CN107328740A - Polarize domain optical coherence tomography spectroscopic calibration method - Google Patents
Polarize domain optical coherence tomography spectroscopic calibration method Download PDFInfo
- Publication number
- CN107328740A CN107328740A CN201710420299.XA CN201710420299A CN107328740A CN 107328740 A CN107328740 A CN 107328740A CN 201710420299 A CN201710420299 A CN 201710420299A CN 107328740 A CN107328740 A CN 107328740A
- Authority
- CN
- China
- Prior art keywords
- interference spectrum
- calibration
- spectrum
- sample
- wave number
- 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.)
- Granted
Links
Classifications
-
- 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
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
Abstract
One kind polarization domain optical coherence tomography spectroscopic calibration method, the method for more precisely carrying out polarizing domain optical coherence tomography spectroscopic calibration by Automatic-searching wave number k optimal calibration factor.This method first carries out photodetector pixels to each spectrum and calibrated roughly with wavelength corresponding relation, then on the basis of spectrum all the way (V) wave number, the wave number of another road spectrum (H) is multiplied by into optimal coefficient and realizes accurate calibration.Optimal coefficient is automatically determined by judging the A line signals degrees of correlation of spectrum H after spectrum V and calibration.The present invention has expanded the scope of application of spectroscopic calibration, and gaussian sum non-gaussian type spectrum is applicable, while improving calibration accuracy, is conducive to the calculating of sample polarization parameter.
Description
Technical field
The present invention relates to domain optical coherence tomography (Fourier-Domain Optical Coherence
Tomography, abbreviation FD-OCT), particularly a kind of polarization domain optical coherence tomography spectroscopic calibration method, more precisely
It is that the optimal calibration factor of Automatic-searching wave number k a kind of carries out the side of polarization domain optical coherence tomography spectroscopic calibration that ground, which is said,
Method.
Background technology
Optical coherent chromatographic imaging (Optical Coherence Tomography, OCT) is a kind of non-intruding, based on low
The biomedical imaging technology of coherent light interference.The time domain OCT of early stage needs to move reference arm to detect the different depth of sample
Position signalling.The frequency domain OCT (FD-OCT) then grown up is without mobile reference arm, and only need to once detect can obtain sample
Internal depth information (A-line signals), then carry out transversal scanning and can obtain the vertical section image of sample (B-scan schemes
Picture), the characteristics of with high speed and high resoltuion.Polarize frequency domain OCT (Fourier domain polarization-sensitive
OCT, FD-PS-OCT) (referring to first technology [1], Michael R.Hee and David Huang, " Polarization-
sensitive low-coherence reflectometer for birefringence characterization and
Ranging ", J.Opt.Soc.Am.B, Vol.9, No.6,903-908,1992) it is a kind of work(grown up on this basis
Energy OCT technology, can obtain the delayed image and fast axle image of sample while birefringence sample strength image is obtained, being capable of volume
The outer birefringence information for providing sample, has been widely used in the fields such as skin, dentistry and ophthalmology.FD-OCT is become by Fourier
Change Polaroid to sample different depth position, depth location z correspondence wave number k in Fourier transformation (k=2 π/λ, λ are wavelength).
But in FD-OCT, the detection of the photodetector such as CCD is the equally spaced data of wavelength.Accurate B-scan images are obtained,
Need to carry out data processing at equal intervals to wave number k, this is accomplished by carrying out accurate wavelength calibration, i.e., accurate mapping spectrometer detection
Corresponding relation between the pixel and wavelength of device.The wavelength mapping of mistake can make point spread function broadening, produce similar dispersion pair
The influence of point spread function.Therefore, traditional FD-OCT needs to calibrate wavelength.And FD-PS-OCT is except acquisition intensity map
As outer, the polarization informations such as delay and the fast axle of quantitative description sample are also wanted, wavelength calibration is inaccurate to introduce Interferometric phase error,
Polarization parameter computational accuracy is caused to decline, therefore accurate wavelength calibration is even more important.In addition, FD-PS-OCT is in order to obtain sample
Product polarization parameter, at least needs while gathering orthogonal horizontal polarization interference spectrum H and vertical polarization interference spectrum V two-way interference letter
Number.And two paths of signals is due to respective wave-length coverage or the not equal reason of spectral resolution, for same depth location, it may appear that two
Road A-line signal cross_placing phenomenons, increase phase calculation error.Therefore in addition to above-mentioned wavelength calibration, in addition it is also necessary to which H and V is carried out
Alignment is (referring to first technology [2], M.Wojtkowski, R.Leitgeb, A.Kowalczyk, T.Bajraszewski, and
A.F.Fercher, " In vivo human retinal imaging by Fourier domain opticalcoherence
Tomography ", J.Biomed.Opt.Vol.7, No.3,457-463,2002), two paths of signals is kept identical k distributions,
Improve computational accuracy.
Wojtkowski et al. (referring to first technology [2]) points out the importance of spectroscopic calibration in FD-OCT for the first time.
The wavelength calibration that Park et al. points out faults can produce birefringence calculation error (referring to first technology [3], B.H.Park,
M.C.Pierce,B.Cense,S.H.Yun,M.Mujat,G.J.Tearney,B.E.Bouma,and J.F.de Boer,
“Real-time fiber-based multi-functional spectral-domain optical coherence
1.3 μm of tomography at ", Opt.Express, 13 (11), 3931-3944,2005).In typically polarization frequency domain OCT
In, interference signal is divided into H and V two-way, and the wavelength dislocation even if very little can also produce the calculation error of birefringence relevant parameter.This
Sample light is after one section of propagation distance, and error can accumulate increase, may lead to not the birefringence parameter produced with sample itself
Distinguish.The proportionate relationship of wave number k dislocation is obtained in Mujat et al. propositions using the peak of H and V two-way A-line signals,
Then on the basis of all the way, another road signal is calibrated (referring to first technology [4], Mujat M, Park B H, Cense B, et
al,“Autocalibration of spectral-domain optical coherence tomography
spectrometers for in vivo quantitative retinal nerve fiber layer
Birefringence determination, " Journal of biomedical optics, 12 (4), 041205-
041205-6,2007).This method is adapted to the preferable light source of Gauss spectral pattern, because A-line signals have preferable single peak value,
K proportionality coefficient can accurately be obtained.But for non-gaussian spectral pattern light source, A-line has multiple peaks or highest peak position
Put not in center position, calibration error can be caused larger.
The content of the invention
The present invention provides a kind of polarization domain optical coherence tomography spectroscopic calibration method, more precisely, being a kind of
The method that Automatic-searching wave number k optimal calibration factor carries out polarization domain optical coherence tomography spectroscopic calibration, to collection
The interference spectrum arrived, first rough calibration carries out accurate calibration again, and accurate calibration passes through Automatic-searching k's on the basis of signal all the way
Proportionality coefficient is commented to be calibrated to another road signal using the cross correlation results of two paths of signals as the standard of Automatic-searching
Sentence optimal calibration factor.Instant invention overcomes the deficiency of above-mentioned first technology, using the degree of correlation come evaluation result, to the spectrum of light source
Type is not required, Gaussian, non-gaussian type spectrum are applicable.
The technical solution of the present invention is as follows：
The optimal calibration factor of Automatic-searching wave number k a kind of carries out polarization domain optical coherence tomography spectroscopic calibration
Method, this method first carries out photodetector pixels and the rough calibration of wavelength corresponding relation to each spectrum, then with all the way
On the basis of the wave number of spectrum (V), the wave number of another road spectrum (H) is multiplied by optimal coefficient and realizes accurate calibration；Optimal coefficient leads to
Cross and judge the A-line signals degree of correlation of spectrum H after spectrum V and calibration to automatically determine, when cross-correlation is maximum, it is believed that calibration effect
Preferably, now corresponding coefficient is optimal calibration factor to fruit；When sample is measured, with obtained optimal calibration factor to spectrum H
Wave number k calibration, then with calibration after k resampling is carried out to H, with reference to judge spectrum V, realize the meter of sample polarization parameter
Calculate.
The Automatic-searching wave number k of the present invention optimal calibration factor carries out polarization domain optical coherence tomography spectrum school
Accurate method, is comprised the following steps that：
1. the two-way quadrature interference signals that polarization frequency domain OCT systems are detected, respectively horizontal polarization interference spectrum IHRWith it is vertical
Polarization interference composes IVR；For per interference spectrum all the way, photodetector pixels and the rough school of wavelength X corresponding relation are carried out respectively
It is accurate；
2. a simple sample is used, photodetector detects the horizontal interference spectrum I of the sampleHWith vertical interference spectrum IV：
Wherein, subscript H and V represent horizontal interference spectrum H and vertical interference spectrum V respectively；IH0Represent horizontal interference spectrum
DC terms and auto-correlation；IV0Represent the DC terms and auto-correlation of vertical interference spectrum；S (k) represents light source light spectrum；RrTable
Show the reflectivity of reference mirror；RsnRepresent the reflectivity of sample n-th layer；ΔznRepresent the light path between each layer of sample arm and reference arm
Difference；δnRepresent from sample surfaces to the retardation of sample n-th layer；θnRepresent the quick shaft direction of sample n-th layer；
3. the data I that photodetector is detected is judgedHAnd IVWhether it is spacedly distributed with wave number, if data are
What wave number was spacedly distributed, then without entering row interpolation pretreatment to wave number k, pass directly to step 4.；If data are not wave numbers
It is spacedly distributed, then enters row interpolation pretreatment to wave number k, obtain the wave number k of equally spaced horizontal interference spectrumHAt equal intervals
Vertical interference spectrum wave number kV；
4. to the wave number k of equally spaced horizontal interference spectrumHZoom in and out：Choose one group of calibration factor P=[P1, P2...,
Pi..., Pn-1, Pn], wherein, i, n is natural number, calibration factor P sequence number is represented, with the ripple of equally spaced vertical interference spectrum
Number kVOn the basis of, pass through formula k'H=kH+Pi·(kH-kH0) to the wave number k of horizontal interference spectrumHZoom in and out, obtain one group it is new
Wave number k'H, wherein kH0It is kHCenter wave number , " ﹒ " represent be multiplied, with new k'HTo horizontal interference spectrum IHAdopted again
Sample, IHIt is changed on k'HInterference signal IH(k'H)：
To the I after resamplingH(k'H) signal progress Fourier transformation, obtain the horizontal interference spectrum after resampling in z domains
A-line signals；
Equally, the data I that photodetector is detected is judgedVIt is spacedly distributed with wave number, is, then directly to vertical
Interference spectrum IVThe processing such as Fourier transformation is carried out, the A-line signals of vertical interference spectrum in z domains are obtained；Photodetector is visited
The data I measuredVBe not spacedly distributed with wave number, then the wave number k of the vertical interference spectrum first 3. obtained with stepVTo hanging down
Straight interference spectrum IVCarry out carrying out the processing such as Fourier transformation after resampling again, obtain the A-line of vertical interference spectrum in z domains
Signal；
5. last A-line signals and the A-line signals of vertical interference spectrum to the horizontal interference spectrum after resampling
Cross-correlation calculation is carried out, calibration factor P is obtainediCorresponding cross correlation value C (Pi)；Said process is repeated, calculating obtains each in P
Individual FACTOR PiCorresponding cross correlation value, calibration effect is thought when two-way A-line signals cross-correlation is maximum preferably, i.e. Max (C
(Pi),Pi∈ P)=C (Po), calibration factor now used is optimal coefficient Po, and optimal coefficient P is calculated by following integrating photometeroSchool
The wave number k' of horizontal interference spectrum after standardHPo：
k'HPo=kH+Po·(kH-kH0). (3)
6. after above-mentioned calibration, the A-line signals of the horizontal interference spectrum in z domains and the A- of vertical interference spectrum
Line signals can be with completely overlapped, but also needs to further calibrate the spectral pattern of interference signal in k domains：5. obtained with step
K'HPoTo horizontal interference spectrum IHResampling is carried out, Fourier transformation is then carried out, the horizontal interference spectrum after being calibrated
Corresponding A-line signals, the signal related to simple sample is filtered out with wave filter；In filtering out step 4. with wave filter simultaneously
To vertical interference spectrum A-line signals in the signal related to sample；The signal related to sample to this two-way filtered out
Inverse Fourier transform is carried out respectively, respectively obtains the signal profile diagram of horizontal interference spectrum H and vertical interference spectrum V in k domains；
Make cross-correlation calculation to this two width signal profile diagram, when cross-correlation is maximum, the amount of horizontal interference spectrum H signal profile diagram movement
As k'HPoNeed mobile pixel count Nshift(kVKeep constant), by formula (4) by mobile pixel count k'HPoChange into shifting
Momentum kshift：
kshift=Nshift·[(k'HPomax-k'HPomin)/N], (4)
Wherein, k'HPomaxAnd k'HPominK' is represented respectivelyHPoMaximum and minimum value, N represents k'HPoTotal amount of data,
That is the pixel count of photodetector；
K after final calibrationHCalculated by following formula (5) and be designated as k "HPo：
k″HPo=k'HPo+kshift. (5)
7. any testing sample is measured, after the two-way quadrature interference signals for obtaining sample, the k " 6. obtained with stepHPoIt is right
The H roads signal of sample carries out resampling, obtains the H spectrum after sample calibration；The V light of H spectrum and sample after being calibrated to sample
Spectrum carries out the steps such as conventional Fourier transformation to polarization frequency domain OCT data processing, obtains structural information, the delay information of sample
With quick shaft direction information.
Described rough calibration, can use the method such as spectral signature curve method or interference spectrum comparison method.Spectral signature is bent
Collimation method is to obtain several known characteristic spectral lines by measurement, and finds out corresponding photodetector pixels, by this
Corresponding relation directly solves multinomial coefficient, primarily determines that respective wave-length coverage.Interference spectrum comparison method uses business spectrum
The spectrometer of calibration is needed to separately detect the corresponding interference spectrum of a sample speculum in instrument and system, by comparing two interference spectrums
Crest and trough obtain multigroup wavelength and the corresponding relation of pixel, then analysis obtain multinomial coefficient, realize spectroscopic calibration.
Rough calibration is not limited to above two method, can be that any other results in photodetector pixels pass corresponding with wavelength
The calibration method of system.
Described photodetector, is CCD or CMOS array or other detectors with photoelectric signal transformation function
Array.
Described simple sample, can be plane mirror or other similar samples.
It is described to enter row interpolation pretreatment to wave number k, to improve calibration accuracy, k can be carried out 4 times of interpolation processings or its
The interpolation processing of his multiple, corresponding zero padding interpolation processing will be also carried out to related interference spectrum.
Described calibration factor P, is the coefficient range provided in advance, the spectral response characteristic with photodetector in system
It is relevant.As the wave number k of horizontal interference spectrumHWith the wave number k of vertical interference spectrumVWhen differing larger, increase P span with
Guarantee can find the wave number best correspondence of two-way, otherwise can reduce P span.
The described wave number k with vertical interference spectrumVOn the basis of, it is not limited to kVOn the basis of or with horizon bar
Relate to the wave number k of spectrumHThe content being related in benchmark, step all accordingly exchanges H and V.
Compared with first technology, the present invention has advantages below：
1. the present invention evaluates calibration result using the degree of correlation, light source spectral pattern is not required, to Gaussian and non-gaussian
Type spectrum is applicable, and application has been expanded, with more universality.
, can be with 2. the present invention is used as evaluation function using cross-correlation maximum, it is to avoid find error during peak
Reach identical or higher calibration accuracy.
Brief description of the drawings
Fig. 1 is the flow chart of spectroscopic calibration of the present invention.
Fig. 2 is the non-gaussian light source light spectrum in the embodiment of the present invention 1.
Fig. 3 is the A-line signals of two-way channel of polarization H and V in the embodiment of the present invention 1.
Fig. 4 is the H and V A-line signals before and after the calibration in the embodiment of the present invention 1, wherein, figure (a) is using different
The A-line signals of H and V before and after method calibration, figure (b) are the enlarged drawing of dashed rectangle b parts in figure (a), and figure (c) is figure
(a) enlarged drawing of dashed rectangle c parts in, figure (d) is the enlarged drawing of dashed rectangle d parts in figure (a).
Fig. 5 is the calculation error absolute value of retardation and phase retardation in inventive embodiments 1, wherein figure (a) is delay
The calculation error absolute value of amount, figure (b) is the calculation error absolute value of phase retardation.
Fig. 6 is the average value and standard deviation of retardation and the Error Absolute Value of phase retardation in the embodiment of the present invention 1, its
Middle figure (a) is the average value and standard deviation of the Error Absolute Value of retardation, and figure (b) is the flat of the Error Absolute Value of phase retardation
Average and standard deviation.
Gauss light source light spectrum in Fig. 7 embodiment of the present invention 2.
Fig. 8 is the average value and standard deviation of retardation and the Error Absolute Value of phase retardation in the embodiment of the present invention 2, its
In (a) be the average value and standard deviation of the Error Absolute Value of retardation, figure (b) being averaged for the Error Absolute Value of phase retardation
Value and standard deviation.
Embodiment
With reference to embodiment and accompanying drawing, the invention will be further described, but should not limit the present invention's with this embodiment
Protection domain.
Fig. 1 is the flow chart of spectroscopic calibration of the present invention.As seen from the figure, Automatic-searching wave number k of the present invention is most
The method that excellent calibration factor carries out polarization domain optical coherence tomography spectroscopic calibration, this method comprises the following steps：
1. the two-way quadrature interference signals that polarization frequency domain OCT systems are detected, respectively horizontal polarization interference spectrum IHRWith it is vertical
Polarization interference composes IVR；For per interference spectrum all the way, photodetector pixels and the rough school of wavelength X corresponding relation are carried out respectively
It is accurate.
2. a simple sample is used, photodetector detects H the and V two-way quadrature interference signals for obtaining the sample, respectively
For horizontal interference spectrum IHWith vertical interference spectrum IV,
Wherein, subscript H and V represent horizontal interference spectrum H and vertical interference spectrum V respectively；IH0Represent horizontal interference spectrum
DC terms and auto-correlation；IV0Represent the DC terms and auto-correlation of vertical interference spectrum；S (k) represents light source light spectrum；RrTable
Show the reflectivity of reference mirror；RsnRepresent the reflectivity of sample n-th layer；ΔznRepresent the light path between each layer of sample arm and reference arm
Difference；δnRepresent from sample surfaces to the retardation of sample n-th layer；θnRepresent the quick shaft direction of sample n-th layer.
3. the data I that photodetector is detected is judgedHAnd IVWhether it is spacedly distributed with wave number：If data are
What wave number was spacedly distributed, then without entering row interpolation pretreatment to wave number k, pass directly to step 4.；If data are not wave numbers
It is spacedly distributed, then enters row interpolation pretreatment to wave number k, obtain the wave number k of equally spaced horizontal interference spectrumHAt equal intervals
Vertical interference spectrum wave number kV；
4. to the wave number k of equally spaced horizontal interference spectrumHZoom in and out：Choose one group of calibration factor P=[P1, P2...,
Pi..., Pn-1, Pn], wherein, i, n is natural number, represents calibration factor P sequence number；With the ripple of equally spaced vertical interference spectrum
Number kVOn the basis of, pass through formula k'H=kH+Pi·(kH-kH0) to the wave number k of horizontal interference spectrumHZoom in and out, obtain one group it is new
Wave number k'H, wherein kH0It is kHCenter wave number , " ﹒ " represent be multiplied；With new k'HTo horizontal interference spectrum IHAdopted again
Sample, IHIt is changed on k'HInterference signal IH(k'H)：
To the I after resamplingH(k'H) signal progress Fourier transformation, obtain the horizontal interference spectrum after resampling in z domains
A-line signals；
Equally, to vertical interference spectrum IVHandled, obtain the A-line signals of vertical interference spectrum in z domains；
5. last A-line signals and the A-line signals of vertical interference spectrum to the horizontal interference spectrum after resampling
Cross-correlation calculation is carried out, calibration factor P is obtainediCorresponding cross correlation value C (Pi)；Said process is repeated, calculating obtains each in P
Individual FACTOR PiCorresponding cross correlation value.Calibration effect is thought when two-way A-line signals cross-correlation is maximum preferably, i.e. Max (C
(Pi),Pi∈ P)=C (Po).Calibration factor now used is the optimal coefficient P to be obtainedo.Pass through PoAfter being calibrated
The wave number k' of horizontal interference spectrumHPo：
k'HPo=kH+Po·(kH-kH0). (8)；
6. after above-mentioned calibration, the A-line signals of the horizontal interference spectrum in z domains and the A- of vertical interference spectrum
Line signals can be with completely overlapped, but also needs to calibrate the spectral pattern of interference signal in k domains.The k' 5. obtained with stepHPo
To horizontal interference spectrum IHResampling is carried out, Fourier transformation is then carried out, the horizontal interference spectrum after being calibrated is corresponding
A-line signals, the signal related to simple sample is filtered out with wave filter；What is obtained in filtering out step 4. with wave filter simultaneously hangs down
The signal related to sample in the A-line signals of straight interference spectrum；The signal related to sample to this two-way filtered out enters respectively
Row inverse Fourier transform, respectively obtains the signal profile diagram of horizontal interference spectrum H and vertical interference spectrum V in k domains, to this two
Width signal profile diagram makees cross-correlation calculation, when cross-correlation is maximum, and the amount of horizontal interference spectrum H signal profile diagram movement is
k'HPoNeed mobile pixel count Nshift(kVKeep constant).Mobile pixel count changes into k'HPoAmount of movement kshift：
kshift=Nshift·[(k'HPomax-k'HPomin)/N], (9)
Wherein, k'HPomaxAnd k'HPominK' is represented respectivelyHPoMaximum and minimum value, N represents k'HPoTotal amount of data,
That is the pixel count of photodetector.
K after final calibrationHCalculated by following formula and be designated as k "HPo：
k″HPo=k'HPo+kshift. (10)；
7. any testing sample is measured, after the two-way quadrature interference signals for obtaining sample, the k " 6. obtained with stepHPo
Resampling is carried out to the H roads signal of sample, the H spectrum after sample calibration are obtained；The V of H spectrum and sample after being calibrated to sample
Spectrum carries out the polarization frequency domain OCT data processing such as conventional Fourier transformation, obtains the structural information of sample, postpones information and fast
Direction of principal axis information.
Need to calculate the intensity image R (z) (structural information) of simple sample, delayed image δ (z) (delay letters in embodiment
Breath) and fast axle image θ (z) (quick shaft direction information), it can be obtained by following formula：
Wherein, AH,V(z) each self-corresponding A-line letters of horizontal interference spectrum H and vertical interference spectrum V after calibration are represented
Number amplitude, ΦH,V(z) horizontal interference spectrum H and each self-corresponding A-line signals of vertical interference spectrum V after calibration are represented
Phase, subscript represents H and the passages of V two respectively.
Described rough calibration, can use the method such as spectral signature curve method or interference spectrum comparison method.Spectral signature is bent
Collimation method is to obtain several known characteristic spectral lines by measurement, and finds out corresponding photodetector pixels, by this
Corresponding relation directly solves multinomial coefficient, primarily determines that respective wave-length coverage.Interference spectrum comparison method uses business spectrum
The spectrometer of calibration is needed to separately detect the corresponding interference spectrum of a sample speculum in instrument and system, by comparing two interference spectrums
Crest and trough obtain multigroup wavelength and the corresponding relation of pixel, then analysis obtain multinomial coefficient, realize spectroscopic calibration.
Rough calibration is not limited to above two method, can be that any other results in photodetector pixels pass corresponding with wavelength
The calibration method of system.
Described photodetector, is CCD or CMOS array or other detectors with photoelectric signal transformation function
Array.
Described simple sample, can be plane mirror or other similar samples.
It is described to enter row interpolation pretreatment to wave number k, to improve calibration accuracy, k can be carried out 4 times of interpolation processings or its
The interpolation processing of his multiple, corresponding zero padding interpolation processing will be also carried out to related interference spectrum.
Described calibration factor P, is the coefficient range provided in advance, the spectral response characteristic with photodetector in system
It is relevant.As the wave number k of horizontal interference spectrumHWith the wave number k of vertical interference spectrumVWhen differing larger, increase P span with
Guarantee can find the wave number best correspondence of two-way, otherwise can reduce P span.
The described wave number k with vertical interference spectrumVOn the basis of, it is not limited to kVOn the basis of or with horizon bar
Relate to the wave number k of spectrumHThe content being related in benchmark, step all accordingly exchanges H and V.
The present embodiment 1, light source light spectrum is non-gaussian spectrum, as shown in Figure 2.Abscissa represents wavelength, ordinate table in figure
Show relative light intensity.In the present embodiment, light source center wavelength is 835nm, and full width at half maximum is 45nm.Sample be 3 layers, representative sample with
The different optical path difference positions of reference arm, i.e. actual grade position, the optical path difference of each layer and reference arm is respectively 200 μm, 700 μ
m,1200μm.Every layer of corresponding retardation δ is respectively 0.4969rad, 0.8065rad, 1.1282rad, corresponding fast axis direction
Angle θ is respectively 1.2226rad, 0.7083rad, 0.4501rad.Photodetector uses CCD.Same depth position is corresponded in theory
Put, the A-line signals of H and V two-way should overlap.But the spectral resolution difference, angle of diffraction due to two paths are not
Equal reason, H and V spectrum misplace, as shown in Figure 3.Dislocation causes polarization parameter calculation error to increase, reduction imaging matter
Amount.In figure, dotted line represents the A-line signals of H spectrum, and solid line represents the A-line signals of V spectrum.
According to being calibrated the step of above-mentioned calibration method of the invention to H the and V spectrum in embodiment 1.A- after calibration
Line signal results are as shown in Figure 4." H " and " V " represents the A-line signals of the H and V two-way before calibration, " peaks " table in Fig. 4
Show the calibration result using the H spectrum obtained after Peak Intensity Method (first technology [4]) calibration, " cor " represents that the present invention is provided most
The H spectroscopic calibration results that excellent Y-factor method Y calibration is obtained, " △ " represents actual grade position.It is figure respectively to scheme (b), (c) and (d)
(a) enlarged drawing of respective dashed Blocked portion in.It can be seen that after two methods are calibrated, H A-line signals
Center is all overlapped with V A-line signal centers substantially, but is used after the inventive method calibration, and two paths of signals is more preferably overlapping, H
Signal shape closer to V signal, figure (c) in it is particularly evident.Scheme in (c) at peak, using present invention side
After method calibration, variation tendency is more likely to V signal, and calibration effect is more preferable.
The retardation δ and phase retardation θ at actual grade position are calculated after calibration, respective calculation error absolute value is such as
Shown in Fig. 5.Here only need to obtain the offset between calculated value and true value, therefore the error calculation in the present embodiment is all pin
The absolute value of error is calculated.It can be seen that close at zero optical path difference position, calibration method of the present invention prolongs
Amount error amount is less than Peak Intensity Method late, and the calculation error of phase retardation is proximate to it.As optical path difference increases, in second layer position
Place, the retardation and fast axis direction angle error of Peak Intensity Method are respectively 0.025rad and 0.033rad, and the present invention is respectively
0.015rad and 0.005rad, it is with the obvious advantage, it can more accurately calibrate H and V spectrum.In non-gaussian spectrum, Fourier becomes
The peak of the A-line signals obtained after changing may deviate actual grade position, using peak method calibration might have compared with
Big error.At Fig. 5 (b) third layer position, it is obvious that the meter of the phase retardation after being calibrated using Peak Intensity Method
Calculation error is larger, and Error Absolute Value has reached 0.091rad.And use after the inventive method calibration, the calculating of phase retardation is missed
Poor absolute value falls below 0.029rad, and precision can improve more than 50%.
Fig. 6 is the data that experiment repeats to obtain after 20 times, and obtained retardation and fast axle side are calculated using the data
The average value and standard deviation of the Error Absolute Value of parallactic angle." peaks " is that peak method calculates obtained error result, and " cor " is
The method provided with the present invention calculates obtained error result.Fig. 6 (a) is retardation δ error condition, Peak Intensity Method and the present invention
The method of offer calculates obtained AME all 10 respectively-2In level, but the inventive method error amount is significantly less than
Peak method.At the 3rd layer of position, the stdev average of peak method is 0.00041rad, and the present invention is
0.00026rad, reduces 36.6%, with higher measurement accuracy and stability.Fig. 6 (b) is phase retardation θ mistake
Poor situation, close at zero optical path difference position, the AME and standard deviation and Peak Intensity Method of the calibration method that the present invention is provided
It is close.As optical path difference increases, the error amount of two methods is all in increase.At the 3rd layer of position, the AME of Peak Intensity Method
For 0.092rad, the inventive method is 0.030rad, much smaller than peak method, can more precisely compute the fast axis direction of sample
Angle, with higher calibration accuracy.The experimental verification present invention is repeated suitable for the situation that light source is non-gaussian spectral pattern, Neng Gouti
High calibration accuracy.
Embodiment 2, light source is Gauss spectrum, and other parameters in the same manner as in Example 1, are kept constant.Experiment repeats 20
It is secondary.Fig. 7 is the light source light spectrum used in embodiment 2, is Gaussian.Fig. 8 is that the error of the retardation and phase retardation calculated is exhausted
To the average value and error result of value.Fig. 8 (a) is the average value and standard deviation of the Error Absolute Value of retardation, AME
All 10-3In magnitude, error very little, it is evident that the present invention is better than Peak Intensity Method from figure.Fig. 8 (b) is phase retardation
Calculation error, as optical path difference increases, AME and standard deviation all become big, similar with the non-gaussian spectral pattern in embodiment 1.
The standard deviation of two methods is all 10-4In magnitude, the AME of Peak Intensity Method is about 0.041rad, and the inventive method is about
For 0.026rad, 36.6% is improved than Peak Intensity Method precision.
Embodiment 1 and embodiment 2 demonstrate the feasibility for the method that the present invention is provided.The present invention is applicable not only to Gauss light
Spectrum, also has preferable performance, computational accuracy is significantly improved than Peak Intensity Method in non-gaussian spectrum.
Claims (7)
1. one kind polarization domain optical coherence tomography spectroscopic calibration method, it is characterised in that this method comprises the following steps：
1. the two-way quadrature interference signals that polarization frequency domain OCT systems are detected, respectively horizontal polarization interference spectrum IHRAnd vertical polarization
Interference spectrum IVR；For per interference spectrum all the way, photodetector pixels and the rough calibration of wavelength X corresponding relation are carried out respectively；
2. a simple sample is used, photodetector detects the horizontal interference spectrum I of the sampleHWith vertical interference spectrum IV：
Wherein, subscript H and V represent horizontal interference spectrum H and vertical interference spectrum V respectively；IH0Represent the straight of horizontal interference spectrum
Flow item and auto-correlation；IV0Represent the DC terms and auto-correlation of vertical interference spectrum；S (k) represents light source light spectrum；RrRepresent ginseng
Examine the reflectivity of mirror；RsnRepresent the reflectivity of sample n-th layer；ΔznRepresent the optical path difference between each layer of sample arm and reference arm；
δnRepresent from sample surfaces to the retardation of sample n-th layer；θnRepresent the quick shaft direction of sample n-th layer；
3. the data I of photodetector detection is judgedHAnd IVWhether it is spacedly distributed with wave number, if data are wave numbers etc.
It is spaced apart, then without entering row interpolation pretreatment to wave number k, passes directly to step 4.；If data be not wave number at equal intervals
Distribution, then enter row interpolation pretreatment to wave number k, obtain the wave number k of equally spaced horizontal interference spectrumHWith it is equally spaced vertical
The wave number k of interference spectrumV；
4. to the wave number k of equally spaced horizontal interference spectrumHZoom in and out；Choose one group of calibration factor P=[P1, P2...,
Pi..., Pn-1, Pn], wherein, i, n is natural number, represents calibration factor P sequence number；With the ripple of equally spaced vertical interference spectrum
Number kVOn the basis of, pass through formula k'H=kH+Pi·(kH-kH0) to the wave number k of horizontal interference spectrumHZoom in and out, obtain one group it is new
Wave number k'H, wherein kH0It is kHCenter wave number , " ﹒ " represent be multiplied；With new k'HTo horizontal interference spectrum IHAdopted again
Sample, IHIt is changed on k'HInterference signal IH(k'H)：
To the I after resamplingH(k'H) signal progress Fourier transformation, obtain the A- of the horizontal interference spectrum in z domains after resampling
Line signals；
Equally, the data I detected to photodetectorVHandled, obtain the A-line signals of vertical interference spectrum in z domains；
5. A-line signals and the A-line signals of vertical interference spectrum to the horizontal interference spectrum after resampling carries out mutual
Close and calculate, obtain calibration factor PiCorresponding cross correlation value C (Pi)；Said process is repeated, calculating obtains the FACTOR P of each in Pi
Corresponding cross correlation value；Calibration effect is thought when two-way A-line signals cross-correlation is maximum preferably, i.e. Max (C (Pi),Pi∈P)
=C (Po)；Calibration factor now is optimal coefficient Po；The wave number k' of horizontal interference spectrum after being calibrated by PoHPo：
k'HPo=kH+Po·(kH-kH0)；
6. after above-mentioned calibration, the A-line signals of the horizontal interference spectrum in z domains and the A-line letters of vertical interference spectrum
Number can be with completely overlapped, but also need to further calibrate the spectral pattern of interference signal in k domains；The k' 5. obtained with stepHPoTo water
Flat interference spectrum IHResampling is carried out, Fourier transformation is then carried out, the corresponding A- of horizontal interference spectrum after being calibrated
Line signals, the signal related to simple sample is filtered out with wave filter；What is obtained in filtering out step 4. with wave filter simultaneously is vertical
The signal related to sample in the A-line signals of interference spectrum；The signal related to sample to this two-way filtered out is carried out respectively
Inverse Fourier transform, respectively obtains the signal profile diagram of horizontal interference spectrum H and vertical interference spectrum V in k domains；To this two width
Signal profile diagram makees cross-correlation calculation, when cross-correlation is maximum, and the amount of horizontal interference spectrum H signal profile diagram movement is k'HPo
Need mobile pixel count Nshift(kVKeep constant)；By following equation by mobile pixel count k'HPoChange into amount of movement
kshift：
kshift=Nshift·[(k'HPomax-k'HPomin)/N],
Wherein, k'HPomaxAnd k'HPominK' is represented respectivelyHPoMaximum and minimum value, N represents k'HPoTotal amount of data, i.e. light
The pixel count of electric explorer；
K after final calibrationHIt is calculated as follows and is designated as k "HPo：
k″HPo=k'HPo+kshift；
7. any testing sample is measured, after the two-way quadrature interference signals for obtaining sample, the k " 6. obtained with stepHPoTo sample
H roads signals carry out resampling, obtain the H spectrum after sample calibration；The V spectrum of H spectrum and sample after being calibrated to sample are pressed
Conventional polarization frequency domain OCT data handling process is handled, and obtains the structural information, delay information and quick shaft direction letter of sample
Breath.
2. polarization domain optical coherence tomography spectroscopic calibration method according to claim 1, it is characterised in that described
Rough calibration, handled using spectral signature curve method or interference spectrum comparison method；Spectral signature curve method is by measurement
Several known characteristic spectral lines are obtained, and find out corresponding photodetector pixels, directly will by this corresponding relation
Multinomial coefficient is solved, and primarily determines that respective wave-length coverage；Interference spectrum comparison method is used to be needed in business spectrometer and system
The spectrometer of calibration separately detects the corresponding interference spectrum of a sample speculum, is obtained by the crest and trough that compare two interference spectrums
To multigroup wavelength and the corresponding relation of pixel, then analysis obtains multinomial coefficient, realizes spectroscopic calibration.
3. polarization domain optical coherence tomography spectroscopic calibration method according to claim 1, it is characterised in that described
Photodetector, be CCD or CMOS array or other detector array with photoelectric signal transformation function.
4. polarization domain optical coherence tomography spectroscopic calibration method according to claim 1, it is characterised in that described
Simple sample, be plane mirror or other similar samples.
5. polarization domain optical coherence tomography spectroscopic calibration method according to claim 1, it is characterised in that described
Enter row interpolation pretreatment to wave number k, to improve calibration accuracy, the interpolation of 4 times of interpolation processings or other multiples can be carried out to k
Processing, corresponding zero padding interpolation processing will be also carried out to related interference spectrum.
6. polarization domain optical coherence tomography spectroscopic calibration method according to claim 1, it is characterised in that described
Calibration factor P, be the coefficient range provided in advance, it is relevant with the spectral response characteristic of photodetector in system；Work as level
The wave number k of interference spectrumHWith the wave number k of vertical interference spectrumVWhen differing larger, increase P span to ensure to find
The wave number best correspondence of two-way, on the contrary P span can be reduced.
7. polarization domain optical coherence tomography spectroscopic calibration method according to claim 1, it is characterised in that described
The wave number k with vertical interference spectrumVOn the basis of, it is not limited to kVOn the basis of, can also horizontal interference spectrum wave number kHBase
The content being related in standard, step exchanges corresponding H and V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710420299.XA CN107328740B (en) | 2017-06-06 | 2017-06-06 | Polarize domain optical coherence tomography spectroscopic calibration method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710420299.XA CN107328740B (en) | 2017-06-06 | 2017-06-06 | Polarize domain optical coherence tomography spectroscopic calibration method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107328740A true CN107328740A (en) | 2017-11-07 |
| CN107328740B CN107328740B (en) | 2019-10-18 |
Family
ID=60193908
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710420299.XA Active CN107328740B (en) | 2017-06-06 | 2017-06-06 | Polarize domain optical coherence tomography spectroscopic calibration method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107328740B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110081815A (en) * | 2019-04-25 | 2019-08-02 | 天津大学 | Low coherence interference striped distortion correction method based on white light LEDs |
| CN116050230A (en) * | 2022-10-25 | 2023-05-02 | 上海交通大学 | Full-wavelength signal simulation method of FD-OCT (fiber-optic coherence tomography) based on Monte Carlo |
| CN116818717A (en) * | 2023-08-28 | 2023-09-29 | 泉州装备制造研究所 | Compensation method and system for wavelength calibration error in spectral domain optical coherence tomography |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050222595A1 (en) * | 2004-03-31 | 2005-10-06 | Siemens Aktiengesellschaft | Device for removing a total vascular occlusion with OCT monitoring |
| CN101214145A (en) * | 2008-01-03 | 2008-07-09 | 中国科学院上海光学精密机械研究所 | Frequency domain photics coherent chromatography imaging method and system with large detecting depth |
| CN101822530A (en) * | 2009-03-06 | 2010-09-08 | 佳能株式会社 | Optical coherence tomography method and optical coherence tomography apparatus |
| CN102393382A (en) * | 2011-11-28 | 2012-03-28 | 天津迈达医学科技有限公司 | Rapid spectral detection system for frequency-domain optical coherence tissue tomography |
| CN103222852A (en) * | 2012-01-26 | 2013-07-31 | 佳能株式会社 | Optical coherence tomographic apparatus |
| CN104849221A (en) * | 2015-05-21 | 2015-08-19 | 清华大学深圳研究生院 | Optical coherence tomography-based phase calibration method |
| CN105588847A (en) * | 2016-01-05 | 2016-05-18 | 佛山科学技术学院 | Great-depth OCT (optical coherence tomograph) scanning device and method for nearly transparent minerals |
-
2017
- 2017-06-06 CN CN201710420299.XA patent/CN107328740B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050222595A1 (en) * | 2004-03-31 | 2005-10-06 | Siemens Aktiengesellschaft | Device for removing a total vascular occlusion with OCT monitoring |
| CN101214145A (en) * | 2008-01-03 | 2008-07-09 | 中国科学院上海光学精密机械研究所 | Frequency domain photics coherent chromatography imaging method and system with large detecting depth |
| CN101822530A (en) * | 2009-03-06 | 2010-09-08 | 佳能株式会社 | Optical coherence tomography method and optical coherence tomography apparatus |
| CN102393382A (en) * | 2011-11-28 | 2012-03-28 | 天津迈达医学科技有限公司 | Rapid spectral detection system for frequency-domain optical coherence tissue tomography |
| CN103222852A (en) * | 2012-01-26 | 2013-07-31 | 佳能株式会社 | Optical coherence tomographic apparatus |
| CN104849221A (en) * | 2015-05-21 | 2015-08-19 | 清华大学深圳研究生院 | Optical coherence tomography-based phase calibration method |
| CN105588847A (en) * | 2016-01-05 | 2016-05-18 | 佛山科学技术学院 | Great-depth OCT (optical coherence tomograph) scanning device and method for nearly transparent minerals |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110081815A (en) * | 2019-04-25 | 2019-08-02 | 天津大学 | Low coherence interference striped distortion correction method based on white light LEDs |
| CN110081815B (en) * | 2019-04-25 | 2021-01-05 | 天津大学 | Low-coherence interference fringe distortion correction method based on white light LED |
| CN116050230A (en) * | 2022-10-25 | 2023-05-02 | 上海交通大学 | Full-wavelength signal simulation method of FD-OCT (fiber-optic coherence tomography) based on Monte Carlo |
| CN116050230B (en) * | 2022-10-25 | 2023-08-22 | 上海交通大学 | Full-wavelength signal simulation method of FD-OCT (fiber-optic coherence tomography) based on Monte Carlo |
| CN116818717A (en) * | 2023-08-28 | 2023-09-29 | 泉州装备制造研究所 | Compensation method and system for wavelength calibration error in spectral domain optical coherence tomography |
| CN116818717B (en) * | 2023-08-28 | 2023-11-07 | 泉州装备制造研究所 | Compensation method and system for wavelength calibration error in spectral domain optical coherence tomography |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107328740B (en) | 2019-10-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8565499B2 (en) | Methods, systems, and computer readable media for synthetic wavelength-based phase unwrapping in optical coherence tomography and spectral domain phase microscopy | |
| JP5787255B2 (en) | Program for correcting measurement data of PS-OCT and PS-OCT system equipped with the program | |
| US20110109914A1 (en) | Method and apparatus for polarization-sensitive optical coherence tomography | |
| JP4461259B2 (en) | Optical tomographic image processing method | |
| US6493093B2 (en) | Bat-wing attenuation in white-light interferometry | |
| CN107328740B (en) | Polarize domain optical coherence tomography spectroscopic calibration method | |
| CN203720071U (en) | Polarization frequency domain optical coherence tomography system based on single detector | |
| CN112525070B (en) | Vibration-resistant white light interference measurement method based on non-uniform sampling correction | |
| CN1952594B (en) | Surface profile measuring method and apparatus thereof | |
| CN104068825A (en) | Short coherence light interference measuring method and device | |
| WO2023088409A1 (en) | Interferometric three-dimensional profile solving method | |
| CN115046469A (en) | Interference fringe envelope extraction method for optical fiber white light interference | |
| Cao et al. | Non-harmonic analysis applied to optical coherence tomography imaging | |
| Serizawa et al. | 3-D surface profile measurement using spectral interferometry based on continuous wavelet transform | |
| CN106767391A (en) | The sensitivity intensifier and method of four wavefront lateral shearing interference Wavefront sensors | |
| US9091633B2 (en) | Apparatus and method for locating the centre of a beam profile | |
| CN101750146B (en) | Adjustable frequency domain optical coherence chromatography imaging method and system thereof | |
| CN111121661B (en) | Narrow-band non-monochromatic light n +1 amplitude phase shift test algorithm for smooth surface topography measurement | |
| Baumann et al. | Improved accuracy of quantitative birefringence imaging by polarization sensitive OCT with simple noise correction and its application to neuroimaging | |
| US20130314692A1 (en) | Etching monitor device | |
| Ding et al. | A new spectral calibration method for Fourier domain optical coherence tomography | |
| CN106872407A (en) | One kind improves frequency sweep optical coherent chromatographic imaging resolution method | |
| CN204575033U (en) | Based on the high precision distance measurement system of cross dispersion spectral domain interferometer | |
| Yurdakul et al. | Line-field coherent sensing with LED illumination | |
| CN105115940A (en) | Curve measuring method and device for refractive index of optical material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |