CN1924633A - Digital micro-lens components based interference-free parallel OCT imaging method and system - Google Patents

Abstract

This invention discloses one parallel optical coherent tomography method and system without crosstalk based on digital micro deice, which adopts wide band point source to realize shining, wherein, the light path adds one DMD and optical system design ensures the equivalent size of the level size on the sample conjugate surface and the level size of the system resolution sample; the micro lens is at 12 degrees at open status to lead the relative part into interference system; the DMD coding changes parallel status of the images to depress biological body imaging of fixed signal series; extracting interference signals by the four step integration detection method of sine phase modulation technique.

Description

Based on the nothing of Digital Micromirror Device crosstalk parallel OCT formation method and system

Technical field

The present invention relates to a kind of method and system that the parallel optical coherence chromatographic imaging is crosstalked that suppresses, relate in particular to and a kind ofly suppress the method and system that the parallel optical coherence chromatographic imaging is crosstalked based on Digital Micromirror Device.

Background technology

Optical coherent chromatographic imaging (Optical Coherence Tomography, be called for short OCT) be the chromatography imaging technique that developed recently gets up, can realize noncontact, not damaged, the high-resolution imaging of biological tissue structure and physiological function, thereby in biomedical sector and clinical diagnosis, be used widely, in material science and fundamental research, also will play a significant role.

The parallel imaging of OCT is compared with the pointwise imaging, has the following advantages: 1, do not need pointwise to become like that quick mechanical scanning campaign, mechanical stability accesses assurance; 2, all pixels in the piece image all are synchronous acquisition, can avoid because the vacation picture that factors such as periodicity life regular movements cause produces; 3, can use high power light source; 4, can realize fast two-dimensional or three-dimensional imaging, and reduce the complexity of system.Owing to above reason, parallel OCT imaging mode is widely adopted in various occasions.

In parallel OCT imaging system, if the face illumination is formed problem that each parallel detecting is interchannel in the time of then can't avoiding the scatterer imaging crosstalks (cross talk) by the broadband pointolite.Crosstalking is a kind of noise source, will be reduced to image contrast, resolution and the maximum probe degree of depth, must be added on to overcome.

Adopt the space incoherent illumination, as thermal light source, the interchannel cross-interference issue of each parallel detecting in the time of can avoiding the scatterer imaging has that system is simple, cost is low and the axial resolution advantages of higher, but has the low limitation of spectral energy density.Because thermal light source is the blackbody radiation luminophor, its radiation energy depends on colour temperature, is example with mercury-arc lamp the most frequently used, that colour temperature is the highest (6000K magnitude) at present, and it can offer the energy of each sensing point still less than 1 μ w.Too low energy limited detection sensitivity and image acquisition speed.

Therefore, in two kinds of lighting systems of parallel OCT imaging system, the spatial coherence illumination that is formed by the broadband pointolite can offer the higher energy of each sensing point, can realize high detection sensitivity and rapid image collection, but between each detection channels crosstalk phenomenon can take place; Though and avoided crosstalk phenomenon based on the space incoherent illumination of thermal light source, its energy that offers each sensing point is very low, has limited detection sensitivity and image acquisition speed.

Summary of the invention

In order to solve the problem that exists in the background technology, the purpose of this invention is to provide a kind of nothing when adopting the spatial coherence lighting system crosstalk parallel OCT formation method and system.This method and system adopts Digital Micromirror Device (Digital Micromirror Device is called for short DMD), the crosstalk phenomenon when effectively suppressing to walk abreast the OCT imaging by encoding.

The technical solution adopted for the present invention to solve the technical problems is:

One, based on the nothing of the DMD parallel OCT formation method of crosstalking, it is characterized in that comprising:

1) micro mirror be in+12 ° of angles are " opening " state ,-12 ° of angles are " pass " state; Digital Micromirror Device is encoded in the following manner: micro mirror is divided into sub-piece by 2 * 2 patterns, 4 micro mirrors are arranged in each sub-piece, be numbered 1,2,3,4 respectively, the micro mirror of corresponding position gives identical numbering in the different sub-pieces, thereby all micro mirrors of Digital Micromirror Device are divided into 4 classes by the locus: micro mirror 1, micro mirror 2, micro mirror 3 and micro mirror 4; All micro mirror 1 synchronization actions, when being in " opening " state, all the other micro mirrors are all located " pass " state; The rest may be inferred, and micro mirror is in " opening " state one by one by numbering 1-2-3-4, makes that the point of conjugation is illuminated with it on sample and the reference mirror;

2) the area array CCD detector adopts 2 * 2 pixels splicing mode of operation;

3) reference arm and sample arm reference mirror and microcobjective axial displacement together respectively to defocused by the electronic control translation stage band of reference arm, carry out the light path match and regulate of two interference arms;

4) the piezoelectric ceramic actuator band the reference mirror vibration, thereby pull-in frequency is that f, amplitude are that ψ, phase place are the sinusoidal phase modulation ψ sin (2 π ft+ θ) of θ in interference signal, the interference signal I that this moment, the area array CCD detector received (x, y t) are expressed as:

I(x，y，t)＝I ₀+A(x，y)cos[φ(x，y)+ψsin(2πft+θ)]；

In the formula: I ₀Be the constant term of interference signal, φ (x y) is initial phase difference, and A (x, y) then directly related with the OCT signal;

5) in a modulation period T=1/f, micro mirror 1-2-3-4 in order triggers successively with frequency 16f, duration 1/16f; The area array CCD detector is gathered four width of cloth image E with frequency 4f synchronous triggering ₁₁, E ₁₂, E ₁₃And E ₁₄, they be respectively the interference signal I that the area array CCD detector receives (x, y, t) in 1/4th modulation periods to the result of time integral, that is:

${\mathrm{<figure-callout\; id="11"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{11}={\&Integral;}_0^{T/4}I(x,y,t)\mathrm{dt},$ ${\mathrm{<figure-callout\; id="12"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{12}={\&Integral;}_{T/4}^{T/2}I(x,y,t)\mathrm{dt},$ ${\mathrm{<figure-callout\; id="13"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{13}={\&Integral;}_{T/2}^{3T/4}I(x,y,t)\mathrm{dt},$ ${\mathrm{<figure-callout\; id="14"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{14}={\&Integral;}_{3T/4}^{T}I(x,y,t)\mathrm{dt};$

6) repeating step 5) N time improving signal to noise ratio (S/N ratio), and the result of N acquisition is sued for peace, obtain four width of cloth image E ₁, E ₂, E ₃And E ₄, that is:

${\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_1=E_{11}+E_{21}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_0^{T/4}I(x,y,t)\mathrm{dt},$

${\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_2={\mathrm{<figure-callout\; id="12"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{12}+E_{22}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_{T/4}^{T/2}I(x,y,t)\mathrm{dt},$

${\mathrm{<figure-callout\; id="3"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_3={\mathrm{<figure-callout\; id="13"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{13}+E_{23}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_{T/2}^{3T/4}I(x,y,t)\mathrm{dt},$

${\mathrm{<figure-callout\; id="4"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_4=E_{14}+E_{24}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="4"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_{3T/4}^{T}I(x,y,t)\mathrm{dt};$

7) (x, y is t) with n rank Bessel function of the first kind J interference signal I _n(ψ) launch, and after the integration type in the step 6) carried out computing, can set up following relational expression:

∑ _S＝-E ₁+E ₂+E ₃-E ₄＝(4NT/π)Γ _SAsinφ，

∑ _C＝-E ₁+E ₂-E ₃+E ₄＝(4NT/π)Γ _CAcosφ，

In the formula: ${\mathrm{\&Gamma;}}_S=\underset{n=0}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^n\frac{J_{2n+1}\left(\mathrm{\&psi;}\right)}{2n+1}\sin \left[(2n+1)\mathrm{\&theta;}\right],$ ${\mathrm{\&Gamma;}}_c=\underset{n=0}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^n\frac{J_{4n+2}\left(\mathrm{\&psi;}\right)}{2n+1}\sin \left[2(2n+1)\mathrm{\&theta;}\right];$

J wherein _2n+1(ψ) be 2n+1 rank Bessel function of the first kind, J _4n+2(ψ) be 4n+2 rank Bessel function of the first kind;

8) make Γ _S=Γ _C, ∑ then _S ²+ ∑ _C ²With A ²Be directly proportional; Work as Γ _SWhen getting maximal value, ∑ _S ²+ ∑ _C ²Also obtain maximal value, this moment, image had optimum contrast; Can calculate modulation parameter ψ and θ value by aforementioned condition, and the Г of this moment _SValue; Go set-up procedure 4 with ψ that tries to achieve and θ numerical value) in phase modulated signal;

9) set by step 4) operate, come the OCT image of calculation sample then by following formula to step 6):

$A=\frac{\mathrm{\&pi;}}{4\mathrm{NT}{\mathrm{\&Gamma;}}_S}{[{(-{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_1+E_2+E_3-E_4)}^2+{(-{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_1+E_2-E_3+E_4)}^2]}^{1/2};$

10) the electronic control translation stage band of computer control reference arm reference mirror and microcobjective axial displacement d together, changes the reference arm light path; If the refractive index of sample is n, then the computing machine electronic control translation stage band of controlling sample arm simultaneously microcobjective axial displacement d/n, carries out focal adjustment, to realize the tomography of sample different depth place section; Repeating step 9), can obtain sample at the OCT at this degree of depth place image.

Two, based on the nothing of the DMD parallel OCT imaging system of crosstalking:

Comprise broadband pointolite, collimation lens, DMD, lens, broadband Amici prism, a pair of identical microcobjective, reference mirror, piezoelectric ceramic actuator, first electronic control translation stage, second electronic control translation stage, imaging len, area array CCD detector; The light that the broadband pointolite sends is on the parallel DMD of being incident in behind the collimation lens, be among the DMD+12 ° of angles " open " light of the micro mirror reflection of state, be divided into transmitted light and reflected light behind lens and broadband Amici prism: transmitted light arrives reference mirror through microcobjective, reference mirror is fixed on the piezoelectric ceramic actuator, and microcobjective and piezoelectric ceramic actuator are fixed on first electronic control translation stage; Reflected light arrives sample through microcobjective, and microcobjective is fixed on second electronic control translation stage; After turning back to the broadband Amici prism from the light of reference mirror reflection with from sample reflection or backward scattered light along former road, through imaging len plane of incidence battle array ccd detector.

Described area array CCD detector is through image acquisition and analog to digital conversion clamping computing machine, and DMD links to each other with computing machine with signal wire, and computing machine is exported two-way behind the multi-channel digital and analogue transition card: the one tunnel connects piezoelectric ceramic actuator; Two-way is exported on another road behind controllor for step-by-step motor, connect first electronic control translation stage and second electronic control translation stage respectively.

Become 24 ° of angles from the parallel incident light of collimation lens 2 and the normal of Digital Micromirror Device 3, be in the Digital Micromirror Device 3+reflected light of state micro-mirrors " is opened " along the normal direction outgoing in 12 ° of angles.

Described broadband pointolite is the spatial coherence pointolite, specifically is short-pulse laser light source, superradiance light source SLD/SLED or amplified spontaneous emission light source ASE.

The present invention compares the beneficial effect that has with background technology:

1, the broadband pointolite of the present invention's employing is the spatial coherence light source, compare with the spatial incoherent light source, has higher spectral energy density, can provide higher energy for each sensing point, the system that makes has higher detection sensitivity and image acquisition speed, and the crosstalk phenomenon that causes owing to the usage space illumination of coherent light source is suppressed by coding by DMD;

2, the coded system that DMD of the present invention adopted has the advantages that to realize simple and efficient work: guarantee that by design of Optical System the breadth wise dimension of micro mirror on the sample conjugate plane is suitable with the distinguishable sample breadth wise dimension of system; When on the sample certain is put when illuminated, adjacent with it have a few all not illuminatedly, realized that local point surveys imaging, effectively suppressed the generation of crosstalk phenomenon; And see that from the overall situation point of sum 1/4 is thrown light on simultaneously, and realized overall parallel imaging, guaranteed the imaging efficiency of system;

3, the signal extraction mode of the present invention's employing has the advantages that the single operation imaging need not image mosaic: in the traditional application scenario of DMD, often current sensing point is operated, after obtaining the image of this point, move to next sensing point again and carry out identical operations, image until obtaining whole sensing points synthesizes a complete sample image to these images at last again; And in the present invention, can obtain the OCT image a phase modulation (PM) in cycle, for improving signal to noise ratio (S/N ratio) duplicate measurements N time, this N time measurement is defined as the OCT imaging operation one time, once such operation can obtain a complete OCT image, and need not image mosaic, avoided the various errors that cause thus;

4, the area array CCD detector of the present invention's use adopts 2 * 2 pixels splicing mode of operation, and it is corresponding by the processing mode that 2 * 2 patterns are divided into sub-piece with DMD; Because the change of the effective pixel yardstick of ccd detector is big, expanded the dynamic range of system; And, make the speed of data transmission effectively improve owing to need the minimizing of the pixel quantity of processing.

Description of drawings

Fig. 1 is a system layout synoptic diagram of the present invention;

Fig. 2 is a control block diagram of the present invention;

Fig. 3 is the coding synoptic diagram of DMD;

Fig. 4 is the synchronous control signal synoptic diagram.

Among the figure: 1. broadband pointolite, 2. collimation lens, 3. Digital Micromirror Device (DMD), 4. lens, 5. broadband Amici prism, 6,7. a pair of identical microcobjective, 8. reference mirror, 9. sample, 10. piezoelectric ceramic actuator, 11. first electronic control translation stage, 12. second electronic control translation stages, 13. imaging lens, 14. the area array CCD detector, 15. image acquisition and analog-to-digital conversion card, 16. computing machines, 17. the multi-channel digital and analogue transition card, 18. controllor for step-by-step motor.

Embodiment

The present invention is further illustrated below in conjunction with drawings and Examples:

Crosstalk parallel OCT imaging system as shown in Figure 1 based on the nothing of DMD, and the light that broadband pointolite 1 sends is behind collimation lens 2 collimations, along becoming 24 ° of parallel incident DMD3 in angular direction with the normal of DMD3.Be among the DMD3+12 ° of angles " open " light of the micro mirror reflection of state, normal direction outgoing along DMD3, be divided into transmitted light and reflected light behind lens 4 and broadband Amici prism 5: transmitted light is focused on the reference mirror 8 by microcobjective 6, reference mirror 8 is fixed on the piezoelectric ceramic actuator 10, and microcobjective 6 and piezoelectric ceramic actuator 10 are fixed on first electronic control translation stage 11; Reflected light is focused on the sample 9 by microcobjective 7, and microcobjective 7 is fixed on second electronic control translation stage 12.From reference mirror 8 reflections with from sample 9 reflection or backward scattered light, after Yan Yuanlu turns back to broadband Amici prism 5, through the light-sensitive surface of imaging len 13 plane of incidence battle array ccd detectors 14.

Control system of the present invention as shown in Figure 2, the output signal of area array CCD detector 14 inputs to computing machine 16 through image acquisition and analog-to-digital conversion card 15, and comes chain of command battle array ccd detector 14 to carry out image acquisition by computing machine 16.Computing machine 16 usefulness signal wires link to each other with DMD 3, control DMD 3 by coded program work.Another road output signal of computing machine 16 is exported two-way behind multi-channel digital and analogue transition card 17: the one road drives piezoelectric ceramic actuator 10, is being with reference mirror 8 vibrations to introduce the sinusoidal phase modulation signal by it; Two-way is exported on another road behind controllor for step-by-step motor 18: the one road drives first electronic control translation stage 11 is being with microcobjective 6 and piezoelectric ceramic actuator 10 axial displacement d together, changes the reference arm light path; Another road drives second electronic control translation stage 12 with microcobjective 7 axial displacement d/n (wherein n is the refractive index of sample), carries out focal adjustment, to realize the tomography of sample different depth place section;

Image acquisition and analog-to-digital conversion card 15 and multi-channel digital and analogue transition card 17 can be bought from market, and the former is as the DH-CG410 of Beijing Imax Corp. of Daheng, and the USB7322 of wound scientific ﹠ technical corporation grinds in Thailand in the latter such as Beijing.Controllor for step-by-step motor 18 is auxiliary products with electronic control translation stage 11 and 12, can buy together, as the TSA30-C electronic control translation stage and the SC3 controllor for step-by-step motor of Beijing Zolix Instrument Co., Ltd..

The coding synoptic diagram that Fig. 3 adopts for DMD3 of the present invention, micro mirror is in+and 12 ° of angles are " opening " state,-12 ° of angles are " pass " state, realize following coding by computer programming: micro mirror is divided into sub-piece by 2 * 2 patterns to DMD3,4 micro mirrors are arranged in each sub-piece, be numbered 1,2,3,4 respectively, the micro mirror of corresponding position gives identical numbering in the different sub-pieces, thereby all micro mirrors are divided into 4 classes by the locus: micro mirror 1, micro mirror 2, micro mirror 3 and micro mirror 4; All micro mirror 1 synchronization actions, when being in " opening " state, all the other micro mirrors are all located " pass " state; The rest may be inferred, and micro mirror is in " opening " state one by one by numbering 1-2-3-4, makes that the point of conjugation is illuminated with it on sample and the reference mirror.From above-mentioned coded system as can be known: when on the sample certain is put when illuminated, adjacent with it have a few all not illuminatedly, realized that local point surveys imaging, effectively suppressed the generation of crosstalk phenomenon; And see that from the overall situation point of sum 1/4 is thrown light on simultaneously, and realized overall parallel imaging, guaranteed the imaging efficiency of system.

Fig. 4 is the synchronizing signal synoptic diagram, is being with reference mirror 8 vibrations to introduce the sinusoidal phase modulation signal by piezoelectric ceramic actuator 10.In a modulation period T=1/f, micro mirror 1-2-3-4 in order triggers successively with frequency 16f, each micro mirror duration 1/16f; Area array CCD detector 14 is with frequency 4f synchronous triggering, gathers four width of cloth images that the interference signal that received by area array CCD detector 14 obtained time integral in four 1/4th modulation periods.Be the raising signal to noise ratio (S/N ratio), and repeat aforementioned operation N time.

The nothing based on DMD that the present invention the proposes parallel OCT formation method of crosstalking is characterized in that comprising:

1) micro mirror be in+12 ° of angles are " opening " state ,-12 ° of angles are " pass " state; Digital Micromirror Device is encoded in the following manner: micro mirror is divided into sub-piece by 2 * 2 patterns, 4 micro mirrors are arranged in each sub-piece, be numbered 1,2,3,4 respectively, the micro mirror of corresponding position gives identical numbering in the different sub-pieces, thereby all micro mirrors of Digital Micromirror Device are divided into 4 classes by the locus: micro mirror 1, micro mirror 2, micro mirror 3 and micro mirror 4; All micro mirror 1 synchronization actions, when being in " opening " state, all the other micro mirrors are all located " pass " state; The rest may be inferred, and micro mirror is in " opening " state one by one by numbering 1-2-3-4, makes that the point of conjugation is illuminated with it on sample and the reference mirror;

2) the area array CCD detector adopts 2 * 2 pixels splicing mode of operation;

3) reference arm and sample arm reference mirror and microcobjective axial displacement together respectively to defocused by the electronic control translation stage band of reference arm, carry out the light path match and regulate of two interference arms;

4) the piezoelectric ceramic actuator band the reference mirror vibration, thereby pull-in frequency is that f, amplitude are that ψ, phase place are the sinusoidal phase modulation ψ sin (2 π ft+ θ) of θ in interference signal, the interference signal I that this moment, the area array CCD detector received (x, y t) are expressed as:

I(x，y，t)＝I ₀+A(x，y)cos[φ(x，y)+ψsin(2πft+θ)]；

In the formula: I ₀Be the constant term of interference signal, φ (x y) is initial phase difference, and A (x, y) then directly related with the OCT signal;

5) in a modulation period T=1/f, micro mirror 1-2-3-4 in order triggers successively with frequency 16f, duration 1/16f; The area array CCD detector is gathered four width of cloth image E with frequency 4f synchronous triggering ₁₁, E ₁₂, E ₁₃And E ₁₄, they be respectively the interference signal I that the area array CCD detector receives (x, y, t) in 1/4th modulation periods to the result of time integral, that is:

${\mathrm{<figure-callout\; id="11"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{11}={\&Integral;}_0^{T/4}I(x,y,t)\mathrm{dt},$ ${\mathrm{<figure-callout\; id="12"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{12}={\&Integral;}_{T/4}^{T/2}I(x,y,t)\mathrm{dt},$ ${\mathrm{<figure-callout\; id="13"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{13}={\&Integral;}_{T/2}^{3T/4}I(x,y,t)\mathrm{dt},$ ${\mathrm{<figure-callout\; id="14"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{14}={\&Integral;}_{3T/4}^{T}I(x,y,t)\mathrm{dt};$

6) repeating step 5) N time improving signal to noise ratio (S/N ratio), and the result of N acquisition is sued for peace, obtain four width of cloth image E ₁, E ₂, E ₃And E ₄, that is:

${\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_1={\mathrm{<figure-callout\; id="11"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{11}+{\mathrm{<figure-callout\; id="21"\; label="E"\; filenames="A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_{21}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_0^{T/4}I(x,y,t)\mathrm{dt},$

${\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_2={\mathrm{<figure-callout\; id="12"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{12}+E_{22}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_{T/4}^{T/2}I(x,y,t)\mathrm{dt},$

${\mathrm{<figure-callout\; id="3"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_3={\mathrm{<figure-callout\; id="13"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{13}+E_{23}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_{T/2}^{3T/4}I(x,y,t)\mathrm{dt},$

${\mathrm{<figure-callout\; id="4"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_4={\mathrm{<figure-callout\; id="14"\; label="E"\; filenames="A20061005360600121.png"\; state="\{\{state\}\}">E</figure-callout>}}_{14}+E_{24}+\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{<figure-callout\; id="4"\; label="E\; N"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_N=N{\&Integral;}_{3T/4}^{T}I(x,y,t)\mathrm{dt};$

7) (x, y is t) with n rank Bessel function of the first kind J interference signal I _n(ψ) launch, and after the integration type in the step 6) carried out computing, can set up following relational expression:

∑ _S＝-E ₁+E ₂+E ₃-E ₄＝(4NT/π)Г _SAsinφ，

∑ _C＝-E ₁+E ₂-E ₃+E ₄＝(4NT/π)Г _CAcosφ，

In the formula: ${\mathrm{\&Gamma;}}_S=\underset{n=0}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^n\frac{J_{2n+1}\left(\mathrm{\&psi;}\right)}{2n+1}\sin \left[(2n+1)\mathrm{\&theta;}\right],$ ${\mathrm{\&Gamma;}}_c=\underset{n=0}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^n\frac{J_{4n+2}\left(\mathrm{\&psi;}\right)}{2n+1}\sin \left[2(2n+1)\mathrm{\&theta;}\right];$

J wherein _2n+1(ψ) be 2n+1 rank Bessel function of the first kind, J _4n+2(ψ) be 4n+2 rank Bessel function of the first kind;

8) make Г _S=Г _C, ∑ then _S ²+ ∑ _C ²With A ²Be directly proportional; Work as Г _SWhen getting maximal value, ∑ _S ²+ ∑ _C ²Also obtain maximal value, this moment, image had optimum contrast; Can calculate modulation parameter ψ and θ value by aforementioned condition, and the Г of this moment _SValue; Go set-up procedure 4 with ψ that tries to achieve and θ numerical value) in phase modulated signal;

9) set by step 4) operate, come the OCT image of calculation sample then by following formula to step 6):

$A=\frac{\mathrm{\&pi;}}{4\mathrm{NT}{\mathrm{\&Gamma;}}_S}{[{(-{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_2+E_3-E_4)}^2+{(-{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_1+E_2-{\mathrm{<figure-callout\; id="3"\; label="E"\; filenames="A20061005360600121.png,A20061005360600131.png"\; state="\{\{state\}\}">E</figure-callout>}}_3+E_4)}^2]}^{1/2};$

10) the electronic control translation stage band of computer control reference arm reference mirror and microcobjective axial displacement d together, changes the reference arm light path; If the refractive index of sample is n, then the computing machine electronic control translation stage band of controlling sample arm simultaneously microcobjective axial displacement d/n, carries out focal adjustment, to realize the tomography of sample different depth place section; Repeating step 9), can obtain sample at the OCT at this degree of depth place image.

Claims (5)

1, based on the nothing of the Digital Micromirror Device parallel OCT formation method of crosstalking, it is characterized in that comprising:

1) micro mirror be in+12 ° of angles are " opening " state ,-12 ° of angles are " pass " state; Digital Micromirror Device is encoded in the following manner: micro mirror is divided into sub-piece by 2 * 2 patterns, 4 micro mirrors are arranged in each sub-piece, be numbered 1,2,3,4 respectively, the micro mirror of corresponding position gives identical numbering in the different sub-pieces, thereby all micro mirrors of Digital Micromirror Device are divided into 4 classes by the locus: micro mirror 1, micro mirror 2, micro mirror 3 and micro mirror 4; All micro mirror 1 synchronization actions, when being in " opening " state, all the other micro mirrors are all located " pass " state; The rest may be inferred, and micro mirror is in " opening " state one by one by numbering 1-2-3-4, makes that the point of conjugation is illuminated with it on sample and the reference mirror;

2) the area array CCD detector adopts 2 * 2 pixels splicing mode of operation;

3) reference arm and sample arm reference mirror and microcobjective axial displacement together respectively to defocused by the electronic control translation stage band of reference arm, carry out the light path match and regulate of two interference arms;

4) the piezoelectric ceramic actuator band the reference mirror vibration, thereby pull-in frequency is that f, amplitude are that ψ, phase place are the sinusoidal phase modulation ψ sin (2 π ft+ θ) of θ in interference signal, the interference signal I that this moment, the area array CCD detector received (x, y t) are expressed as:

I(x，y，t)＝I ₀+A(x，y)cos[φ(x，y)+ψsin(2πft+θ)]；

In the formula: I ₀Be the constant term of interference signal, φ (x y) is the initial phase difference of two interference arms, and A (x, y) then directly related with the OCT signal;

5) in a modulation period T=1/f, micro mirror 1-2-3-4 in order triggers successively with frequency 16f, duration 1/19f; The area array CCD detector is gathered four width of cloth image E with frequency 4f synchronous triggering ₁₁, E ₁₂, E ₁₃And E ₁₄, they be respectively the interference signal I that the area array CCD detector receives (x, y, t) in 1/4th modulation periods to the result of time integral, that is:

$E_{11}={\&Integral;}_0^{T/4}I(x,y,t)\mathrm{dt},E_{12}={\&Integral;}_{T/4}^{T/2}I(x,y,t)\mathrm{dt},E_{13}={\&Integral;}_{T/2}^{3T/4}I(x,y,t)\mathrm{dt},E_{14}={\&Integral;}_{3T/4}^{T}I(x,y,t)\mathrm{dt};$

6) repeating step 5) N time improving signal to noise ratio (S/N ratio), and the result of N acquisition is sued for peace, obtain four width of cloth image E ₁, E ₂, E ₃And E ₄, that is:

$E_1=E_{11}+E_{21}+\&CenterDot;\&CenterDot;\&CenterDot;+E_{N1}=N{\&Integral;}_0^{T/4}I(x,y,t)\mathrm{dt},$

$E_2=E_{12}+E_{22}+\&CenterDot;\&CenterDot;\&CenterDot;+E_{N2}=N{\&Integral;}_{T/4}^{T/2}I(x,y,t)\mathrm{dt},$

$E_3=E_{13}+E_{23}+\&CenterDot;\&CenterDot;\&CenterDot;+E_{N3}=N{\&Integral;}_{T/2}^{3T/4}I(x,y,t)\mathrm{dt},$

$E_4=E_{14}+E_{24}+\&CenterDot;\&CenterDot;\&CenterDot;+E_{N4}=N{\&Integral;}_{3T/4}^{T}I(x,y,t)\mathrm{dt};$

7) (x, y t) use Bessel function of the first kind J interference signal I _n(ψ) launch, and after the integration type in the step 6) carried out computing, can set up following relational expression:

∑ _S＝-E ₁+E ₂+E ₃-E ₄＝(4NT/π)Γ _SAsinφ，

∑ _C＝-E ₁+E ₂-E ₃+E ₄＝(4NT/π)Γ _CAcosφ，

In the formula: ${\mathrm{\&Gamma;}}_S=\underset{N=0}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^n\frac{J_{2n+1}\left(\mathrm{\&psi;}\right)}{2n+1}\sin \left[(2n+1)\mathrm{\&theta;}\right],{\mathrm{\&Gamma;}}_c=\underset{n=0}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^n\frac{J_{4n+2}\left(\mathrm{\&psi;}\right)}{2n+1}\sin \left[2(2n+1)\mathrm{\&theta;}\right];$

J wherein _2n+1(ψ) be 2n+1 rank Bessel function of the first kind, J _4n+2(ψ) be 4n+2 rank Bessel function of the first kind;

8) make Г _S=Г _C, ∑ then _S ²+ ∑ _C ²With A ²Be directly proportional; Work as Г _SWhen getting maximal value, ∑ _S ²+ ∑ _C ²Also obtain maximal value, this moment, image had optimum contrast; Can calculate modulation parameter ψ and θ value by aforementioned condition, and the Г of this moment _SValue; Go set-up procedure 4 with ψ that tries to achieve and θ numerical value) in phase modulated signal;

9) set by step 4) operate, come the OCT image of calculation sample then by following formula to step 6):

$A=\frac{\mathrm{\&pi;}}{{4\mathrm{NT\&Gamma;}}_S}{[{(-E_1+E_2+E_3-E_4)}^2+{(-E_1+E_2-E_3+E_4)}^2]}^{1/2};$

10) the electronic control translation stage band of computer control reference arm reference mirror and microcobjective axial displacement d together, changes the reference arm light path; If the refractive index of sample is n, then the computing machine electronic control translation stage band of controlling sample arm simultaneously microcobjective axial displacement d/n, carries out focal adjustment, to realize the tomography of sample different depth place section; Repeating step 9), can obtain sample at the OCT at this degree of depth place image.

2, based on the nothing of the Digital Micromirror Device parallel OCT imaging system of crosstalking, it is characterized in that: comprise broadband pointolite (1), collimation lens (2), Digital Micromirror Device (3), lens (4), broadband Amici prism (5), a pair of identical microcobjective (6,7), reference mirror (8), piezoelectric ceramic actuator (10), first electronic control translation stage (11), second electronic control translation stage (12), imaging len (13), area array CCD detector (14); The light that broadband pointolite (1) sends is through parallel being incident on the Digital Micromirror Device (3) behind the collimation lens (2), be in the Digital Micromirror Device (3)+12 ° of angles " open " light of the micro mirror reflection of state, be divided into transmitted light and reflected light behind lens (4) and broadband Amici prism (5): transmitted light arrives reference mirror (8) through microcobjective (6), reference mirror (8) is fixed on the piezoelectric ceramic actuator (10), and microcobjective (6) and piezoelectric ceramic actuator (10) are fixed on first electronic control translation stage (11); Reflected light arrives sample (9) through microcobjective (7), and microcobjective (7) is fixed on second electronic control translation stage (12); After turning back to broadband Amici prism (5) from the light of reference mirror (8) reflection with from sample (9) reflection or backward scattered light along former road, through imaging len (13) plane of incidence battle array ccd detector (14).

3, the nothing based on the Digital Micromirror Device according to claim 2 parallel OCT imaging system of crosstalking, it is characterized in that: described area array CCD detector (14) connects computing machine (16) through image acquisition and analog-to-digital conversion card (15), Digital Micromirror Device (3) links to each other with computing machine (16) with signal wire, and computing machine (16) is exported two-way behind multi-channel digital and analogue transition card (17): the one tunnel connects piezoelectric ceramic actuator (10); Two-way is exported on another road behind controllor for step-by-step motor (18), connect first electronic control translation stage (11) and second electronic control translation stage (12) respectively.

4, the nothing based on the Digital Micromirror Device according to claim 2 parallel OCT imaging system of crosstalking, it is characterized in that: the parallel incident light that comes from collimation lens (2) and the normal of Digital Micromirror Device (3) become 24 ° of angles, and Digital Micromirror Device is in (3)+and the reflected light of state micro-mirrors " is opened " along the normal direction outgoing in 12 ° of angles.

5, the nothing based on the Digital Micromirror Device according to claim 2 parallel OCT imaging system of crosstalking, it is characterized in that: described broadband pointolite (1) is the spatial coherence light source, specifically is short-pulse laser light source, superradiance light source SLD/SLED or amplified spontaneous emission light source ASE.

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