CN-122016721-A - Full-depth spectral domain optical coherence tomography system and imaging method thereof

CN122016721ACN 122016721 ACN122016721 ACN 122016721ACN-122016721-A

Abstract

The invention discloses a full-depth spectral domain optical coherence tomography system, and belongs to the technical field of optical coherence tomography. The full-depth spectral domain optical coherence tomography system disclosed by the invention has the advantages that the low-distortion and chromatic dispersion-free high-speed optical delay line is introduced through the reference arm, and the mirror image/conjugate image removal is realized, meanwhile, the energy loss is obviously reduced and the system stability is improved. The design effectively avoids the problems of delay errors and aberration caused by mechanical moving parts in the traditional phase shift technology, remarkably improves imaging sensitivity and axial resolution, and maintains uniform imaging quality in the full depth range.

Inventors

Huo tiancheng
SUN WEI
LIN JINFA
ZHU CHENYU
HU XUEYAN
PAN ZHENGYI
HOU DAWEI

Assignees

常州微亿智造科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (9)

1. A full depth spectral domain optical coherence tomography system, comprising: The chromatographic imaging unit comprises a sample arm, a reference arm and a data acquisition system, wherein the sample arm is used for guiding an optical signal to a sample to be detected and receiving a reflected signal, the reference arm is used for carrying out phase modulation and reflection on the optical signal, and the data acquisition system is used for converting a received analog electronic signal into a digital signal; the sample carrying unit (2), the sample carrying unit (2) comprises a carrying platform, and the carrying platform is used for placing a sample to be detected; The image processing unit (3) is used for carrying out complex signal demodulation, inverse Fourier transformation and image reconstruction on the acquired digital signals; Wherein: The reference arm comprises a low-distortion non-dispersion high-speed optical delay line (1-4-2), the low-distortion non-dispersion optical delay line (1-4-2) has linear phase modulation characteristics, the bearing platform drives the sample to be detected to move into an optical path focusing area of the sample arm, and the image processing unit (3) is electrically connected with the data acquisition system.
2. The full-depth spectral domain optical coherence tomography system of claim 1, wherein the low-distortion non-dispersive high-speed optical delay line (1-4-2) comprises a collimator second (4-2-1), a diaphragm (4-2-2), a dispersion compensator (4-2-3), a high-speed scanning galvanometer (4-2-4), a cylindrical mirror (4-2-5) and a reflection plane mirror (4-2-6) sequentially arranged along the light propagation direction, the collimator second (4-2-1) is used for collimating an input light beam into parallel light, the diaphragm (4-2-2) is used for limiting the beam diameter, the dispersion compensator (4-2-3) is used for correcting spectral dispersion, the high-speed scanning galvanometer (4-2-4) is used for phase modulation, the cylindrical mirror (4-2-5) is used for asymmetrically controlling the light beam, and the reflection plane mirror (4-2-6) reflects the modulated reference light back to the interference system.
3. The full-depth spectral domain optical coherence tomography system of claim 2, wherein defining the direction of the outgoing light of collimator two (4-2-1) as the positive z-axis direction, establishing a spatial coordinate system with the z-axis, then: The projection of the high-speed scanning galvanometer (4-2-4) in the y-z plane is intersected with the z axis, the intersection angle is phi g, the optical path difference change is generated by the change of the mirror surface rotation angle of the high-speed scanning galvanometer (4-2-4), the mirror surface rotation angle of the high-speed scanning galvanometer (4-2-4) is thetag, the projection of the cylindrical mirror (4-2-5) in the y-z plane is intersected with the y axis, the intersection angle is alpha g, the projection of the reflecting plane mirror (4-2-6) in the y-z plane is intersected with the y axis, and the intersection angle is beta g; the light delay delta L of the low-distortion non-dispersion high-speed optical delay line (1-4-2) meets the formula: Wherein, the H is the off-axis distance between the beam and the rotation axis of the high-speed scanning galvanometer (4-2-4).
4. The full-depth spectral domain optical coherence tomography system of claim 1, wherein the reference arm further comprises a second optical fiber polarization controller (1-4-1), the second optical fiber polarization controller (1-4-1) is used for dynamically adjusting the polarization state of the light waves in the reference arm, and the second optical fiber polarization controller (1-4-1) is arranged at the light inlet end of the low-distortion non-dispersive high-speed optical delay line (1-4-2).
5. The full-depth spectral domain optical coherence tomography system of claim 1, wherein the sample arm comprises a collimator I (1-3-2), a deflection system (1-3-3) and a lens system (1-3-4) which are sequentially arranged along the light propagation direction, the lens system (1-3-4) is arranged above the bearing platform, the collimator I (1-3-2) collimates divergent light output by the optical fiber into parallel light beams, the deflection system (1-3-3) is used for carrying out two-dimensional scanning on the light beams, and the lens system (1-3-4) focuses the scanned parallel light onto the surface of the sample.
6. The full-depth spectral domain optical coherence tomography system of claim 5, wherein the sample arm further comprises a first fiber polarization controller (1-3-1), the first fiber polarization controller (1-3-1) being disposed at an entrance end of the first collimator (1-3-2), the first fiber polarization controller (1-3-1) being configured to dynamically adjust a polarization state of light waves incident on the sample.
7. The full-depth spectral domain optical coherence tomography system of claim 1, wherein the tomography unit further comprises a light source (1-1), a coupler (1-2), a spectrometer and a synchronous control system, wherein the coupler (1-2) is arranged in the light emitting direction of the light source (1-1), the sample arm and the reference arm are arranged in the light emitting direction of the coupler (1-2), the synchronous control system and the data acquisition system are integrated in the data controller (1-6), the spectrometer is connected with the light emitting end of the coupler (1-2), and the spectrometer is connected with the data controller.
8. The full-depth spectral domain optical coherence tomography system of claim 7, wherein the spectrometer comprises a fiber polarization controller three (1-5-1), a collimator three (1-5-5), a grating (1-5-4), a lens group (1-5-3) and a line scanning camera (1-5-2) sequentially arranged along the light propagation direction, wherein the fiber polarization controller three (1-5-1) is used for adjusting the polarization state of an optical signal incident on the grating (1-5-4), the collimator three (1-5-5) collimates interference light into parallel light, the lens group (1-5-3) focuses diffracted spectral components on a photosurface of the line scanning camera (1-5-2), the line scanning camera (1-5-2) is used for acquiring a modulation spectrum of an interference signal, and the line scanning camera (1-5-2) is connected with the data acquisition system.
9. A full depth spectrum domain optical coherence tomography method applied to the full depth spectrum domain optical coherence tomography system as recited in any one of claims 1-8, comprising the steps of: S1, after the data acquisition system is used for datamation of the acquired signals, a line of original information of the depth direction of the coupled structural information is obtained, and by combining the two-dimensional scanning function of the galvanometer, each scanning position corresponds to one depth information, and finally three-dimensional original data I (x, y, lambda) of a sample to be detected can be obtained; s2, performing Hilbert transformation on a frame of original signal along the fast axis direction of B scanning and removing a direct current component to obtain a complex signal Î (x, lambda) only containing sample structure information; s3, carrying out wave number linear fitting, interpolation and zero padding treatment on a complex signal scanned by a certain A along the wavelength direction to obtain a complex signal Î (k) uniformly distributed in a wave number domain; S4, applying a dispersion compensation phase factor exp [ i psi (k) ] to the complex signal Î (k) along the k direction, wherein psi (k) is a compensation phase; S5, carrying out a Hanning window and other filter treatments on the compensated complex signal Î (k) exp [ i psi (k) ] to inhibit side lobe effects, then carrying out an inverse fast Fourier transform, and converting the inverse fast Fourier transform from a wave number domain to a space domain to obtain a complex envelope signal corresponding to the depth direction of the sample on the A scanning line; S6, obtaining scattering intensity distribution in the full depth range, namely an axial structural image of the sample, by extracting amplitude information of the scattering intensity distribution, repeating the steps S2 to S5 in the slow axis direction, processing each A scanning line in the three-dimensional data set line by line, and finally reconstructing a three-dimensional tomographic image of the sample to be detected.

Description

Full-depth spectral domain optical coherence tomography system and imaging method thereof Technical Field The invention relates to the technical field of optical coherence tomography, in particular to a full-depth spectral domain optical coherence tomography system and an imaging method thereof. Background Optical Coherence Tomography (OCT) is a low coherence optical interference imaging technique based on a broadband light source. The technique measures scattered/reflected light signals at different depths inside the sample by means of interferometry, thereby achieving three-dimensional "tomographic" imaging of the inside of the sample. One of the rapid imaging methods in optical coherence tomography is spectral domain optical coherence tomography (SD-OCT), and the conventional SD-OCT can only adopt images of a positive optical path area or a negative optical path area to avoid image or conjugate image interference under normal conditions, but the method only uses half of imaging areas, the other half of imaging areas are abandoned to cause waste of data resources and calculation resources, when a sample to be detected crosses an aplanatic plane, image overlapping occurs in the positive optical path area and the negative optical path area, effective information in the overlapping area is completely indistinguishable, and imaging sensitivity is maximum near the aplanatic plane and decreases along with depth, so that the high sensitivity characteristic of the SD-OCT cannot be fully utilized by the method of only using the positive optical path or the negative optical path, and the chromatographic image quality is difficult to reach an optimal level. In order to solve the above problem of the mirror image/conjugate image of the SD-OCT, a full depth OCT is used, the basic principle of which is based on a phase shift (phase-shifting) method, so as to obtain a complex signal of the SD-OCT interference signal, and then an inverse fourier transform is performed, so that the mirror image/conjugate image is naturally removed. However, the existing phase shift method has advantages and disadvantages in the aspects of imaging speed, cost, stability, imaging quality and the like, and partial schemes have derivative problems of synchronism, aberration and the like, so that the clinical requirements of high-precision, high-speed and real-time imaging are difficult to meet. Disclosure of Invention The invention aims to solve the technical problems that the existing phase shift method for removing the mirror image/conjugate image has the defects in the aspects of imaging speed, cost and stability, and provides a full-depth spectral domain optical coherence tomography system, wherein a low-distortion non-dispersion high-speed optical delay line is introduced into a reference arm, so that the removal of the mirror image/conjugate image is realized, the energy loss is obviously reduced, and the system stability is improved. The design effectively avoids the problems of delay errors and aberration caused by mechanical moving parts in the traditional phase shift technology, remarkably improves imaging sensitivity and axial resolution, and maintains uniform imaging quality in the full depth range. The technical scheme adopted by the invention for solving the technical problems is that the full-depth spectral domain optical coherence tomography system comprises: The chromatographic imaging unit comprises a sample arm, a reference arm and a data acquisition system, wherein the sample arm is used for guiding an optical signal to a sample to be detected and receiving a reflected signal, the reference arm is used for carrying out phase modulation and reflection on the optical signal, and the data acquisition system is used for converting a received analog electronic signal into a digital signal; The sample carrying unit comprises a carrying platform, wherein the carrying platform is used for placing a sample to be detected, and the carrying platform realizes three-dimensional accurate positioning under the cooperative control of an automatic horizontal translation platform and a manual vertical translation platform, so that the sample is always kept in focus alignment in the full-depth scanning process, and the imaging consistency and the structural analysis precision are ensured; The image processing unit is used for carrying out complex signal demodulation, inverse Fourier transformation and image reconstruction on the acquired digital signals, so as to realize high-quality three-dimensional tomography without mirror image interference in the full depth range; Wherein: the reference arm comprises a low-distortion non-dispersive high-speed optical delay line, wherein the low-distortion non-dispersive high-speed optical delay line has linear phase modulation characteristics and is used for realizing rapid phase modulation of a reference light path; Therefore, the full-depth spectral domain optical coherence tomography system can acqu