⁇ LiSapphire lasers. These lasers have reduced laser head sizes and also reduced cooling requirements (smaller power supplies and coolers are typically used relative to standard TirSapphire technology, and Cr:Li Sapphire lasers can be run off batteries for limited periods). These lasers are also potentially inexpensive because of the elimination of the need for a costly pump laser. The limitation of these lasers is that many of them have average optical output powers limited to 20-50mW.
- a particularly efficient generation- detection scheme to use in this scenario is photoconductive generation and EOS detection. This allows the a majority of the optical power available from the optical laser to be channelled to the photoconductive switch (20-5 OmW), whilst minimal power (5-20 ⁇ W) is used in the optical probe beam needed for EOS detection.
- photoconductive emission devices may be used, encompassing different material systems such as low temperature GaAs, semi-insulating GaAs, silicon on sapphire, semi-insulating InGaAs, low temperature InGaAs, semi -insulating InP, low temperature InP, and As implanted GaAs.
- Surface electrodes based on classical dipoles embedded in transmission lines, dipoles imbedded in bow-tie antennas, and strip transmission lines may be used.
- photoconductive detectors can use the above materials systems and electrode geometries. Other schemes are also known from prior art and can be incorporated.
- average optical powers in excess of 20-50mW are not useful in photoconductive emitters and detectors due to saturation and possible heating effects. Radiation or heating damage and/or limited device lifetime can result.
- the frequency conversion member is provided with phase matching means to keep the input radiation and the emitted radiation in phase with each other as they pass through the frequency conversion member.
- phase matching means may be provided by varying the refractive index of the frequency conversion member, to match the phase of the emitted beam and that of a beat frequency component of the probe radiation at all points within the frequency conversion member.
- the emitter preferably further comprises a lens that focuses the probe pulse onto the frequency conversion member.
- the THz beam is preferably emitted through a THz collimator that forms a THz window for the probe.
- a filter may be provided in the emitter to prevent pulses from the probe pulse from being transmitted with the THz beam.
- the detector can be used to detect either transmitted THz radiation and/or reflected THz radiation.
- the THz pulse emitted from or reflected by the sample is collected by a THz lens. If the detector is located within the probe, either in addition to or instead of the emitter, the detector has the same problem in that it is not viable to send the detected THz outside of the probe for analysis.
- the information carried by the emitted or reflected THz must be converted to a medium which can be transported away from the probe for analysis.
- this is performed by transferring the information in the detected THz radiation to radiation of a different wavelength or by converting information carried by the detected THz radiation into an electronic form.
- a preferable method for deriving information from the detected THz radiation is provided by the AC Pockels effect in what is called electro-optic sampling (EOS).
- EOS electro-optic sampling
- the optical pulse is preferably the probe pulse which is also provided to the emitter.
- the probe assembly preferably further comprises delay means for delaying the probe pulse so that the probe pulse and THz pulse arrive at the same time at the non-linear material.
- the detector works on the principle of the AC Pockels effect. Therefore, it is preferable if the detector comprises a detection member which has non-linear properties.
- Preferred detection members are:
- LiIO 3 LiIO 3 , NH 4 H 2 PO 4 , ADP, KH 2 PO 4 , KH 2 ASO 4 , Quartz, AlPO 4 , ZnO, CdS, GaP, GaAs, BaTiO 3 , LiTaO 3 , LiNbO 3 , Te, Se, ZnTe, ZnSe, Ba 2 NaNb 5 O ⁇ 5 , AgAsS 3 , proustite, CdSe, CdGeAs 2 , AgGaSe 2 , AgSbS 3 , ZnS, DAST (4-N-methylstilbazolium) or Si.
- Terahertz endoscopes Another important application of Terahertz endoscopes is to produce spectroscopic images or diagnostic information based on high bandwidth detectors and emitters. Coverage of the far-infrared (100GHz-20THz) and mid infrared (20THz-80THz) is useful because intermolecular vibration signatures occur in the former range, whereas intramolecular vibrations occur in the latter. The ability to determine absorption and index of refraction data in these two ranges where the vibration modes are qualitatively different might enable molecules to be uniquely identified, important in the diagnosis of diseased tissue.
- GaSe gallium selenide
- photoconductive emitters based on p-I-n photodiodes may be used in emission due to their superior performance at higher frequencies in cases where optical pump power is limited, for example 15-20mW maximum optical pump power is typically used in such devices in free space, compared to the 100s m W average powers typically required for DFG.
- p-i-n diodes are ideal photoconductive emitters for wide bandwidth (25GHz-80THz) endoscopic applications.
- a photoconductve detector could also be used, such detectors generally comprise a photoconductive material such as those previously described with reference to photoconductive emitters. Electrodes are provided on the photoconductive material, such electrodes may be surface electrodes based on classical dipoles embedded in transmission lines, dipoles embedded in bow-tie antennas and strip transmission lines may be used.
- the radiation which has been combined with the THz radiation may be transmitted back to an external analysing means, it may also be separated into horizontally and vertically polarised components. These orthogonal components can then be transmitted separately (i.e. along separate optical fibres) back to an external analyser where they will be recombined into a single beam.
- the horizontally and vertically polarised components can be transmitted collinearly back to an external analyser using a polarisation preserving optical fibre.
- the optical beam is reflected in the detection member as opposed to being transmitted by the detection member.
- This reflected optical beam carrying the THz imaging information is then transmitted back down an optical fibre for analysis by an analysing means which is remote to the probe.
- the analysing means may be configured to produce an image of the sample being examined and/or to give compositional information about the sample at the point being probed.
- the detector may be configured such that the probe radiation is reflected back from the detection member along a different axis to that of the incident probe radiation beam.
- the probe radiation may be supplied to the detection member and be reflected back from the detection member along the same path.
- the detector comprises a fibre optic circulator or the like.
- a fibre optic circulator will allow the probe radiation to be transmitted through itself to reach the detector crystal. It will then allow the reflected probe radiation to be collected by the fibre optic circulator and transmitted out of a different port to that to which the initial probe radiation was inputted into the fibre optic circulator.
- the combining of the probe pulse with the detected THz radiation may also be achieved by providing a wedged surface in the detector which can be used to reflect the probe radiation to combine with the THz signal in the detection member.
- the detected radiation may also be further processed within detector itself.
- the THz and optical pulse are combined to produce radiation which can be transmitted down a fibre optic cable. This will be referred to as visible radiation, but any radiation can be used which can be transmitted down an optical fibre can be used, which has a rotated polarisation vector due to the presence of detected THz.
- the visible radiation which has been combined with the THz could be passed through a variable polariser in the detector.
- the polariser could be set so as to block optical light which had not had its polarisation rotated by the THz.
- the output from the polariser could then be read directly into a CCD array which is provided in the detector.
- This CCD array would then transmit information back to an image analyser.
- a plurality of optical fibres may be provided to channel the spatial variations in the probe radiation away from the detector after it has passed through the polariser. This would permit spatial variation in the THz beam to be measured via spatial variations in the probe radiation polarisation.
- These optical fibres could then lead to a CCD camera provided with the external analysing means. This improves spatial resolution and also affords imaging capabilities; different spatial sections of the probe radiation, encoded with different spatial areas of the THz beam, may be resolved by the CCD, leading to an image of the object from which the THz beam has been transmitted or reflected.
- the emitter irradiates a sample area and the detector detects radiation from this sample area.
- the detector detects radiation from this sample area.
- Using a CCD camera within the detector or a bundle of optical fibres within the detector to carry the signal from the polariser back to an external CCD camera allows the probe to detect spatial information from a single sample area. This technique can thus be used to improve the resolution of the probe.
- the probe may comprise a single detection head which can operate as previously described. Alternatively, it may comprise a plurality of detection heads. These detection heads may be arranged in a bundle around the emitter. Each of the heads may comprise a detector as previously described to combine the THz radiation with an optical beam from the probe pulse.
- the optical radiation produced by this method can either be fed back to an external analysing means or the radiation from each of the detector heads can be fed to a polariser and possibly a CCD Array.
- a single CCD array can be provided for all of the detector heads.
- Each of the fibres may be provided with its own detection member, alternatively, each of the fibres may output to a single large detection member.
- the detector member and the frequency conversion member can be the same material, the detection member may also be used as the frequency conversion member.
- the emitter and detectors would be using different parts of the combined frequency conversion member/detection member.
- the probe can have a number of designs. It can be provided with a separate emitter and detector where the input signal to the emitter is fed through a different cable to that of the detector.
- the emitter and detector may be provided in the same housing, but the device may be configured so that the detector only detects transmitted radiation hence, the emitter will be on opposing side of the object to be imaged to that of the detector.
- the detector may also work by reflection, wherein the emitter would be spatially separated from the detector. In this case, the detector would be provided on the same side of the object as the emitter and possibly, within the same housing.
- the detector and emitter can be housed in the same probe to perform both transmission measurements and reflection measurements, the emitter may be provided in the probe without the detector.
- the emitter may be provided in an endoscope and the detector may be a large angle detector provided outside the body.
- the present invention provides a probe assembly for examining a sample, the assembly comprising a probe, communicating means for communicating signals to and/or from the probe, an emitter for emitting radiation to irradiate the sample and an electro-magnetic radiation detector for detecting radiation which is transmitted or reflected from the sample, the emitter comprising a frequency conversion member which emits radiation in response to being irradiated with input radiation which has a different frequency to that of the emitted radiation, wherein the emitter is located in the probe.
- the preseent invention provide, a probe assembly for examining a sample, the assembly comprising a probe, communication means for communicating signals to and/or from the probe, an emitter for emitting radiation to irradiate the sample and an electro-magnetic radiation detector for detecting radiation which is transmitted or reflected from the sample, the emitter comprising a frequency conversion member which emits radiation in response to being irradiated with input radiation which has a different frequency to that of the emitted radiation, the detector being located in the probe and wherein information from the detected radiation is transmitted out of the probe by radiation with a different wavelength to that of the detected radiation.
- the emitter is preferably of the type which requires input radiation. However, it may also be THz emitter which only requires an electrical input to generate the radiation.
- the probe can be configured for many different uses.
- the probe can be configured as an endoscope which can be inserted into a human or animal body.
- the probe may also be made very small (of the order of microns) for use in key-hole surgery.
- the width of the probe which is to be inserted will be less than 50mm, more preferably less than 10mm. More preferably, it will be less than 1mm, or even more preferably less than lOO ⁇ m.
- the probe assembly preferably further comprises imaging means for producing an image sample.
- the probe assembly may also comprise compositional and analysing means for determining information about the composition of the sample from the detected radiation. Some materials have been shown to have distinctive absorption patterns in the THz frequency regime which allows such compositional information to be determined.
- the probe is particularly for use for imaging teeth.
- the probe may be provided with tooth clamping means that allow the emitter and the detector to be positioned on either side of the tooth.
- THz radiation provides a valuable technique for the study of teeth and tooth disease, particularly caries.
- Dental caries, or teeth erosion in the enamel and dentine layers is a serious problem that affects over 90% of the UK population.
- With introduction of food and beverages with high sugar content and other substances, world-wide incidence of caries is expected to rise appreciably over the next decade.
- Frequent or regular screening of the population with a sensitive and selective imaging technique would dramatically reduce the incidence of caries, resulting in a dramatic enhancement in the dental health of the population and a large and significant cost savings to health services, insurance companies, and patients around the world.
- Dental caries is commonly considered an infectious disease that causes localised destruction of the dental hard tissues by acids in the microbial deposits adhering to teeth.
- Caries proceeds by the creation of surface or sub-surface lesions in the enamel region. Acid, created from sugar or other substances on the tooth surfaces, permeates the enamel and forms lesions underneath or on top of the enamel surface. Eventually these lesions may grow or migrate into the dentine and begin to destroy the dentine layer. The extension of a lesion may reach the enamel-dentine junction without macroscopically visible breakdown or even microcavity formation in the enamel surface. Lesions are accompanied by demineralisation of the enamel and dentine; dentine is approximately 70% mineral, and enamel is approximately 99% mineral. Erosion is accompanied by a chemical change in the dentine or enamel, which in some cases leads to a change in water content in this region.
- Previous techniques for identifying caries include visual inspection, which is not quantitative, not capable of detecting many carious lesions that are simply missed, and does not supply any appreciable diagnostic information.
- polarised light microscopy and quantitative fluorescence have also been used to detect caries, but typically are limited either by a) the ability to detect caries only after it progresses to the dentine layer and becomes infected, b) radiation scatter at these short wavelengths, c) scatter/absorption due to stains on the teeth which interrupts the signal, d) limited probe depths below the enamel surface, or e) by a combination of these mechanisms.
- Other imaging techniques such as ultrasound are limited by the lack of flat surfaces on teeth, or are limited by excessive cost as in the case of MRI. There is clearly a need for a more safe, selective and sensitive means of detecting caries.
- Secondary caries is the term used to describe caries which appears around tooth fillings. Moreover, secondary caries has very poor ( ⁇ 20%) selectivity with x-ray, and poor selectivity with optical techniques due to the presence of fillings. However, new fillings made of plastics, resins, polymers, silica, or many other materials are partially transparent at THz frequencies, allowing for easier detection of secondary caries.
- the present invention provides a method for of detecting dental caries, the method comprising the steps of:
- the beam of radiation may be a pulsed beam of radiation having a plurality of frequencies or a beam of substantially continuous radiation having a single frequency or a plurality of discreet frequencies.
- the method of the fourth aspect of the present invention can be used to detect primary or secondary caries.
- the enamel appears hard and shiny, and consists of hydroxyapatite crystals packed very tightly, such that the enamel has a glass-like appearance.
- the crystals in the enamel are arranged in an orderly fashion forming rods and inter-rod enamel.
- the rod enamel is terminated in a prism shape.
- the packing of rods is slightly looser as regards the rod periphery compared with the rod and interrod enamel.
- the enamel layers are highly crystalline and possess a high degree of structural ordering. Even though the packing of crystals is very tight at the macroscopic level, each crystal is separated from its neighbours by tiny intercrystalline spaces. These spaces are filled with water and other organic materials. These spaces constitute pores in the enamel.
- the method of the fourth aspect of the present invention can thus be preferably configured to detect a change in the porosity of the enamel.
- THz radiation in the Terahertz frequency range i.e. 0.1 THz to 84 THz can be performed using many different techniques.
- THz radiation of a single frequency may be used.
- the tooth is examined using a plurality of frequencies supplied in the form of a pulse of THz radiation.
- a single frequency or a plurality of frequencies from this pulse may be detected.
- THz radiation Many different parameters may be measured using THz radiation to determine the presence of caries.
- panchromatic absorption image or at a fixed frequency ⁇ or a select, limited frequency range covered by the THz pulse (a so-called monochromatic absorption image)
- Thickness of the object time-of-flight image, or
- Refractive index «( ⁇ ) at a fixed frequency a so-called monochromatic image
- refractive index image a co-called panchromatic image
- the absorption coefficient ⁇ ( ⁇ ) over the entire frequency bandwidth of the THz pulse can be used to detect chemical changes associated with demineralisation.
- the demineralisation accompanying dental caries in the enamel leads chemical changes that can result in significant changes in the absorption band over the frequency range of 0.1 THz to 84 THz.
- one of the major differences between regions of enamel and dentine is the extent of mineralisation; as noted above, enamel is nearly 99% mineral, whereas dentine is approximately 70%.
- there is heavy mineralisation in enamel relative to dentine This results in different integrated absorption coefficients ⁇ ( ⁇ ) over the entire frequency bandwidth of the THz pulse the two regions.
- Demineralisation will also be accompanied by differences in the water content of the two regions as well as other chemical differences such as the presence of bacteria if the regions were carious regions.
- Other chemical modifications that may take place in the enamel include reactions between the enamel apatite and the surrounding liquid phase. These may also have characteristic spectral signatures in the THz region, and hence form the basis of identifying caries.
- the image is processed to determine the water content of the tooth.
- panchromatic THz techniques are very sensitive to water content. This is demonstrated by the strong and frequency-dependent abso ⁇ tion spectrum associated with water. As such, the differences in water content between carious and non-carious regions (as discussed above in terms of an increase in porosity) will also allow the THz examination techniques to be used in the identification of carious regions in enamel. In particular, increased porosity near or at carious regions should lead to increased panchromatic abso ⁇ tion in these regions, which leads to a contrast mechanism between healthy and carious tissue using THz.
- THz can also be used to look at changes in abso ⁇ tion associated with modification of crystallisation.
- structural differences in enamel induced by caries namely the destruction or modification of the crystalline structure or rod/layer ordering in the enamel, will change the THz panchromatic abso ⁇ tion due to the modification of phonon and low frequency vibrational modes in the crystalline structure which accompanies demineralisation via caries.
- THz can also be used to detect the thickness of the object being examined. Hence, it can be used to determine enamel thickness using a time of flight technique, i.e. measuring the time a THz pulse takes to travel through the object being examined.
- caries can reduce the thickness of the enamel. For enamel changes during tooth eruption, the final enamel surface may appear moth-eaten and in areas of the outmost microns of the enamel may disappear. These changes may not be clinically or macroscopically visible using conventional means. Other changes in enamel thickness may also accompany caries.
- THz images may be constructed from the time of flight of the THz pulse through the tooth which is directly related to the tooth thickness
- TPI time-of-flight images may be used to identify carious lesions in the enamel which induce changes in enamel thickness of as little as 1 ⁇ m.
- a refractive index image is also a measure of the time of flight.
- the high contrast in refractive index between the enamel and the dentine+enamel results in a much longer time of flight in the enamel.
- the refractive index can also be used to probe chemical changes associated with demineralisation.
- the demineralisation accompanying dental caries in the enamel should lead chemical changes that may result in significant changes in the refractive index n( ⁇ ) over bandwidth probed in THz experiments.
- n( ⁇ ) refractive index
- one of the major differences between regions of enamel and dentine is the extent of mineralisation; as noted above, enamel is nearly 99% mineral, whereas dentine is approximately 70%.
- there is heavy mineralisation in enamel relative to dentine This results in different integrated abso ⁇ tion coefficients n( ⁇ ) over the entire frequency bandwidth of the THz pulse in the two regions.
- This difference may also reflect differences in the water content of the two regions as well as other chemical differences such as the presence of bacteria if the regions were carious regions, but the overall difference suggests that panchromatic «( ⁇ ) in the THz range is a useful mechanism for monitoring demineralisation associated with caries in enamel.
- the refractive index can also be used to probe differences in the refractive index associated with water.
- images formed by panchromatic THz are very sensitive to water content. This is demonstrated by the strong and frequency-dependent n( ⁇ ) spectrum associated with water, which varies from approximately 1.3 to 3.3 over the THz/infrared frequency range.
- the differences in water content between carious and non-carious regions will also allow the THz panchromatic n( ⁇ ) images to be used in the identification of carious regions in enamel simply by plotting the time of flight.
- increased porosity near or at carious regions should lead to different «( ⁇ ) in these regions, which should lead to a contrast mechanism between healthy and carious tissue in THz.
- n( ⁇ ) Changes in n( ⁇ ) can also be associated with modification of crystallisation.
- the structural differences in enamel induced by caries namely the destruction or modification of the crystalline structure or rod/layer ordering in the enamel, will change the THz panchromatic n( ⁇ ) due to the modification of phonon and low frequency vibrational modes in the crystalline structure which accompanies demineralisation via caries.
- n( ⁇ ) is determined by the birefringence of the material, which depends on the crystalline structure in many materials. n( ⁇ ) may therefore be a tensor (not scalar) quantity in enamel, with a particular birefringence. This birefringence may change during demineralisation associated with caries, and be detected using polarisation sensitive THz.
- panchromatic and monochromatic images may be formed either from time-of-flight data and/or from modelling of the complex Fourier spectrum.
- a caries lesion reaches the enamel dentine junction, the highly porous enamel lesion allows for further diffusion of acids into the dentine.
- An immediate reaction throughout the involved parts of the dentine is seen.
- dentine and the pulp cavity underneath it comprise an integral part of the living tissue with the odontoblast cytoplasmic extension running out in the thousands of tubules which form the dentine, while cell body lines the pulp chamber.
- Odontoblasts are similar to fibroblasts in skin and other tissue and are specialised connective tissue cells that build the dentine and subsequently maintain it.
- Odontoblasts lie on the inner surface of the dentine and on the periphery of the pulp. They can extend all the way from the pulp cavity up to the dentine mantle (adjacent to the enamel). They form tubules that can have lengths of up to 5mm and typical widths of l ⁇ m in the dentine removed from the pulp.
- the spaces occupied by the odontoblastic processes as they become longer during dentogenisis (dentine growth) have the shape of long tubes extending through the mineralised dentine. They are filled with cytoplasm and gel and are called dentine tubules.
- the tubules are regularly arranged, the specific arrangement depending on the type of tooth and location in that tooth, and typically one might find 20,000 tubules/mm 2 .
- the walls of the tubules are covered by a very dense and mineralised material referred to as peritubular dentine, which are hydroxyapatite crystals in the form of hexagonal prisms.
- peritubular dentine which are hydroxyapatite crystals in the form of hexagonal prisms.
- the dental tubules with their coating of peritubular dentine are separated from each other by intertubular dentine, which is less densely mineralised.
- Intertubular dentine consists of collagen fibres that form an interwoven structure that lies pe ⁇ endicular to the paths of the dentine tubules and enmeshes them.
- the demineralised dentine layers adjacent to the enamel are also invaded by bacteria, and result in the production of a range of hydrolytic enzymes with the potential for destruction of the organic matrix of the dentine.
- groups of dentinal tubules which have been located in the centre of the demineralised dentine, appear and form a so-called dead tract that may be invaded by microorganisms. Some such tubules may also contain larger and more irregular crystals.
- the reaction of the pulp to invasion of the dentine may lead to the formation of additional, irregular tubules in the dentine in much fewer numbers than the primary dentine.
- THz can also be used to probe the area associated with the pulp cavity in a tooth.
- the pulp cavity consists of soft tissue including blood, water, and nerve tissue. Coupling this capability with the fact that THz can be used to probe water and blood, THz is useful for providing information on the rate of blood flow to the cavity, the presence of pulp stones in the cavity, and any bacteria or germs in the cavity region. Both panchromatic and monochromatic abso ⁇ tion imaging, as well as time-of-flight imaging, are useful for cavity diagnosis.
- the present invention provides a method of detecting blood flow into the pulp cavity of a tooth, the method comprising the steps of:
- the beam of radiation may be a pulsed beam of radiation having a plurality of frequencies or a beam of substantially continuous radiation having a single frequency or a plurality of discreet frequencies.
- THz can also be used to detect periodontal disease.
- Periodontal disease affects the gums, bone and other supporting tissues of the teeth. Although most individuals suffer gum inflammation from time to time, around 10% of the population appear to suffer from the more severe forms of the disease which cause loss of supporting bone. This group appears to be at greatest risk of losing teeth through periodontal disease.
- the bacteria cause it that regularly collect on teeth.
- periodontal disease can manifest itself through a weakening of the bone below the thin skin or mucous layers at the base of the tooth. 3 major factors are thought to be responsible. Family history, stress and smoking are all-important risk factors. Stopping smoking is an important. Certain general diseases such as diabetes may also make an individual more susceptible.
- the signs and symptoms of periodontal disease are extremely variable but may include gums that bleed on brushing together with signs of more advanced disease such mobility or drifting of the teeth.
- the present invention provides a method of detecting periodontal disease in a tooth, the method comprising the steps of:
- the beam of radiation may be a pulsed beam of radiation having a plurality of frequencies or a beam of substantially continuous radiation having a single frequency or a plurality of discreet frequencies.
- THz can be used to image bone. Moreover, changes in the 1) density, 2) hardness, 3) structure, or 4) chemical composition will result in changes in the quantities responsible for contrast mechanisms available by using THz.
- the methods of the fifth and sixth aspects of the present invention can benefit if the data is processed to determine the abso ⁇ tion coefficient of the tooth or bone or the refractive index of the tooth or bone.
- the image derived in the method of any of the second to fourth aspects of the invention can be processed to determine differences in the composition of the tooth or, it can be used to determine the exact composition of the tooth or bone.
- a particularly preferable method of producing the image can be achieved by comparing radiation from the tooth or bone which is not passed through the tooth or bone, calculating the delay between radiation which is passed through the tooth or bone and radiation which has not passed through the tooth or bone and plotting the delay for different points of the tooth or bone.
- the data derived from the detected THz can be used to determine compositional information of the tooth or bone. It can also be used to detect the presence of bacteria which have been found to affect the abso ⁇ tion characteristics of the tooth.
- the present invention provides an apparatus for imaging caries in teeth, the apparatus comprising:
- the beam of radiation may be a pulsed beam of radiation having a plurality of frequencies or a beam of substantially continuous radiation having a single frequency or a plurality of discreet frequencies.
- the present invention provides an apparatus for imaging periodontal disease in teeth, the apparatus comprising means for irradiating the bone located below a tooth with a beam of radiation having at least one frequency in the range from 0.1 THz to 84 THz; means for detecting the radiation from the bone to obtain image data; means for processing the image data to determine the presence of periodontal disease.
- the beam of radiation may be a pulsed beam of radiation having a plurality of frequencies or a beam of substantially continuous radiation having a single frequency or a plurality of discreet frequencies.
- the present invention provides an apparatus for imaging the blood flow into the pulp cavity of a tooth, the apparatus comprising: a) means for irradiating a tooth with a beam of radiation having at least one frequency in the range from 0. ITHz to 84THz;
- the beam of radiation may be a pulsed beam of radiation having a plurality of frequencies or a beam of substantially continuous radiation having a single frequency or a plurality of discreet frequencies.
- the imaging means comprises means for comparing the radiation from the tooth or bone with radiation which has not passed through the tooth or bone, means for calculating the delay between radiation which has passed through the tooth or bone and radiation which has not passed through the tooth or bone, and means for plotting the delay for different points of the tooth or bone.
- the means for irradiating the tooth and the means for detecting radiation from the tooth or bone are located in a probe which can be placed in a human or animal mouth.
- Figure 1 shows a schematic outline of a THz probe according to an embodiment of the invention
- Figure 2 shows an emitter for use with the THz probe in accordance with a preferred embodiment of the first aspect of the present invention
- Figure 3 shows a variation on the emitter of Figure 2
- Figure 4 shows a variation on the emitters of Figures 2 and 3 ;
- Figure 5 shows a detector in accordance with a preferred embodiment of a first aspect of the present invention
- Figure 6 shows a variation on the detector of Figure 5;
- Figures 7A and 7B show variations on the detectors of Figures 5 and 6;
- Figure 8 shows a variation on the detectors of Figures 5 to 7;
- Figure 9 shows a variation on the detector of Figure 8.
- Figure 10 shows a variation on the detector principle
- Figure 11 shows a probe in accordance with the first aspect of the present invention with a plurality of detector heads
- Figure 12 shows the detector of Figure 11 in more detail
- Figure 13 shows a photo-conductive emitter which can be used as the frequency conversion member in accordance with an embodiment of the present invention
- Figure 14 shows a probe in accordance with a preferred embodiment of the present invention having a photo-conductive emitter
- Figure 15 shows a probe in accordance with a preferred embodiment of the present invention having a photo-conductive detector
- Figure 16 shows a further variation on a THz probe in accordance with an embodiment of the present invention, where the frequency conversion member is provided by a p-i-n diode;
- Figure 17 shows a schematic outline of a THz emission and detection system using CW laser diodes in accordance with an embodiment of the present invention
- Figure 18 shows a further variation on the system of Figure 17;
- Figure 19 shows a variation on the systems of Figures 17 and 18 using two THz frequencies to illuminate the sample
- Figure 20 shows a probe in accordance with a preferred embodiment of the first aspect of the present invention used with a tooth
- Figure 21 shows a variation on the probe of Figure 13 used with a tooth
- Figures 22 A shows a probe in accordance with a preferred embodiment of the first aspect of the present invention used for probing a tooth using reflection
- Figure 22B shows the probe of 22A using both transmission and reflection
- Figure 23 A and 23B show photographs of a human tooth
- Figure 23C shows a CCD image of the tooth of Figures 23 A and 23B
- Figure 24A shows the CCD scan of Figure 23C
- Figure 24B to 24D show time domain THz pulses as they pass through the three regions denoted with reference to Figure 23
- Figure 24E shows a plot of the temporal shift of the measured peaks from Figures 24B to 24D against x-axis
- Figure 25 shows a plot of the temporal position of the peaks in a THz pulse passed through the tooth of Figure 23;
- Figure 26 shows the temporal positions of THz pulses in an x-y plane of the tooth of Figure 23;
- Figure 27 shows a three dimensional plot using the data from Figure 17 to 19;
- Figure 28 shows a two dimensional contour plot of the tooth of Figure 16
- Figure 29 shows a panchromatic abso ⁇ tion image of the tooth of Figure 16
- Figures 30A and 30B shows a plot of THz transmissions through a saturated glucose solution
- Figure 31 is a plot of THz transmission against frequency of a new born calf serum
- Figure 32 shows a further plot of transmission of THz against frequency through a methanol solution
- Figure 33 shows a plot of THz transmission against frequency through clotted blood.
- Figure 34 shows a bone image taken using THz transmission.
- Figure 1 shows a schematic outline of the functions of the THz probe.
- the object to be examined by the probe is tooth 1.
- An ultra fast laser source 3 provides pulsed radiation to a beam splitter 5.
- Beam splitter 5 then splits the beam to travel along two fibre optic cables 7, 11.
- Fibre optic cable 7 is connected to the THz emitter 9.
- Fibre Optic 11 is provided to the THz detection system 13.
- the THz detection system 13 has a THz detector 15 which detects radiation which is either passed through and/or been reflected from the tooth 1.
- the delay control may alternatively be placed in the fibre optic cable 7 leading to the THz emitter 9.
- Fibre optic circulator 17 is in effect a radiation valve which is used to direct the beam from fibre 11 into the THz detector for encoding with the information from the detected THz, and it is used to direct the beam with the encoded THz information into polarisation bridge 21.
- the reference beam is passed through delay control means 19 to match the temporal shift of the reference beam with that of the detected THz signal.
- the encoded THz information is then derived using polarisation bridge 21. Details of the polarisation detection system will be described with reference to Figure 10
- FIG. 2 shows a further configuration for the emitter.
- a beam 23 (pump pulse) taken from optical fibre 7 ( Figure 1) is directed into probe housing 25.
- a focusing lens 27 is provided in the probe housing 25.
- the focusing lens 27 focuses the beam 23 onto a non-linear crystal 29.
- the non-linear crystal which is the THz emitter is configured to emit radiation with at least one frequency in the range from 0.1 THz to 84 THz (colloquially known as "THz radiation") when it is irradiated with beam 23.
- the non-linear crystal is configured to emit radiation with a frequency which is substantially equal to that of the difference of two frequencies of the incident radiation.
- Part of the housing 25 is covered with a protective sleeve 31.
- the housing 25 has a fibre coupler 26 for connecting fibre optic 7 to the housing.
- a protective cover 33 Behind this protective cover is a filter for residual visible pulses 35.
- the protective cover may also function to be a collimator for the THz beam.
- the THz beam 37 is thus emitted through the protective cover 33.
- the collimator maybe an Si polyethylene lens, or a lens made out of other suitable (non-absorbing and non dispersive THz) material.
- the collimator might also be configured to focus the THz to a spot on the sample, or be configured to supply a given THz beam profile which matches the THz beam to the detector after reflection or transmission from the object 1 under study.
- a condensing cone may also be provided.
- FIG 3 shows a further example of an emitter.
- the emitter housing 25 is the same as that shown in Figure 2. The details of the component within the housing 25 will not be repeated.
- the beam 23 is supplied to the emitter housing 25 from fibre optic cable 7.
- this fibre optic cable is a minimum dispersion fibre which has a positive dispersion effect on pulses travelling through the fibre.
- the pulses are passed through a dispersion compensator 39 which compresses the pulses in time prior to focusing on the generation crystal 29.
- the dispersion compensator 39 has a negative dispersion effect on the pulses whereas the minimum dispersion fibre has a positive dispersion effect on the pulses.
- Figure 4 shows a further configuration of optical fibre 7 for compensating for the dispersion effects which occur in the optical pulse when it is passing through the fibre 7.
- the optical fibre 7 is provided with positive dispersion segments 41 which serve to increase dispersion of the pulse and negative dispersion segments 43.
- the negative dispersion segments cancel out the effect of the positive dispersion segments. Therefore, the pulses remain compressed on arrival at the emitter housing 25.
- Figure 5 shows an example of a detector.
- the detector is provided in housing 51.
- the detector is provided with a reference beam (or probe pulse) 53 which is taken from fibre optic cable 11 ( Figure 1).
- the probe pulse 53 is passed through fibre optic circulator 54 from a first port of the circulator and out through a second port of the circulator, onto lens 63 which serves to focuses the probe pulse 53 onto a detection member 61.
- the detection member 61 is a non-linear crystal which, will transmit the probe pulse. However, if the probe pulse 53 mixes with a THz pulse 55 in the detection member 61, the polarisation of the probe pulse will be rotated due to the birefringence caused by the THz pulse. This effect is known as the AC Pockels effect and the detection technique is generally called electro-optic sampling (EOS). The change in polarisation of the probe pulse can be detected by known techniques.
- the probe pulse 53 is reflected back through detection member 61 by mirror 59 which is located on the opposite side of the detection member 61 to the point of entry of the probe pulse 53 into the probe.
- a THz pulse 55 which is either transmitted by or reflected from the sample is collected by THz lens 57.
- the lens 57 may alternatively be a condenser cone, or a combination of a lens and a condenser cone.
- the pulse 55 then passes through dielectric layer 59 which is provided behind the THz lens 57.
- the dielectric layer 59 enhances the reflection efficiency of the probe pulse.
- the dielectric layer is highly transparent at THz frequencies, thus it transmits the THz.
- the THz pulse then passes through detection member 61 and combines with the probe pulse 53 to rotate the polarisation of the probe pulse.
- the reflected probe pulse then passed back onto the fibre optic circulator 54 through the second port of the circulator.
- the fibre optic circulator transmits the reflected probe pulse out of a third port of the circulator.
- the transmitted probe pulse 56 which carries the information from the detected THz pulse 55 is then carried by a fibre optic cable to an external analysing means.
- FIG 6 shows another variation on the detector.
- the probe pulse 71 is essentially the reference beam. To avoid repetition, the features which are the same as those shown in Figure 5 will be given the same reference numerals and will not be described here.
- the THz beam is transmitted into electro-optical medium 61.
- the probe pulse which will be at optical frequencies is transmitted down channel 73 through focusing lens 63 into electro-optical medium which it combines with the THz pulse 55.
- the THz pulse affects the polarisation characteristic of the probe pulse 71. Therefore, the polarisation of the probe pulse can be used to determine the presence of the THz beam.
- the probe pulse 71 is then reflected into channel 75 and then into optical fibre 77 for analysis.
- FIGS 7 A and 7B show further examples of the detector.
- the THz pulse is collected by THz lens 57.
- the THz pulse 55 passes through the lens 57 and is directed onto material A 81 which is transparent to THz.
- the THz pulse is transmitted through material A and through material B 83 which is adjacent to material A.
- Material B is transparent to both THz and visible light.
- a reflective coating 85 is provided on the junction between materials 81 and 83.
- the reflective coating 85 is transparent and non dispersive to THz radiation.
- the boundary between materials 81 and 83 is inclined at an angle of about 45° to that of the incident THz pulse, and hence the reflective coating is inclined at an angle of about 45° to that of the incident THz pulse.
- An anti-reflective coating is provided where the probe pulse enters Material B83, to avoid unwanted reflections.
- Adjacent material B is an electro-optical medium 87.
- the THz pulse and the visible pulse will be combined.
- the incident probe pulse enters through channel 89.
- the incident probe pulse is then focused by lens 91.
- This lens functions to focus the incident probe pulse at the electro-optical medium 87.
- a wedge is provided to reflect the incident probe pulse into material B and hence onto the electro-optical medium 87 via the interface between materials A and B.
- Material A is not transparent to the optical pulse.
- the optical signal with the THz data is then transmitted away from the probe via channel 93.
- Material B 83 may be electro-optic material (which can serve as the detection member), and the modification of the probe pulse polarisation due to the presence of THz may occur in Material B 83 in addition to or instead of medium 87.
- a liquid crystal variable waveplate 88 is provided such that the probe pulse with the encoded THz information passes through this after passing through material 87.
- This plate can be used to block radiation with a certain polarisation, or it can be used to rotate the polarisation of incident radiation.
- Figure 8 shows yet another variation on the detector arrangement of Figure 7. To avoid unnecessary repetition, the same reference numerals in Figure 7 are used in Figure 8 and the description thereof will not be repeated.
- lens 91 functions not to focus the optical pulse of the electro-optical medium 87 surface. Instead, it expands the incident probe pulse to fit the whole of the electro-optical medium 87 surface.
- the incident probe pulse is inserted into the detector via channel 89 (as described with reference to Figures 7A and 7B).
- the pulse is then reflected in the same manner into the electro-optical medium 87 where it is combined with the THz pulse 55.
- a probe pulse carrying the THz information is then passed through liquid crystal variable retarder 95.
- the retarder can block optical pulses with a specific polarisation, it can also be used to rotate the polarisation of pulses if required.
- the THz beam serves to rotate the polarisation of the probe pulse. Therefore, by setting the retarder to block polarisation at the original polarisation of the incident probe pulse, the retarder will block any optical pulses with a polarisation which has not been rotated by the THz.
- Figure 9 shows a variation on the detector of Figure 8. Again, like components will have the same reference numerals. The only difference between these two is instead of the CCD array 97 provided within the detector itself, an optical fibre bundle 99 collects the output from the liquid crystal retarder 95. Each fibre of the optical fibre bundle 99 can be thought of as representing a pixel. The optical fibres will be polarisation preserving fibres which do not destroy the polarisation of the probe pulse as it travels towards an external analyser. Each fibre of the bundle 99 will carry spatial information back away from the probe. This improves spatial resolution and/or provides enhanced imaging capability.
- Figure 10 shows a detection system which can be used with any of the detectors of figures 5 to 9.
- the incident probe pulse is supplied via channel 101 to the detection head 103.
- the THz pulse 55 is collected by detection head 103.
- the THz pulse 55 and the visible probe beam 101 are combined in the detection head.
- the retarded visible probe is channelled away from the detection head via channel 105.
- the pulse is split into horizontally 107 and vertically 109 polarisation's via beam splitter 1 1 1.
- the horizontal and vertical polarised beams are then transmitted down separate fibre optic cables to a balanced detection system located in the control apparatus for the detector.
- the linearly polarised beam can become slightly elliptical. This effect is compensated for by a variable retardation waveplate, e.g. a quarter waveplate 115.
- the beam from the detector 105 is converted into a circularly polarised beam 1 17 using quarter wave plate 115. This is then split into two linearly polarised beams by a Wollaston Prism 119 (or equivalent device for separating orthogonal polarisation components) which directs the two orthogonal components of the polarised beam onto a balanced photodiode 121.
- the balanced photodiode signal is adjusted using wave plate 115 such that the difference in outputs between the two diodes is zero when no THz is detected. However, if the detector detects a THz beam, the angle ⁇ through which the polarisation is rotated by is not negligible.
- the probe pulse 101 and the THz beam 55 should stay in phase as they pass through the crystal detection member. Otherwise the polarisation rotation ⁇ is obscured. Therefore, the detection member has phase matching means to produce a clear signal.
- Figure 1 1 shows a multiple detector design.
- the emitter and detector are housed in housing 131.
- An emitter 133 is provided in the centre of the housing 131.
- Multiple detector heads (fibre optical cables) 135 are provided around the emitter 133.
- the detector head 135 can be any of those described with reference to Figures 5 to 9.
- the emitter can be any of those described with reference to Figures 2 to 4.
- the number of detectors will vary depending on the application and spatial resolution required. Alternative designs may be used with only a bundle of detectors and with an emitter as a single fibre source, which is spatially separated from the detector heads 135.
- Figure 12 shows a further variation on the multiple detector design.
- a plurality of detector heads 135 are arranged around emitter 133.
- the emitter is provided with a generation pulse from channel 137.
- the detected THz radiation is picked up by fibres 135.
- the probe beam for each fibre is provided by bundle of fibres 140, which itself is provided from single optical fibre 139 via a coupling means 142.
- a probe signal from each single fibre 141 of bundle 139 is directed into the detector head via fibres 135, and modified probe beam in 135 which contains the encoded THz signal is coupled via 143 into the polariser array 145 and then CCD array 147.
- the polariser array 145 is crossed relative to the polarisation of the incident probe beam from fibre 139.
- the multiple detector heads can be configured to have separate electro-optical crystals for each fibre or alternatively, a single electro-optic crystal for use with all fibres. The this case, both the detector and the emitter could use the same electro-optic member.
- emitter may be used which also emit radiation with a frequency in the desired range in response to irradiation by one or more input beams which can be carried to the probe by one or more optic fibre cables.
- FIG. 13 illustrates a so-called photoconductive emitter.
- the emitter comprises a member 301 comprising a semiconductor such as low temperature GaAs, semi- insulating GaAs, silicon on Sapphire, semi-insulating InGaAs, low temperature InGaAs, semi-insulating InP or As implanted GaAs, etc.
- the semiconductor member has a pair of electrodes 303a and 303b located on its surface, the electrodes 303a and 303b are connected to a power supply such that a field can be generated between the two electrodes 303a and 303b.
- the electrodes may be triangular and arranged in a bow-tie shape, a so-called bow-tie antenna or they may be interdigitated electrodes at the centre of a bow tie or spiral antenna. Alternatively, such designs may be inco ⁇ orated into transmission lines on the chip.
- the semiconductor member is irradiated by two pump beams with frequencies col and ⁇ >2.
- the pump beams impinge on the semiconductor member 301 on the part of its surface between the electrodes 303a and 303b, i.e. where the field is applied.
- the beating of the two visible or near-infrared lasers in the non-linear region of the semiconductor member between the two electrodes 303a and 303b results in the emission of THz radiation from the semiconductor member 301.
- the semiconductor member 301 is provided with a lens 305, which may be of a hemispherical or other design, on its surface which is opposite to that of the surface with the electrodes, to allow the emission of a beam of THz radiation.
- the emitter of Figure 13 can also be configured as a photoconductive detector.
- THz radiation is incident on a back surface of the semiconductor member 301.
- On the opposing side of the semiconductor member 301 are located a pair of electrodes 303a and 303b.
- the region between these two electrodes 303a and 303b is illuminated by radiation of the visible or near infrared range (probe pulse).
- the detector needs to know information about the phase of the radiation emitted from the emitter 1 this radiation preferably carries such information.
- the THz radiation which is used to image the sample will be derived from this radiation.
- the near-infrared/visible radiation illuminates the surface of the detector between the electrodes 303a and 303b.
- the Terahertz radiation induces a photocurrent through the region between the electrodes 303a and 303b which is being illuminated by the visible/infrared radiation.
- the current which can be detected by the electrodes is proportional to the strength of the THz field.
- the electrodes 303a and 303b may be of a simple diode formation embedded in a transmission line. Alternatively, they may be triangular and arranged in the shape of a bow-tie to from a so-called bow-tie antenna. They may also be interdigitated electrodes at the centre of a bow-tie or spiral antenna.
- Figure 14 shows the photo conductive emitter of Figure 13 in a probe in accordance with an embodiment of the present invention. It will be noted that the arrangement is very similar to that of Figure 2. Therefore, to avoid unnecessary repetition or confusion, like reference numerals will be used to denote like features.
- a pump beam 23 is taken from optical fibre 7 ( Figure 1 ) and is directed into probe housing 25.
- a focusing lens 27 is provided in the probe housing 25.
- the focusing lens 27 focuses the beam 23 onto photo conductive emitter body 301.
- the photo conductive emitter body is the same as that described with reference to Figure 13.
- Electrodes 303a and 303b overlying said emitter body are biased to create a field between themselves.
- electrode 303a is connected to ground via wire 307 and electrode 303b is connected to a positive bias via wire 309. THz radiation is generated as explained with reference to Figure 13.
- the part of the housing is covered with the protective sleeve 31.
- the housing 25 has a fibre coupler 26 for connecting fibre optic 7 to housing 25.
- a protective cover 33 At the end of the housing, there is a protective cover 33. Behind this protective cover is a fibre for residual visible pulse 35.
- the protective cover may also function as a collimator for the THz beam.
- the THz beam 37 is thus emitted through protective cover 33.
- the collimator may be a Si polyethylene lens, or a lens made out of other suitable (non-absorbing and non-dispersive THz) material.
- the collimator might also be configured to focus the THz beam to a spot on the sample, or be configured to supply a given THz beam profile which matches the THz beam to the detector after reflection or transmission from the object 1 under study.
- a condensing cone may also be provided.
- Figure 15 shows a detector housed in a probe using a photo conductive detector. It should be noted that the design is very similar to that described with reference to Figure 14. In this situation, pump pulse 23 is provided to the probe from optical fibre 7. The pump pulse is focused via lens 27 onto photo conductive antenna body 301 as described with reference to Figure 14.
- no bias is applied across electrodes 303a and 303b. Therefore, there is no incentive for the photo excited carriers to move towards either electron 303a or 303b.
- THz beam 55 The THz beam enters the detector through protective cover 33. It then impinges on photo conductive antenna body 301 and causes the photo excited carriers to move either towards electrode 303a or 303b resulting in a current slowing from lead wires 307 to 309. In this example, the current is carried away by wire 309. The change in the phase of the THz radiation as it passed through the sample can be detected by measuring the induced current.
- the current is then amplified using pre- amp 311.
- the pre-amp output is then fed into locking amplifier and/or AD converter and/or signal processor 313 which is then analysed by computer 315.
- a plurality of detectors as described with reference to Figure 15 can be the detector heads 135 as described with reference to Figure 11.
- An emitter as described with reference to Figure 14 or for example, any other type of emitter described previously can be seen as emitter probe 133.
- emitter probe 133 can be seen as emitter probe 133.
- detector heads 135 in combination with a photo conductive emitter 133.
- Figure 16 shows a further variation on an emitter. To avoid unnecessary repetition, like reference numerals will be used to denote like features as described with reference to Figures 14 and 2.
- the probe pulse is directed through lens 27 onto p-i-n diode 317.
- the p-i-n diode works in a similar manner to the photo conductive emitter described with reference to Figure 14.
- a bias is applied via leads 307 and 309, an application of a suitable bias results in the emission of THz beam 37 through THz lens 33.
- this p-i-n diode can be used to function as a detector as described with reference to Figure 15.
- FIG. 17 shows a system which comprises two laser diodes 321, 323 which are configured to emit radiation with frequencies ⁇ > ⁇ and ⁇ 2 respectively.
- the radiation emitted from both laser diodes 321 and 323 is combined using beam splitter/combiner 325.
- the combined radiation which contains both frequencies ⁇ > ⁇ and ⁇ 2 is then directed into fibre optic coupler 327 which directs the emitted radiation into fibre optic cable 329.
- Cable 329 carries the radiation to THz source 331 for emitting THz radiation.
- the THz radiation is produced with a frequency of ⁇ i - ⁇ 2 and THz source 331 can use any of the previous described methods such as EOS or photo conductive emitters for generating the THz radiation.
- the beams emitted from laser diodes 321, 323 are taken as the probe beam 333 using beam splitter 325.
- This probe beam 333 will be used to give the detector information about the phase of the radiation which is emitted from the THz source 331.
- the probe beam is fed into optical delay line 335 which is used as the delay control means 19 explained with reference to Figure 1.
- the probe beam 333 is reflected off cube mirror 337 which is used to reflect the light through 180° and onto mirror 339 which in turn reflects the probe beam 333 into fibre optic coupler 341.
- Fibre optic coupler 341 directs the probe beam into fibre optic 343 and into THz detector head 345.
- Improvements in the signal to noise ratio and hence acquisition times can be made by various modulation schemes.
- dithering or oscillating of the mirror 337 will cause sinusoidal variations in the d p that can be detected using standard lock-in techniques. This is essentially a frequency modulation of the THz waveform as it is plotted out versus d p .
- Figure 18 shows the system of Figure 17 using EOS to detect the THz beam.
- the reference beam 343 is carried to THz detector via fibre optic cable 343. Fibre optic cable 343 is terminated by fibre optic coupler 347.
- the reference beam is then combined with the detected THz radiation via beam combiner 349.
- the combined beam is then directed into Non-linear material 351.
- the non-linear material is configured so that the polarisation of the reference beam is rotated in accordance with the detected THz beam.
- the beam with the rotated polarisation vector is then fed in fibre 353 via fibre optic couple 355.
- Fibre optic cable 353 directs the radiation back to the analysis equipment. Fibre optic cable is terminated by fibre optic couples 357. This radiation is then fed into a polarisation analyser as described with reference to Figure 10.
- the sample is illuminated with two frequencies in the THz range.
- the THz generator is based on the generator described with reference to Figures 3 and 4.
- the first laser diode 401 emits radiation with a frequency ⁇ i into beam splitter 407.
- Beam splitter 407 directs part of the beam into beam combiner 409 where it combines with radiation of a frequency ⁇ emitted from the second diode.
- the other part of the beam is directed towards combiner 41 1, where it is combined in beam combiner 411 with radiation from the third diode 305 having a frequency ⁇ .
- Radiation from beam combiner 409 is directed into beam splitter 413 which in turn splits the beam into an input for the phase control means 7 and an input for the THz source 417.
- Radiation from beam combiner 411 is directed into beam splitter 415 where it is split into an input for the phase control means 7 and an input to the THz source 417.
- the THz source is configured to output beams in the THz range with frequencies ⁇ ⁇ 2 and co ⁇ -co 3 . These two beams travel through the sample 3.
- the two THz frequencies co ⁇ - ⁇ 2 and ⁇ j- ⁇ 3 will be chosen such that they can be used to probe different materials which make up the sample.
- the two transmitted THz beams are combined with the two reference beams as previously described.
- the detector can be any type of detector which has been previously described for the use of one THz beam.
- the different frequency components can be split by Fourier transforming the signal obtained due to the detected radiation.
- FIG 20 shows an application of the THz probe.
- the sample to be imaged is a tooth 201 which is in a gum 203.
- An emitter 205 which may be an emitter of the type described with reference to any of Figures 2 to 5 and a multielement detector head 207 is provided on the opposite side of tooth 201 to the emitter head 205. Both the emitter 205 and the detector 207 receive a pulse from laser source 209.
- the laser source 209 also serves to collect the data transmitted from detector 207.
- the laser source is then connected to imaging analysis means 21 1 which provides a THz image of the tooth.
- the probe may also be positioned on either side of the bone below the tooth. This can be used to detect periodontal disease.
- Figure 21 shows a variation on the system of Figure 13.
- a single probe 213 is provided.
- the single probe 213 is Y-shaped.
- a THz emitter 215 is provided on one of the Y and a THz detector 217 is provided on the opposing end of the Y shape. All the fibres are delivered along a single cable 219 to the probe 213.
- the laser source 209 and the analysis means 21 1 remain the same as those for Figure 13.
- Figure 22 A shows a further example of the probe.
- the probe works on reflection as opposed to transmission.
- the laser source 209 and image analysis 211 provide the same function. All signals to and from the probe are provided by a single cable 211.
- the probe 223 is positioned next to the tooth. The emitter and detector must sit at the same space of the probe. This could be achieved using the arrangement of Figure 11 or that of Figure 12.
- Figure 22B shows a further example of the probe.
- the probe works on both transmission as well as reflection.
- the probe has the Y shape configuration of Figure 21. To avoid repetition, the same reference numerals will be used to denote the same features.
- Transmission detector head 217 is provided with a plurality of detector elements.
- Reflection head 218 is provided with a plurality of detection elements 220 and an emitter element 222. The emitter irradiates the tooth and the section head 217 detects transmitted radiation and the detection head 218 detects reflected radiation.
- Figure 23 shows photographs and a CCD image of a tooth.
- Figure 23 A shows an outside view of the tooth showing the shiny enamel.
- Figure 23B shows the inside of a tooth, the enamel 301 can be seen at the outside of the tooth, the dentine 303 is seen inside the enamel and the pulp cavity 305 is located in the centre of the tooth.
- Figure 23C shows a CCD image of the cut tooth of Figure 23B. Again, the enamel 301, the dentine 303 and the root cavity can be clearly distinguished.
- the outside of the tooth is denoted by numeral I
- the enamel will be denoted by numeral II
- the dentine/root cavity will be denoted by III.
- the tooth in Figure 23 is an extracted premolar with no large, obvious carious region in the main portion of the tooth.
- the abso ⁇ tion coefficient was estimated at 8cm "1 from a tooth that was roughly 9mm thick.
- Figure 24 is used to describe THz data taken from the tooth of Figure 23.
- Figure 24A shows the CCD scan of Figure 23C.
- an axis 307 has been entered onto the figure.
- box 309 which represents the sampling area for the THz.
- the time of flight or delay of a THz pulse as it passes through an object of thickness d and refracted index n, relative to a reference pulse travelling through the air it is given by:
- the thickness D can be determined to an accuracy of typically plus or minus 1 ⁇ m.
- FIGS. 24B to 24D show time domain traces of the THz pulse as it passes through the three regions:
- X and Y are defined in Figure 24A.
- a delay of (1 Ops) occurs as the pulse travels through the tooth enamel.
- a large decrease in the delay is observed (reduction to 5ps) in spite of a very small change in overall tooth thickness.
- Figure 24E is a plot of the temporal shift of measured peaks from Figures 24B to D plotted against position alone the x-axis 307 of box 309. The squares correspond to the maximum peak shift observed and the triangles correspond to the minimum peak shift observed.
- the enamel region 2 can be seen to have the largest shifts in peaks.
- the enamel and dentine region 3 has a much lower peak shift.
- Figure 24 is a schematic cross section of the tooth.
- Figure 24F and 24E have been joined to illustrate how the THz changes throughout the path of the tooth.
- Figure 25 A is a plot of temporal position of the peaks in the THz pulse as a function of x position in the tooth.
- the x-axis is shown on Figure 25B.
- the same tooth is used as described in Figure 23.
- the three regions outside tooth, enamel and enamel plus dentine are the same as previously described with reference to Figures 23 and 24.
- Figure 25B shows the position of the THz scans. Three scans were taken at three different points along the y-axis (11mm, 12mm and 12.66mm). For each x-line scan, a given y, the time delay of the positive going portion of the THz pulse is plotted at a function of x.
- Figure 26 shows the temporal positions of THz pulses in an x, y plane of the tooth.
- Figure 26 shows an area 311 which represents the sample scanning area.
- Figure 26A is a plot of the temporal position of the THz pulses against x-axis. The squares correspond to the maximum time difference measured and the circles correspond to the time delay. For ease of viewing, the squares and circles on the right hand side of the picture which correspond to the boundary between the enamel and the dentine and enamel have been made smaller.
- Figure 27 shows a three dimensional plot using all of the data from Figures 24 to 26. The time delay is plotted for each pixel.
- Figure 28 shows a two dimensional contour plot of the tooth which shows that the difference between enamel only and enamel and dentine can be easily established.
- Figure 29 shows a panchromatic abso ⁇ tion image which shows the presence of the pulp cavity.
- Figures 30A and 30B shows a plot of THz transmission through a saturated glucose solution mixed with different parts of water.
- the upper trace refers to saturated glucose solution.
- the lower trace is pure water. It can be seen that the abso ⁇ tion of the THz signal decreases as the glucose concentration is increased.
- Figure 3 OB shows the data of Figure 30A plotted as a percentage change in transmission from pure water.
- Figure 30 shows the power of using THz to examine teeth.
- Figure 31 is a plot of transmission of THz signal across frequency of a new born calf serum.
- the lower trace shows the serum with bacteria growth.
- the upper trace shows the serum with no bacterial growth.
- FIG. 32 shows a further plot of transmission of THz against frequency. This time, the solution is methanol and water is progressively added. As water is added to the solution, the transmission through the sample decreases.
- Figure 33 shows a plot of THz transmission against frequency for clotted blood.
- the upper trace is the reference, the lower trace is 90 ⁇ m of clotted blood.
- the clotted blood is seen to have a higher abso ⁇ tion than that of the reference.
- FIG 34 shows THz being used to image different types of animal tissue. Here, it is used to image bone.
- the ability to image bone composition clearly shows that THz can be used to image periodontal disease which manifests itself in loss of bone from below the tooth.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU60082/00A AU778292B2 (en) | 1999-07-23 | 2000-07-24 | A radiation probe and detecting tooth decay |
EP00946211A EP1202664A1 (en) | 1999-07-23 | 2000-07-24 | A radiation probe and detecting tooth decay |
JP2001511811A JP4391714B2 (en) | 1999-07-23 | 2000-07-24 | Radiation probe and tooth detection |
US11/011,703 US8027709B2 (en) | 1999-07-23 | 2004-12-14 | Radiation probe and detecting tooth decay |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9917407A GB2352512B (en) | 1999-07-23 | 1999-07-23 | A radiation probe and detecting tooth decay |
GB9917407.0 | 1999-07-23 |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10031784 A-371-Of-International | 2000-07-24 | ||
US11/011,703 Continuation US8027709B2 (en) | 1999-07-23 | 2004-12-14 | Radiation probe and detecting tooth decay |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001006915A1 true WO2001006915A1 (en) | 2001-02-01 |
Family
ID=10857876
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2000/002849 WO2001006915A1 (en) | 1999-07-23 | 2000-07-24 | A radiation probe and detecting tooth decay |
Country Status (6)
Country | Link |
---|---|
US (1) | US8027709B2 (en) |
EP (1) | EP1202664A1 (en) |
JP (1) | JP4391714B2 (en) |
AU (1) | AU778292B2 (en) |
GB (1) | GB2352512B (en) |
WO (1) | WO2001006915A1 (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1230578A4 (en) * | 1999-10-14 | 2004-03-03 | Picometrix Inc | Compact fiber pigtailed terahertz modules |
FR2854504A1 (en) * | 2003-04-30 | 2004-11-05 | Thales Sa | TERAHERTZ TRANSMISSION SOURCE AND OPTICAL SYSTEM COMPRISING SUCH A SOURCE |
US6816647B1 (en) | 1999-10-14 | 2004-11-09 | Picometrix, Inc. | Compact fiber pigtailed terahertz modules |
JP2005517925A (en) * | 2002-02-15 | 2005-06-16 | テラビュー リミテッド | Analytical apparatus and method |
DE10297037B4 (en) * | 2001-07-02 | 2008-01-17 | Advantest Corp. | Spreading measuring device and propagation measuring method |
US7449695B2 (en) | 2004-05-26 | 2008-11-11 | Picometrix | Terahertz imaging system for examining articles |
WO2009036561A1 (en) * | 2007-09-21 | 2009-03-26 | National Research Council Of Canada | Method and apparatus for periodontal diagnosis |
EP2098839A2 (en) | 2008-03-04 | 2009-09-09 | Sony Corporation | Terahertz spectrometer |
EP2273254A1 (en) * | 2008-04-30 | 2011-01-12 | Hamamatsu Photonics K.K. | Total reflection terahertz wave measurement device |
DE102009051692B3 (en) * | 2009-10-27 | 2011-04-07 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and device for identifying a material |
DE102011112697A1 (en) | 2011-08-31 | 2013-02-28 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and apparatus for determining a substance using THz radiation |
Families Citing this family (150)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060240381A1 (en) | 1995-08-31 | 2006-10-26 | Biolase Technology, Inc. | Fluid conditioning system |
US11026768B2 (en) | 1998-10-08 | 2021-06-08 | Align Technology, Inc. | Dental appliance reinforcement |
GB2371618B (en) * | 2001-01-30 | 2004-11-17 | Teraprobe Ltd | A probe, apparatus and method for examining a sample |
JP2002243416A (en) * | 2001-02-13 | 2002-08-28 | Tochigi Nikon Corp | Method and instrument for thickness measurement and wafer |
DE10119543A1 (en) * | 2001-04-21 | 2002-10-24 | Philips Corp Intellectual Pty | Arrangement for magnetic resonance signal optical transmission has electrooptical modulator material between crossed polarizers so light extinguished if no voltage induced in coil |
GB0119564D0 (en) * | 2001-08-10 | 2001-10-03 | Univ Cambridge Tech | Radiation device |
GB2405200B (en) * | 2003-08-22 | 2005-09-07 | Teraview Ltd | A method and apparatus for investigating a sample |
GB2405466B (en) * | 2003-08-27 | 2006-01-25 | Teraview Ltd | Method and apparatus for investigating a non-planner sample |
JP2005172779A (en) * | 2003-12-10 | 2005-06-30 | Semiconductor Res Found | Method and apparatus for measuring bacteria, virus and toxic substance by irradiation with electromagnetic wave |
JP4209766B2 (en) * | 2003-12-26 | 2009-01-14 | 潤一 西澤 | Terahertz electromagnetic wave reflection measuring device |
US20100151406A1 (en) | 2004-01-08 | 2010-06-17 | Dmitri Boutoussov | Fluid conditioning system |
GB2410081B (en) * | 2004-01-19 | 2007-02-21 | Limited Cambridge University T | Terahertz radiation sensor and imaging system |
GB2411093B (en) * | 2004-02-13 | 2007-10-24 | Teraview Ltd | Terahertz imaging system |
US9492245B2 (en) | 2004-02-27 | 2016-11-15 | Align Technology, Inc. | Method and system for providing dynamic orthodontic assessment and treatment profiles |
GB0417394D0 (en) * | 2004-08-04 | 2004-09-08 | Council Cent Lab Res Councils | Scanning imaging device |
SI1788966T1 (en) * | 2004-08-13 | 2013-07-31 | Biolase Inc | |
FR2878424B1 (en) | 2004-11-26 | 2008-02-01 | Oreal | METHOD FOR OBSERVING A BIOLOGICAL TISSUE, IN PARTICULAR HUMAN SKIN |
EP1830705B1 (en) * | 2004-11-26 | 2010-12-29 | L'Oréal | A method of observing biological tissue, in particular human skin |
US9968526B1 (en) | 2005-01-24 | 2018-05-15 | Dental Alliance Holdings, Lll | System for caries management by risk assessment |
US20090131799A1 (en) * | 2005-04-22 | 2009-05-21 | Kanazawa University | Bone density measuring device |
CA2517252A1 (en) * | 2005-08-29 | 2007-02-28 | Neks Technologies Inc. | Detection of interproximal caries aided by optical sensor examining the occlusal surface of teeth |
DE102005052294A1 (en) * | 2005-10-26 | 2007-05-03 | Jaruszewski, Lutz, Dr. | Measuring device for determining the activity status of initially carious enamel lesions has an optical distance-measuring system in a hand-piece for measuring pores in tooth enamel |
US20070184402A1 (en) * | 2006-01-03 | 2007-08-09 | Dmitri Boutoussov | Caries detection using real-time imaging and multiple excitation frequencies |
US8417010B1 (en) | 2006-01-12 | 2013-04-09 | Diagnoscan, LLC | Digital x-ray diagnosis and evaluation of dental disease |
US9427384B2 (en) | 2006-01-23 | 2016-08-30 | Dental Alliance Holdings, Llc | System for caries management by risk assessment |
GB2438215B (en) * | 2006-05-19 | 2011-06-08 | Teraview Ltd | A THz investigation apparatus and method |
CA2654205A1 (en) * | 2006-06-02 | 2007-12-13 | Picometrix, Llc | Dispersion and nonlinear compensator for optical delivery fiber |
US8270689B2 (en) | 2006-09-12 | 2012-09-18 | Carestream Health, Inc. | Apparatus for caries detection |
US10143633B2 (en) | 2006-10-16 | 2018-12-04 | Dental Alliance Holdings, Llc | Treating cariogenic diseased oral biofilm with elevated pH |
JP2008197081A (en) * | 2007-02-15 | 2008-08-28 | Tohoku Univ | Detection and analysis method for substance in living body or excreted from living body |
JP2008197080A (en) * | 2007-02-15 | 2008-08-28 | Tohoku Univ | Tooth decay detection method and device |
US8734466B2 (en) | 2007-04-25 | 2014-05-27 | Medtronic, Inc. | Method and apparatus for controlled insertion and withdrawal of electrodes |
US20090012509A1 (en) * | 2007-04-24 | 2009-01-08 | Medtronic, Inc. | Navigated Soft Tissue Penetrating Laser System |
US8301226B2 (en) | 2007-04-24 | 2012-10-30 | Medtronic, Inc. | Method and apparatus for performing a navigated procedure |
US8108025B2 (en) | 2007-04-24 | 2012-01-31 | Medtronic, Inc. | Flexible array for use in navigated surgery |
US8311611B2 (en) | 2007-04-24 | 2012-11-13 | Medtronic, Inc. | Method for performing multiple registrations in a navigated procedure |
US9289270B2 (en) | 2007-04-24 | 2016-03-22 | Medtronic, Inc. | Method and apparatus for performing a navigated procedure |
US7878805B2 (en) | 2007-05-25 | 2011-02-01 | Align Technology, Inc. | Tabbed dental appliance |
GB2452267B (en) * | 2007-08-28 | 2010-06-16 | Teraview Ltd | Scanning Terahertz probe |
EP2031374B1 (en) * | 2007-08-31 | 2012-10-10 | Canon Kabushiki Kaisha | Apparatus and method for obtaining information related to terahertz waves |
DE102007043366A1 (en) * | 2007-09-12 | 2009-03-19 | Degudent Gmbh | Method for determining the position of an intraoral measuring device |
DE102007044839A1 (en) * | 2007-09-14 | 2009-05-20 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for generating and coherently detecting terahertz radiation |
EP2039288A1 (en) * | 2007-09-18 | 2009-03-25 | Olympus Corporation | Dental observation apparatus |
US8251903B2 (en) * | 2007-10-25 | 2012-08-28 | Valencell, Inc. | Noninvasive physiological analysis using excitation-sensor modules and related devices and methods |
US8738394B2 (en) | 2007-11-08 | 2014-05-27 | Eric E. Kuo | Clinical data file |
US8108189B2 (en) | 2008-03-25 | 2012-01-31 | Align Technologies, Inc. | Reconstruction of non-visible part of tooth |
DE102008020217A1 (en) * | 2008-04-22 | 2009-11-05 | Universität Stuttgart | Apparatus and method for carrying out measurements in cavities |
KR100945280B1 (en) | 2008-05-14 | 2010-03-03 | 서울시립대학교 산학협력단 | Apparatus and method for generating high resolution image of human body using terahertz electromagnetic wave and endoscope using the same |
KR100963836B1 (en) | 2009-02-19 | 2010-06-16 | 서울시립대학교 산학협력단 | Method and apparatus for generating image of human body with high sensitivity via differential detection using terahertz electromagnetic wave and endoscope employing the same |
JP4897007B2 (en) * | 2008-05-14 | 2012-03-14 | ユニヴァーシティー・オヴ・ソウル・ファウンデイション・オヴ・インダストリー・アカデミック・コウオペレイション | High-resolution biological image generation apparatus using terahertz electromagnetic waves, high-resolution image generation method, and endoscope apparatus using the same |
US8092215B2 (en) | 2008-05-23 | 2012-01-10 | Align Technology, Inc. | Smile designer |
US9492243B2 (en) | 2008-05-23 | 2016-11-15 | Align Technology, Inc. | Dental implant positioning |
DE102008026190B4 (en) * | 2008-05-30 | 2010-10-21 | Menlo Systems Gmbh | Apparatus for generating or receiving terahertz radiation |
US8172569B2 (en) | 2008-06-12 | 2012-05-08 | Align Technology, Inc. | Dental appliance |
US9849310B2 (en) | 2008-06-24 | 2017-12-26 | Dental Alliance Holdings, Llc | Dental appliance, oral care product and method of preventing dental disease |
US9160996B2 (en) * | 2008-06-27 | 2015-10-13 | Texas Instruments Incorporated | Imaging input/output with shared spatial modulator |
US8152518B2 (en) | 2008-10-08 | 2012-04-10 | Align Technology, Inc. | Dental positioning appliance having metallic portion |
GB0818775D0 (en) * | 2008-10-13 | 2008-11-19 | Isis Innovation | Investigation of physical properties of an object |
JP2009075134A (en) * | 2009-01-05 | 2009-04-09 | Junichi Nishizawa | Identification device for bacterium or toxic substance |
US8292617B2 (en) | 2009-03-19 | 2012-10-23 | Align Technology, Inc. | Dental wire attachment |
KR101055313B1 (en) * | 2009-05-15 | 2011-08-09 | 한국과학기술원 | Image Restoration System and Method in 3D Space Using Terahertz Pulse Reflection |
US8765031B2 (en) | 2009-08-13 | 2014-07-01 | Align Technology, Inc. | Method of forming a dental appliance |
JP2011112548A (en) * | 2009-11-27 | 2011-06-09 | Sony Corp | Biosample analysis method, biosample analyzer, and biosample analysis program |
JP2015099379A (en) * | 2010-03-04 | 2015-05-28 | キヤノン株式会社 | Terahertz wave generating unit, terahertz wave detecting unit, and terahertz time-domain spectroscopic device |
JP5709562B2 (en) | 2010-03-04 | 2015-04-30 | キヤノン株式会社 | Terahertz wave generating element and terahertz time domain spectrometer |
US8816279B2 (en) * | 2010-04-09 | 2014-08-26 | Northeastern University | Tunable laser-based infrared imaging system and method of use thereof |
US9211166B2 (en) | 2010-04-30 | 2015-12-15 | Align Technology, Inc. | Individualized orthodontic treatment index |
US9241774B2 (en) | 2010-04-30 | 2016-01-26 | Align Technology, Inc. | Patterned dental positioning appliance |
EP2575706B1 (en) * | 2010-05-28 | 2017-04-05 | Resmed Sas | Apparatus, system and method for determining compliant use of an intraoral appliance |
US8716666B1 (en) * | 2010-06-10 | 2014-05-06 | Emcore Corporation | Method of detecting contaminant materials in food products |
KR101149352B1 (en) * | 2010-11-04 | 2012-05-30 | 서울시립대학교 산학협력단 | Terahertz imaging method and apparatus for producing three-dimensional image of tumor |
JP2012238695A (en) * | 2011-05-11 | 2012-12-06 | Canon Inc | Terahertz wave generating device and measurement device having the same |
DE102011103301B4 (en) * | 2011-06-04 | 2019-05-09 | Gilbert Duong | Toothbrush navigation system for displaying the current cleaning results during tooth brushing |
US9801552B2 (en) | 2011-08-02 | 2017-10-31 | Valencell, Inc. | Systems and methods for variable filter adjustment by heart rate metric feedback |
US9403238B2 (en) | 2011-09-21 | 2016-08-02 | Align Technology, Inc. | Laser cutting |
JP2013068526A (en) * | 2011-09-22 | 2013-04-18 | Aisin Seiki Co Ltd | Terahertz wave generating and detecting device |
GB201116518D0 (en) | 2011-09-23 | 2011-11-09 | Isis Innovation | Investigation of physical properties of an object |
US9901256B2 (en) * | 2012-01-20 | 2018-02-27 | University Of Washington Through Its Center For Commercialization | Dental demineralization detection, methods and systems |
US9375300B2 (en) | 2012-02-02 | 2016-06-28 | Align Technology, Inc. | Identifying forces on a tooth |
US9220580B2 (en) | 2012-03-01 | 2015-12-29 | Align Technology, Inc. | Determining a dental treatment difficulty |
US9414897B2 (en) | 2012-05-22 | 2016-08-16 | Align Technology, Inc. | Adjustment of tooth position in a virtual dental model |
US10010250B2 (en) * | 2012-12-19 | 2018-07-03 | Koninklijke Philips N.V. | Dental apparatus and method of utilizing the same |
EP2934290A1 (en) * | 2012-12-19 | 2015-10-28 | Koninklijke Philips N.V. | Frequency domain time resolved fluorescence method and system for plaque detection |
WO2015108836A1 (en) | 2014-01-14 | 2015-07-23 | Inventive Medical Devices, Llc | Detection of hard and soft tissue mass/density |
US10080484B2 (en) | 2014-01-31 | 2018-09-25 | University Of Washington | Multispectral wide-field endoscopic imaging of fluorescence |
CA2943576C (en) | 2014-04-10 | 2023-04-04 | Institut National De La Recherche Scientifique | Fully-coherent terahertz detection method and system |
US10772506B2 (en) | 2014-07-07 | 2020-09-15 | Align Technology, Inc. | Apparatus for dental confocal imaging |
US9675430B2 (en) | 2014-08-15 | 2017-06-13 | Align Technology, Inc. | Confocal imaging apparatus with curved focal surface |
US9610141B2 (en) | 2014-09-19 | 2017-04-04 | Align Technology, Inc. | Arch expanding appliance |
US10449016B2 (en) | 2014-09-19 | 2019-10-22 | Align Technology, Inc. | Arch adjustment appliance |
JP6751388B2 (en) * | 2014-09-29 | 2020-09-02 | コーニンクレッカ フィリップス エヌ ヴェKoninklijke Philips N.V. | Device and method for plaque detection |
US9744001B2 (en) | 2014-11-13 | 2017-08-29 | Align Technology, Inc. | Dental appliance with cavity for an unerupted or erupting tooth |
US10504386B2 (en) | 2015-01-27 | 2019-12-10 | Align Technology, Inc. | Training method and system for oral-cavity-imaging-and-modeling equipment |
US10248883B2 (en) | 2015-08-20 | 2019-04-02 | Align Technology, Inc. | Photograph-based assessment of dental treatments and procedures |
JP2017078599A (en) * | 2015-10-19 | 2017-04-27 | フェムトディプロイメンツ株式会社 | Terahertz time-resolved spectroscopy apparatus |
US10945618B2 (en) | 2015-10-23 | 2021-03-16 | Valencell, Inc. | Physiological monitoring devices and methods for noise reduction in physiological signals based on subject activity type |
US10610158B2 (en) | 2015-10-23 | 2020-04-07 | Valencell, Inc. | Physiological monitoring devices and methods that identify subject activity type |
US11931222B2 (en) | 2015-11-12 | 2024-03-19 | Align Technology, Inc. | Dental attachment formation structures |
US11554000B2 (en) | 2015-11-12 | 2023-01-17 | Align Technology, Inc. | Dental attachment formation structure |
US11103330B2 (en) | 2015-12-09 | 2021-08-31 | Align Technology, Inc. | Dental attachment placement structure |
US11596502B2 (en) | 2015-12-09 | 2023-03-07 | Align Technology, Inc. | Dental attachment placement structure |
CN105841816B (en) * | 2016-04-18 | 2017-06-06 | 深圳市太赫兹科技创新研究院 | Terahertz time-domain spectroscopy system |
CN105962880B (en) * | 2016-04-18 | 2017-12-29 | 浙江大学 | A kind of Terahertz endoscope and detection method suitable for enteron aisle lesion detection |
DE102016206965B4 (en) * | 2016-04-25 | 2022-02-03 | Bruker Optik Gmbh | Method for measuring and determining a THz spectrum of a sample |
US10383705B2 (en) | 2016-06-17 | 2019-08-20 | Align Technology, Inc. | Orthodontic appliance performance monitor |
US10470847B2 (en) | 2016-06-17 | 2019-11-12 | Align Technology, Inc. | Intraoral appliances with sensing |
US10181544B2 (en) * | 2016-07-07 | 2019-01-15 | Lawrence Livermore National Security, Llc | Photoconductive switch package configurations having a profiled resistive element |
WO2018009736A1 (en) | 2016-07-08 | 2018-01-11 | Valencell, Inc. | Motion-dependent averaging for physiological metric estimating systems and methods |
US10507087B2 (en) | 2016-07-27 | 2019-12-17 | Align Technology, Inc. | Methods and apparatuses for forming a three-dimensional volumetric model of a subject's teeth |
KR102595753B1 (en) | 2016-07-27 | 2023-10-30 | 얼라인 테크널러지, 인크. | Intraoral scanner with dental diagnostics capabilities |
US11883132B2 (en) | 2016-10-28 | 2024-01-30 | University Of Washington | System and method for ranking bacterial activity leading to tooth and gum disease |
CN113648088B (en) | 2016-11-04 | 2023-08-22 | 阿莱恩技术有限公司 | Method and apparatus for dental imaging |
EP3547952B1 (en) | 2016-12-02 | 2020-11-04 | Align Technology, Inc. | Palatal expander |
US11026831B2 (en) | 2016-12-02 | 2021-06-08 | Align Technology, Inc. | Dental appliance features for speech enhancement |
AU2017366755B2 (en) | 2016-12-02 | 2022-07-28 | Align Technology, Inc. | Methods and apparatuses for customizing rapid palatal expanders using digital models |
US11376101B2 (en) | 2016-12-02 | 2022-07-05 | Align Technology, Inc. | Force control, stop mechanism, regulating structure of removable arch adjustment appliance |
US10548700B2 (en) | 2016-12-16 | 2020-02-04 | Align Technology, Inc. | Dental appliance etch template |
US10456043B2 (en) | 2017-01-12 | 2019-10-29 | Align Technology, Inc. | Compact confocal dental scanning apparatus |
US10779718B2 (en) | 2017-02-13 | 2020-09-22 | Align Technology, Inc. | Cheek retractor and mobile device holder |
US11054455B2 (en) * | 2017-03-06 | 2021-07-06 | Osaka University | Electromagnetic wave measurement apparatus and electromagnetic wave measurement method |
US10613515B2 (en) | 2017-03-31 | 2020-04-07 | Align Technology, Inc. | Orthodontic appliances including at least partially un-erupted teeth and method of forming them |
US11045283B2 (en) | 2017-06-09 | 2021-06-29 | Align Technology, Inc. | Palatal expander with skeletal anchorage devices |
WO2018234447A1 (en) * | 2017-06-21 | 2018-12-27 | Koninklijke Philips N.V. | Method and apparatus for early caries detection |
WO2019005808A1 (en) | 2017-06-26 | 2019-01-03 | Align Technology, Inc. | Biosensor performance indicator for intraoral appliances |
US10885521B2 (en) | 2017-07-17 | 2021-01-05 | Align Technology, Inc. | Method and apparatuses for interactive ordering of dental aligners |
WO2019018784A1 (en) | 2017-07-21 | 2019-01-24 | Align Technology, Inc. | Palatal contour anchorage |
CN115462921A (en) | 2017-07-27 | 2022-12-13 | 阿莱恩技术有限公司 | Tooth staining, transparency and glazing |
US10517482B2 (en) | 2017-07-27 | 2019-12-31 | Align Technology, Inc. | Optical coherence tomography for orthodontic aligners |
WO2019035979A1 (en) | 2017-08-15 | 2019-02-21 | Align Technology, Inc. | Buccal corridor assessment and computation |
US11123156B2 (en) | 2017-08-17 | 2021-09-21 | Align Technology, Inc. | Dental appliance compliance monitoring |
TW201915474A (en) * | 2017-09-01 | 2019-04-16 | 美商阿自倍爾北美研發公司 | Apparatus and method for real-time non-invasive composition sensing and imaging |
US10813720B2 (en) | 2017-10-05 | 2020-10-27 | Align Technology, Inc. | Interproximal reduction templates |
CN114939001A (en) | 2017-10-27 | 2022-08-26 | 阿莱恩技术有限公司 | Substitute occlusion adjustment structure |
EP3703608B1 (en) | 2017-10-31 | 2023-08-30 | Align Technology, Inc. | Determination of a dental appliance having selective occlusal loading and controlled intercuspation |
CN115252177A (en) | 2017-11-01 | 2022-11-01 | 阿莱恩技术有限公司 | Automated therapy planning |
WO2019100022A1 (en) | 2017-11-17 | 2019-05-23 | Align Technology, Inc. | Orthodontic retainers |
WO2019108978A1 (en) | 2017-11-30 | 2019-06-06 | Align Technology, Inc. | Sensors for monitoring oral appliances |
WO2019118876A1 (en) | 2017-12-15 | 2019-06-20 | Align Technology, Inc. | Closed loop adaptive orthodontic treatment methods and apparatuses |
US10980613B2 (en) | 2017-12-29 | 2021-04-20 | Align Technology, Inc. | Augmented reality enhancements for dental practitioners |
CA3086553A1 (en) | 2018-01-26 | 2019-08-01 | Align Technology, Inc. | Diagnostic intraoral scanning and tracking |
US11937991B2 (en) | 2018-03-27 | 2024-03-26 | Align Technology, Inc. | Dental attachment placement structure |
WO2019200008A1 (en) | 2018-04-11 | 2019-10-17 | Align Technology, Inc. | Releasable palatal expanders |
WO2020014213A1 (en) * | 2018-07-09 | 2020-01-16 | Georgia Tech Research Corporation | Acousto-optical sensors for mri safety evaluation |
CN109199382A (en) * | 2018-09-30 | 2019-01-15 | 北京联合大学 | A kind of oral cavity information integration detection method and system based on terahertz imaging |
US11360023B2 (en) | 2019-11-05 | 2022-06-14 | Institut National De La Recherche Scientifique | Method and a system for homodyne solid-state biased coherent detection of ultra-broadband terahertz pulses |
CN111700588B (en) * | 2020-06-05 | 2021-02-19 | 中国人民解放军军事科学院国防科技创新研究院 | Interventional imaging system |
DE102020123167A1 (en) | 2020-09-04 | 2022-03-10 | Technische Universität Dresden, Körperschaft des öffentlichen Rechts | DENTAL DETECTION DEVICE AND METHOD OF OPERATING THE SAME |
JP2022191808A (en) * | 2021-06-16 | 2022-12-28 | 浜松ホトニクス株式会社 | Spectroscopic measurement device |
CN114452026B (en) * | 2022-01-12 | 2023-10-10 | 深圳北航新兴产业技术研究院 | Enamel caries detection system based on terahertz spectroscopy imaging |
US20230284925A1 (en) * | 2022-03-09 | 2023-09-14 | National Tsing Hua University | SCANNING BASED THz NEARFIELD IMAGING DEVICE |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0438353A1 (en) * | 1990-01-18 | 1991-07-24 | Fuji Optical Systems, Inc. | Dental instrument including laser device and electronic video dental camera |
EP0864298A2 (en) * | 1997-03-14 | 1998-09-16 | Egawa Corporation | Tooth improving apparatus and tooth improving material |
WO1998052460A1 (en) * | 1997-05-23 | 1998-11-26 | Medical Laser Technologies Limited | Non-invasive diagnostic method and apparatus |
US5862287A (en) * | 1996-12-13 | 1999-01-19 | Imra America, Inc. | Apparatus and method for delivery of dispersion compensated ultrashort optical pulses with high peak power |
Family Cites Families (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4479499A (en) * | 1982-01-29 | 1984-10-30 | Alfano Robert R | Method and apparatus for detecting the presence of caries in teeth using visible light |
US4564355A (en) | 1984-01-09 | 1986-01-14 | Dentonaut Lab, Ltd. | Method and apparatus for the non-invasive examination of the tooth-jaw structure of a patient to determine the characteristics of unerupted teeth and to control nutritional intake pursuant thereto |
US5772597A (en) * | 1992-09-14 | 1998-06-30 | Sextant Medical Corporation | Surgical tool end effector |
DE4307411A1 (en) * | 1993-03-09 | 1994-09-15 | Mira Gmbh | Dental examination instrument |
US5710430A (en) * | 1995-02-15 | 1998-01-20 | Lucent Technologies Inc. | Method and apparatus for terahertz imaging |
JPH08233758A (en) * | 1995-02-24 | 1996-09-13 | Lion Corp | Initial caries detector |
JPH09276299A (en) * | 1996-04-12 | 1997-10-28 | Aisin Seiki Co Ltd | Periodontal disease caecum measuring device |
US5952818A (en) * | 1996-05-31 | 1999-09-14 | Rensselaer Polytechnic Institute | Electro-optical sensing apparatus and method for characterizing free-space electromagnetic radiation |
EP0828184A1 (en) * | 1996-09-04 | 1998-03-11 | Eastman Kodak Company | Imaging element containing an electrically conductive polymer blend |
US5789750A (en) | 1996-09-09 | 1998-08-04 | Lucent Technologies Inc. | Optical system employing terahertz radiation |
US5773829A (en) * | 1996-11-05 | 1998-06-30 | Iwanczyk; Jan S. | Radiation imaging detector |
US6201880B1 (en) * | 1996-12-31 | 2001-03-13 | Electro-Optical Sciences | Method and apparatus for electronically imaging a tooth through transillumination by light |
US6078047A (en) * | 1997-03-14 | 2000-06-20 | Lucent Technologies Inc. | Method and apparatus for terahertz tomographic imaging |
JPH11160264A (en) | 1997-11-28 | 1999-06-18 | Lion Corp | Detector for pore or crack |
US6373970B1 (en) * | 1998-12-29 | 2002-04-16 | General Electric Company | Image registration using fourier phase matching |
US6753966B2 (en) * | 2000-03-10 | 2004-06-22 | Textron Systems Corporation | Optical probes and methods for spectral analysis |
CN1662931A (en) * | 2002-05-09 | 2005-08-31 | 索尼株式会社 | Bio-pattern detecting means, bio-pattern detecting device, biometrics method and biometrics device |
-
1999
- 1999-07-23 GB GB9917407A patent/GB2352512B/en not_active Expired - Lifetime
-
2000
- 2000-07-24 AU AU60082/00A patent/AU778292B2/en not_active Ceased
- 2000-07-24 WO PCT/GB2000/002849 patent/WO2001006915A1/en active IP Right Grant
- 2000-07-24 EP EP00946211A patent/EP1202664A1/en not_active Withdrawn
- 2000-07-24 JP JP2001511811A patent/JP4391714B2/en not_active Expired - Fee Related
-
2004
- 2004-12-14 US US11/011,703 patent/US8027709B2/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0438353A1 (en) * | 1990-01-18 | 1991-07-24 | Fuji Optical Systems, Inc. | Dental instrument including laser device and electronic video dental camera |
US5862287A (en) * | 1996-12-13 | 1999-01-19 | Imra America, Inc. | Apparatus and method for delivery of dispersion compensated ultrashort optical pulses with high peak power |
EP0864298A2 (en) * | 1997-03-14 | 1998-09-16 | Egawa Corporation | Tooth improving apparatus and tooth improving material |
WO1998052460A1 (en) * | 1997-05-23 | 1998-11-26 | Medical Laser Technologies Limited | Non-invasive diagnostic method and apparatus |
Non-Patent Citations (4)
Title |
---|
ARNONE D ET AL.: "Applications of Terahertz (THz) Technology to Medical Imaging", PROCEEDINGS OF THE SPI-THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING, vol. 3828, June 1999 (1999-06-01), pages 209 - 219, XP000964528 * |
HOSHI N ET AL: "STUDY ON DIAGNOSIS FOR TOOTH USING MILLIMETER-WAVES", IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST,US,NEW YORK, NY: IEEE, 7 June 1998 (1998-06-07), pages 759 - 762, XP000822099, ISBN: 0-7803-4472-3 * |
SCHMITT J M ET AL: "OPTICAL DETERMINATION OF DENTAL PULP VITALITY", IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING,US,IEEE INC. NEW YORK, vol. 38, no. 4, 1 April 1991 (1991-04-01), pages 346 - 352, XP000235764, ISSN: 0018-9294 * |
ZHANG X -C: "Generation and detection of pulsed microwave signals by THz optoelectronics", 1997 SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE. LINKING TO THE NEXT CENTURY'. PROCEEDINGS, NATAL, BRAZIL, 11-14 AUG. 1997, vol. 1, 1997, New York, USA, pages 215 - 220, XP002152659 * |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6816647B1 (en) | 1999-10-14 | 2004-11-09 | Picometrix, Inc. | Compact fiber pigtailed terahertz modules |
EP1230578A4 (en) * | 1999-10-14 | 2004-03-03 | Picometrix Inc | Compact fiber pigtailed terahertz modules |
DE10297037B4 (en) * | 2001-07-02 | 2008-01-17 | Advantest Corp. | Spreading measuring device and propagation measuring method |
JP2005517925A (en) * | 2002-02-15 | 2005-06-16 | テラビュー リミテッド | Analytical apparatus and method |
FR2854504A1 (en) * | 2003-04-30 | 2004-11-05 | Thales Sa | TERAHERTZ TRANSMISSION SOURCE AND OPTICAL SYSTEM COMPRISING SUCH A SOURCE |
WO2004097382A1 (en) * | 2003-04-30 | 2004-11-11 | Thales | Terahertz emission source and optical system comprising one such source |
US7449695B2 (en) | 2004-05-26 | 2008-11-11 | Picometrix | Terahertz imaging system for examining articles |
US8738116B2 (en) | 2007-09-21 | 2014-05-27 | National Research Council Of Canada | Method and apparatus for periodontal diagnosis |
WO2009036561A1 (en) * | 2007-09-21 | 2009-03-26 | National Research Council Of Canada | Method and apparatus for periodontal diagnosis |
EP2098839A2 (en) | 2008-03-04 | 2009-09-09 | Sony Corporation | Terahertz spectrometer |
US8179527B2 (en) | 2008-03-04 | 2012-05-15 | Sony Corporation | Terahertz spectrometer |
EP2273254A4 (en) * | 2008-04-30 | 2014-02-26 | Hamamatsu Photonics Kk | Total reflection terahertz wave measurement device |
EP2273254A1 (en) * | 2008-04-30 | 2011-01-12 | Hamamatsu Photonics K.K. | Total reflection terahertz wave measurement device |
DE102009051692B3 (en) * | 2009-10-27 | 2011-04-07 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and device for identifying a material |
US9103774B2 (en) | 2009-10-27 | 2015-08-11 | Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. | Method and device for identifying a material |
DE102011112697A1 (en) | 2011-08-31 | 2013-02-28 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and apparatus for determining a substance using THz radiation |
WO2013029746A1 (en) | 2011-08-31 | 2013-03-07 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and apparatus for determining a substance using thz radiation |
US9354168B2 (en) | 2011-08-31 | 2016-05-31 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and apparatus for determining a substance using THz radiation |
Also Published As
Publication number | Publication date |
---|---|
GB2352512B (en) | 2002-03-13 |
US8027709B2 (en) | 2011-09-27 |
JP4391714B2 (en) | 2009-12-24 |
EP1202664A1 (en) | 2002-05-08 |
US20050100866A1 (en) | 2005-05-12 |
AU6008200A (en) | 2001-02-13 |
GB9917407D0 (en) | 1999-09-22 |
JP2003505130A (en) | 2003-02-12 |
GB2352512A (en) | 2001-01-31 |
AU778292B2 (en) | 2004-11-25 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8027709B2 (en) | Radiation probe and detecting tooth decay | |
US5570182A (en) | Method for detection of dental caries and periodontal disease using optical imaging | |
JP6860210B2 (en) | Terahertz endoscopy through a laser-driven terahertz source and detector | |
CN101262822B (en) | Method and apparatus using infrared photothermal radiometry (PTR) and modulated laser luminescence (LUM) for diagnostics of defects in teeth | |
KR100686409B1 (en) | Non-invasive subject-information imaging method and apparatus | |
US6584341B1 (en) | Method and apparatus for detection of defects in teeth | |
Tabatabaei et al. | Thermophotonic lock-in imaging of early demineralized and carious lesions in human teeth | |
US20020156380A1 (en) | Raman endoscope | |
US20090069653A1 (en) | Measurement apparatus | |
Ciesla et al. | Biomedical applications of terahertz pulse imaging | |
JPH08510321A (en) | Glucose fluorescence inspection apparatus and method | |
JP2004520583A (en) | Apparatus and method for investigating a sample | |
JPH08254497A (en) | Method for inspecting scattered medium using intensity modulated light | |
Sowa et al. | Precision of Raman depolarization and optical attenuation measurements of sound tooth enamel | |
JP4469977B2 (en) | Teeth optical interference tomography device | |
JP2008197080A (en) | Tooth decay detection method and device | |
JPH09173301A (en) | Method for evaluating chapping of skin or damage and deterioration of hair or nail and device therefor | |
JP4327273B2 (en) | Biopsy device and method | |
af Klinteberg et al. | Diffusely scattered femtosecond white-light examination of breast tissue in vitro and in vivo | |
Sudworth et al. | The optical properties of human tissue at terahertz frequencies | |
JP4077477B2 (en) | Method and apparatus for measuring absorption information of scatterers | |
Kumari | New Caries Diagnostic Methods-A Review. | |
RU2779524C2 (en) | Method and device for multispectral high-speed acquisition spatial images in terahertz spectrum area | |
Crawley et al. | Three-dimensional terahertz pulse imaging of dental tissue | |
JP4077476B2 (en) | Method and apparatus for measuring absorption information of scatterers |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
WWE | Wipo information: entry into national phase |
Ref document number: 2000946211 Country of ref document: EP Ref document number: 60082/00 Country of ref document: AU |
|
WWP | Wipo information: published in national office |
Ref document number: 2000946211 Country of ref document: EP |
|
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 10031784 Country of ref document: US |
|
WWG | Wipo information: grant in national office |
Ref document number: 60082/00 Country of ref document: AU |