CN201855257U - Mirror image separation system based on group delay wave-number carrier frequency - Google Patents

Abstract

The utility model discloses a mirror image separation system based on group delay wave-number carrier frequency. A grating type optical delay line is arranged in a reference arm of a Fourier-domain optical coherence tomography system; and based on a specific included angle between a reflector in the optical delay line and a surface perpendicular to an optical axis, additional bit phasor quantities are introduced in individual spectral components, which can linearly change along with spectral wave numbers, so as to achieve the effect of specific group delay in case of zero-phase delay of reference light. After group delay, reference light fuses with sample light to generate an interference spectrum of relevant carrier frequency. The image reconstruction of the interference spectrum is performed by means of fast Fourier transform, a conjugated mirror image of the interference spectrum offsets the position where the carrier frequency is zero, and equivalent offset quantities are far larger than the additional bit phasor quantities introduced in the individual spectral components, so as to effectively separate the direct current top from the conjugated mirror image under the premise of minimizing the drop of interference signal sensitivity, and achieve the full-range image formation of the Fourier-domain optical coherence tomography. The mirror image separation system is applied to the spectral-domain optical coherence tomography systems and the frequency-sweeping optical coherence tomography systems.

Description

A kind of mirror image piece-rate system based on group delay wave number carrier frequency

Technical field

This utility model relates to Optical Coherence Tomography Imaging Technology and fourier-domain optical coherence chromatography imaging technique, relates in particular to a kind of mirror image piece-rate system based on group delay wave number carrier frequency.

Background technology

Optical coherence tomography (Optical Coherence Tomography, abbreviation OCT) imaging technique is a kind of novel optical image technology, can carry out non-intruding, noncontact, high-resolution imaging in vivo to the organizational structure and the physiological function of tested live body sample interior, at the early diagnosis of disease with in body biopsy field extensive application prospect.

The fourier-domain optical coherence chromatographic imaging system comprises two kinds of patterns of spectral domain optical coherence tomography system and frequency sweep optical coherence tomography system.The spectral coverage OCT system adopts the structure of wideband light source and quick multi-channel spectrometer based, and frequency sweep OCT system adopts the structure of fast tunable laser instrument and point probe.By quick collection interference spectrum signal, do not need to carry out axial scan, by the interference spectrum signal being carried out the axial depth information that fast fourier transform can obtain sample, have at a high speed and highly sensitive characteristics.But also there is its inherent defect in the fourier-domain optical coherence tomography, when the interference signal of sample depth information is carried in collection, also collect mutual interference signal between each layer of sample, each layer of sample itself from coherent interference signal, reference light itself from coherent noises such as coherent interference signals.And owing to what collect is the real part of interference spectrum signal, rather than plural interference spectrum signal, this is done solid work relate to spectral signal to carry out the result that fast fourier transform obtains be Hermitian conjugate, caused in image, having produced being superimposed upon on the actual picture of sample about the zero complete symmetric conjugate lens picture in light path position.

In order to eliminate the conjugate lens picture in the fourier-domain optical coherence tomographic map, usually the light path official post zero light path face of regulating between sample arm and the reference arm moves on to beyond the sample surface, can make actual picture and conjugate image not overlapping on image like this, but because near the fringe visibility zero light path is the highest, be that image sensitivity is the highest, each spectral component in the light source is introduced same optical path difference, cause the sample image signal to noise ratio along with descending rapidly away from zero light path face.The way that zero light path face is removed in employing causes highly sensitive image-region can't obtain utilizing, and because zero light path face is positioned at outside the sample, has caused the imaging depth of fourier-domain optical coherence tomographic system only to utilize half.Eliminate the conjugate image mirror of Fourier domain OCT, near the high sensitivity zone can better utilization zero light path, and make imaging depth expand one times, external a lot of scientific research institutions have all carried out the research of this respect.People such as M.Wojtkowski propose to utilize piezoelectric ceramic actuator to move the method for the reflecting mirror of reference arm, the Zhongping Chen group in Irving branch school, University of California proposes to adopt the method for electro-optic phase modulator, Duke University Izatt group proposes to adopt the method for 3 * 3 fiber couplers, by between adjacent axial interference spectrum signal, introducing fixed additive phase, adopt plural interference spectrum recovery algorithms to reconstruct the plural form of interference spectrum signal, carry out inverse fourier transform again, thereby eliminate the complex conjugate picture.Medical college G.J.Tearney group of Harvard University proposes to adopt acousto-optic frequency shifters that the interference spectrum signal is carried out the method for carrier frequency and the method for polarization encoder is removed the complex conjugate picture.People such as Hofer propose to adopt chromatic dispersion material that chromatic dispersion is provided and eliminate the method for complex conjugate picture with complicated iterative algorithm, and people such as S.Witte remove the complex conjugate picture to the elimination spike algorithm that also adopts chromatic dispersion material and carry out the chromatic dispersion coding and propose to simplify.Thereby the two-way interference signal that people such as the J.P.Rolland of Rochester University propose to utilize two balance detection devices to survey respectively and have 90 degree phase contrasts is eliminated the complex conjugate mirror image in order to make up plural interference spectrum signal.

Above-mentioned these methods, all there is its inherent defect, as utilizes piezoelectric ceramic actuator to carry out the multistep phase-moving method need to take multiple measurements same position, reduce image taking speed, and, be subjected to of the influence of various environmental perturbations easily to phase place to the stability requirement height of phase place; Utilize the method for electro-optic phase modulator and acousto-optic frequency shifters need introduce more complicated and expensive instrument and equipment, and the system data picking rate has been proposed harsh requirement; Utilizing the method for 3 * 3 fiber couplers to be subjected to temperature easily causes and recovers the inaccurate of plural interference spectrum, the complex conjugate suppression ratio that influence is whole the influence of the coefficient of coup; The existing mirror method that disappears that utilizes chromatic dispersion that proposes need rely on complicated iterative algorithm, and the simplification of algorithm has also been reduced the complex conjugate suppression ratio; Utilize the method for two balance detections to increase system complexity, and the phase contrast of introducing has higher requirement to environmental stability, be not suitable for the optical-fiber type system.Therefore be necessary to study and be easy to realize and the mirror method that disappears that the complex conjugate suppression ratio is high.

Summary of the invention

The purpose of this utility model is to provide a kind of mirror image piece-rate system based on group delay wave number carrier frequency.The raster optical delay line is set in the reference arm of fourier-domain optical coherence chromatographic imaging system, separates conjugate lens picture in the fourier-domain optical coherence tomographic map by introducing group delay wave number carrier frequency.

The purpose of this utility model is achieved by the following technical solution:

One, a kind of mirror image separation method based on group delay wave number carrier frequency:

The raster optical delay line is set in the reference arm of fourier-domain optical coherence chromatographic imaging system, by making reflecting mirror and the vertical axial plane of optical axis in the optical delay line depart from certain degree, in each spectral component of reference light, introduce an extra order phasor with spectrum wave number linear change, character according to Fourier transform, the linear extra order phasor of spectral domain is corresponding to the equivalent light path side-play amount of spatial domain, realize that the particular cluster under reference light zero phase retardation postpones, effectively separate DC terms and conjugation mirror image, the equivalent offset amount is much larger than the additional optical distance amount of introducing in above-mentioned each spectral component, can avoid the rapid decline of the interference fringe sensitivity that causes along with the separation of conjugate lens picture, realize the gamut imaging of Fourier domain; The concrete steps of this method are as follows:

1) the raster optical delay line in the adjusting reference arm, balzed grating, in the raster optical delay line is positioned on the front focal plane of fourier transform lens, and the balzed grating, face is perpendicular to the optical axis of fourier transform lens, reflecting mirror in the raster optical delay line is positioned on the back focal plane of fourier transform lens, makes the light source center wavelength along the optical axis direction diffraction;

2) reflecting mirror of regulating in the raster optical delay line makes itself and the vertical axial plane of optical axis depart from special angle, to the extra order phasor of each spectral component introducing with spectrum wave number linear change, be equivalent to the interference spectrum signal is introduced corresponding wave number carrier frequency, make the conjugate lens picture separate the distance of equivalent light path side-play amount each other;

3) collect the interference spectrum data of introducing group delay wave number carrier frequency by data collecting card, the interference spectrum data are handled, recover the optical coherence tomography image of no mirror image by programmed algorithm; Perhaps collect the interference spectrum data of introducing group delay wave number carrier frequency, the interference spectrum data are handled, recover the optical coherence tomography image of no mirror image by programmed algorithm by CCD.

Two, a kind of mirror image piece-rate system based on group delay wave number carrier frequency:

One of technical scheme:

Comprise light source, broadband optical fiber coupler, sample arm, reference arm and OCT interference spectrum signal detecting device, the low-coherent light that light source comes out enters broadband optical fiber coupler, after beam split, enter reference arm and sample arm respectively, the interference spectrum signal that returns is through entering OCT interference spectrum signal detecting device, and the OCT interference spectrum signal of formation is gathered.Described light source is the low-coherent light that wideband light source sends, and enters first end of broadband optical fiber coupler; Described sample arm comprises the sample arm collimating mirror, the sample arm scanning galvanometer, and sample arm condenser lens and sample behind light process sample arm collimating mirror, sample arm scanning galvanometer and the sample arm condenser lens of broadband optical fiber coupler second end, are incident upon on the sample; Described reference arm comprises collimating mirror, balzed grating,, fourier transform lens, first reflecting mirror and second reflecting mirror, the light of broadband optical fiber coupler the 3rd end enters the light of reference arm through collimating mirror, balzed grating,, fourier transform lens, first reflecting mirror, second reflecting mirror, return collimating mirror along original optical path, in the 3rd end of broadband optical fiber coupler and interference after the sample light that sample arm is returned converges; Described OCT interference spectrum signal detecting device is a spectrogrph, comprise spectrogrph collimating mirror, spectrogrph balzed grating,, spectrometer focusing lens and CCD, the light of described reference arm and the light of sample arm converge the back and form OCT interference spectrum signal, by broadband optical fiber coupler the 4th end through the spectrogrph collimating mirror, the spectrogrph balzed grating,, spectrometer focusing lens and CCD survey, and machine is gathered as calculated.

Two of technical scheme:

Comprise light source, broadband optical fiber coupler, sample arm, reference arm and OCT interference spectrum signal detecting device, the low-coherent light that light source comes out enters broadband optical fiber coupler, after beam split, enter reference arm and sample arm respectively, the interference spectrum signal that returns is through entering OCT interference spectrum signal detecting device, and the OCT interference spectrum signal of formation is gathered.Described light source is the low-coherent light that scanning light source sends, and enters first end of broadband optical fiber coupler; Described sample arm comprises the sample arm collimating mirror, the sample arm scanning galvanometer, and sample arm condenser lens and sample behind light process sample arm collimating mirror, sample arm scanning galvanometer and the sample arm condenser lens of broadband optical fiber coupler second end, are incident upon on the sample; Described reference arm comprises collimating mirror, balzed grating,, fourier transform lens, first reflecting mirror and second reflecting mirror, the light of broadband optical fiber coupler the 3rd end enters the light of reference arm through collimating mirror, balzed grating,, fourier transform lens, first reflecting mirror, second reflecting mirror, return collimating mirror along original optical path, in the 3rd end of broadband optical fiber coupler and interference after the sample light that sample arm is returned converges; Described OCT interference spectrum signal detecting device is the single-point survey meter, the light of described reference arm and the light of sample arm converge the back and form OCT interference spectrum signal, survey through the single-point survey meter by broadband optical fiber coupler the 4th end, gather through data collecting card and computer.

Compare with background technology, the beneficial effect that the utlity model has is:

1, by in each spectral component, introducing additional optical distance amount with the wave number linear change, accordingly interference spectrum is introduced the equivalent offset loading gage frequently, realize the separation of conjugate lens picture, compare and traditional zero light path face is shifted out the outer mirror image separation method of sample surfaces, can guarantee that equivalent light path side-play amount is much larger than the side-play amount of introducing in each spectral component, interference fringe sensitivity descends little, the image quality height.

2, owing to do not introduce the phase-modulator of any electric control or machinery control, as piezoelectric ceramics micrometric displacement platform, electro-optic phase modulator or acousto-optic frequency shifter, only need to set different mirror deflection angles and can introduce that particular cluster postpones and corresponding equivalent offset amount, thereby be not subjected to the restriction of time response of any phase place modulation controller.And the mirror image separation method based on electro-optic phase modulator or acousto-optic frequency shifter only is applicable to frequency sweep OCT system and is not suitable for the spectral coverage OCT system that the method that the utility model proposes is applicable to spectral coverage OCT and two kinds of systems of frequency sweep OCT, and is applied widely.

3, with respect to the disappear method of mirror image of multistep phase shift, only need a set of image data can recover not have mirror image OCT image, can realize at a high speed, the high sensitivity imaging.

Description of drawings

Fig. 1 is a spectral domain optical coherence tomography system sketch map of the present utility model.

Fig. 2 is a frequency sweep optical coherence tomography system sketch map of the present utility model.

Fig. 3 is a spectral domain optical coherence tomography system hardware controls structural representation of the present utility model.

Fig. 4 is a frequency sweep optical coherence tomography system hardware controls structural representation of the present utility model.

Fig. 5 is the optical path difference and the equivalent light path side-play amount comparison diagram of each spectral component correspondence of the present utility model.

Among the figure: 1, wideband light source, 2, broadband optical fiber coupler, 3, the sample arm collimating mirror, 4, the sample arm scanning galvanometer, 5, sample arm condenser lens, 6, sample, 7, collimating mirror, 8, balzed grating,, 9, fourier transform lens, 10, first reflecting mirror, 11, second reflecting mirror, 12, the spectrogrph collimating mirror, 13, the spectrogrph balzed grating,, 14, spectrometer focusing lens, 15, CCD, 16, swept light source, 17, single-point survey meter, 18, data collecting card, 19, computer.

The specific embodiment

Below in conjunction with drawings and Examples this utility model is further described.

As Fig. 1, shown in Figure 3, this utility model comprises light source, broadband optical fiber coupler, sample arm, reference arm and OCT interference spectrum signal detecting device, the low-coherent light that light source comes out enters broadband optical fiber coupler, after beam split, enter reference arm and sample arm respectively, the interference spectrum signal that returns is through entering OCT interference spectrum signal detecting device, and the OCT interference spectrum signal of formation is gathered.Described light source is the low-coherent light that wideband light source 1 sends, and enters first end of broadband optical fiber coupler 2; Described sample arm comprises sample arm collimating mirror 3, sample arm scanning galvanometer 4, sample arm condenser lens 5 and sample 6 behind light process sample arm collimating mirror 3, sample arm scanning galvanometer 4 and the sample arm condenser lens 5 of broadband optical fiber coupler 2 second ends, are incident upon on the sample 6; Described reference arm comprises collimating mirror 7, balzed grating, 8, fourier transform lens 9, first reflecting mirror 10 and second reflecting mirror 11, the light of broadband optical fiber coupler 2 the 3rd end enters the light of reference arm through collimating mirror 7, balzed grating, 8, fourier transform lens 9, first reflecting mirror 10, second reflecting mirror 11, return collimating mirror 7 along original optical path, in the 3rd end of broadband optical fiber coupler 2 and interference after the sample light that sample arm is returned converges; Described OCT interference spectrum signal detecting device is a spectrogrph, comprise spectrogrph collimating mirror 12, spectrogrph balzed grating, 13, spectrometer focusing lens 14 and CCD15, the OCT interference spectrum signal that the light of described reference arm and the light of sample arm converge back formation passes through broadband optical fiber coupler 2 the 4th end through spectrogrph collimating mirror 12, spectrogrph balzed grating, 13, spectrometer focusing lens 14 and CCD15 survey, and gather by image pick-up card and computer 19.Computer 19 control sample arm scanning galvanometers 4 high speed rotating make detecting light beam carry out transversal scanning to sample 6 and obtain two dimension or three-dimensional OCT data.

As Fig. 2, shown in Figure 4, this utility model comprises light source, broadband optical fiber coupler, sample arm, reference arm and OCT interference spectrum signal detecting device, the low-coherent light that light source comes out enters broadband optical fiber coupler, after beam split, enter reference arm and sample arm respectively, the interference spectrum signal that returns is through entering OCT interference spectrum signal detecting device, and the OCT interference spectrum signal of formation is gathered; Described light source is the low-coherent light that scanning light source 16 sends, and enters first end of broadband optical fiber coupler 2; Described sample arm comprises sample arm collimating mirror 3, sample arm scanning galvanometer 4, sample arm condenser lens 5 and sample 6 behind light process sample arm collimating mirror 3, sample arm scanning galvanometer 4 and the sample arm condenser lens 5 of broadband optical fiber coupler 2 second ends, are incident upon on the sample 6; Described reference arm comprises collimating mirror 7, balzed grating, 8, fourier transform lens 9, first reflecting mirror 10 and second reflecting mirror 11, the light of broadband optical fiber coupler 2 the 3rd end enters the light of reference arm through collimating mirror 7, balzed grating, 8, fourier transform lens 9, first reflecting mirror 10, second reflecting mirror 11, return collimating mirror 7 along original optical path, in the 3rd end of broadband optical fiber coupler 2 and interference after the sample light that sample arm is returned converges; Described OCT interference spectrum signal detecting device is a single-point survey meter 17, the light of described reference arm and the light of sample arm converge the back and form OCT interference spectrum signal, survey through single-point survey meter 17 by broadband optical fiber coupler 2 the 4th end, gather through data collecting card 18 and computer 19.Computer 19 control sample arm scanning galvanometers 4 high speed rotating make detecting light beam carry out transversal scanning to sample 6 and obtain two dimension or three-dimensional OCT data.

Figure 3 shows that spectral domain optical coherence tomography system hardware controls structural representation of the present utility model, comprise sample arm scanning galvanometer 4, CCD15, computer 19.Wherein CCD15 links to each other with computer 19, and computer 19 links to each other with sample arm scanning galvanometer 4.Computer 19 control CCD15 gather the OCT interference signal, import computer 19 into by data/address bus and carry out date processing and image reconstruction.Computer 19 control sample arm scanning galvanometers 4 are realized the transversal scanning of detecting light beam to sample, with the two dimension and the three-dimensional information data of collected specimens.

Figure 4 shows that frequency sweep optical coherence tomography system hardware controls structural representation of the present utility model.Comprise sample arm scanning galvanometer 4, single-point survey meter 17, data collecting card 18 and computer 19.Wherein data collecting card 18 links to each other with computer 19, and computer 19 links to each other with sample arm scanning galvanometer 4.The interference spectrum signal that 18 pairs of single-point survey meters of computer 19 control data capture cards 17 produce is gathered, and imports computer 19 into by data/address bus and carries out date processing and image reconstruction.Computer 19 control sample arm scanning galvanometers 4 are realized the transversal scanning of detecting light beam to sample, with the two dimension and the three-dimensional information data of collected specimens.

Figure 5 shows that the optical path difference and the equivalent light path side-play amount comparison diagram of described each spectral component correspondence of the present utility model.Below the curve among Fig. 5 is described.

When the reflecting mirror in the optical scan delay-line and optical axis hang down the axial plane angle when being zero, the optical path difference of establishing sample arm and reference arm is Δ z, and the intensity expression formula of the interference spectrum signal that then detects is:

$I\left(k\right)=S\left(k\right)R_R+S\left(k\right){\∫}_{-\∞}^{+\∞}{\∫}_{-\∞}^{+\∞}{\left[R_S\left(\mathrm{\Δz}\right)R_S\left({\mathrm{\Δz}}^{\′}\right)\right]}^{1/2}\×\exp \left\{i\right[k\left({\mathrm{\Δz}-\mathrm{\Δz}}^{\′}\right)+\mathrm{\φ}\left(\mathrm{\Δz}\right)-\mathrm{\φ}\left({\mathrm{\Δz}}^{\′}\right)\left]\right\}\mathrm{d\Δzd}{\mathrm{\Δz}}^{\′}$ $+2S\left(k\right){\∫}_{-\∞}^{+\∞}\sqrt{R_R{R}_S\left(\mathrm{\Δz}\right)}\exp [-{\left(\frac{\mathrm{\δk}\·\mathrm{\Δz}}{4\sqrt{\ln 2}}\right)}^2]\cos [\mathrm{k\Δz}+\mathrm{\φ}\left(\mathrm{\Δz}\right)]\mathrm{d\Δz}$

Wherein, k is a wave number, and I (k) is an interference spectrum intensity, and S (k) is the light source power spectral density function, R _RBe reference arm reflectance, R _S(Δ z) optical path difference is the sample reflectance at Δ z place, R _S(Δ z ') is the sample reflectance that Δ z ' locates for optical path difference, φ (Δ z) is the phase place of optical path difference for Δ z place, φ (Δ z ') is the phase place that Δ z ' locates for optical path difference, δ k is a spectral line width, first DC terms light intensity for returning from reference arm, second between the DC terms returned from sample arm and each layer of sample interior from the coherent term light intensity, the 3rd is the interference term light intensity I of sample arm and reference arm _Int, wherein establish spectral line width and satisfy Gauss distribution, then

Be the interference fringe amplitude function that changes with spectral line width δ k and optical path difference Δ z, as shown in Figure 5.I (k) is carried out Fourier transform can obtain the axial reflective information of sample.But DC terms and also sneak into final result from the conversion item of coherent term and form distracter simultaneously.

When if the first mirror corner in the control raster optical delay line is γ, the expression formula of then introducing with the extra order phase φ (k) of wave number linear change is:

Wherein f is the focal length of fourier transform lens in the grating type delay line, and d is the grating constant of balzed grating, in the grating type delay line, k ₀Be the center wave number of light source, k is the light source wave number.This moment, the interference term expression formula became:

$I_{\mathrm{int}}=2S\left(k\right){\∫}_{-\∞}^{+\∞}\sqrt{R_R{R}_S\left(\mathrm{\Δz}\right)}\exp [-{\left(\frac{\mathrm{\δk}\·(\mathrm{\Δz}-\frac{\mathrm{\φ}\left(k\right)}{k})}{4\sqrt{\ln 2}}\right)}^2]\cos [\mathrm{k\Δz}-\mathrm{\φ}\left(k\right)+\mathrm{\φ}\left(\mathrm{\Δz}\right)]\mathrm{d\Δz}$

$=2S\left(k\right){\∫}_{-\∞}^{+\∞}\sqrt{R_R{R}_S\left(\mathrm{\Δz}\right)}\exp [-{\left(\frac{\mathrm{\δk}\·(\mathrm{\Δz}-\frac{\mathrm{\φ}\left(k\right)}{k})}{4\sqrt{\ln 2}}\right)}^2]\cos [k(\mathrm{\Δz}+\frac{8\mathrm{\π\γf}}{d\·k_0})-\frac{8\mathrm{\π\γf}}{d}+\mathrm{\φ}\left(\mathrm{\Δz}\right)]\mathrm{d\Δz}$

Interference fringe sensitivity drops to

As shown in Figure 5.And reference arm DC terms and sample arm DC terms and remain unchanged from coherent term.Therefore the reflecting mirror in the raster optical delay line is equivalent to introduce a wave number carrier frequency about the vertical minute angle γ of axial plane deflection of optical axis in interference signal, corresponding to the equivalent offset amount

Because the group delay Δ l that the raster optical delay line is introduced _gFor

Promptly the interference spectrum signal is introduced group delay wave number carrier frequency.

Because the mirror deflection angle γ in the raster optical delay line makes the interference term signal produce group delay wave number carrier frequency, so the conjugate lens picture after the Fourier transform separates 2z each other ₀Distance.Behind interference spectrum signal that to introduce group delay wave number carrier frequency, the plural axial space signal after the Fourier transform is carried out filtering, eliminate mirror shaft to spacing wave, DC terms and from the coherent term signal, with this plural axial space parallel moving of signal-z ₀Distance, inverse fourier transform light echo spectral space is promptly only comprised the spectrographic complex signal of interference term again, expression formula is:

$I_{\mathrm{int}}=2S\left(k\right){\∫}_{-\∞}^{+\∞}\sqrt{R_R{R}_S\left(\mathrm{\Δz}\right)}\exp [-{\left(\frac{\mathrm{\δk}\·(\mathrm{\Δz}-\frac{\mathrm{\φ}\left(k\right)}{k})}{4\sqrt{\ln 2}}\right)}^2]\exp \{i[\mathrm{k\Δz}+\mathrm{\φ}\left(\mathrm{\Δz}\right)]\}\mathrm{d\Δz}$

Can obtain do not have the optical coherence tomography image of mirror image again to its algorithm process of carrying out the demarcation of wave number space homogenization, Fourier transform this moment.

If adopt the method for translation reference mirror to separate the conjugate lens picture, establish translation reference mirror distance and be z ₀, the polychromatic light direct irradiation is in reference mirror and retrieval system, and the extra order phase φ (k) that changes with wave number that then introduces is a constant φ ₀, the interference term expression formula is:

$I_{\mathrm{int}}=2S\left(k\right){\∫}_{-\∞}^{+\∞}\sqrt{R_R{R}_S\left(\mathrm{\Δz}\right)}\exp [-{\left(\frac{\mathrm{\δk}\·(\mathrm{\Δz}+z_0)}{4\sqrt{\ln 2}}\right)}^2]\exp \{i[\mathrm{k\Δz}+{\mathrm{kz}}_0+\mathrm{\φ}\left(\mathrm{\Δz}\right)]\}\mathrm{d\Δz}$

The interference fringe amplitude drops to

As shown in Figure 5, adopt the method for this utility model patent, interference fringe amplitude decline index is much smaller than the interference fringe amplitude decline index that adopts traditional translation reference mirror method.

Estimate interference fringe amplitude slippage by substitution canonical parameter value, establishing f is 60 millimeters, and grating constant d is 1/235.8 millimeter, k ₀=2 π/λ ₀=4760 (mm ^-1), make equivalent light path side-play amount

Be 1 millimeter, then mirror deflection angle γ is 0.01338 radian.The additional optical path difference of each spectral component is

The ratio of the maximum additional optical distance amount in then group delay optical path difference and the spectral component is K wherein ₂Be edge wave numerical value.The graph of relation of the optical path difference of each spectral component and equivalent light path side-play amount as shown in Figure 5.

The utility model discloses a kind of mirror image separation method and system based on group delay wave number carrier frequency, under the prerequisite of guaranteeing interference signal sensitivity reduced minimum, separate the conjugate lens picture, and do not introduce the phase place modulation controller of any electric control or machinery control, realize that high speed, highly sensitive mirror image separate, and have very strong practicality in spectral domain and frequency sweep optical coherence tomography system.

Claims (2)

1. mirror image piece-rate system based on group delay wave number carrier frequency, comprise light source, broadband optical fiber coupler, sample arm, reference arm and OCT interference spectrum signal detecting device, the low-coherent light that light source comes out enters broadband optical fiber coupler, after beam split, enter reference arm and sample arm respectively, the interference spectrum signal that returns is through entering OCT interference spectrum signal detecting device, and the OCT interference spectrum signal of formation is gathered; It is characterized in that: described light source is the low-coherent light that wideband light source (1) sends, and enters first end of broadband optical fiber coupler (2); Described sample arm comprises sample arm collimating mirror (3), sample arm scanning galvanometer (4), sample arm condenser lens (5) and sample (6), the light of broadband optical fiber coupler (2) second ends is incident upon on the sample (6) through behind sample arm collimating mirror (3), sample arm scanning galvanometer (4) and the sample arm condenser lens (5); Described reference arm comprises collimating mirror (7), balzed grating, (8), fourier transform lens (9), first reflecting mirror (10) and second reflecting mirror (11), the light of broadband optical fiber coupler (2) the 3rd end enters the light of reference arm through collimating mirror (7), balzed grating, (8), fourier transform lens (9), first reflecting mirror (10), second reflecting mirror (11), return collimating mirror (7) along original optical path, in the 3rd end of broadband optical fiber coupler (2) and interference after the sample light that sample arm is returned converges; Described OCT interference spectrum signal detecting device is a spectrogrph, comprise spectrogrph collimating mirror (12), spectrogrph balzed grating, (13), spectrometer focusing lens (14) and CCD (15), the OCT interference spectrum signal that the light of described reference arm and the light of sample arm converge back formation passes through broadband optical fiber coupler (2) the 4th end through spectrogrph collimating mirror (12), spectrogrph balzed grating, (13), spectrometer focusing lens (14) and CCD (15) survey, and machine (19) is gathered as calculated.

2. mirror image piece-rate system based on group delay wave number carrier frequency, comprise light source, broadband optical fiber coupler, sample arm, reference arm and OCT interference spectrum signal detecting device, the low-coherent light that light source comes out enters broadband optical fiber coupler, after beam split, enter reference arm and sample arm respectively, the interference spectrum signal that returns is through entering OCT interference spectrum signal detecting device, and the OCT interference spectrum signal of formation is gathered; It is characterized in that: described light source is the low-coherent light that scanning light source (16) sends, and enters first end of broadband optical fiber coupler (2); Described sample arm comprises sample arm collimating mirror (3), sample arm scanning galvanometer (4), sample arm condenser lens (5) and sample (6), the light of broadband optical fiber coupler (2) second ends is incident upon on the sample (6) through behind sample arm collimating mirror (3), sample arm scanning galvanometer (4) and the sample arm condenser lens (5); Described reference arm comprises collimating mirror (7), balzed grating, (8), fourier transform lens (9), first reflecting mirror (10) and second reflecting mirror (11), the light of broadband optical fiber coupler (2) the 3rd end enters the light of reference arm through collimating mirror (7), balzed grating, (8), fourier transform lens (9), first reflecting mirror (10), second reflecting mirror (11), return collimating mirror (7) along original optical path, in the 3rd end of broadband optical fiber coupler (2) and interference after the sample light that sample arm is returned converges; Described OCT interference spectrum signal detecting device is single-point survey meter (17), the light of described reference arm and the light of sample arm converge the back and form OCT interference spectrum signal, survey through single-point survey meter (17) by broadband optical fiber coupler (2) the 4th end, gather through data collecting card (18) and computer (19).

Images