CN201139554Y - Frequency domain optical coherence tomography device with large detection depth - Google Patents
Frequency domain optical coherence tomography device with large detection depth Download PDFInfo
- Publication number
- CN201139554Y CN201139554Y CNU2008200544246U CN200820054424U CN201139554Y CN 201139554 Y CN201139554 Y CN 201139554Y CN U2008200544246 U CNU2008200544246 U CN U2008200544246U CN 200820054424 U CN200820054424 U CN 200820054424U CN 201139554 Y CN201139554 Y CN 201139554Y
- Authority
- CN
- China
- Prior art keywords
- sample
- spectrum
- gratings
- light source
- coherence tomography
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 55
- 238000012014 optical coherence tomography Methods 0.000 title claims abstract description 54
- 230000003595 spectral effect Effects 0.000 claims abstract description 38
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- 238000005286 illumination Methods 0.000 claims abstract description 7
- 238000013519 translation Methods 0.000 claims abstract description 7
- 238000001444 catalytic combustion detection Methods 0.000 claims description 48
- 238000011835 investigation Methods 0.000 claims description 37
- 238000012360 testing method Methods 0.000 claims description 13
- 239000000835 fiber Substances 0.000 claims description 4
- 238000001228 spectrum Methods 0.000 abstract description 53
- 238000003384 imaging method Methods 0.000 abstract description 10
- 230000001427 coherent effect Effects 0.000 abstract description 7
- 238000004587 chromatography analysis Methods 0.000 abstract 1
- 239000000523 sample Substances 0.000 description 53
- 230000003287 optical effect Effects 0.000 description 17
- 238000000034 method Methods 0.000 description 11
- 238000005516 engineering process Methods 0.000 description 6
- 239000004744 fabric Substances 0.000 description 5
- 238000005070 sampling Methods 0.000 description 4
- 238000004611 spectroscopical analysis Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012472 biological sample Substances 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 210000002257 embryonic structure Anatomy 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007499 fusion processing Methods 0.000 description 1
- 210000003128 head Anatomy 0.000 description 1
- 238000001727 in vivo Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000012800 visualization Methods 0.000 description 1
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
A frequency domain optical coherence tomography device with large detection depth comprises a low-coherence light source, wherein a collimating lens and a Michelson interferometer are sequentially arranged in the illumination direction of the low-coherence light source, the Michelson interferometer comprises a light splitter, a sample arm and a reference arm, the reference arm comprises a reference arm objective lens and a reference reflector, the sample arm comprises a reflector, a sample arm objective lens, a sample to be detected and a three-dimensional precise translation platform for placing the sample to be detected; the output end of the Michelson interferometer is connected with a spectrometer, the spectrometer is composed of a combined diffraction grating, a toroidal focusing mirror and a spectrum detection array, and the spectrum detection array is connected with a computer through a multi-path image acquisition and analog-to-digital conversion card. The utility model discloses a combination diffraction grating carries out the spectrum folding, has increased the effective detection pixel number N of spectral detection, has improved the detection degree of depth and the SNR of chromatography chart of the coherent chromatographic imaging system of optics.
Description
Technical field
This utility model relates to optical coherent chromatographic imaging, especially a kind of domain optical coherence tomography device of big investigation depth.
Background technology
Optical coherent chromatographic imaging (Optical Coherence Tomography, be called for short OCT) be the optical image technology that developed recently gets up, can carry out the micro-structure in the several mm depth scopes of scattering medium such as biological tissue inside non-contacting, body, high-resolution imaging, have important application prospects in fields such as biological tissue's imaging and medical science detections.
(the Fourier Domain Optical CoherenceTomography of domain optical coherence tomography system, be called for short FD-OCT) be a kind of New O CT system, by surveying interference spectrum and it being carried out the tomographic map that inverse Fourier transform obtains object, with respect to initial time domain optical coherence tomography system (Time Domain Optical Coherence Tomography, be called for short TD-OCT), have and need not depth direction scanning, image taking speed is fast and detectivity is high advantage, be more suitable for the realtime imaging of biological tissue.
The depth bounds that the OCT system surveys at first is to be determined by the scattering nature of sample and the intensity of light source, and for weak scattering media such as eyes and embryos, investigation depth can surpass 2 centimetres, and for strong scattering medium such as skins, investigation depth has only several millimeters.Here the intrinsic investigation depth that the maximum probe degree of depth of properties of samples decision is called sample.In FD-OCT, the restriction of the spectral resolution that investigation depth also is subjected to calls system's degree of depth to the maximum probe degree of depth of system's decision here.FD-OCT utilizes spectrogrph to survey interference spectrum and this interference spectrum is carried out the tomographic map that inverse Fourier transform obtains object, and spectrogrph is made up of diffraction grating, imaging len and detection array (as CCD).Incident interference light signal is imaged on the CCD test surface by an achromat and converts the signal of telecommunication to after the diffraction grating beam split, by analog-digital converter the interference spectrum data is sent into computer then.In order to reach theoretical longitudinal resolution, require the detection spectrum width Δ Λ of spectrogrph to satisfy:
Under this condition, system's degree of depth
Wherein δ λ is the spectral resolution that spectrogrph is surveyed, λ
0Be the light source center wavelength.And δ λ=Δ Λ/N, N are the valid pixel number of CCD.As can be seen, for specific light source, under the prerequisite that satisfies the OCT longitudinal resolution, because the restriction of CCD pixel count N, spectral resolution δ λ can not be infinitely small, the depth delta L of system
zBe limited within limits.In addition, in the OCT system, vertically the pass of (degree of depth) resolution ax/z and light source spectrum width Δ λ is:
Thus formula as can be seen, longitudinal resolution and light source spectrum width Δ λ are inversely proportional to, and realize that high longitudinal resolution need use the light source with higher spectrum width.But λ is big more for light source spectrum width Δ, and the detection spectrum width Δ Λ of spectrogrph is also big more, and under the constant situation of CCD pixel N, spectrum minimum resolution δ λ is also just big more, investigation depth Δ L
zMore little.Longitudinal resolution is high more, investigation depth Δ L
zJust more little, for example, be λ for centre wavelength
0=830nm, the super width of cloth of spectrum width Δ λ=20nm is penetrated diode (SLD), spectrogrph adopts the line array CCD of pixel count N=2048, this moment longitudinal resolution Δ z ≈ 15.2 μ m, the depth capacity that can survey is Δ L
z≈ 7.8mm; For central wavelength lambda
0=830nm, the titanium gem femto-second laser (Ti:Sapphire Laser) of spectrum width Δ λ=144nm is still used the line array CCD of pixel count N=2048, longitudinal resolution Δ z ≈ 2.1 μ m, the depth capacity that can survey is Δ L
z≈ 1.1mm.As can be seen, for ti sapphire laser, because its light source spectrum width broad realized higher longitudinal resolution, but system's investigation depth is very little, even is failed to reach the intrinsic investigation depth of sample.Moreover, different with the intrinsic investigation depth of sample is, above-mentioned system's investigation depth is half of optical path difference of reference arm and sample arm in the OCT system, under a lot of situations, optical path difference will comprise portion of air or other medium, rather than sample surfaces is to the absolute distance of a certain degree of depth of sample.Be used to observe the OCT system (as endoscope) of in-vivo tissue for some, be difficult to the distance between control tissue and the detecting head, tissue visualization is being surveyed within the optical path difference in order to guarantee, requires to improve the OCT system and can survey maximum optical path difference, promptly improves system's degree of depth.Simultaneously, high-resolution is target and the development trend that OCT pursues always, improves investigation depth and become distinct issues in the high-resolution FD-OCT system when pursuing high longitudinal resolution.
The method that improves investigation depth at present has following several:
Improve the intensity of light source: improve the intensity of light source, survey light and can arrive the bigger degree of depth of sample interior, the scattered light intensity of sample strengthens, and the signal to noise ratio of system increases, and investigation depth increases.But the intensity of light source is subjected to the restriction of technology, can not accomplish very high; Simultaneously, for the OCT system that is applied to biological sample, in order to guarantee the safety of biological tissue such as human eye, exposure dose can not be too big, so the method that relies on the raising intensity of light source to improve investigation depth is restricted.
Layered probe: this method also becomes the dynamic focusing method, at first for solve lateral resolution and light source survey the contradiction of depth of focus propose (referring to technology [1] formerly, M.Pircher, E.
C.K.Hitzenberger, " dynamic focus in optical coherence tomography for retinalimaging, " J.Biomed.Opt.11 (5), 54013,2006).Its thought is that mobile zero optical path difference position is write down tomographic map respectively to the sample different depth, surveys a certain depth bounds of counter sample at every turn, then each tomographic map stack is formed a width of cloth tomographic map, thereby improves investigation depth.But this method need repeatedly be surveyed sample, reduced the image taking speed of OCT system, and imaging speed is pursuing one's goal of OCT always.In addition, several figure are fused into the difficulty that also there is accurate positioning in a width of cloth figure, fusion process has also increased more computing, has reduced the image taking speed of OCT system.
Spectrographic detection array sub-pix Sampling techniques are (referring to technology [2] formerly, Z.Wang, Z.Yuan, H.Wang, Y.Pan, " increasing the imaging depth of spectral-domain OCT by usinginterpixel shift technique; " Opt.Express 14 (16), 7014-7023,2006): to each crosswise spots, survey one group of interference spectrum with line array CCD; By the mode of rotating grating or mobile CCD, make spectrum face or CCD test surface move half-pixel then, survey one group of interference spectrum again along the spectral distribution direction; Two groups of interference spectrums are intersected stack mutually, and to form a group length be the interference spectrum of former interference spectrum twice.This method has improved the sample rate of interference spectrum, has been equivalent to improve the pixel count N of CCD, thereby has improved spectral resolution and investigation depth.But this method needs mobile CCD or rotating grating that interference spectrum is taken multiple measurements equally, has reduced the image taking speed of OCT; And because system comprises mechanical movement means, system complex, error are big.
Summary of the invention
Deficiencies such as the background technology intensity of light source is limited in order to overcome, speed of detection reduction, a kind of domain optical coherence tomography device of big investigation depth is provided, with the investigation depth of raising optical coherence tomography system and the signal to noise ratio of tomographic map, simplified system, the error of avoiding mechanical movement to bring.
Technical solution of the present utility model is as follows:
A kind of domain optical coherence tomography device of big investigation depth, be characterized in comprising a low-coherence light source, on the illumination direction of this low-coherence light source, place collimating lens and Michelson's interferometer in turn, this Michelson's interferometer comprises beam splitter, sample arm and reference arm, reference arm comprises reference arm object lens and reference mirror, and sample arm comprises reflecting mirror, sample arm object lens, testing sample and a three-dimensional accurate translation stage of putting this testing sample; The outfan of this Michelson's interferometer connects a spectrogrph, and this spectrogrph is made up of combination diffraction grating, anchor ring focus lamp and spectrographic detection array, and described combination diffraction grating is made up of the polylith sub-gratings, the every pairing wavelength window Δ of sub-gratings λ
mThe diffraction light direction be distributed within the identical scope i.e. θ
1,1+ i
1,1=θ
2,2+ i
2,2=...=θ
N, n+ i
N, n, in the formula: θ
M, kRepresent that m piece sub-gratings is to wavelength X
kThe angle of diffraction, i
M, kRepresent that m piece sub-gratings is to wavelength X
kAngle of incidence; Described anchor ring focus lamp, has less focal length in the direction parallel with spectral distribution, has bigger focal length with the vertical direction of spectral distribution, described spectrographic detection array is positioned on the pairing focal plane of less focal length of described anchor ring focus lamp, and this spectrographic detection array links to each other with computer with analog-to-digital conversion card by multiplex image acquisition.
Described Michelson's interferometer is the bulk optics system, or the fiber optic system of being made up of 2 * 2 fiber couplers.
Described low-coherence light source is positioned on the front focal plane of collimating lens, and reference mirror is positioned on the back focal plane of reference arm object lens, and sample is positioned on the back focal plane of sample arm object lens.
Described spectrographic detection array can be a plurality of line array CCDs, also can be an area array CCD.
The work process of this system is as follows:
The light that low-coherence light source sends is behind the collimating lens collimation, be divided into two bundles at the beam splitter place, a branch of light enter reference arm through the reference arm object lens focusing on reference mirror, a branch of in addition sample arm that enters, through reflecting mirror and sample arm object lens focusing in sample; Light of returning from the reference mirror surface reflectance and the light that different depth reflection or backscattering are returned in the sample are collected by object lens and are returned along reference arm and sample arm, and the place interferes at beam splitter; Interference light incides combination diffraction grating surface diffraction takes place, and diffraction light is imaged on the spectrographic detection array through the anchor ring focus lamp and converts the signal of telecommunication to, and this signal of telecommunication converts digital signal to through multiplex image acquisition and analog-to-digital conversion card and sends into computer; Spectroscopic data obtains broad-band high-resolution spectrum through spectroscopic calibration and splicing; This spectrum along wave vector k double sampling and remove noise and interference, is obtained tomographic map by inverse fourier transform then; By the accurate translation stage of three-dimensional sample edge and detection light optical axis vertical direction are carried out transversal scanning, repeat above-mentioned steps, obtain the two dimension or the three-dimensional tomographic map of sample.
Below principle of the present utility model is described as follows:
The step of the domain optical coherence tomography device work of the big investigation depth of this utility model is as follows:
1) interference light signal through collimation incides on the combination diffraction grating with polylith sub-gratings, accurately adjusts the angle of incidence i of incident illumination for every block of grating by the gyrator grating
m, make the every pairing wavelength window Δ of sub-gratings λ
mThe diffraction light direction be distributed within the identical scope.
For reflection-type diffraction grating, grating equation is:
mλ＝d(sinθ+sini) (1)
Wherein, d is a grating constant, and m is that the order of diffraction is inferior, and θ is the angle of diffraction, and i is an angle of incidence.
For first-order diffraction (m=1), wavelength window Δ λ
1Be distributed in corresponding diffraction angle
1And θ
2Between:
sinθ
2-sinθ
1＝(λ
2-λ
1)/d＝Δλ
1/d (2)
The gyrator grating is accurately adjusted the angle of incidence i of incident illumination for every sub-gratings
m, make the every pairing wavelength window Δ of sub-gratings λ
mThe diffraction light direction be distributed within the identical scope.Use θ
M, kRepresent that m piece sub-gratings is to wavelength X
kThe angle of diffraction, the angle of diffraction satisfies following relation:
θ
1，1+i
1，1＝θ
2，2+i
2，2＝...＝θ
n，n+i
n，n (3)
Be the corresponding λ of sub-gratings m
mDiffraction direction and the corresponding λ of sub-gratings m+1
M+1Diffraction direction identical.By the imaging of anchor ring focus lamp, can make the λ of the 1st sub-gratings
1～λ
2The λ of wave band, the 2nd sub-gratings
2～λ
3Wave band ..., the λ of n piece sub-gratings
n～λ
N+1Wave band is imaged on the different rows of spectrographic detection array plane, to guarantee spectrographic linking.
2) adopt the anchor ring focus lamp diffraction light of each spectral coverage to be imaged on the test surface of spectrographic detection array and carry out spectra collection, spectroscopic data is inputed to computer by multi-channel data acquisition card and analog-to-digital conversion card.
This anchor ring focus lamp has less focal distance f in the spectral distribution direction
∥, have bigger focal distance f with the vertical direction of spectral distribution
⊥, guarantee when light spectrum image-forming is on detection array different spectrum segment Δ λ
mWith Δ λ
M+1Be distributed on the different row.
Described spectrographic detection array can adopt area array CCD, also can adopt a plurality of line array CCDs.OCT system for line sweep parallel detecting mode adopts area array CCD, but because corresponding spectral line of each point, spectrum before the line sweep detection mode is folding is a two-dimension spectrum face, spectrum is folding to be folding along the spectral distribution direction to the two-dimension spectrum face, so will guarantee adjacent light spectral coverage Δ λ
mWith Δ λ
M+1Separate enough distances, to avoid the spectrum segment Δ λ of last point on the line
mSpectrum segment Δ λ with first point
M+1Overlapping.OCT system for the spot scan mode, can adopt area array CCD, spectrum before this moment is folding is a spectral line, but because the acquisition rate of area array CCD generally is lower than line array CCD, so this mode can reduce the image taking speed of OCT system, and adopt many line array CCDs to survey, with spectrum segment Δ λ different in the spectral line
mBe imaged on the different CCD and gather simultaneously, this mode can not influence the image taking speed of OCT.
3) spectroscopic calibration:
Because different grating diffration efficient differences, the response of different CCD also is different, and simultaneously, because the chromatic dispersion of anchor ring focus lamp, causing between CCD pixel and the wavelength is not linear relationship, so for each spectral coverage Δ λ
m, the wavelength and the response of calculating each pixel correspondence need be carried out spectroscopic calibration.Here adopt a mathematics multinomial to calculate the corresponding relation of wavelength X and pixel x:
λ(x)＝a
0+a
1x+a
2x
2+a
3x
3 (4)
Probe value I to each wavelength
0(λ) factor p (λ) that multiply by a correspondence eliminates the influence of the different responses with CCD of sub-gratings diffraction efficiency, obtains final probe value I (λ):
I(λ)＝p(λ)I
0(λ) (5)
To each spectrographic detection section Δ λ
mTo demarcate above-mentioned polynomial coefficient a in advance by experiment
0, a
1, a
2, a
3With the value of factor p (λ), and deposit computer in, each later on spectral value of surveying directly utilizes these parameters to carry out spectroscopic calibration by computer.
4) spectrum splicing is spliced into a successive spectrum with each spectral coverage:
I
Δλ(λ)＝I
Δλ1(λ)+I
Δλ2(λ)+...+I
Δλn(λ) (6)
5) because ED-OCT carries out the tomographic map that inverse Fourier transform obtains object by the interference spectrum signal to the k territory, be the interference spectrum signal in λ territory, so will be to the spectral signal I that surveys and spectrographic detection obtains
Δ λ(λ) obtain I (k) along wave vector k double sampling.
6) from I (k), eliminate between background noise and the sample interior different layers from the coherent superposition item, the optical frequency territory interference signal I that obtains
Int(k), then k is done inverse fourier transform and obtains the tomographic map that a width of cloth investigation depth is improved:
I(z)＝iFT{I
int(k)} (7)
7) computer along carrying out transversal scanning with detection light optical axis vertical direction, repeated for 1 to 6 step to sample through digital-to-analogue conversion card driven sweep galvanometer or scanning platform, obtained the three-dimensional optical coherent tomographic figure of sample.
The beneficial effect that this utility model compared with prior art has is:
1, the folding of this utility model spectral coverage realized by the different diffraction gratings of placing of polylith, accurately adjusts the angle of incidence i of incident illumination for every block of grating by the gyrator grating
m, make the every pairing wavelength window Δ of sub-gratings λ
mThe diffraction light direction be distributed within the identical scope, focus on the test surface of spectrographic detection array by the diffraction light of an anchor ring focus lamp then each spectral coverage.Folding by spectrum, the effective detected pixel that has increased spectrographic detection is counted N, thereby has improved the investigation depth of optical coherence tomography system, has improved the signal to noise ratio of tomographic map;
2, to the FD-OCT system of line sweep parallel detecting, adopt the area array CCD detection mode, OCT system for spot scan adopts many line array CCDs detection mode, and these detection modes do not reduce the image taking speed of OCT system when realizing the wide spectrographic detection of high-resolution;
3, realize that folding spectrographic detection does not need mechanical movement means, system is simple, and the error of having avoided mechanical movement to bring;
4, adopt folding spectrographic detection mode to improve the investigation depth of system, spectroscopic data is spliced, rather than the tomographic map data of each crosswise spots different depth are merged, numerical operation is simple.
Description of drawings
Fig. 1 is the bulk optics system structure sketch map of domain optical coherence tomography device in horizontal plane of the big investigation depth of this utility model.
Fig. 2 is the light path sketch map of spectrogrph 11 in vertical.
Among the figure: 1-low-coherence light source, 2-collimating lens, 3-Michelson's interferometer, the 4-beam splitter, 5-reference arm object lens, 6-reference mirror, the 7-reflecting mirror, 8-sample arm object lens, 9-testing sample, the three-dimensional accurate translation stage of 10-, the 11-spectrogrph, 12-makes up diffraction grating, 13-anchor ring focus lamp, 14-spectrographic detection array, 15-multiplex image acquisition and analog-to-digital conversion card, 16-computer.
The specific embodiment
The utility model is described in further detail below in conjunction with embodiment and accompanying drawing, but should not limit protection domain of the present utility model with this.
FD-OCT system in the spot scan mode is embodiment below, sets up the domain optical coherence tomography device of the big investigation depth of a cover.As shown in Figure 1, as seen from the figure, the domain optical coherence tomography device of the big investigation depth of this utility model, comprise a low-coherence light source 1, on the illumination direction of this low-coherence light source 1, place collimating lens 2 and Michelson's interferometer 3 in turn, this Michelson's interferometer 3 comprises beam splitter 4, sample arm and reference arm, reference arm comprises reference arm object lens 5 and reference mirror 6, and sample arm comprises reflecting mirror 7, sample arm object lens 8, testing sample 9 and a three-dimensional accurate translation stage 10 of putting this testing sample; The outfan of this Michelson's interferometer 3 connects a spectrogrph 11, this spectrogrph 11 is made up of combination diffraction grating 12, anchor ring focus lamp 13 and spectrographic detection array 14, described combination diffraction grating 12 is made up of the polylith sub-gratings, the every pairing wavelength window Δ of sub-gratings λ
mThe diffraction light direction be distributed within the identical scope; Described anchor ring focus lamp 13, has less focal length in the direction parallel with spectral distribution, has bigger focal length with the vertical direction of spectral distribution, described spectrographic detection array 14 is positioned on the pairing focal plane of less focal length of described anchor ring focus lamp 13, and this spectrographic detection array 14 links to each other with computer 16 with analog-to-digital conversion card 15 by multiplex image acquisition.
The light that low-coherence light source 1 sends enters Michelson's interferometer 3 behind collimating lens 2 collimations, 4 places are divided into two bundles at beam splitter, transmitted light beam enters reference arm and focuses on the reference mirror 6 through reference arm object lens 5, an other folded light beam enters sample arm, through reflecting mirror 7 and sample arm object lens focusing 8 in sample 9; Light of returning from reference mirror 6 surface reflectances and the light that different depth reflection or backscattering are returned in the sample 9 are collected and are returned along reference arm and sample arm by thing reference arm object lens 5 and sample arm object lens 8 respectively, and 4 places interfere at beam splitter; Interference light enters spectrogrph 11, incide combination diffraction grating 12 surfaces diffraction takes place, diffraction light is imaged on the spectrographic detection array 14 through anchor ring focus lamp 13 and converts the signal of telecommunication to, and this signal of telecommunication converts digital signal to through multiplex image acquisition and analog-to-digital conversion card 15 and sends into computer 16.Along carrying out transversal scanning, be used for obtaining the two dimension or the three-dimensional tomographic map of sample 9 by 10 pairs of samples of the accurate translation stage of three-dimensional 9 with detection light optical axis vertical direction.
In the present embodiment, the light signal full width at half maximum is 144nm, central wavelength lambda=830nm, and the detection spectrum width Δ Λ=260nm of spectrogrph 11, the corresponding wavelength scope is 700～960nm.Spectrum is folded into two window 700～830nm and 830～960nm surveys, i.e. λ
1=700nm, λ
2=830nm, λ
3=960nm, Δ λ
1=Δ λ
2=130nm.Raster density is 600g/mm, adopts two diffraction gratings to constitute combination diffraction grating 12, and blaze wavelength is 750nm, and the grating effective width is 25mm, for the light of λ=960nm, and the minimum light spectral resolution of grating
Adopt two line array CCDs as spectrographic detection array 14, every CCD pixel count N=1024, the size of each pixel is 20 μ m * 20 μ m.On two CCD, anchor ring focus lamp 13 is in the focal distance f of spectral distribution direction the grating diffration photoimaging for employing anchor ring focus lamp 13
∥Be 250mm, in focal distance f perpendicular to the spectral distribution direction
⊥Be 500mm.Since anchor ring focus lamp 13 spectral distribution direction (horizontal direction) with have different focal lengths perpendicular to the spectral distribution direction, make light path inequality at both direction, in order better to explain the image-forming principle of anchor ring focus lamp 13, sketch map (Fig. 1) and spectrogrph the light path sketch map (Fig. 2) vertical in of the system structure of having drawn respectively in horizontal plane.Referring to Fig. 2, first block of grating diffration light in a horizontal plane, corresponding wavelength window Δ λ
1, be imaged on first CCD by anchor ring focus lamp 13; Second block of grating diffration light in another horizontal plane, corresponding another wavelength window Δ λ
2(dotted line) is imaged on second CCD by anchor ring focus lamp 13; Because the anchor ring focus lamp is that the horizontal direction focal length is little in the spectral distribution direction, and it is big at the vertical direction focal length, vertical direction is isolating when having guaranteed that two blocks of grating diffration light focus on the CCD plane in the horizontal direction, thereby can adopt corresponding C CD to gather spectroscopic data.
The domain optical coherence tomography method of the big investigation depth of this utility model, its concrete steps are:
1) interference light signal through collimation incides on the combination grating with two sub-gratings.Rotate first sub-gratings, adjust its angle of incidence i
1=50.40 °; Rotate second sub-gratings, control its angle of incidence i
2, make first sub-gratings at λ
1～λ
2Second sub-gratings of the diffraction direction of wave band is at λ
2～λ
3The diffraction direction of wave band is identical, i.e. diffraction angle
M, mSatisfy following relation:
i
1+θ
1，1＝i
2+θ
2，2 (8)
Can calculate the angle of incidence i of second sub-gratings by following formula and optical grating diffraction equation (1)
2=29.96 °.Linear dispersion on the CCD plane is about 6.4nm/mm at this moment, and the development distance of 130nm spectrum width correspondence is 20.3mm; CCD detection array length l is: l=20 μ m * 1024=20.48mm, corresponding detection spectrum width has been full of the pixel of line array CCD substantially, has made full use of line array CCD.
2) adopt anchor ring focus lamp 13 diffraction light of each spectral coverage to be imaged on the test surface of spectrographic detection array 14 and carry out spectra collection, input to computer 16 by multi-channel data acquisition card and analog-to-digital conversion card 15.
Because this embodiment adopts two line array CCDs to survey, with spectrum segment Δ λ different in the spectral line
iBe imaged on two CCD and gather simultaneously, this mode can not influence the image taking speed of OCT.For the corresponding same spectrum of data that guarantees that two line array CCDs are gathered, need to guarantee that two CCD are synchronous, present embodiment adopts two identical line array CCDs, and two CCD are carried out identical configuration, adopt identical synchronizing signal, thereby it is synchronous to have guaranteed that CCD gathers.
3) spectroscopic calibration:
Adopt the corresponding relation of mathematics polynomial computation wavelength X and pixel x:
λ(x)＝a
0+a
1x+a
2x
2+a
3x
3 (9)
Probe value I to each wavelength
0(λ) factor that multiply by a correspondence is eliminated the influence of the different responses with CCD of diffraction efficiency of grating, obtains final probe value I (λ):
I(λ)＝p(λ)I
0(λ) (10)
4) spectrum splicing.Two spectral coverages are spliced into a successive spectrum:
I
Δλ(λ)＝I
Δλ1(λ)+I
Δλ2(λ) (11)
5) the spectral signal I to surveying
Δ λ(λ) obtain I (k) along wave vector k double sampling.
6) from I (k), eliminate between background noise and the sample interior different layers after the coherent superposition item, the optical frequency territory interference signal I that obtains
Int(k), then k is done inverse fourier transform and obtains the tomographic map that a width of cloth investigation depth has been improved:
I(z)＝iFT{I
int(k)} (12)
7) computer along carrying out transversal scanning with detection light optical axis vertical direction, repeated for 1 to 6 step to sample through digital-to-analogue conversion card driven sweep galvanometer or scanning platform, can obtain three-dimensional optical coherent tomographic figure.
The line array CCD that adopts a N=1024 is as detector, and the detection spectrum width is 260nm, and directly the spectral resolution of spectrographic detection is δ λ ≈ 0.254nm, investigation depth Δ L
z≈ 0.68mm; Fold spectrographic detection according to embodiment, the 260nm detective bandwidth is folded into 700～830nm and two windows of 830～960nm are surveyed, spectral resolution is δ λ=0.127nm, investigation depth Δ L
z≈ 1.36mm.So can improve the investigation depth of FD-OCT system by folding spectrographic detection, and not influence the image taking speed of FD-OCT system.
Claims (4)
1, a kind of domain optical coherence tomography device of big investigation depth, it is characterized in that comprising a low-coherence light source (1), on the illumination direction of this low-coherence light source (1), place collimating lens (2) and Michelson's interferometer (3) in turn, this Michelson's interferometer (3) comprises beam splitter (4), sample arm and reference arm, reference arm comprises reference arm object lens (5) and reference mirror (6), and sample arm comprises reflecting mirror (7), sample arm object lens (8), testing sample (9) and a three-dimensional accurate translation stage (10) of putting this testing sample; The outfan of this Michelson's interferometer (3) connects a spectrogrph (11), this spectrogrph (11) is made up of combination diffraction grating (12), anchor ring focus lamp (13) and spectrographic detection array (14), described combination diffraction grating (12) is made up of the polylith sub-gratings, the every pairing wavelength window Δ of sub-gratings λ
mThe diffraction light direction be distributed within the identical scope, promptly
θ
1，1+i
1，1＝θ
2，2+i
2，2＝...＝θ
n，n+i
n，n
In the formula: θ
M, kRepresent that m piece sub-gratings is to wavelength X
kThe angle of diffraction, i
M, kRepresent that m piece sub-gratings is to wavelength X
kAngle of incidence; Described anchor ring focus lamp (13), has less focal length in the direction parallel with spectral distribution, has bigger focal length with the vertical direction of spectral distribution, described spectrographic detection array (14) is positioned on the pairing focal plane of less focal length of described anchor ring focus lamp (13), and this spectrographic detection array (14) links to each other with computer (16) with analog-to-digital conversion card (15) by multiplex image acquisition.
2, the domain optical coherence tomography device of big investigation depth according to claim 1 is characterized in that described Michelson's interferometer is the bulk optics system, or the fiber optic system of being made up of 2 * 2 fiber couplers.
3, the domain optical coherence tomography device of big investigation depth according to claim 1 is characterized in that described spectrographic detection array (14) is a plurality of line array CCDs, or an area array CCD.
4, the domain optical coherence tomography device of big investigation depth according to claim 1, it is characterized in that described low-coherence light source (1) is positioned on the front focal plane of described collimating lens (2), described reference mirror (6) is positioned on the back focal plane of reference arm object lens (5), and described testing sample (9) is positioned on the back focal plane of sample arm object lens (8).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008200544246U CN201139554Y (en) | 2008-01-03 | 2008-01-03 | Frequency domain optical coherence tomography device with large detection depth |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008200544246U CN201139554Y (en) | 2008-01-03 | 2008-01-03 | Frequency domain optical coherence tomography device with large detection depth |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201139554Y true CN201139554Y (en) | 2008-10-29 |
Family
ID=40067273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2008200544246U Expired - Fee Related CN201139554Y (en) | 2008-01-03 | 2008-01-03 | Frequency domain optical coherence tomography device with large detection depth |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201139554Y (en) |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102095694A (en) * | 2011-01-06 | 2011-06-15 | 中国科学院上海光学精密机械研究所 | Frequency domain optical coherence tomography system |
| CN102428343A (en) * | 2009-02-23 | 2012-04-25 | 维森盖特有限公司 | Optical tomography system with high-speed scanner |
| CN102628799A (en) * | 2012-04-25 | 2012-08-08 | 中国科学院上海光学精密机械研究所 | Method and system of time-domain optical coherence tomography without depth scan |
| CN103983610A (en) * | 2014-05-12 | 2014-08-13 | 复旦大学 | Trace fluid refractive index measuring device and measuring method based on spectrum interference |
| CN104490362A (en) * | 2014-12-19 | 2015-04-08 | 上海电力学院 | High-transverse-resolution optical coherence chromatography system based on photon nanometer spraying |
| CN105486937A (en) * | 2015-12-25 | 2016-04-13 | 中南民族大学 | Device for detecting piezoelectric constant d31 of piezoelectric ceramic |
| CN106248624A (en) * | 2016-09-12 | 2016-12-21 | 南京理工大学 | Tandem whole-field optically laminated imaging device based on compensating interferometer instrument and method |
| CN109211415A (en) * | 2018-11-20 | 2019-01-15 | 电子科技大学 | A kind of Wavelength calibration method based on light source light spectrum characteristic wavelength |
| CN109807471A (en) * | 2019-02-01 | 2019-05-28 | 佛山科学技术学院 | A kind of laser mark printing device and method |
| CN110044848A (en) * | 2019-04-30 | 2019-07-23 | 中国科学院重庆绿色智能技术研究院 | A kind of weak coherence tomography system and method based on Fizeau principle of interference |
| CN111157486A (en) * | 2018-11-08 | 2020-05-15 | 北京大学 | Three-dimensional terahertz imaging method and imaging system thereof |
| CN113317784A (en) * | 2021-06-08 | 2021-08-31 | 南京师范大学 | Micron-scale linear focusing scanning microspectrum optical coherence tomography system |
| CN114847882A (en) * | 2022-05-06 | 2022-08-05 | 山东探微医疗技术有限公司 | High-resolution jump type multiband spectrometer and working method |
-
2008
- 2008-01-03 CN CNU2008200544246U patent/CN201139554Y/en not_active Expired - Fee Related
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102428343A (en) * | 2009-02-23 | 2012-04-25 | 维森盖特有限公司 | Optical tomography system with high-speed scanner |
| CN102428343B (en) * | 2009-02-23 | 2014-08-20 | 维森盖特有限公司 | Optical tomography system with high-speed scanner |
| CN102095694A (en) * | 2011-01-06 | 2011-06-15 | 中国科学院上海光学精密机械研究所 | Frequency domain optical coherence tomography system |
| CN102628799A (en) * | 2012-04-25 | 2012-08-08 | 中国科学院上海光学精密机械研究所 | Method and system of time-domain optical coherence tomography without depth scan |
| CN103983610A (en) * | 2014-05-12 | 2014-08-13 | 复旦大学 | Trace fluid refractive index measuring device and measuring method based on spectrum interference |
| CN103983610B (en) * | 2014-05-12 | 2016-09-28 | 复旦大学 | Trace quantity liquid refractivity measurement apparatus based on spectral interference and measuring method |
| CN104490362A (en) * | 2014-12-19 | 2015-04-08 | 上海电力学院 | High-transverse-resolution optical coherence chromatography system based on photon nanometer spraying |
| CN105486937A (en) * | 2015-12-25 | 2016-04-13 | 中南民族大学 | Device for detecting piezoelectric constant d31 of piezoelectric ceramic |
| CN106248624A (en) * | 2016-09-12 | 2016-12-21 | 南京理工大学 | Tandem whole-field optically laminated imaging device based on compensating interferometer instrument and method |
| CN106248624B (en) * | 2016-09-12 | 2020-01-03 | 南京理工大学 | Series full-field optical tomography device and method based on compensation interferometer |
| CN111157486A (en) * | 2018-11-08 | 2020-05-15 | 北京大学 | Three-dimensional terahertz imaging method and imaging system thereof |
| CN109211415A (en) * | 2018-11-20 | 2019-01-15 | 电子科技大学 | A kind of Wavelength calibration method based on light source light spectrum characteristic wavelength |
| CN109807471A (en) * | 2019-02-01 | 2019-05-28 | 佛山科学技术学院 | A kind of laser mark printing device and method |
| CN109807471B (en) * | 2019-02-01 | 2024-03-26 | 佛山科学技术学院 | Laser marking device and method |
| CN110044848A (en) * | 2019-04-30 | 2019-07-23 | 中国科学院重庆绿色智能技术研究院 | A kind of weak coherence tomography system and method based on Fizeau principle of interference |
| CN110044848B (en) * | 2019-04-30 | 2022-01-28 | 中国科学院重庆绿色智能技术研究院 | Weak coherence tomography system and method based on Fizeau interference principle |
| CN113317784A (en) * | 2021-06-08 | 2021-08-31 | 南京师范大学 | Micron-scale linear focusing scanning microspectrum optical coherence tomography system |
| CN114847882A (en) * | 2022-05-06 | 2022-08-05 | 山东探微医疗技术有限公司 | High-resolution jump type multiband spectrometer and working method |
| CN114847882B (en) * | 2022-05-06 | 2024-08-13 | 山东探微医疗技术有限公司 | High-resolution jump type multiband spectrometer and working method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101214145B (en) | Frequency domain optical coherence tomography method and system with large detection depth | |
| CN201139554Y (en) | Frequency domain optical coherence tomography device with large detection depth | |
| CN104523239B (en) | Full-depth spectral domain optical coherent tomography device and method | |
| CN105842257B (en) | A kind of the glass subsurface defect detection device and method of sub-micrometer scale | |
| CA2786755C (en) | Systems and method for endoscopic angle-resolved low coherence interferometry | |
| CN108514404B (en) | Optical coherence tomography system | |
| WO2019183838A1 (en) | Optical coherence tomography system | |
| US20190223729A1 (en) | Apparatus and method for confocal microscopy using dispersed structured illumination | |
| US7583385B2 (en) | Optical tomography system | |
| US20150062591A1 (en) | Apparatuses, systems, and methods for low-coherence interferometry (lci) | |
| KR101552290B1 (en) | System and method for measuring internal dimensions of an object by optical coherence tomography | |
| US10292595B2 (en) | Systems and methods for endoscopic angle-resolved low coherence interferometry | |
| EP1870030A1 (en) | Apparatus and method for frequency domain optical coherence tomography | |
| JP2007101263A (en) | Optical tomographic imaging device | |
| CN104568842B (en) | The device and method of biological tissue's group delay dispersion is measured with reference to FDOCT | |
| EP1870028A1 (en) | Apparatus and method for frequency domain optical coherence tomography | |
| CN102525406A (en) | Three-dimensional imaging device for retina | |
| CN202568206U (en) | Retina three-dimensional imaging device | |
| EP1870029A1 (en) | Apparatus and method for frequency domain optical coherence tomography | |
| RU196595U1 (en) | Device for spectroscopic optical coherence tomography with an endoscopic probe | |
| AU2014250634B2 (en) | Apparatuses, systems, and methods for low-coherence interferometry (LCI) |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20081029 Termination date: 20110103 |