A medical endoscope three-dimensional imaging system and method based on microstructure light projection

Abstract

The application discloses a kind of medical endoscope three-dimensional imaging system and method based on microstructure light projection, including image processor and the endoscope head end including structure light projection channel, the endoscope head end includes microstructure light source channel, white light source channel and imaging channel in;Microstructure light source channel is projected structure light pattern to target object by projection lens and photoetching mask plate.Image processor will the image with stereoscopic parallax that imaging channel is shot, and standard distance image matching generates the three-dimensional point cloud of target object.The application realizes active three-dimensional imaging to target object by projecting structure light pattern sequence, and the identification degree of area is high to cover, weak texture or there is repeated texture, and it is not easy to produce false match;Realize high-speed three-dimensional topography imaging to target object topography, and it is convenient for real-time diagnosis the morphology of micro lesion.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a three-dimensional imaging system and method for medical endoscopes based on microstructured light projection. Background Technology

[0002] Most medical endoscopes use tiny CMOS sensors to create miniature imaging probes at their tips. These probes, along with the flexible endoscope body, are inserted into body cavities to acquire images. During diagnosis and surgery, they assist doctors in obtaining high-resolution two-dimensional images of the body. Current endoscopic systems are predominantly two-dimensional, which meets the needs of doctors in confined spaces. However, two-dimensional images cannot provide doctors with depth information about lesions and tissues, limiting the information available to them. Three-dimensional endoscopes have emerged to address this need. Currently, commercially available three-dimensional endoscopes mostly employ binocular stereoscopic vision to provide users with depth perception. When used with 3D glasses, they offer a sense of depth and three-dimensionality, but still cannot achieve accurate three-dimensional measurement. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a medical endoscope three-dimensional imaging system and method based on micro structured light projection, which addresses the shortcomings of the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A medical endoscope three-dimensional imaging system based on micro-structured light projection includes an endoscope lens tip and an image processor; the endoscope lens tip contains a structured light projection channel, specifically including: an imaging channel, a white light source channel, and a micro-structured light source channel; it may also include a clamp channel and a water vapor channel, etc.

[0005] The white light source channel emits visible light to illuminate the object under test, and the imaging channel acquires two-dimensional image information of the object under test.

[0006] The microstructured light source channel emits coded structured light, which is projected onto the object under test, and the imaging channel acquires the coded structured light image of the object under test.

[0007] Preferably, the microstructured light source channel includes a high-power LED, a light guide rod, a quaternary photolithography mask based on an M-array, and a projection lens based on a Q-type aspherical lens, arranged sequentially along the light emission direction of the optical axis.

[0008] Preferably, the distance between the microstructured light source channel and the imaging channel satisfies the following relationship: Where radii1 and radii2 are the radii of the imaging channel and the microstructured light channel, respectively, b is the distance between the microstructured light source channel and the imaging channel, and L min α1 is the minimum working distance between the endoscope lens and the object being measured, α2 is the field of view of the imaging channel, and α3 is the field of view of the micro-structured light projection.

[0009] Preferably, the M-array-based photolithography mask uses a primitive polynomial based on order 6 GF(4) to generate a quaternary M-sequence, which is then filled into the two-dimensional array. Its primitive polynomial is: h(x) = x 6 +x 2 +x+1 In this two-dimensional array, the feature encoding value of each 3*2 primitive window is unique, thereby enabling the determination of the relative position of each primitive.

[0010] Preferably, in the quaternary array, four easily identifiable and distinguishable primitives are used to represent the codewords 0, 1, 2, and 3 in the two-dimensional array. Four basic primitives are preferred: horizontal rectangle, vertical rectangle, circle, and crosshair. Compared to other primitives, these four basic primitives are easier to identify and distinguish in endoscopic applications. Combined with the projection lens, light guide, and high-power LED projecting structured light patterns of the mask design onto the area, the encoding of the area can be effectively completed. The side length L of the quaternary photolithography mask... M The following conditions must be met: Where h1 is the half-image height of the imaging channel at the minimum working distance of the endoscope, b is the distance between the microstructured light source channel and the imaging channel, and β is the magnification of the projection lens at the minimum working distance of the endoscope. In the mask, the size of each graphic element and the spacing between them must ensure that they can be clearly projected and distinguished after passing through the projection lens. The shortest side of graphic elements containing rectangles and the spacing between each graphic element must meet the following conditions: Wherein, Δ is the shortest side of the rectangular primitive or the spacing between primitives, lp is the spatial frequency of the projection lens, and γ is an integer multiple of the spatial frequency, generally taken as 3 to 10, which can be selected according to the actual size and requirements.

[0011] Preferably, the projection lens based on a Q-type aspherical lens comprises, from the object side to the image side: a protective sapphire plate, a first lens with negative optical power, a second lens with positive optical power, an aperture stop, a third lens with positive optical power, a fourth lens with positive optical power, and an infrared filter; the object-side and image-side of the first lens are both concave; the object-side of the second lens is convex, and the image-side is concave; the object-side and image-side of the third lens are both convex; the object-side and image-side of the fourth lens are both convex; the first and fourth lenses are plastic aspherical lenses; the second and third lenses are glass spherical lenses; the above projection lens satisfies the following condition: 0.8 < (D3 + D11) / T311 < 1.0 Wherein, D3 is the effective aperture size of the object side of the first lens; D11 is the effective aperture size of the image side of the fourth lens; and T311 is the distance on the optical axis between the object side of the first lens and the image side of the fourth lens.

[0012] Preferably, the projection lens based on the Q-type aspherical lens satisfies the following condition: 0.5 <tanω<1.6 Where ω is the half field of view of the projection lens.

[0013] Preferably, the projection lens based on the Q-type aspherical lens satisfies the following condition: TTL≤4mm Where TTL is the total optical length of the lens, which is the distance on the optical axis from the object side of the sapphire plate to the image side of the infrared filter.

[0014] Preferably, the projection lens based on the Q-type aspherical lens satisfies the following condition: Vd1-Vd2>30 Wherein, Vd1 is the dispersion coefficient of the first lens (L1); Vd2 is the dispersion coefficient of the second lens.

[0015] The imaging channel is calibrated using the Zhang Zhengyou calibration method under the illumination of the white light source channel. By taking multiple images of the chessboard with known physical dimensions, the corner positions in the chessboard images are obtained, the lens distortion of the zoom channel is calculated, and the camera's focal length f and principal point position (x0, y0) are obtained, thus completing the calibration of the imaging channel.

[0016] The micro structured light channel projects a structured light pattern onto a standard whiteboard, and captures standard distance images at a fixed distance between the whiteboard and the lens end (within equal step sizes within the working distance range).

[0017] The standard whiteboard structured light images captured at different standard distances were calibrated using the camera's calibration parameters based on Zhang Zhengyou's calibration method, thus completing the calibration of the standard distance images.

[0018] The standard distance image is subjected to OTSU thresholding. Based on the image's grayscale characteristics, a threshold TH exists, dividing the pixels in the image into two classes: C1 (less than TH) and C2 (greater than TH), thus separating the image into foreground and background. The image segmentation threshold is calculated to maximize the inter-class variance between the foreground and background, where the inter-class variance σ... 2 The formula is: σ 2 =p1(m1-m G ) 2 +p2(m2-m G ) 2 Among them, the mean values ​​of the two types of pixels are m1 and m2 respectively, and the global mean value of the image is m. G The probabilities of pixels being divided into two classes are p1 and p2, respectively. Where i is the corresponding grayscale value, p i L is the probability of pixel i in the image. For an 8-bit image, L is 256. Substituting this into the above formula, we find the value of k that maximizes the inter-class variance, which is the threshold we are looking for. We then binarize the standard distance image using this threshold to obtain a binary image.

[0019] The standard distance image is binarized using the threshold obtained above to obtain a binary image.

[0020] To identify the primitives in the standard distance image, it is necessary to extract a set of primitives in a 3*2 window, starting from each primitive.

[0021] The standard distance image is processed as described above to obtain the pixel coordinates of each feature point at each distance. Based on the triangulation principle, the following formula is obtained: Where z1 and z2 are two standard distances, Δd is the disparity between each pair of feature points, and f is the focal length of the system. The baseline length b of the system can be calculated using this formula, thus completing the calibration of the system's structured light channel.

[0022] The target area is illuminated by opening a microstructured light source channel to complete the encoding of the target area.

[0023] Homomorphic filtering is applied to the two-dimensional image of the target region to separate the high-frequency and low-frequency components of the image. Frequency domain filtering is performed using filter H(u,v), which is designed as follows: H(u,v)=(γ H -γ L )H hp (u,v)+γ L Where, γ H >1, γ L <1, used to control the range of filter amplitude, H hp (u,v) uses a Gaussian high-pass filter.

[0024] The image after homomorphic filtering is then sharpened to obtain an image with clearer primitive outlines.

[0025] The sharpened image is subjected to adaptive binarization processing, which divides the target image into several sub-regions. The weighted sum of gray values ​​of the pixel blocks in each sub-region is calculated and used as the binarization threshold for each sub-region, thereby realizing adaptive segmentation of the image and completing the binarization processing of the target image.

[0026] The sharpened image is subjected to primitive recognition and localization to achieve feature point recognition of the target region and feature point pair matching with the standard distance image. The disparity d is calculated for each feature point pair, and based on the triangulation principle, combined with the following formula: Achieve 3D point cloud reconstruction and topography restoration of the target region.

[0027] For the white light illumination channel, the imaging channel is used to capture a white light image, which provides texture mapping information for the 3D point cloud. This information is then fused with the 3D point cloud to complete the 3D texture and output a 3D image.

[0028] The beneficial effects of this invention are:

[0029] (1) This invention comprises three optical units: an imaging channel, a white light source channel, and a micro-structured light source channel. Illumination via the white light source channel allows for the acquisition of a two-dimensional image of the lesion area, providing texture mapping information for the three-dimensional point cloud. Illumination via the micro-structured light source channel projects a structured light pattern onto the lesion area, completing the encoding of the lesion area. The image processor decodes and reconstructs the structured light image, combining it with the two-dimensional texture information to achieve three-dimensional reconstruction and output a three-dimensional image. Compared to traditional two-dimensional images, the three-dimensional image provides more comprehensive information, offering more precise numerical values ​​for the physical dimensions of the lesion, assisting doctors in measuring the size of relevant tissue structures within the lesion, and improving the success rate of diagnosis and treatment.

[0030] (2) In this invention, the optical design of the micro structured light source channel has a large field of view, small distortion and high resolution. The structured light projection system realizes high-resolution projection of structured light patterns in a narrow space at the head end and is easy to install.

[0031] (3) In this invention, the structured light mask adopts a primitive design based on M array. In the endoscopic scene, four specific primitives that are easy to extract and identify are used, which consumes less computing resources and has good real-time reconstruction performance.

[0032] (4) The system structure of the present invention is simple, easy to use, compatible with existing endoscopes, has low learning cost, and is easy for doctors to operate by hand. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the principle of the three-dimensional imaging system of the present invention;

[0034] Figure 2 This is a schematic diagram of the head end structure of the medical endoscope three-dimensional imaging system based on a micro structured light projection system of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of the microstructured light source channel of the present invention;

[0036] Figure 4 This is a schematic diagram of the projection lens of the present invention;

[0037] Figure 5 This is a schematic diagram of the photolithographic mask pattern of the present invention;

[0038] Figure 6 This is a flowchart illustrating the calibration of the three-dimensional imaging system of the present invention;

[0039] Figure 7 This is a flowchart of the primitive recognition and classification process of the present invention;

[0040] Figure 8 This is a flowchart of the three-dimensional imaging process of the present invention.

[0041] Explanation of reference numerals in the attached figures:

[0042] 101-First white light source channel; 102-Water vapor channel; 103-Clamping channel; 104-Miniature structured light source channel; 105-Second white light source channel; 106-Imaging channel; 201-Projection lens; 202-Photolithography mask; 203-Beam guide; 204-High-power LED; SP-Sapphire flat panel; L1-First lens; L2-Second lens; ST-Aperture; L3-Third lens; L4-Fourth lens; IR-Infrared filter. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0044] It should be understood that terms such as “having,” “comprising,” and “including” used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0045] This embodiment presents a medical endoscope three-dimensional imaging system based on a micro-structured light projection system, including an endoscope lens tip and an image processor. The working principle of the system is as follows: Figure 1 As shown.

[0046] like Figure 2 As shown, the endoscope lens tip includes: an imaging channel 106, two white light source channels 101 and 105, a micro-structured light source channel 104, a clamp channel 103, and a water vapor channel 102.

[0047] The white light source channel emits visible light to illuminate the object under test, and the imaging channel acquires two-dimensional image information of the object under test.

[0048] The miniature structured light source channel emits coded structured light, which is projected onto the object under test. The coded structured light image of the object under test is acquired through the imaging channel.

[0049] In a preferred embodiment, the distance between the microstructured light source channel and the imaging channel satisfies the following relationship: Where radii1 and radii2 are the radii of the imaging channel and the microstructured light channel, respectively, b is the distance between the microstructured light source channel and the imaging channel, and L min α1 is the minimum working distance of the endoscope lens, α2 is the field of view of the imaging channel, and α3 is the field of view of the micro-structured light projection.

[0050] like Figure 3 As shown, in a preferred embodiment, the microstructured light source channel includes a high-power white LED 204, a beam guide 203, a photolithography mask based on an M-array, and a projection lens 201 based on a Q-type aspherical lens arranged sequentially along the incident light path;

[0051] In a preferred embodiment, the projection lens structure design based on the Q-type aspherical lens is as follows: Figure 4As shown, the medical endoscope objective optical system comprises a protective sapphire plate SP, a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, and an infrared filter IR. The first lens L1 has concave object-side and image-side surfaces. The second lens L2 has a convex object-side surface and a concave image-side surface. The third lens L3 has convex object-side and image-side surfaces. The fourth lens L4 has convex object-side and image-side surfaces. The first lens L1 and the fourth lens L4 are plastic aspherical lenses. The second lens L2 and the third lens L3 are glass spherical lenses. The above-described medical endoscope objective optical system satisfies the following condition: 0.8 < (D3 + D11) / T311 < 1.0 Wherein, D3 is the effective aperture size of the object side of the first lens L1; D11 is the effective aperture size of the image side of the fourth lens L4; and T311 is the distance on the optical axis between the object side of the first lens L1 and the image side of the fourth lens L4.

[0052] In a preferred embodiment, the objective optical system of the projection lens based on a Q-type aspherical lens satisfies the following condition: 0.5 <tanω<1.6 Where ω is the half field of view of the objective lens optical system of this medical endoscope.

[0053] In a preferred embodiment, the objective optical system of the projection lens based on a Q-type aspherical lens satisfies the following condition: TTL≤4mm Where TTL is the total optical length of the lens, and is the distance on the optical axis from the object side of the sapphire flat plate SP to the image side of the infrared filter IR.

[0054] In a preferred embodiment, the objective optical system of the projection lens based on a Q-type aspherical lens satisfies the following condition: Vd1-Vd2>30 Wherein, Vd1 is the dispersion coefficient of the first lens L1; and Vd2 is the dispersion coefficient of the second lens L2.

[0055] In one embodiment, the M-array-based photomask 202 uses a primitive polynomial based on the sixth-order GF(4) to generate a quaternary M-sequence, which is then filled into a two-dimensional array. In this two-dimensional array, the feature encoding value of each 3*2 primitive window is unique, thereby determining the relative position of each primitive.

[0056] In a preferred embodiment, refer to Figure 5In the quad array based on the M-array photolithography mask, horizontal rectangles, vertical rectangles, circles, and crosshairs are used to represent the four codewords 0, 1, 2, and 3, respectively.

[0057] The system calibration process is as follows: Figure 6 The imaging channel is calibrated using the Zhang Zhengyou calibration method under the illumination of the white light source channel. By taking multiple images of the chessboard with known physical dimensions, the corner positions in the chessboard images are obtained, the lens distortion of the imaging channel is calculated, and the focal length f and principal point position (x0, y0) of the camera are obtained, thus completing the calibration of the imaging channel.

[0058] A miniature structured light channel projects a structured light pattern onto a standard whiteboard, and takes multiple images at distances of 15mm, 20mm, 25mm, and 30mm from the head end of the whiteboard, which are then used as standard distance images.

[0059] In a preferred embodiment, a diffuse white background is used as the standard white board to ensure image quality. This standard white board is used for imaging at various standard distances to calibrate the microstructured light channel. For the standard white board structured light images at different standard distances, the camera calibration parameters are used based on the Zhang Zhengyou calibration method to calibrate the standard distance images.

[0060] In a preferred embodiment, the pixel coordinates of each feature point at each distance are calculated and combined, and the following formula is obtained based on the triangulation principle: Where z1 and z2 are two standard distances, Δd is the disparity between each pair of feature points, and f is the focal length of the system. This formula allows for the calculation of the system's baseline length, thus completing the calibration of the system's structured light channel. In a preferred embodiment, feature points in an image at a standard distance of 20mm are selected as reference feature points, and the positions, feature window vectors, and feature values ​​of the feature points in the standard image are recorded.

[0061] In a preferred embodiment, the process for identifying and classifying graphic elements refers to... Figure 7 OTSU thresholding is performed on the standard distance image. Based on the image's grayscale characteristics, a threshold TH exists, dividing the pixels in the image into two classes: C1 (less than TH) and C2 (greater than TH), representing foreground and background. The image segmentation threshold is calculated to maximize the inter-class variance between the foreground and background, where the inter-class variance σ... 2 The formula is: σ 2 =p1(m1-m G ) 2 +p2(m2-m G ) 2 Among them, the mean values ​​of the two types of pixels are m1 and m2 respectively, and the global mean value of the image is m. G The probabilities of pixels being divided into two classes are p1 and p2, respectively. Where i is the corresponding grayscale value, p i L is the probability of pixel i in the image. For an 8-bit image, L is 256. Substituting this into the above formula, we find the value of k that maximizes the inter-class variance, which is the threshold we are looking for. We then binarize the standard distance image using this threshold to obtain a binary image.

[0062] In a preferred embodiment, the connected regions in the binary image are processed, and the bounding rectangle and roundness C of each connected region are calculated. The width Δx and height Δy of the bounding rectangle of each connected region are also calculated. The roundness C of the connected region is calculated as follows: Where F is the area of ​​the connected region, and max is the maximum distance from the center of the connected region to all contour pixels.

[0063] A threshold THRESH_CIRCLE is set for the roundness of connected components in a binary image. When the roundness is greater than THRESH_CIRCLE, the connected component is determined to be circular.

[0064] Calculate the aspect ratio Δx / Δy for connected components in a binary image. Set thresholds THRESH_1 and THRESH_2 based on the horizontal and vertical rectangles respectively. When the aspect ratio is greater than THRESH_1, the connected component is determined to be a horizontal rectangle. When the aspect ratio is less than THRESH_2, the connected component is determined to be a vertical rectangle.

[0065] For connected components in a binary image, those that do not meet the above three threshold conditions are identified as crosshairs, thus completing the recognition and classification of the standard distance image.

[0066] The target area is illuminated by opening a microstructured light source channel, thereby completing the encoding of the target area.

[0067] In a preferred embodiment, the reconstruction process refers to... Figure 8 Homomorphic filtering is applied to the two-dimensional image of the target region to separate the high-frequency and low-frequency components. Frequency domain filtering is performed using filter H(u,v), which is designed as follows: H(u,v)=(γ H -γ L )H hp(u,v)+γ L Where, γ H >1, γ L <1, used to control the range of filter amplitude, H hp (u,v) uses a Gaussian high-pass filter.

[0068] In a preferred embodiment, the image after homomorphic filtering is sharpened using the Laplacian operator, whose operator template H is: Sharpening results in an image with clearer primitive outlines.

[0069] The sharpened image is subjected to adaptive binarization processing, which divides the target image into several sub-regions. The weighted sum of the gray values ​​of the pixel blocks in each sub-region is calculated and used as the binarization threshold for each sub-region, thereby realizing adaptive image segmentation and completing the binarization processing of the target image.

[0070] For the identified primitives in the sharpened image, it is necessary to extract a set of primitives within a 3x2 window, starting from each primitive. This requires finding the right and lower neighbors of the current primitive.

[0071] In a preferred embodiment, the horizontal and vertical rectangles closest to the current graphic element are found respectively. The directions of the horizontal and vertical rectangles are calculated using the second moment of the image, and used as the search directions for the right and lower neighbors of the current graphic element. The graphic element set corresponding to each graphic element is determined in turn, thereby uniquely determining the relative position of the window in the projection pattern.

[0072] In a preferred embodiment, the relative positions of the window and the primitives are determined to achieve feature point recognition of the target area and feature point pair matching with the standard distance image. The disparity d is calculated for each feature point pair, and based on the triangulation principle, the following formula is used: z0 is the standard distance actually used, and x, y, and z are the three-dimensional point cloud coordinates of the feature points in the target area, realizing the three-dimensional point cloud reconstruction and shape restoration of the target area.

[0073] For the white light illumination channel, the imaging channel is used to capture a white light image, which provides texture mapping information for the 3D point cloud. This information is then fused with the 3D point cloud to complete the 3D texture and output a 3D image.

[0074] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A three-dimensional imaging system for medical endoscopes based on microstructured light projection, characterized in that: include: An endoscope end with a structured light projection channel includes: The microstructured light source channel is provided with a high-power LED, a light guide rod, a quaternary photolithography mask based on an M-array, and a projection lens based on a Q-type aspherical lens design, arranged sequentially along the light emission direction of the optical axis. This is used to project structured light patterns and encode the object under test. The white light source channel is used to emit white light to illuminate the object under test; the imaging channel acquires a two-dimensional image of the object under test. And an imaging channel, used to capture two-dimensional images of the test object under white light illumination and coded images under structured light projection; An image processor is used to decode and match the encoded image to obtain a three-dimensional point cloud, and to match the texture information of the two-dimensional image into the three-dimensional point cloud to reconstruct a three-dimensional image of the object under test. The projection lens based on the Q-type aspherical lens design comprises, from object to image, a sapphire flat panel (SP), a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, an aperture stop (ST), a third lens (L3) with positive optical power, a fourth lens (L4) with positive optical power, and an infrared filter (IR); wherein: The object-side and image-side surfaces of the first lens (L1) are both concave; the object-side surface of the second lens (L2) is convex and the image-side surface is concave; the object-side and image-side surfaces of the third lens (L3) are both convex; and the object-side and image-side surfaces of the fourth lens (L4) are both convex. The first lens (L1) and the fourth lens (L4) are plastic aspherical lenses; the second lens (L2) and the third lens (L3) are glass spherical lenses; and they satisfy the following condition: Wherein, D3 is the effective aperture size of the object side of the first lens (L1); D11 is the effective aperture size of the image side of the fourth lens (L4); and T311 is the distance on the optical axis between the object side of the first lens (L1) and the image side of the fourth lens (L4).

2. The medical endoscope three-dimensional imaging system based on micro-structured light projection according to claim 1, characterized in that, The distance between the microstructured light source channel and the imaging channel needs to satisfy the following relationship: in and These are the radii of the imaging channel and the microstructured light channel, respectively. It is the distance between the microstructured light source channel and the imaging channel. It is the minimum working distance between the endoscope lens and the object being measured. It is the field of view of the imaging channel. It is the field of view of microstructured light projection.

3. The medical endoscope three-dimensional imaging system based on micro-structured light projection according to claim 1, characterized in that, The aforementioned M-array-based quaternary photolithography mask uses an M-sequence based on a sixth-order GF(4) to generate a two-dimensional pseudo-random code array, the primitive polynomial of which is: The graphic information under each 3*2 graphic element window is unique.

4. The medical endoscope three-dimensional imaging system based on micro-structured light projection according to claim 3, characterized in that, The quaternary photolithography mask uses four basic primitives: horizontal rectangle, vertical rectangle, circle, and crosshair.

5. The medical endoscope three-dimensional imaging system based on micro-structured light projection according to claim 4, characterized in that, The side length of the quaternary photolithography mask The following conditions must be met: in, This represents the half-image height of the imaging channel at the minimum working distance of the endoscope. This represents the distance between the microstructured light source channel and the imaging channel. The magnification of the projection lens at the minimum working distance of the endoscope; In the mask, the size of each graphic element and the spacing between them must ensure that they can be clearly projected and distinguished after passing through the projection lens. The shortest side of the graphic elements containing rectangles, as well as the spacing between each graphic element, must meet the following conditions: in, This refers to the shortest side of a rectangular primitive or the spacing between primitives. The spatial frequency of the projection lens. It is an integer multiple of the spatial frequency.

6. A three-dimensional imaging method for medical endoscopes based on microstructured light projection, characterized in that, Based on the system implementation as described in any one of claims 1-5, the method includes system calibration, coded image preprocessing, primitive matching, point cloud reconstruction, and texture mapping; wherein system calibration includes: Under the illumination of the white light source channel, the imaging channel is calibrated using the Zhang Zhengyou calibration method to obtain the camera's focal length and principal point position, thus completing the calibration of the imaging channel. For the micro structured light source channel, a structured light pattern is projected onto a standard white board, and images are taken at equal step lengths within the working distance range to obtain standard distance images at various standard distances. The camera calibration parameters are then used to calibrate based on Zhang Zhengyou's calibration method to complete the calibration of each standard distance image. The image processor is used to extract and recognize features from images at different standard distances, and feature points are matched to calculate the disparity between pairs of standard distance images. The baseline length of the system is then determined according to the following formula. The calibration, in: , These are the two standard distances corresponding to the two standard distance images used for calculation. The disparity between each pair of feature points. is the focal length of the system.

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