Anterior and posterior segment wide-field optical coherence tomography blood flow imaging system

Abstract

The present invention relates to an anterior-posterior segment wide-field wide-area optical coherence tomography angiography imaging system, comprising a swept-frequency laser light source, a fiber interferometer module, a photoelectric balance detector, a high-speed acquisition card, a signal acquisition card, a sample arm module, and a reference arm module. The fiber interferometer module comprises a first coupler, a second coupler, a first circulator, and a second circulator. The first coupler is connected to the swept-frequency laser light source, the first circulator, and the second circulator, respectively, and the second coupler is connected to the first circulator, the second circulator, and the photoelectric balance detector, respectively. The high-speed acquisition card is connected to the swept-frequency laser light source and the photoelectric balance detector, respectively. The signal acquisition card is connected to the high-speed acquisition card and the sample arm module, respectively. The first circulator is connected to the sample arm module via a first polarization controller, and the second circulator is connected to the reference arm module via a second polarization controller. Compared with the prior art, the present invention has the advantages of enabling ultra-wide-field OCTA imaging of the fundus and a simple structure.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, in particular to an anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system. Background Art

[0002] Optical coherence tomography (OCTA) is a new, noninvasive, and reproducible ophthalmic imaging technology that provides high-precision images of fundus blood flow density. Conventional OCTA diagnostic scanning focuses on the macula, resulting in a limited imaging range. Recent studies have shown that some eye diseases are often accompanied by vascular lesions in other retinal regions, such as vascular proliferation or loss. Therefore, expanding the OCTA imaging range and acquiring wide-field OCTA images are crucial for medical diagnosis. While research on fundus retinal lesions is increasingly mature, research on anterior segment blood flow is relatively limited. Anterior segment lesions can lead not only to structural changes but also to altered blood flow in the iris, conjunctiva, and cornea. These changes can lead to symptoms such as decreased vision, lipid deposition, and corneal scarring. Therefore, examination and diagnosis of the anterior segment are equally important.

[0003] Currently, techniques for examining the anterior and posterior segment structures and blood vessels generally require different equipment and examination methods. Detection of fundus lesions primarily relies on traditional techniques such as wide-angle fundus photography and fundus fluorescein angiography (FFA). However, the neovascularization seen in the early stages of some ophthalmic diseases is not easily observed with traditional fundus photography. Furthermore, FFA requires contrast agents, which is invasive and time-consuming, and can even trigger allergic reactions in severe cases. Ultra-wide-angle fundus OCTA imaging offers advantages such as in-vivo, non-invasive, and real-time imaging, as well as high resolution, making it valuable for practical clinical diagnosis. Anterior segment OCT provides high-resolution structural information. OCTA is more effective than traditional fluorescein angiography for examining the vascular system and is more effective at detecting ischemia than clinical examination. Given that many conditions, such as panuveitis, high myopia, and glaucoma, can cause changes in anterior and posterior segment structure and blood flow, rapid, wide-field imaging of anterior and posterior segment structure and blood flow has practical implications for clinical diagnosis and disease research.

[0004] Due to the differences in the anterior and posterior segment structures and imaging ranges, wide-field wide-area OCTA uses different methods. For fundus OCTA, under the current conditions where imaging speed is limited, two feasible methods are to use image stitching to achieve wide-field imaging and to increase the single scanning angle for wide-angle imaging. Some foreign studies have used multiple small-scale image stitching to achieve wide-field fundus OCTA images. With the development of OCTA technology, the latest generation of OCT can obtain 15mm*9mm or (12)mm*(12)mm OCTA images, with a scanning field of view of 40°. Some commercial OCT devices can achieve a single scanning range of 15mm*(12)mm. Through montage technology, a wider range of OCTA images can generally be obtained, but there are still limitations. Due to the urgent need for peripheral retinal imaging, expanding the OCTA imaging field of view has become a hot spot and direction for the development of OCT / OCTA technology. In anterior segment OCTA, one-time imaging of the iris is necessary for the study of many eye diseases. Imaging the anterior and posterior segments of the eye is crucial for glaucoma, especially in open-angle glaucoma, where the lesions are typically located in the trabecular meshwork and Schrem's canal surrounding the anterior and posterior segments. Currently, due to issues such as iris pigmentation and subtle angle structure in East Asians, wide-field OCTA of the anterior and posterior segments has been a key area of ​​technological development. Therefore, there is an urgent need to design and implement a wide-field OCTA imaging system for the anterior and posterior segments to more effectively and accurately image the optic disc and retinal periphery. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide an anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A wide-field optical coherence tomography angiography system for anterior and posterior segments, comprising a frequency-sweeping laser light source, a fiber optic interferometer module, a photoelectric balance detector, a high-speed acquisition card, a signal acquisition card, a sample arm module, a reference arm module, a fixation light source, and an iris camera; the fiber optic interferometer module comprises a first coupler, a second coupler, a first circulator, and a second circulator; the first coupler is connected to the frequency-sweeping laser light source, the first circulator, and the second circulator, respectively, for dividing the output light of the frequency-sweeping laser light source into sample light and reference light, respectively, and inputting them into the first circulator and the second circulator; the second coupler is connected to the first circulator, the second ... and the sample light and the reference light respectively. The second circulator is connected to the photoelectric balance detector, and is used to receive the returned sample light and reference light and form an interference signal; the high-speed acquisition card is respectively connected to the swept laser light source and the photoelectric balance detector; the signal acquisition card is respectively connected to the high-speed acquisition card and the sample arm module, and is used to process the signal and obtain the OCTA image; the first circulator is connected to the sample arm module through the first polarization controller; the second circulator is connected to the reference arm module through the second polarization controller; the fixation light source and the iris camera are respectively connected to the sample arm module, and are used to collect OCTA image information of different areas of the eye by changing the focusing state of the eye.

[0008] Furthermore, the sample arm module includes a second beam expansion collimator, a scanning galvanometer and a third dichroic mirror; the second beam expansion collimator is used to receive the light signal sent by the fiber optic interference module and reflect it through the scanning galvanometer; the reflection direction of the scanning galvanometer is sequentially provided with a first anterior segment lens, a fifth dichroic mirror, a first dichroic mirror and a third anterior segment lens; the third dichroic mirror is used to reflect the signal light emitted by the fixation light source, and the reflection direction is sequentially provided with a fourth dichroic mirror, a second anterior segment lens and a second dichroic mirror; the fourth dichroic mirror and the fifth dichroic mirror are arranged in parallel; the first dichroic mirror and the second dichroic mirror are arranged in parallel.

[0009] Furthermore, the scanning angle of the scanning galvanometer is 12.5°.

[0010] Furthermore, the first dichroic mirror, the second dichroic mirror, the third dichroic mirror, the fourth dichroic mirror and the fifth dichroic mirror are all half-reflecting half-mirror mirrors.

[0011] Furthermore, the first anterior segment lens, the second anterior segment lens and the third anterior segment lens are all achromatic doublet lenses made of two pieces of glass with different refractive indices and dispersions.

[0012] Furthermore, the two pieces of glass with different refractive index and dispersion are crown glass and flint glass respectively.

[0013] Furthermore, a group of twelve red LED devices is provided below the third anterior segment lens, and is used as a signal light source for the iris camera; the iris camera and the fixation light source share an optical path.

[0014] Furthermore, the reference arm module includes a first beam expander collimator and a reflector; the second polarization controller is connected to the first beam expander collimator; and the reflector is arranged parallel to and below the first beam expander collimator.

[0015] Furthermore, the first polarization controller and the second polarization controller are both fiber circular polarization controllers.

[0016] Furthermore, the fiber circular polarization controller uses three coils in a row, with the middle coil serving as a half-wave plate and the coils on both sides serving as quarter-wave plates. Each coil can rotate along the axis of the input and output optical fibers. By adjusting the orientation of the three coils, the polarization state of a specific incident wavelength can be converted into any output polarization state.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention combines an OCTA imaging system with a fixation light source and an iris camera to achieve ultra-wide-field OCTA imaging of the fundus. Furthermore, the system structure of the present invention is simple. By sharing the optical path, it avoids the disadvantage of the previously overly large sample arm module, making it easy to operate. The anterior and posterior segment wide-field wide-area optical coherence tomography angiography imaging system of the present invention, combined with image stitching technology, can effectively perform OCTA imaging of the optic disc and peripheral retinal areas, helping doctors diagnose and treat diseases.

[0019] Second, the present invention can perform structural imaging of the anterior segment of the eye, helping to study the relationship between diseases such as glaucoma, high myopia, and uveitis and structural changes in the anterior segment of the eye; and the present invention can achieve structural and blood flow imaging of the conjunctiva and iris, and the larger scanning range can perform complete imaging of the iris.

[0020] 3. The lateral field of view of the present invention is mainly determined by the scanning range of the galvanometer. Reducing the beam diameter can make it easier for the incident light to enter the pupil. On the premise of ensuring that parallel light always passes through the pupil when the galvanometer vibrates, increasing the scanning angle of the galvanometer can achieve imaging in a wider range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the system structure of the present invention;

[0022] Figure 2 A diagram showing the coupling between the sample arm and the fixation optical path of the present invention;

[0023] Figure 3 This is a working principle diagram of the iris camera of the present invention;

[0024] Figure 4 This is a schematic diagram of the fundus OCTA image after preliminary splicing of the present invention.

[0025] The numbers in the figure indicate:

[0026] 1. Sweep-frequency laser light source, 2. First coupler, 3. Second coupler, 4. First circulator, 5. Second circulator, 6. First polarization controller, 7. Second polarization controller, 8. Photoelectric balance detector, 9. High-speed acquisition card, 10. Signal acquisition card, 11. Reflector, 12. Fixation light source, 13. Iris camera, 14. First dichroic mirror, 15. Second dichroic mirror, 16. Third dichroic mirror, 17. Fourth dichroic mirror, 18. Fifth dichroic mirror, 19. Red light LED device, A. Fiber optic interferometer module, B. Sample arm module, C. Reference arm module, G1. Scanning galvanometer, L1. First beam expander and collimator, L2. Second beam expander and collimator, L3. First anterior segment lens, L4. Second anterior segment lens, L5. Third anterior segment lens. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0028] Example

[0029] like Figure 1As shown, a wide-field wide-area optical coherence tomography blood flow imaging system for anterior and posterior segments includes a swept-frequency laser light source 1, an optical fiber interference module A, a photoelectric balance detector 8, a high-speed acquisition card 9, a signal acquisition card 10, a sample arm module B, a reference arm module C, a fixation light source 12, and an iris camera 13; the optical fiber interference module A includes a first coupler 2, a second coupler 3, a first circulator 4, and a second circulator 5; the first coupler 2 is connected to the swept-frequency laser light source 1, the first circulator 4, and the second circulator 5, respectively, for dividing the output light of the swept-frequency laser light source 1 into sample light and reference light in proportion, respectively inputting the light into the first circulator 4 and the second circulator 5, and distributing the returned sample light and reference light to the second coupler 3, wherein the optical paths of the sample light and the reference light are matched; the second coupler 3 is connected to the first circulator 4, the second circulator 5, and the photoelectric balance detector 8, respectively, for The returned sample light and reference light are received and form an interference signal. The fiber interferometer module A uses a circulator to independently isolate the input and output beams, reducing the loss of light carrying biological tissue information in the optical path and effectively improving imaging quality. The high-speed acquisition card 9 is connected to the swept laser light source 1 and the photoelectric balance detector 8, respectively. The signal acquisition card 10 is connected to the high-speed acquisition card 9 and the sample arm module B, respectively, for processing signals and obtaining OCT / OCTA images. The first circulator 4 is connected to the sample arm module B via a first polarization controller 6; the second circulator 5 is connected to the reference arm module C via a second polarization controller 7. The fixation light source 12 and iris camera 13 are respectively connected to the sample arm module B. By switching the indicator lights in different areas, the focus state of the eye is adjusted, thereby achieving the purpose of collecting OCTA image information from different areas of the eye. The present invention uses montage technology to splice small-scale OCTA images of the fundus from different areas into an ultra-wide-angle OCTA image with a scanning angle greater than 100°, thereby imaging the anterior segment of the eye in one go.

[0030] The sample arm module B includes a second beam expansion collimator L2, a scanning galvanometer G1 and a third dichroic mirror 16; the second beam expansion collimator L2 is used to receive the light signal sent by the fiber interference module A and reflect it through the scanning galvanometer G1; the direction of reflection of the scanning galvanometer G1 is provided with a first anterior segment lens L3, a fifth dichroic mirror 18, a first dichroic mirror 14 and a third anterior segment lens L5 in sequence; the third dichroic mirror 16 is used to reflect the signal light emitted by the fixation light source 12, and the reflection direction is provided with a fourth dichroic mirror 17 in sequence The second anterior segment lens L4 and the second dichroic mirror 15 are arranged in parallel. The fourth dichroic mirror 17 and the fifth dichroic mirror 18 are arranged in parallel. The first dichroic mirror 14 and the second dichroic mirror 15 are arranged in parallel. The fixation light source 12 emits signal light, which is reflected by the third dichroic mirror 16 and enters the second anterior segment lens L4 for focusing. The focused light is reflected by the second dichroic mirror 15 at a 45° angle and intersects with the fundus lens optical path. It is coupled with the fundus lens optical path and finally re-diverged into parallel light through the third anterior segment lens L5. When the fixation light source 12 changes its focus position, the signal light emitted by the fundus lens group collects the signal and returns to the fiber optic interferometer module A. It is then processed by the photoelectric balance detector 8 and the computer to form an OCTA image of the area. Among them, the first dichroic mirror 14, the second dichroic mirror 15, the third dichroic mirror 16, the fourth dichroic mirror 17 and the fifth dichroic mirror 18 are all half-reflecting half-transparent lenses; the first anterior segment lens L3, the second anterior segment lens L4 and the third anterior segment lens L5 are all achromatic doublet lenses made of two pieces of glass with different refractive indices and dispersions, usually crown glass and flint glass. The effect quality produced by such a combination is better than that of a single lens, and can effectively suppress the generation of some hardware artifacts.

[0031] The reference arm module C includes a first beam expander collimator L1 and a reflector 11; the second polarization controller 7 is connected to the first beam expander collimator L1; and the reflector 11 is arranged parallel to and below the first beam expander collimator L1.

[0032] The first polarization controller 6 and the second polarization controller 7 are both fiber circular polarization controllers; the fiber circular polarization controller uses three coils in a row, the middle coil serves as a half-wave plate, and the coils on both sides serve as quarter-wave plates. Each coil can rotate along the axis of the incident and output optical fibers. By adjusting the direction of the three coils, the polarization state of the incident specific wavelength can be converted into any output polarization state.

[0033] like Figure 2As shown, the fixation light source 12 emits the signal light required for fixation. The signal light passes through the semi-transparent and semi-reflective third dichroic mirror 16 and is reflected at a 90° angle directly to the second anterior segment lens L4. The parallel signal light is focused by the second anterior segment lens L4. The focused signal light is vertically reflected by the first dichroic mirror 14 placed at a 45° angle and intersects with the sample arm. It is then re-dispersed into parallel light by the third anterior segment lens L5. Anterior segment imaging and fundus imaging are achieved through Figure 2 When imaging the anterior segment of the eye, the signal light passes through the first anterior segment lens L3, is reflected by the fifth dichroic mirror 18, enters the fourth dichroic mirror 17, is reflected by the second anterior segment lens L4, is reflected by the second dichroic mirror 15, enters the first dichroic mirror 14, is reflected by the third anterior segment lens L5, and is finally focused on the anterior segment of the eye. When imaging the fundus of the eye, the signal light passes through the first anterior segment lens L3, is transmitted through the fifth dichroic mirror 18, enters the first dichroic mirror 14, is transmitted by the third anterior segment lens L5, and is finally focused on the fundus.

[0034] like Figure 3 As shown, a group of twelve red LEDs 19 are provided below the third anterior segment lens L5 as a signal light source. The signal light can be considered as parallel light entering the eye, acquiring the desired optical information of the biological tissue, and then reflecting back into the third anterior segment lens L5. After being focused by the third anterior segment lens L5, the signal light is vertically reflected by the first dichroic mirror 14 and then enters the second anterior segment lens L4, completing the optical path conversion. The focused light signal then passes through the second anterior segment lens L4 and re-emitted as parallel light. The parallel light is then transmitted through the third dichroic mirror 16 and enters the iris camera 13. The iris camera 13 and the fixation light source 12 share a common optical path.

[0035] In the sample arm module B with integrated anterior and posterior ocular segments, the focal length of the first anterior segment lens L3 is f1, the focal length of the second anterior segment lens L4 is f2, and the focal length of the third anterior segment lens L5 is f3. The optical path must meet the following conditions:

[0036] In the optical path of anterior and posterior segment imaging, the optical path must match the optical path of the reference arm module C, and the distance between lenses and the focal length must match; in the optical path of the fixation light source 12, the distance between lenses and their corresponding focal lengths must match; and in order to avoid increasing the space occupied by the system, the iris camera 13 is combined with the optical path of the fixation light source 12 to maximize space savings and reduce the size of the equipment.

[0037] The present invention can make fine adjustments based on the focus of the anterior segment of the eye or the posterior segment of the eye, such as the retina, so as to change the focus position and achieve the purpose of obtaining tissue structures at different levels. By adding / removing optical elements from the sample arm and adjusting the length of the reference arm, the respective images of the anterior segment of the eye and the retina are successively obtained. Compared with the existing technology, the present invention combines fundus imaging with a fixation light source and an iris camera, and increases the scanning depth of the system by using an anti-conjugation algorithm and a frequency doubling circuit to double the clock frequency, so that the system can ensure deep coverage during large field of view scanning. The lateral field of view range is mainly determined by the scanning range of the scanning galvanometer G1. Reducing the beam diameter can make it easier for the incident light to enter the pupil. Under the premise of ensuring that the parallel light always passes through the pupil when the scanning galvanometer G1 vibrates, increasing the scanning angle of the scanning galvanometer G1 can achieve a wider range of imaging. The scanning angle of the scanning galvanometer G1 is 12.5°. By reducing the beam diameter and adjusting the position, an imaging range of 12mm*12mm can be achieved.

[0038] like Figure 4 As shown in Figure 1, this embodiment uses a phase-resolved Doppler OCT algorithm combined with a speckle variance processing algorithm to generate OCTA images. The Doppler OCT algorithm calculates the frequency shift by obtaining the phase of the complex-analysis signal, thereby determining the velocity and direction of blood flow. The speckle variance algorithm calculates the intensity of the complex-analysis signal to extract signals indicating blood flow in the sample, effectively separating the flowing and stationary components of tissue.

[0039] In the Doppler OCT algorithm, the real signal of the photoelectric balance detector 8 is converted into a complex analytical signal through the Hilbert transform, where I represents the signal, z represents the depth, and t represents the time:

[0040]

[0041] Then find the phase:

[0042]

[0043] After calibration, the phase difference between adjacent A-lines can be obtained Then we can find the frequency shift and flow velocity:

[0044]

[0045] v(z,t)=λΔf(z,t) / 2cosθ

[0046] In the speckle variance processing algorithm, the intensity variance at the corresponding positions of two adjacent B-scans is calculated:

[0047]

[0048] Where i, j, and f represent the depth position, horizontal position, and frame number, respectively. mean Indicates the average intensity of two adjacent B-scans.

[0049] Image stitching uses the SIFT algorithm to extract feature points and perform matching. The specific steps are as follows:

[0050] 1. Scale-space extrema detection: Preliminary determination of feature point locations and scales. When detecting scale-space extrema, the red dot is compared with its surrounding 8 pixels at the same scale and its surrounding 9×2 pixels at the corresponding location at the adjacent scale to ensure that local extrema are detected in both scale space and 2D image space.

[0051] 2. Use the fitting function to determine the position and scale of feature points, remove key points and edge points with low contrast, increase the stability of matching, and enhance the ability to resist noise.

[0052] 3. Use the characteristic direction of the pixels in the neighborhood of the feature point to specify its direction parameter, so that the operator has rotation invariance.

[0053]

[0054] θ(x,y)=arctan((L(x,y+1)-L(x,y-1)) / (L(x+1,y)-L(x-1,y)))

[0055] In the above formula, m(x,y) and θ(x,y) are the modulus and direction of the gradient at the pixel point with coordinates (x,y), respectively, and L is the scale of each key point.

[0056] 4. Generate SIFT feature vectors. First, rotate the coordinate axes to the direction of the feature point to ensure rotation invariance. Take an 8×8 window centered on the feature point. Calculate the gradient direction histogram for each of the eight directions on each 4×4 patch and accumulate the value of each gradient direction to form a seed point. Count the gradient value and direction of each pixel in each window.

[0057] The RANSAC algorithm is used to remove some outliers, which are often generated by noise and incorrect acquisition methods. The main steps of its verification are:

[0058] 1) There is a model that is applicable to the assumed interior point, that is, all unknown parameters can be calculated from the assumed interior point.

[0059] 2) Use the model obtained in 1) to test all other data. If a point is suitable for the estimated model, it is considered to be an internal point.

[0060] 3) If enough points are classified as hypothesized inliers, then the estimated model is reasonable enough.

[0061] 4) Then, re-estimate the model using all hypothesized inliers, since it has only been estimated with the initial hypothesized inliers.

[0062] 5) Finally, the model is evaluated by estimating the error rate between the inliers and the model.

[0063] By matching point pairs, we construct the transformation matrix H between the image sequences, thus completing the panoramic image stitching. Solving the transformation matrix H is the core of image registration, and the algorithm flow for solving it is as follows.

[0064] 1) Detect feature points in each image.

[0065] 2) Calculate the matching between feature points.

[0066] 3) Calculate the initial value of the inter-image transformation matrix.

[0067] 4) Iteratively refine the H transformation matrix.

[0068] 5) Guided matching: Use the estimated H to define the search area near the epipolar line to further determine the correspondence of feature points.

[0069] 6) Repeat 4) and 5) until the number of corresponding points is stable.

[0070] Based on the transformation matrix H between the images, the corresponding images can be transformed to determine the overlapping area between the images. The image to be fused can then be mapped onto a new blank image to form a mosaic. During the fusion process, the seam lines need to be processed, and a fast and simple weighted smoothing algorithm is used to address this problem. The main idea of ​​the algorithm is that the grayscale value of the pixel in the overlapping area of ​​the images is the weighted average of the grayscale values ​​of the corresponding points in the two images, Pixel L and Pixel R, that is, Pixel = k × Pixel L + (1-k) × Pixel R, where k is an adjustable factor.

[0071] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A wide-field optical coherence tomography angiography system for anterior and posterior segments, characterized by: The system comprises a frequency sweeping laser light source (1), a fiber optic interference module (A), a photoelectric balance detector (8), a high-speed acquisition card (9), a signal acquisition card (10), a sample arm module (B), a reference arm module (C), a fixation light source (12) and an iris camera (13); the fiber optic interference module (A) comprises a first coupler (2), a second coupler (3), a first circulator (4) and a second circulator (5); the first coupler (2) is connected to the frequency sweeping laser light source (1), the first circulator (4) and the second circulator (5) respectively, and is used to divide the output light of the frequency sweeping laser light source (1) into sample light and reference light, which are input to the first circulator (4) and the second circulator (5) respectively; the second coupler (3) is connected to the first circulator (4), the second circulator (4) and the second circulator (5) respectively. The device (5) is connected to the photoelectric balance detector (8) for receiving the returned sample light and reference light and forming an interference signal; the high-speed acquisition card (9) is respectively connected to the swept laser light source (1) and the photoelectric balance detector (8); the signal acquisition card (10) is respectively connected to the high-speed acquisition card (9) and the sample arm module (B) for processing the signal and obtaining the OCTA image; the first circulator (4) is connected to the sample arm module (B) through the first polarization controller (6); the second circulator (5) is connected to the reference arm module (C) through the second polarization controller (7); the fixation light source (12) and the iris camera (13) are respectively connected to the sample arm module (B) for collecting OCTA image information of different areas of the eye by changing the focusing state of the eye; The sample arm module (B) includes a second beam expanding collimator (L2), a scanning galvanometer (G1) and a third dichroic mirror (16); the second beam expanding collimator (L2) is used to receive the optical signal sent by the fiber interference module (A) and reflect it through the scanning galvanometer (G1); the reflection direction of the scanning galvanometer (G1) is provided with a first anterior segment lens (L3), a fifth dichroic mirror (18), a first dichroic mirror (14) and a third anterior segment lens (L5) in sequence; the third dichroic mirror (16) is used to reflect the signal light emitted by the fixation light source (12), and the reflection direction is provided with a fourth dichroic mirror (17), a second anterior segment lens (L4) and a second dichroic mirror (15) in sequence; the fourth dichroic mirror (17) and the fifth dichroic mirror (18) are arranged in parallel; the first dichroic mirror (14) and the second dichroic mirror (15) are arranged in parallel; A group of twelve red light LED devices (19) are provided below the third anterior segment lens (L5) and are used as a signal light source for the iris camera (13); the iris camera (13) and the fixation light source (12) share a common optical path; The signal light is regarded as parallel light entering the eye, and after obtaining the required optical information of the biological tissue, it is reflected into the third anterior segment lens (L5). After being focused by the third anterior segment lens (L5), the signal light is vertically reflected by the first dichroic mirror (14) into the second anterior segment lens (L4), completing the conversion of the light path. The focused light signal is re-diverged into parallel light after passing through the second anterior segment lens (L4). The parallel light is transmitted through the third dichroic mirror (16) and enters the iris camera (13).

2. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 1, characterized in that: The scanning angle of the scanning galvanometer (G1) is 12.5°.

3. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 1, characterized in that: The first dichroic mirror (14), the second dichroic mirror (15), the third dichroic mirror (16), the fourth dichroic mirror (17) and the fifth dichroic mirror (18) are all half-reflecting half-mirrors.

4. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 1, characterized in that: The first anterior segment lens (L3), the second anterior segment lens (L4) and the third anterior segment lens (L5) are all achromatic doublet lenses made of two pieces of glass with different refractive indices and dispersions.

5. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 4, characterized in that: The two pieces of glass with different refractive index and dispersion are crown glass and flint glass respectively.

6. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 1, characterized in that: The reference arm module (C) comprises a first beam expanding collimator (L1) and a reflector (11); the second polarization controller (7) is connected to the first beam expanding collimator (L1); and the reflector (11) is arranged parallel to and below the first beam expanding collimator (L1).

7. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 1, characterized in that: The first polarization controller (6) and the second polarization controller (7) are both optical fiber circular polarization controllers.

8. The anterior and posterior segment wide-field wide-area optical coherence tomography blood flow imaging system according to claim 7, characterized in that: The fiber circular polarization controller uses three coils in a row, with the middle coil serving as a half-wave plate and the two side coils as quarter-wave plates. Each coil can rotate along the axis of the incident and output optical fibers. By adjusting the orientation of the three coils, the polarization state of a specific incident wavelength can be converted into any output polarization state.

Images