A multi-angle complex optical coherence tomography system and method

Abstract

The present application relates to a kind of multi-angle composite optical coherence tomography system and method, imaging system includes OCT system, the sample arm of OCT system includes multi-angle scanning component and Bscan scanning component, OCT system is shot to sample arm parallel light beam, multi-angle scanning component realizes the multi-angle scanning of sample, Bscan scanning component realizes the Bscan scanning of sample.High-resolution image reconstruction algorithm is with plane wave delay accumulation beam synthesis algorithm as core, the signal of echo data beam synthesis after different angle plane wave emission is coherent compound and is handled into an image.The present application realizes multi-angle scanning mode on system, sample keeps still in detection process, more conducive to the application of this system in clinical diagnosis field, and coherent compound imaging method guarantees that high-resolution OCT image can be reconstructed under limited scanning angle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical coherence tomography, and in particular to a multi-angle compound optical coherence tomography system and method. BACKGROUND

[0002] Optical coherence tomography (OCT) is a non-contact, non-invasive high-resolution tomography technique. It is based on the principle of a coherent light interferometer, and by collecting the backscattered or backreflected signals from biological tissues, it can obtain two-dimensional or three-dimensional structural images. At present, OCT has been widely used in ophthalmology, dermatology and dentistry as a relatively mature technology. However, this imaging technology has always had the problem of imbalance between depth of field and lateral resolution, making it difficult to perform routine imaging of cells and affecting its further development in the field of biomedicine.

[0003] Frequency domain OCT has two distinct resolutions, namely axial resolution in the depth direction and lateral resolution in the lateral image plane. Lateral resolution mainly depends on the light diffraction limit, specifically determined by the numerical aperture (NA) of the system. High NA will make the focused spot finer, thereby improving the lateral resolution, but will lose the depth of field. Low NA will provide a large depth of field, but the focused spot will become thicker, losing the lateral resolution. Traditional OCT systems usually design the lateral resolution to be more than 10 microns to achieve an imaging depth of several hundred microns to several millimeters for the measurement of human tissues. From the aspects of resolution and imaging depth, it can be found that there is always a trade-off between the two parameters. Therefore, how to break through the diffraction limit while achieving large depth of field and high lateral resolution has always been an important direction for the development of frequency domain OCT. In order to solve this problem, previous studies have made different attempts. (1) One improved system that specifically improves resolution is optical coherence microscopy (OCM), which uses a larger NA than traditional OCT to achieve high resolution, and the lateral resolution can usually reach 1 μm, and the longitudinal resolution is about 2-4 μm. Combined with the coherence gate of the OCT system itself, it can image cells in human tissues without the need for external contrast agents. However, as mentioned earlier, it has a natural disadvantage in imaging depth, so it can only form en-face images, and cannot perform tomographic imaging. (2) Dynamic focusing (C-mode scanning) can also effectively improve resolution and depth of field [1], which generates multiple focal regions aligned along the axial direction, thus forming axial focusing with high resolution. Since the corresponding coherent transfer function (CTF) of each focal point is optimal, the resolution and contrast of the image are equivalent to those of the focused image generated by the standard focusing scheme. The lateral and longitudinal resolutions can reach 5-10 microns. Its limitation is that the illumination path must be in free space, and the imaging speed is slow.(3) The principle of beam shape adjustment is to produce non-Gaussian focal points by controlling the pupil function of the focusing lens (also known as Micro OCT). Usually, a ring-shaped aperture produces a Bessel focal point [2] , which is super-resolution in the lateral direction and expands the axial focusing range relative to the Gaussian focal point. A pure phase mask or phase pupil filter combined with a spherical lens can moderately expand the axial focusing range, but at the cost of losing light intensity, and the image contrast will correspondingly decrease.(4) In 2019, Duke University proposed a multi-scan method similar to CT (Computed Tomography) for image reconstruction, thus achieving high-resolution and large-depth-of-field imaging requirements [3] , but it requires the sample to rotate 360°, and the image average is used in the reconstruction algorithm, and only when the rotation angle reaches 360° can the isotropy of lateral and longitudinal resolution be achieved, which limits the application prospect of this method in the field of clinical medicine.

[0004] Imaging speed is another important parameter that affects the application of OCT systems in the field of clinical medicine. Fast imaging speed can reduce artifacts caused by human body jitter in vivo detection. The first generation of OCT systems detects the time delay of optical echoes by mechanically scanning the path length of the interferometer reference arm (time-domain OCT). The development of Fourier-domain detection has made breakthroughs in the sensitivity and speed of OCT imaging. The performance advantages of frequency-domain OCT were independently recognized by several research groups in 2003 [4]Currently, most commercial OCT instruments use spectrometers and line-scan cameras (frequency-domain OCT). Sweep-frequency OCT is an OCT system developed from frequency-domain OCT. It utilizes high-speed photodetectors instead of the spectrometers and line-scan cameras used in frequency-domain OCT. Due to the higher detection efficiency of photodetectors, sweep-frequency OCT reduces detection loss compared to frequency-domain OCT. Furthermore, sweep-frequency OCT systems can image at wavelengths of 1000nm and 1300nm, which is longer than the 840nm wavelength typically used in frequency-domain OCT, allowing for better light penetration and improved imaging depth of scattering tissues. Advances in swept laser technology have facilitated high scan rates. High speed reduces in vivo imaging acquisition time, thus reducing motion artifacts. High speed also allows for more data acquisition, enabling denser sampling densities or wider fields of view within a given acquisition time. High-speed imaging can also extract additional functional imaging parameters from OCT data. High speed facilitates Doppler OCT and angiography, eliminating the need for exogenous contrast agents. Finally, 4D (3D + time) imaging can also be used to measure dynamic structural and functional processes, which requires repeated acquisition of volumetric datasets as a function of time. Another way to improve imaging speed is line-scan OCT. Compared to traditional single-point scanning systems, line-scan OCT systems can capture the entire cross-sectional image (Bscan) in a single scan, rather than just a single Ascan, thus increasing scanning speed. [5] Compared to traditional frequency-domain OCT systems, parallel measurements of Ascans in line-field OCT offer several advantages beyond better phase stability. First, motion-related image distortion and artifacts in the Bscan are significantly reduced due to the lack of time difference between Ascans. Second, because the probe beam is focused into a straight line on the sample surface, it can achieve higher imaging speeds (and signal-to-noise ratios) with lower illumination intensities. This results in faster in vivo imaging and a lower risk of harm to the human body.

[0005] In summary, existing technologies cannot simultaneously achieve both horizontal and vertical resolution. Therefore, it is necessary to design an OCT system solution that can meet the imaging requirements of high resolution and large depth of field.

[0006] References:

[0007] [1] J.Mo, M.de Groot, and JFJOede Boer, "Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography," vol.21, no.8, pp.10048-10061, 2013.

[0008] [2] R. Huber, M. Wojtkowski, J. G. Fujimoto, J. Jiang, and A. J. O. e. Cable, "Three-dimensional and C-mode OCT imaging with a compact, frequency swept laser source at 1300 nm," vol. 13, no. 26, pp. 10523-10538, 2005.

[0009] [3] K. C. Zhou, R. Qian, S. Degan, S. Farsiu, and J. A. J. N. P. Izatt, "Optical coherence refraction tomography," vol. 13, no. 11, pp. 794-802, 2019.

[0010] [4] J. F. de Boer, B. Cense, B. H. Park, M. C. Pierce, G. J. Tearney, and B. E. Bouma, "Improved signal-to-noise ratio in spectral-domain compared with time-domain optical coherence tomography," Optics Letters, vol. 28, no. 21, pp. 2067-2069, Nov 2003.

[0011] [5] S. Lawman et al., "Supercontinuum ultra-high resolution line-field OCT; experimental spectrograph comparison and comparison with current clinical OCT systems by the imaging of a human cornea," in 2nd Canterbury Conference on OCT with Emphasis on Broadband Optical Sources, 2018, vol. 10591, p. 1059104: International Society for Optics and Photonics. SUMMARY

[0012] The present application aims at providing a multi-angle compound optical coherence tomography system and method to overcome the defects of the prior art.

[0013] The object of the present application can be achieved by the following technical solutions.

[0014] According to a first aspect of the present application, a multi-angle compound optical coherence tomography system is provided, comprising an OCT system, a sample arm of the OCT system comprising a multi-angle scanning component and a B-scan scanning component, the OCT system being configured to emit a parallel light beam to the sample arm, the multi-angle scanning component being configured to realize multi-angle scanning of the sample, and the B-scan scanning component being configured to realize B-scan scanning of the sample.

[0015] Further, when the OCT system is a line scanning OCT system, the sample arm comprises a collimator, a focusing lens and a rotating stage, the sample being placed on the rotating stage and rotating with the rotating stage, the parallel light beam emitted from the collimator being incident on the focusing lens, the focusing lens being configured to focus the light beam and make it incident on the sample, the rotating stage being the multi-angle scanning component, and rotation of the rotating stage being configured to realize multi-angle scanning of the sample, and the line array light beam formed by the frequency domain line scanning OCT system being configured to realize B-scan scanning of the sample.

[0016] When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a scanning head, a focusing lens and a rotating stage, the scanning head being provided with a galvanometer, the sample being placed on the rotating stage and rotating with the rotating stage, the galvanometer being configured to reflect the parallel light beam emitted from the collimator to the focusing lens, the focusing lens being configured to focus the light beam and make it incident on the sample, the rotating stage being the multi-angle scanning component, and rotation of the rotating stage being configured to realize multi-angle scanning of the sample, and the galvanometer being the B-scan scanning component, and rotation of the galvanometer being configured to realize B-scan scanning of the sample.

[0017] Further, when the OCT system is a frequency domain line scanning OCT system, the sample arm comprises a collimator, a translation stage and a focusing lens, the collimator being fixed on the translation stage and linearly displacing with the translation stage, the parallel light beam emitted from the collimator being incident on the focusing lens, the focusing lens being configured to focus the light beam and make it incident on the sample, the translation stage being the multi-angle scanning component, and linear displacement of the translation stage being configured to realize multi-angle scanning of the sample, and the line array light beam formed by the frequency domain line scanning OCT system being configured to realize B-scan scanning of the sample.

[0018] When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a scanning head, a translation stage and a focusing mirror, the scanning head is provided with a galvanometer mirror, the scanning head is fixed on the translation stage and linearly translates with the translation stage, the galvanometer mirror is configured to reflect the parallel light beam emitted from the collimator to the focusing mirror, the focusing mirror is configured to focus the light beam and incident to the sample, the translation stage is a multi-angle scanning component, and the translation of the translation stage is used to realize multi-angle scanning of the sample, and the galvanometer mirror is a Bscan scanning component, and the rotation of the galvanometer mirror is used to realize Bscan scanning of the sample.

[0019] Further, when the OCT system is a frequency domain line scanning OCT system, the sample arm comprises a collimator, a galvanometer mirror, a first focusing mirror, a mirror and a second focusing mirror, the galvanometer mirror and the mirror are respectively arranged at the two side focal points of the first focusing mirror, the optical axes of the first focusing mirror and the second focusing mirror are perpendicular, and the mirror is arranged at the common focal point of the first focusing mirror and the second focusing mirror, the galvanometer mirror is configured to reflect the parallel light beam emitted from the collimator to the first focusing mirror, the first focusing mirror is configured to refract the parallel light beam to a parallel light beam parallel to the optical axis of the first focusing mirror and incident to the mirror, the mirror is configured to reflect the parallel light beam parallel to the optical axis of the first focusing mirror to the second focusing mirror, and the second focusing mirror focuses the light beam and then incident to the sample, the galvanometer mirror is a multi-angle scanning component, and the rotation of the galvanometer mirror is used to realize multi-angle scanning of the sample, and the line array light beam formed by the frequency domain line scanning OCT system is used to realize Bscan scanning of the sample.

[0020] When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a first galvanometer mirror, a first focusing mirror, a second galvanometer mirror and a second focusing mirror, the first galvanometer mirror and the second galvanometer mirror are respectively arranged at the two side focal points of the first focusing mirror, the optical axes of the first focusing mirror and the second focusing mirror are perpendicular, and the second galvanometer mirror is arranged at the common focal point of the first focusing mirror and the second focusing mirror, the first galvanometer mirror is configured to reflect the parallel light beam emitted from the collimator to the first focusing mirror, the first focusing mirror is configured to refract the parallel light beam to a parallel light beam parallel to the optical axis of the first focusing mirror and incident to the second galvanometer mirror, the second galvanometer mirror is configured to reflect the parallel light beam parallel to the optical axis of the first focusing mirror to the second focusing mirror, and the second focusing mirror focuses the light beam and then incident to the sample, the first galvanometer mirror is a multi-angle scanning component, and the rotation of the first galvanometer mirror is used to realize multi-angle scanning of the sample, and the second galvanometer mirror is a Bscan scanning component, and the rotation of the second galvanometer mirror is used to realize Bscan scanning of the sample.

[0021] Furthermore, when the OCT system is a frequency domain line scanning OCT system, the sample arm also includes a beam splitter, a third focusing mirror, and a light receiving component. The beam splitter is disposed between the first focusing mirror and the reflecting mirror. The light returning from the sample passes through the beam splitter and is focused by the third focusing mirror before entering the light receiving component.

[0022] When the OCT system is a frequency domain point scanning OCT system, the sample arm also includes a beam splitter, a third focusing mirror, and a light receiving component. The beam splitter is positioned between the first focusing mirror and the second galvanometer. Light returning from the sample passes through the beam splitter and is focused by the third focusing mirror before entering the light receiving component.

[0023] Furthermore, when the OCT system is a frequency domain line scanning OCT system, the sample arm includes a collimator, a cylindrical lens, a first focusing lens, a reflecting mirror, and a second focusing mirror. The cylindrical lens and the reflecting mirror are respectively located at the focal points on both sides of the first focusing mirror. The optical axes of the first focusing mirror and the second focusing mirror are perpendicular, and the reflecting mirror is located at the common focal point of the first focusing mirror and the second focusing mirror. The cylindrical lens is configured to reflect the parallel beam emitted from the collimator to the first focusing mirror. The first focusing mirror is configured to refract the parallel beam into a parallel beam parallel to the optical axis of the first focusing mirror and emit it to the reflecting mirror. The reflecting mirror is configured to reflect the parallel beam parallel to the optical axis of the first focusing mirror to the second focusing mirror. The second focusing mirror focuses the beam and then incident it onto the sample. The cylindrical lens is a multi-angle scanning component. The up and down movement of the cylindrical lens is used to achieve multi-angle scanning of the sample. The linear array beam formed by the frequency domain line scanning OCT system is used to achieve Bscan scanning of the sample.

[0024] When the OCT system is a frequency domain point scanning OCT system, the sample arm includes a collimator, a cylindrical lens, a first focusing lens, a second galvanometer, and a second focusing lens. The cylindrical lens and the second galvanometer are respectively located at the focal points on both sides of the first focusing lens. The optical axes of the first focusing lens and the second focusing lens are perpendicular, and the second galvanometer is located at the common focal point of the first focusing lens and the second focusing lens. The cylindrical lens is configured to reflect the parallel light beam emitted from the collimator to the first focusing lens. The first focusing lens is configured to refract the parallel light beam into a parallel light beam parallel to the optical axis of the first focusing lens and emit it to the second galvanometer. The second galvanometer is configured to reflect the parallel light beam parallel to the optical axis of the first focusing lens to the second focusing lens. The second focusing lens focuses the light beam and then incident it onto the sample. The cylindrical lens is a multi-angle scanning component, and the up-and-down movement of the cylindrical lens is used to achieve multi-angle scanning of the sample. The second galvanometer is a B-scan scanning component, and the rotation of the second galvanometer is used to achieve B-scan scanning of the sample.

[0025] Further, when the OCT system is a frequency domain line scanning OCT system, the sample arm further comprises a beam splitter, a third focusing lens and a light receiving component, the beam splitter is arranged between the first focusing lens and the mirror, the light returned from the sample passes through the beam splitter and is focused by the third focusing lens to enter the light receiving component;

[0026] When the OCT system is a frequency domain point scanning OCT system, the sample arm further comprises a beam splitter, a third focusing lens and a light receiving component, the beam splitter is arranged between the first focusing lens and the second galvanometer, the light returned from the sample passes through the beam splitter and is focused by the third focusing lens to enter the light receiving component.

[0027] According to a second aspect of the present application, a multi-angle complex optical coherence tomography method is provided, a plurality of spectrums returned from different angles in an imaging region are collected by using the multi-angle complex optical coherence tomography system, the obtained data are accumulated by using a time delay accumulation beam synthesis method in a spatial domain, and a reconstructed image is obtained based on the corresponding positions and angles of each Bscan in space by taking an arithmetic average, specifically, comprising:

[0028] Extracting amplitude information I0, obtaining a propagation trajectory of a ray based on a spatial geometric relationship and a refractive index distribution of components in the multi-angle complex optical coherence tomography system, calculating a time delay of a scattering signal to an objective lens based on the propagation trajectory, time-shifting the extracted amplitude information I0 based on the time difference, and calculating an Ascan signal time-shifted from each offset angle:

[0029] I(k)=I0(τ k ), k=1, 2, …N

[0030] In the formula, τ is the time difference, k represents a beam, and N represents the number of beams;

[0031] Superimposing a plurality of Ascan signals of the same target imaging object obtained from a plurality of symmetric angles to obtain a coherent composite image, and performing an arithmetic average on the time-shifted I n Performing an arithmetic average process to obtain a representation of a scattering point in space:

[0032]

[0033] In the formula, z(k) represents an Ascan signal after superimposition and averaging.

[0034] Further, the A-scan formula of the OCT system is represented as:

[0035]

[0036] In the formula, r(z) represents, represents an imaginary part, R S(z) represents the back reflection of each layer structure in the depth direction of the object, N represents the N layer structure in the depth direction, F -1 represents the inverse Fourier transform, represents the optical path from the nth layer to the beam splitter position, k represents the beam, represents the optical path difference between different layers of the sample and the reference light, z R represents the optical path of the reference arm, R S (z) includes amplitude and phase information.

[0037] Further, it also includes:

[0038] The mean square error of the original Ascan and the Ascan of the high-resolution reconstruction based on the environment is calculated, and the refractive index distribution is optimized based on the mean square error.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The present application realizes multi-angle scanning mode on the system, and the sample remains stationary during the detection process, which is more conducive to the application of the system in the field of clinical diagnosis. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 It is an imaging system structure schematic diagram of a frequency domain line scanning OCT system;

[0042] Figure 2 It is an imaging system structure schematic diagram of a frequency domain point scanning OCT system;

[0043] Figure 3 It is a sample arm rotating table design scheme schematic diagram in Example 2;

[0044] Figure 4 It is a sample arm translation table design scheme schematic diagram in Example 3;

[0045] Figure 5 It is a sample arm galvanometer design scheme schematic diagram in Example 4;

[0046] Figure 6 It is a sample arm galvanometer design scheme schematic diagram in Example 5;

[0047] Figure 7 It is a sample arm cylindrical lens design scheme schematic diagram in Example 6;

[0048] Figure 8 It is a sample arm cylindrical lens design scheme schematic diagram in Example 7;

[0049] Figure 9 It is a reconstruction image schematic diagram of different deflection angles;

[0050] Figure 10Fig. 1 is a schematic diagram of the lateral resolution as a function of the compound angle;

[0051] Figure 11 Fig. 2 is a schematic diagram of the contrast as a function of the compound angle;

[0052] Figure 12 Fig. 3 is a schematic diagram of the overall flow of the image reconstruction method;

[0053] Reference signs:

[0054] 1-1, light source, 1-2, emitter (including beam expander), 1-3, cylindrical mirror, 1-4, beam splitter, 1-5, focusing mirror ①, 1-6, reference mirror, 1-7, focusing mirror ②, 1-8, sample, 1-9, focusing mirror ③, 1-10, spectrometer slit, 1-11, focusing mirror ④, 1-12, grating, 1-13, focusing mirror ⑤, 1-14, camera;

[0055] 2-1, light source, 2-2, optical fiber, 2-3, collimator ①, 2-4, galvanometer ①, 2-5, galvanometer ②, 2-6, objective lens, 2-7, sample, 2-8, collimator ②, 2-9, focusing mirror, 2-10, reference mirror, 2-11, spectrometer, 2-12, computer;

[0056] 101, scanning head, 102, focusing mirror, 103, rotating stage, 104, sample;

[0057] 210, translation stage, 202, scanning head, 203, focusing mirror, 204, sample;

[0058] 301, collimator, 302, first galvanometer, 303, first focusing mirror, 304, second galvanometer, 305, second focusing mirror, 306, sample, 307, beam splitter, 308, third focusing mirror, 309, light receiving component;

[0059] 401, collimator, 402, cylindrical lens, 403, first focusing mirror, 404, second galvanometer, 405, second focusing mirror, 406, sample, 407, beam splitter, 408, third focusing mirror, 409, light receiving component. DETAILED DESCRIPTION

[0060] The present application will be described in detail below with reference to the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. The protection scope of the present application is not limited to the following embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0061] In the drawings, identical or similar components are denoted by identical reference numerals, and components having similar functions or structures are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown for the purpose of making the drawings clear, and the size and thickness of each component are not limited. In order to make the drawing clear, the components are appropriately scaled and the distance between the components is increased or decreased.

[0062] In the description of the embodiments of the present application, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0063] In addition, the terms "first", "second", "third", and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0064] In the description of the embodiments of the present application, it should be understood that, unless otherwise explicitly specified and limited, the terms "set", "mount", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0065] Embodiment 1:

[0066] The present application provides a multi-angle complex optical coherence tomography imaging system, comprising an OCT system, the sample arm of the OCT system comprises a multi-angle scanning component and a Bscan scanning component, the OCT system shoots a parallel light beam to the sample arm, the multi-angle scanning component realizes multi-angle scanning of the sample, and the Bscan scanning component realizes Bscan scanning of the sample.

[0067] Specifically, multi-angle scanning can be realized on a frequency domain line scanning OCT system or a frequency domain point scanning OCT system. For the selection of the light source, in order to achieve good axial resolution, a wide wave SLED light source can be selected, because SLED is between a semiconductor and a laser, has high power stability, a relatively flat spectrum, and moderate price. In the present embodiment,

[0068] In this embodiment, the multi-angle complex optical coherence tomography system structure of the frequency domain line scanning OCT system is shown in Figure 1 The system includes a light source, an emitter (including a beam expander), a cylindrical lens, a beam splitter, a focusing lens ①, a reference mirror, a focusing lens ②, a sample, a focusing lens ③, a focusing lens ④, a focusing lens ⑤, a camera, etc. The frequency domain line scanning OCT system based on the Michelson interferometer is built using a cylindrical lens. A parallel light beam is emitted by the light source 1-1. After the parallel light beam passes through the emitter 1-2 and a cylindrical lens 1-3, the longitudinal axis of the light beam remains parallel, and the transverse axis is focused. After the light beam passes through any objective lens, a line array of irradiation is formed at the focusing surface. The beam splitter 1-4 divides the light beam into two paths, which are irradiated to the reference arm and the sample arm, respectively. The reference arm includes a focusing lens ① 1-5 and a reference mirror 1-6, which are consistent with the prior art structure, and will not be described in detail here. The design of the sample arm is the key to realizing multi-angle scanning, and the specific design is described below in embodiment 2-7, which is simplified as a focusing lens ③ 1-9 and a sample 1-8. The light on the reference arm passes through the focusing lens ① 1-5 and the reference mirror 1-6 in turn, and the reflected light returns to the beam splitter 1-4. The light signals returned from the sample 1-8 and the reference mirror 1-6 are mixed and interfered on the beam splitter 1-4. The light signals are received by a spectrometer through a collection arm, and the light signals are converted into electrical signals. The spectrometer part mainly consists of three components: a transmission grating, a cylindrical lens (focusing lens ④ 1-11, focusing lens ⑤ 1-13), and a photoelectric receiver (camera 1-14). Because it is a two-dimensional frequency domain system, a surface array camera needs to be selected. Because the light beam of the frequency domain line scanning OCT becomes a line in front of the beam splitter, the Bscan scanning component is no longer needed on the sample arm, so only the multi-angle scanning component needs to be retained.

[0069] In addition, the multi-angle complex optical coherence tomography system structure of the frequency domain point scanning OCT system is shown in Figure 2 The system includes a light source, a detector, a sample arm, and a reference arm. The light beam of the light source 2-1 passes through the optical fiber 2-2 and is divided into two paths, which enter the sample arm and the reference arm, respectively. The reference arm is basically the same as the existing structure, and is simplified as a collimator ② 2-8, a focusing lens 2-9, and a reference mirror 2-10. The design of the sample arm is described below in embodiment 2-7, which is simplified as a collimator ① 2-3, a galvanometer ① 2-4, a galvanometer ② 2-5, an objective lens 2-6, and a sample 2-7. The multi-layer tissue sample will backscatter the incident photons, which will interfere with the backreflected light in the reference arm at the spectrometer 2-11. The obtained spectrum will be recorded, thereby obtaining the image of the sample.

[0070] The multi-angle scanning component on the sample arm is used to realize multi-angle scanning, and the Bscan scanning component is used to realize transverse scanning (Bscan). The multi-angle scanning sample can be realized by various methods, and for the frequency domain point scanning OCT system, the Bscan scanning component can be realized by a galvanometer.

[0071] The application realizes the multi-angle scanning mode on the OCT system, and the sample remains still during the detection process, which is beneficial to the application of the system in the clinical diagnosis field.

[0072] The application also provides a multi-angle complex optical coherence tomography method, which uses a multi-angle complex optical coherence tomography system, such as the OCT system constructed based on the above-mentioned linear array system, to realize the acquisition of the spectrum of the entire Bscan at one time, and realizes the fast and stable multi-angle scanning of the same position of the target by designing the multi-angle scanning configuration in the sample arm of the OCT. The imaging algorithm is high-resolution OCT image reconstruction. Because there is a difference between the lateral and longitudinal resolutions, the transfer function of the corresponding point spread function in the Fourier space is anisotropic, which means that the high-frequency information in one direction is weakened. By collecting cross-sectional images at multiple angles, the missing high-frequency information can be filled.

[0073] In the embodiment, the reconstruction algorithm is based on the imaging principle of multi-angle plane wave coherence combination, that is, the spectrum returned from multiple different angles in the imaging area is collected, and beam synthesis is completed, the image information of different angles is combined, which is equivalent to high-NA focusing at the spectrum receiving end, so that the lateral resolution of the image is effectively improved. The space domain beam synthesis technology is adopted in the application, and the arithmetic mean is taken based on the corresponding position and angle of each Bscan in the space, so that the reconstructed image is obtained.

[0074] The A-scan formula of the frequency domain point scanning OCT can be simply expressed as:

[0075]

[0076] Wherein, r(z) represents, Im represents the imaginary part, R S (z) represents the backward reflection of each layer structure in the depth direction of the object, N represents the N layer structure in the depth direction, F -1 represents the inverse Fourier transform, represents the optical path from the nth layer to the beam splitter position, k represents the beam, represents the optical path difference between different layers of the sample and the reference light, z R represents the optical path of the reference arm, R S (z) includes amplitude and phase information.

[0077] The first step of the image reconstruction algorithm is to calculate the time delay of the scattering signal to the objective lens according to the trajectory of the ray propagation derived from the geometric relationship and the refractive index distribution in the space, and to perform the corresponding time shift on the amplitude information (I0) extracted in formula (1) at each angle by using the time difference:

[0078] I(k) = I0(τm ), m = 1, 2, … N (2)

[0079] Where τ is the time difference, m represents the number of incident angles of multi-angle scanning, and the distance from each scattering point to the objective lens is shown in a schematic diagram as Figure 8 The delay of the emission signal of the scattering signal of each point is determined by the deflection angle of the incident light. The time required for the central beam and the deflection beam to reach the scattering point (P) is respectively:

[0080] τ(P cen ) = f / c (3)

[0081] τ(P side ) = f / c·cosθ (4)

[0082] θ is the deflection angle of the deflection beam, f represents the focal length, and c is the speed of light, so that the Ascan signals shifted in time from each deflection angle are obtained.

[0083] The second step is superposition and summation. The multiple frames of Ascan signals obtained from the same target imaging object at multiple symmetric angles are superimposed to obtain the coherent composite image. By performing the arithmetic average process on the time-shifted I n , the final representation of the scattering points in space is obtained:

[0084]

[0085] The corresponding calculation is performed for each scattering point in the imaging area until all the images in the imaging space are obtained. Figures 9-11 The simulation results of the composite coherent image reconstruction in the acoustic field are shown, Figure 9 The reconstructed images from 0° to 23° deflection angle are shown, Figure 10 and Figure 11 respectively, which shows that the lateral resolution and contrast are significantly improved and the image quality is improved as the composite angle increases.

[0086] In fact, in the imaging system, the spatial geometric relationship can be determined according to the positions of the sample, the objective lens, and each optical component, but it is difficult to accurately obtain the refractive index distribution. In order to improve the imaging quality, the feedback mechanism is also designed.

[0087] To provide feedback on the accuracy of the time-shifted Ascan obtained in the first step to help optimize it, a differentiable metric is needed to quantify the degree of joint registration between all Ascans. This application describes an intensity-based metric with which the mean square error (MSE) between the original Ascan and the Ascan based on the environment-matched high-resolution reconstruction is calculated. The forward model starts from the current estimate based on the OCT high-resolution reconstruction for each Bscan direction, and then the current estimate is rotated, warped according to the same trajectory, blurred by the PSF of the OCT, depth attenuated, and locally intensity readjusted according to the direction of incidence. The result constitutes the forward prediction of the Ascan, in which the forward model parameters (such as the RI distribution, attenuation parameters, etc.) between the original Ascan data are minimized. The refractive index distribution is also regularized to impose spatial smoothness, stabilize the solution, and optimize. The refractive index distribution is gradually refined by iteration to minimize the difference, and finally the best reconstructed image is obtained. Figure 12 The flow of the entire image reconstruction is shown.

[0088] This application realizes effective improvement of lateral resolution under limited scanning angles. The coherent plane wave compounding imaging method is a commonly used method in ultrafast ultrasound imaging. This algorithm takes the plane wave delay-and-add beamforming algorithm as the core, coherently compounds and processes the signals after beamforming of echo data under different angle plane wave transmission into an image display. In the overlapping area of different angle transmission, the image resolution and quality are improved. The sound field simulation results are shown in Figure 9 The image quality is obviously improved when the compounding angle reaches 20-25°. Because the OCT and ultrasound technology are similar, this application refers the coherent compounding algorithm imaging to the OCT field for high-resolution, large-depth-of-field image reconstruction, and realizes effective improvement of lateral resolution under limited scanning angles.

[0089] Embodiment 2:

[0090] In this embodiment, the OCT system is a frequency domain point scanning OCT system, as shown in Figure 3 The sample arm includes a collimator, a scanning head 101, a focusing mirror 102, and a rotating table 103. The scanning head 101 is provided with a galvanometer mirror. The sample 104 is placed on the rotating table 103 and rotates with the rotating table 103. The galvanometer mirror reflects the parallel light beam emitted from the collimator to the focusing mirror 102. The focusing mirror 102 focuses the light beam and enters it into the sample 104. The rotating table 103 is a multi-angle scanning component. The rotation of the rotating table 103 realizes multi-angle scanning of the sample 104. The galvanometer mirror is a Bscan scanning component. The rotation of the galvanometer mirror realizes Bscan scanning of the sample 104. Figure 3In the process, sample 104 is placed at the focal point of focusing lens 102. The rotation of the rotating stage 103 causes the focused beam to irradiate sample 104 at different incident angles, while the rotation of the galvanometer shifts the angle of the beam, forming a linear scan on sample 104.

[0091] In this embodiment, if the OCT system is a frequency domain line scan OCT system, the Bscan scanning component is removed. The sample arm includes a collimator, a focusing lens, and a rotating stage. The sample is placed on the rotating stage and rotates with the rotating stage. The parallel light beam emitted from the collimator is directed to the focusing lens, which focuses the light beam and directs it onto the sample. The rotating stage is a multi-angle scanning component, and the rotation of the rotating stage enables multi-angle scanning of the sample. The linear array beam formed by the frequency domain line scan OCT system enables Bscan scanning of the sample.

[0092] The advantage of this approach lies in the system's sample arm design; multi-angle scanning is completed by a single rotary stage, requiring no changes to the original OCT system configuration, making it relatively easy to implement. Furthermore, this approach allows multi-angle scanning to reach its theoretical maximum scanning range of 180°, maximizing resolution.

[0093] Example 3:

[0094] Compared to Embodiment 2, this embodiment improves the multi-angle scanning component. For example... Figure 4 As shown, the OCT system is a frequency domain point scanning OCT system. The sample arm includes a collimator, a scanning head 202, a translation stage 201, and a focusing lens 203. The scanning head 202 is equipped with a galvanometer. The scanning head 202 is fixed on the translation stage 201 and moves linearly with the translation stage 201. The galvanometer reflects the parallel light beam emitted from the collimator to the focusing lens 203. The focusing lens 203 focuses the light beam and incident it onto the sample 204. The translation stage 201 is a multi-angle scanning component. The translation of the translation stage 201 realizes multi-angle scanning of the sample 204. The galvanometer is a Bscan scanning component. The rotation of the galvanometer realizes Bscan scanning of the sample 204. Figure 4 In the image, sample 204 is placed at the focal point of focusing lens 203. Given that the focal point of the focusing lens is f, and the distance the platform is offset from the center of the focusing lens is l, then the incident angle (field of view) is:

[0095]

[0096] In this embodiment, if the OCT system is a frequency domain line scan OCT system, the Bscan scanning component is removed. The sample arm includes a collimator, a translation stage, and a focusing lens. The collimator is fixed on the translation stage and moves linearly with the translation stage. The parallel beam emitted from the collimator is directed to the focusing lens, which focuses the beam and directs it onto the sample. The translation stage is a multi-angle scanning component, and the translation of the translation stage enables multi-angle scanning of the sample. The linear array beam formed by the frequency domain line scan OCT system enables Bscan scanning of the sample.

[0097] The advantage of this method is that multi-angle scanning is performed by a translation stage, while the sample can remain stationary, making it suitable for applications in the biomedical field.

[0098] Example 4:

[0099] Compared to Embodiment 2, this embodiment improves the multi-angle scanning component and the Bscan scanning component. For example... Figure 5 As shown, the OCT system is a frequency domain point scanning OCT system. The sample arm includes a collimator 301, a first galvanometer 302, a first focusing lens 303, a second galvanometer 304, and a second focusing lens 305. The first galvanometer 302 and the second galvanometer 304 are respectively located at the focal points on both sides of the first focusing lens 303. The optical axes of the first focusing lens 303 and the second focusing lens 305 are perpendicular, and the second galvanometer 304 is located at the common focal point of the first focusing lens 303 and the second focusing lens 305. The first galvanometer 302 reflects the parallel light beam emitted from the collimator 301 back to the first focusing lens 305. 3. The first focusing mirror 303 refracts the parallel beam into a parallel beam parallel to the optical axis of the first focusing mirror 303 and directs it to the second galvanometer 304. The second galvanometer 304 reflects the parallel beam parallel to the optical axis of the first focusing mirror 303 to the second focusing mirror 305. After being focused by the second focusing mirror 305, the beam is incident on the sample 306. The first galvanometer 302 is a multi-angle scanning component, and the rotation of the first galvanometer 302 realizes multi-angle scanning of the sample 306. The second galvanometer 304 is a Bscan scanning component, and the rotation of the second galvanometer 304 realizes Bscan scanning of the sample 306. Figure 5 In the process, sample 306 is placed at the focal point of the second focusing lens 305.

[0100] In the design scheme of the embodiment, if the OCT system is a frequency domain line scanning OCT system, the Bscan scanning component is removed, the sample arm comprises a collimator, a galvanometer, a first focusing lens, a mirror and a second focusing lens, the galvanometer and the mirror are respectively arranged at two focal points of the first focusing lens, the optical axes of the first focusing lens and the second focusing lens are perpendicular, and the mirror is arranged at a common focal point of the first focusing lens and the second focusing lens, the galvanometer reflects the parallel light beams emitted from the collimator to the first focusing lens, the first focusing lens refracts the parallel light beams into parallel light beams parallel to the optical axis of the first focusing lens and emits the parallel light beams to the mirror, the mirror reflects the parallel light beams parallel to the optical axis of the first focusing lens to the second focusing lens, and the light beams are focused by the second focusing lens and then incident to the sample, the galvanometer is a multi-angle scanning component, and rotation of the galvanometer realizes multi-angle scanning of the sample, and a line array light beam formed by the frequency domain line scanning OCT system realizes Bscan scanning of the sample.

[0101] The advantage of the scheme is that the multi-angle scanning and the Bscan scanning are both completed by the galvanometer, the scanning speed is faster than mechanical operation, the system volume is smaller, the sample can be fixed, and the application scenarios are more.

[0102] Embodiment 5

[0103] The embodiment further improves the system structure on the basis of the embodiment 4. As shown in the figure, Figure 6 the OCT system is a frequency domain point scanning OCT system, and the sample arm further comprises a beam splitter 307, a third focusing lens 308 and a light receiving component 309, the beam splitter 307 is arranged between the first focusing lens 303 and the second galvanometer 304, and the light returned from the sample 306 passes through the beam splitter 307 and is focused by the third focusing lens 308 and then enters the light receiving component 309.

[0104] In the design scheme of the embodiment, if the OCT system is a frequency domain line scanning OCT system, the sample arm further comprises a beam splitter, a third focusing lens and a light receiving component, the beam splitter is arranged between the first focusing lens and the second galvanometer, and the light returned from the sample passes through the beam splitter and is focused by the third focusing lens and then enters the light receiving component.

[0105] The advantage of the scheme, in addition to that mentioned in the embodiment 4, is that the light receiving component can be an optical fiber, the design of the beam splitter + the third focusing lens + the light receiving component enables the light returned from the sample to be focused to the light receiving component, and the phase information of the returned light signal is more accurate because the returned light signal no longer passes through the first galvanometer 302.

[0106] Embodiment 6

[0107] The embodiment improves the multi-angle scanning component compared with the embodiment 4. As shown in the figure, Figure 7As shown, the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator 401, a cylindrical lens 402, a first focusing mirror 403, a second galvanometer 404 and a second focusing mirror 405, the cylindrical lens 402 and the second galvanometer 404 are respectively arranged at two side focal points of the first focusing mirror 403, the optical axes of the first focusing mirror 403 and the second focusing mirror 405 are perpendicular, and the second galvanometer 404 is arranged at a common focal point of the first focusing mirror 403 and the second focusing mirror 405, the cylindrical lens 402 reflects the parallel light beams emitted from the collimator 401 to the first focusing mirror 403, the first focusing mirror 403 refracts the parallel light beams into parallel light beams parallel to the optical axis of the first focusing mirror 403 and emits the parallel light beams to the second galvanometer 404, the second galvanometer 404 reflects the parallel light beams parallel to the optical axis of the first focusing mirror 403 to the second focusing mirror 405, and the parallel light beams are focused by the second focusing mirror 405 and then incident to the sample 406, the cylindrical lens 402 is a multi-angle scanning component, and the up-and-down movement of the cylindrical lens 402 realizes multi-angle scanning of the sample 406, and the second galvanometer 404 is a Bscan scanning component, and the rotation of the second galvanometer 404 realizes Bscan scanning of the sample 406. Figure 7 In this embodiment, the sample 406 is arranged at the focal point of the second focusing mirror 405.

[0108] Under the design scheme of the embodiment, if the OCT system is a frequency domain line scanning OCT system, the Bscan scanning component is removed, the sample arm comprises a collimator, a cylindrical lens, a first focusing mirror, a mirror and a second focusing mirror, the cylindrical lens and the mirror are respectively arranged at two side focal points of the first focusing mirror, the optical axes of the first focusing mirror and the second focusing mirror are perpendicular, and the mirror is arranged at a common focal point of the first focusing mirror and the second focusing mirror, the cylindrical lens reflects the parallel light beams emitted from the collimator to the first focusing mirror, the first focusing mirror refracts the parallel light beams into parallel light beams parallel to the optical axis of the first focusing mirror and emits the parallel light beams to the mirror, the mirror reflects the parallel light beams parallel to the optical axis of the first focusing mirror to the second focusing mirror, and the parallel light beams are focused by the second focusing mirror and then incident to the sample, the cylindrical lens is a multi-angle scanning component, and the up-and-down movement of the cylindrical lens realizes multi-angle scanning of the sample, and the line array light beams formed by the frequency domain line scanning OCT system realize Bscan scanning of the sample.

[0109] The advantage of the scheme is that the sample can be fixed and the application scenarios are more.

[0110] Embodiment 7:

[0111] The embodiment further improves the system structure on the basis of Embodiment 6. Figure 8As shown, the OCT system is a frequency domain point scanning OCT system, the sample arm further comprises a beam splitter 407, a third focusing lens 408 and a light receiving component 409, the beam splitter 407 is arranged between the first focusing lens 403 and the second galvanometer 404, the light returned from the sample 406 passes through the beam splitter 407 and is focused by the third focusing lens 408 and then enters the light receiving component 409.

[0112] Under the design scheme of the embodiment, if the OCT system is a frequency domain line scanning OCT system, the sample arm further comprises a beam splitter, a third focusing lens and a light receiving component, the beam splitter is arranged between the first focusing lens and the second galvanometer, the light returned from the sample passes through the beam splitter and is focused by the third focusing lens and then enters the light receiving component.

[0113] The scheme has the advantage that the light receiving component can be an optical fiber, the design of the beam splitter + the third focusing lens + the light receiving component makes the light returned from the sample focused to the light receiving component, the phase information of the returned light signal is more accurate without passing through the first galvanometer 302.

[0114] The preferred embodiments of the application are described in detail above. It should be understood that those skilled in the art can make many modifications and variations without creative work based on the concept of the application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the prior art according to the concept of the application shall be within the protection scope defined by the claims.

Claims

1. A multi-angle compounding optical coherence tomography system, characterized by, The OCT system comprises a sample arm, the sample arm comprises a multi-angle scanning component and a B-scan scanning component, the OCT system is used for emitting parallel light beams to the sample arm, the multi-angle scanning component is used for realizing multi-angle scanning of the sample, and the B-scan scanning component is used for realizing B-scan scanning of the sample. When the OCT system is a frequency domain line scanning OCT system, the sample arm comprises a collimator, a focusing mirror and a rotating table, the sample is placed on the rotating table and rotates with the rotating table, the parallel light beams emitted from the collimator are incident on the focusing mirror, the focusing mirror is configured to focus the light beams and make the light beams incident on the sample, the rotating table is the multi-angle scanning component, and rotation of the rotating table is used to realize multi-angle scanning of the sample; and a line array light beam formed by the frequency domain line scanning OCT system is used to realize B-scan scanning of the sample. When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a scanning head, a focusing mirror and a rotating table, the scanning head is internally provided with a galvanometer, the sample is placed on the rotating table and rotates with the rotating table, the galvanometer is configured to reflect the parallel light beams emitted from the collimator to the focusing mirror, the focusing mirror is configured to focus the light beams and make the light beams incident on the sample, the rotating table is the multi-angle scanning component, and rotation of the rotating table is used to realize multi-angle scanning of the sample; and the galvanometer is the B-scan scanning component, and rotation of the galvanometer is used to realize B-scan scanning of the sample.

2. A multi-angle complex optical coherence tomography system, characterized by, The OCT system comprises a sample arm, the sample arm comprises a multi-angle scanning component and a B-scan scanning component, the OCT system is used for emitting parallel light beams to the sample arm, the multi-angle scanning component is used for realizing multi-angle scanning of the sample, and the B-scan scanning component is used for realizing B-scan scanning of the sample. When the OCT system is a frequency domain line scanning OCT system, the sample arm comprises a collimator, a translation table and a focusing mirror, the collimator is fixed on the translation table and linearly displaces with the translation table, the parallel light beams emitted from the collimator are incident on the focusing mirror, the focusing mirror is configured to focus the light beams and make the light beams incident on the sample, the translation table is the multi-angle scanning component, and linear translation of the translation table is used to realize multi-angle scanning of the sample; and a line array light beam formed by the frequency domain line scanning OCT system is used to realize B-scan scanning of the sample. When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a scanning head, a translation table and a focusing mirror, the scanning head is internally provided with a galvanometer, the scanning head is fixed on the translation table and linearly translates with the translation table, the galvanometer is configured to reflect the parallel light beams emitted from the collimator to the focusing mirror, the focusing mirror is configured to focus the light beams and make the light beams incident on the sample, the translation table is the multi-angle scanning component, and linear translation of the translation table is used to realize multi-angle scanning of the sample; and the galvanometer is the B-scan scanning component, and rotation of the galvanometer is used to realize B-scan scanning of the sample.

3. A multi-angle complex optical coherence tomography system, characterized by, The OCT system comprises a sample arm comprising a multi-angle scanning component and a B-scan scanning component, and is used to emit parallel light beams to the sample arm, the multi-angle scanning component is used to realize multi-angle scanning of the sample, and the B-scan scanning component is used to realize B-scan scanning of the sample; When the OCT system is a frequency domain line scanning OCT system, the sample arm comprises a collimator, a galvanometer, a first focusing lens, a mirror and a second focusing lens, the galvanometer and the mirror are arranged at two side focal points of the first focusing lens respectively, the optical axes of the first focusing lens and the second focusing lens are perpendicular, and the mirror is arranged at a common focal point of the first focusing lens and the second focusing lens, the galvanometer is configured to reflect the parallel light beams emitted from the collimator to the first focusing lens, the first focusing lens is configured to refract the parallel light beams into parallel light beams parallel to the optical axis of the first focusing lens and emit the parallel light beams to the mirror, the mirror is configured to reflect the parallel light beams parallel to the optical axis of the first focusing lens to the second focusing lens, and the second focusing lens focuses the light beams and then emits the light beams to the sample, the galvanometer is the multi-angle scanning component, and rotation of the galvanometer is used to realize multi-angle scanning of the sample, and a line array light beam formed by the frequency domain line scanning OCT system is used to realize B-scan scanning of the sample; When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a first galvanometer, a first focusing lens, a second galvanometer and a second focusing lens, the first galvanometer and the second galvanometer are arranged at two side focal points of the first focusing lens respectively, the optical axes of the first focusing lens and the second focusing lens are perpendicular, and the second galvanometer is arranged at a common focal point of the first focusing lens and the second focusing lens, the first galvanometer is configured to reflect the parallel light beams emitted from the collimator to the first focusing lens, the first focusing lens is configured to refract the parallel light beams into parallel light beams parallel to the optical axis of the first focusing lens and emit the parallel light beams to the second galvanometer, the second galvanometer is configured to reflect the parallel light beams parallel to the optical axis of the first focusing lens to the second focusing lens, and the second focusing lens focuses the light beams and then emits the light beams to the sample, the first galvanometer is the multi-angle scanning component, and rotation of the first galvanometer is used to realize multi-angle scanning of the sample, and the second galvanometer is the B-scan scanning component, and rotation of the second galvanometer is used to realize B-scan scanning of the sample.

4. The multi-angle complex optical coherence tomography system of claim 3, wherein, When the OCT system is a frequency domain line scanning OCT system, the sample arm further comprises a beam splitter, a third focusing lens and a light receiving component, the beam splitter is arranged between the first focusing lens and the mirror, and light returned from the sample passes through the beam splitter and is focused by the third focusing lens and then enters the light receiving component; When the OCT system is a frequency domain point scanning OCT system, the sample arm further comprises a beam splitter, a third focusing lens and a light receiving component, the beam splitter is arranged between the first focusing lens and the second galvanometer, and light returned from the sample passes through the beam splitter and is focused by the third focusing lens and then enters the light receiving component.

5. A multi-angle compounding optical coherence tomography system, characterized by, The OCT system comprises a sample arm comprising a multi-angle scanning component and a B-scan scanning component, and is used to emit parallel light beams to the sample arm, the multi-angle scanning component is used to realize multi-angle scanning of the sample, and the B-scan scanning component is used to realize B-scan scanning of the sample; When the OCT system is a frequency domain line scanning OCT system, the sample arm comprises a collimator, a cylindrical lens, a first focusing mirror, a mirror and a second focusing mirror, the cylindrical lens and the mirror are arranged at two side focal points of the first focusing mirror respectively, the optical axes of the first focusing mirror and the second focusing mirror are perpendicular, the mirror is arranged at a common focal point of the first focusing mirror and the second focusing mirror, the cylindrical lens is configured to reflect the parallel light beams emitted from the collimator to the first focusing mirror, the first focusing mirror is configured to refract the parallel light beams to parallel light beams parallel to the optical axis of the first focusing mirror and emit the parallel light beams to the mirror, the mirror is configured to reflect the parallel light beams parallel to the optical axis of the first focusing mirror to the second focusing mirror, the second focusing mirror focuses the light beams and then emits the light beams to the sample, the cylindrical lens is the multi-angle scanning component, and up-down movement of the cylindrical lens is used to realize multi-angle scanning of the sample, and a line array light beam formed by the frequency domain line scanning OCT system is used to realize B-scan scanning of the sample; When the OCT system is a frequency domain point scanning OCT system, the sample arm comprises a collimator, a cylindrical lens, a first focusing mirror, a second galvanometer and a second focusing mirror, the cylindrical lens and the second galvanometer are arranged at two side focal points of the first focusing mirror respectively, the optical axes of the first focusing mirror and the second focusing mirror are perpendicular, the second galvanometer is arranged at a common focal point of the first focusing mirror and the second focusing mirror, the cylindrical lens is configured to reflect the parallel light beams emitted from the collimator to the first focusing mirror, the first focusing mirror is configured to refract the parallel light beams to parallel light beams parallel to the optical axis of the first focusing mirror and emit the parallel light beams to the second galvanometer, the second galvanometer is configured to reflect the parallel light beams parallel to the optical axis of the first focusing mirror to the second focusing mirror, the second focusing mirror focuses the light beams and then emits the light beams to the sample, the cylindrical lens is the multi-angle scanning component, and up-down movement of the cylindrical lens is used to realize multi-angle scanning of the sample, and the second galvanometer is the B-scan scanning component, and rotation of the second galvanometer is used to realize B-scan scanning of the sample.

6. The multi-angle complex optical coherence tomography system of claim 5, wherein, When the OCT system is a frequency domain line scanning OCT system, the sample arm further comprises a beam splitter, a third focusing mirror and a light receiving component, the beam splitter is arranged between the first focusing mirror and the mirror, and light returned from the sample passes through the beam splitter and then enters the light receiving component after being focused by the third focusing mirror; When the OCT system is a frequency domain point scanning OCT system, the sample arm further comprises a beam splitter, a third focusing mirror and a light receiving component, the beam splitter is arranged between the first focusing mirror and the second galvanometer, and light returned from the sample passes through the beam splitter and then enters the light receiving component after being focused by the third focusing mirror.

7. A multi-angle compounding optical coherence tomography method, characterized by, The multi-angle complex optical coherence tomography system as claimed in any one of claims 1-6 is used to collect a plurality of spectra returned from different angles in an imaging area, and a space domain time delay accumulation beam synthesis method is used to accumulate the obtained data, and an arithmetic average is taken based on the corresponding positions and angles of each Bscan in space to obtain a reconstructed image, specifically comprising: Extracting amplitude information According to the spatial geometric relation and the refractive index distribution of the components in the multi-angle complex optical coherence tomography system, the propagation trajectory of the ray is obtained, the time delay of the scattering signal to the objective lens is calculated based on the propagation trajectory, and the extracted amplitude information is time-shifted based on the time difference The Ascan signals time-shifted from each offset angle are calculated: In the formula, is a time difference, denotes a beam, denotes the number of beams; The multi-frame Ascan signals of the same target imaging object obtained from multiple symmetric angles are superimposed to obtain a coherent composite image, and each scattering point is time-shifted An arithmetic averaging process is performed to obtain a representation of the scattering points in space: wherein, represents the A-scan signal after superposition averaging.

8. The multi-angle complex optical coherence tomography method of claim 7, wherein, The A-scan formula of the OCT system is represented as: wherein represents, represents the imaginary part, represents the back reflection of each layer structure in the depth direction of the object, represents the N layer structure in the depth direction, represents the inverse Fourier transform, represents the optical path from the layer to the beam splitter position, represents the optical path from the layer to the beam splitter position, represents the beam, represents the optical path difference of the different layers of the sample to the reference light, represents the optical path of the reference arm, includes the amplitude and phase information.

9. The multi-angle complex optical coherence tomography method of claim 7, wherein, Further comprising: The mean square error of the original Ascan and the Ascan based on the environment matching high-resolution reconstruction is calculated, and the refractive index distribution is optimized based on the mean square error.

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