Automatic tool alignment method for repairing surface micro-defects of optical crystal based on double microscope cooperation

Abstract

The application discloses an automatic tool setting method for repairing micro-defects on the surface of an optical crystal based on cooperation of two microscopes, and relates to the technical field of precise optical processing. The application first determines a plane fitting equation of a crystal surface to be repaired through a three-point "trial cutting method", calculates distances from different defect points to be repaired to a tool setting surface according to plane position information of optical surface micro-defects obtained by a scanning microscope, and determines a tool setting feeding distance to improve the safety of tool setting efficiency. Then, the application calculates the distance from a tool tip to the crystal surface to be repaired during tool setting based on the "inverted image method" of a repairing microscope. Finally, the tool setting pit in the scanning microscope is used as a criterion for determining whether tool setting is completed. The tool setting method of the application solves the problem that the "inverted image method" is prone to misjudgment due to tool tip adhesion, and ensures the accuracy of tool setting.

Description

Technical Field

[0001] This invention relates to the field of precision optical processing technology, and more specifically, to an automatic tool setting method for repairing micro-defects on the surface of optical crystals based on dual-microscope collaboration. Background Technology

[0002] In today's society, people's demand for energy is increasing, and the fossil fuels accumulated over a long period of time are no longer sufficient to meet this demand. Furthermore, environmental pollution caused by energy development has become a major problem plaguing countries worldwide, making the development of new clean energy sources imperative. Laser-driven controlled inertial confinement fusion (CIC) is considered the most likely solution to the current energy crisis due to its advantages of safety, controllability, cleanliness, and renewability. The United States has already built the world's highest-energy-output laser fusion device—the National Ignition Facility—which uses over 8,000 large-aperture optical elements and over 30,000 small-aperture optical elements. KDP, due to its superior optical performance, has become an indispensable optical element in current laser fusion devices. However, during the processing of large-aperture soft and brittle KDP crystals, micro-defects (from micrometers to sub-millimeters) may appear on the crystal surface. These defects, under continuous intense laser irradiation, can induce laser damage and expand in size. If not addressed, this can ultimately lead to the scrapping of the entire component. The laser damage caused by micro-defects on the surface of large-aperture optical crystals has become a bottleneck restricting the improvement of output energy in laser fusion devices. Currently, advanced methods are mainly used to repair and remove micro-defects on the crystal surface to slow down damage growth and extend the component's lifespan. Using precision micro-milling technology to repair and remove laser damage defects on the crystal surface is currently the most effective method to suppress laser damage growth and improve the laser load capacity of optical crystal components.

[0003] After repairing micro-defects on the surface of large-diameter KDP crystal elements using high-speed micro-milling with ball end mills, the laser damage threshold can be restored to 85% of that of a defect-free surface. Even so, the engineering application and promotion of micro-milling repair technology for large-diameter KDP crystal elements still faces challenges. The automatic tool setting technology during the repair process is particularly crucial. Traditional tool setting methods rely on CCD images and manual experience to determine parameters such as the distance between the tool and the workpiece surface, and the feed rate. This method suffers from low accuracy and repeatability, and the repeated adjustments to the focal length and magnification are time-consuming and labor-intensive. The new method, "CN108705689 A Automatic Tool Setting Process for Repairing Micro-Defects on the Surface of Large-Diameter Precision Optical Crystals," proposes a tool setting method based on the "reflection method." This solves the problems of low efficiency and poor repeatability associated with manual tool setting, improving the accuracy and precision of automatic tool setting. Furthermore, it is simple to operate and convenient to use. However, in practical applications, this method still has problems such as high requirements for lighting conditions, relatively poor tool setting accuracy, and the use of bright chip as the standard for judging the completion of tool setting. It often causes "false chips" due to the sticky chips blown out by the air-bearing spindle gas, leading to misjudgment. Therefore, the entire tool setting process is easily affected by external environmental interference, resulting in low tool setting accuracy and efficiency. Summary of the Invention

[0004] The technical problem to be solved by this invention is:

[0005] Existing automatic tool setting methods for repairing micro-defects on optical crystal surfaces have high requirements for processing conditions, relatively poor tool setting accuracy, are easily affected by external environmental interference, and have insufficient safety features.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] This invention provides an automated tool setting method for repairing micro-defects on the surface of optical crystals based on dual-microscope collaboration, comprising the following steps:

[0008] Step 1: Install the large-aperture KDP crystal element, assemble and adjust the scanning microscope system and the restoration microscope system, and automatically return each axis of the crystal restoration machine tool system to zero;

[0009] Step 2: Establish a plane fitting equation for predicting the spatial position of the surface to be repaired of a large-diameter KDP crystal using the three-point "trial cutting method". Based on the established plane fitting equation, consider the gravitational deformation of the crystal element to determine the key points for dividing the fine cutting stage and the coarse cutting stage in the cutting stage, and hide and encapsulate them. Design an intuitive crystal plane calibration interface for users.

[0010] Step 3: Obtain the planar position information of micro-defects on the surface of the large-diameter KDP crystal element using a scanning microscope, move the tool below the location of the micro-defect to be repaired, and use a repair microscope to collect tool setting image information in real time. Calculate the actual distance between the tool and the crystal tool setting surface based on the "reflection method" to perform coarse tool setting.

[0011] Step 4: Use a scanning microscope to acquire real-time image information of the crystal tool surface, process the data of each frame of image, and capture the image changes of the local tool-setting area on the crystal surface before and after each tool-setting feed.

[0012] Step 5: Based on the actual distance from the tool tip to the tool setting surface estimated in Step 3, when the distance between the tool tip and the tool setting surface reaches the key point of the fine tool setting stage and the rough tool setting stage, set the program to perform fine tool setting.

[0013] Step 6: After the image of the tool-setting surface captured by the scanning microscope changes, the image processing method of "differential circle extraction" is used to process the acquired image of the tool-setting surface to obtain clear contour information of the tool-setting pit.

[0014] Step 7: Based on the image processing results of Step 6, when the minimum outer circle pixel radius of the tool setting pit reaches the preset threshold, it is used as a sign of successful tool setting, and an automatic tool retraction program is added after tool setting is completed.

[0015] Furthermore, the crystal repair machine tool described in step 1 includes a scanning microscope system for rapidly searching for and acquiring real-time image information of the crystal tool surface during the repair process, a defect repair system for removing defects through three-axis linkage machining, and a repair microscope system for acquiring tool setting image information and calculating the distance between the tool and the crystal tool surface. The tool setting process is the process of feeding the tool upward to the lower surface of the crystal.

[0016] Furthermore, the scanning microscope mentioned in step 3 is a JAI BM-500GE CCD with a resolution of 2456×2058, a maximum frame rate of 15fps, and a pixel size of 3.45μm×3.45μm; the repair microscope is a Vision Imaging MV-VD200SC industrial CCD with a resolution of 1600×1200, a maximum frame rate of 12fps, and its driver provides C++ standard library functions with WDMIAT3.0 as the interface.

[0017] Furthermore, the gravitational deformation of the crystal element described in step 2 is obtained using the finite element simulation method.

[0018] Furthermore, in step 6, the image processing method of "subtraction and circle taking" is used to process the crystal tool surface image acquired by the scanning microscope. First, the images before and after each tool feed are subtracted and binarized. Then, the high grayscale areas of the crystal surface pits generated by the tool are subjected to dilation and erosion morphological processing to reduce noise and enhance features. Finally, the FindContours function is used to find the outer contour of the image and calculate the minimum circumcircle of the tool contour.

[0019] Furthermore, the method for determining the preset threshold of the minimum circumscribed circle pixel radius of the tool setting pit in step 7 is as follows: based on the magnification of the scanning microscope's zoom ring, calculate the theoretical size parameter c of the representative length of a single pixel; when the automatic tool setting depth of the micro-defects on the surface of the crystal element is 0.5 μm, calculate the radius of the corresponding tool setting pit based on the diameter of the ball end mill, and further calculate its corresponding pixel radius, which is the pixel radius threshold of the minimum circumscribed circle of the tool setting pit.

[0020] An automatic tool setting system for repairing micro-defects on the surface of optical crystals based on dual-microscope collaboration is provided. This system has a program module corresponding to the steps of any of the above-mentioned technical solutions, and executes the steps in the above-mentioned automatic tool setting method for repairing micro-defects on the surface of optical crystals based on dual-microscope collaboration when running.

[0021] A computer-readable storage medium storing a computer program configured to, when invoked by a processor, implement the steps of the automatic tool setting method for repairing micro-defects on the surface of optical crystals based on dual-microscope collaboration, as described in any of the above technical solutions.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention relates to an automatic tool setting method for repairing micro-defects on optical crystal surfaces using a dual-microscope collaborative approach. First, a scanning microscope is used to obtain the planar position information of the defects to be repaired across the entire optical element. Then, a repair microscope is used to estimate the distance between the tool tip and the surface to be repaired during tool setting based on the "reflection method." Finally, the appearance of a tool setting pit in the scanning microscope is used as the criterion for successful tool setting. Simultaneously, before tool setting, a mathematical equation for the plane to be repaired is fitted using the three-point height coordinates determined by the three-point "trial cutting method." When repairing different defect points, the distance from the defect to the tool setting surface at different repair points can be calculated based on the planar position information of the micro-defects on the optical surface obtained from the scanning microscope. This determines the tool setting feed distance for the defect point to be repaired, significantly improving tool setting efficiency. This invention eliminates the existing "reflection method" that uses the appearance of bright spots and chips as a sign of successful tool setting. Instead, it uses the tool setting indentation appearing under high magnification with a scanning microscope as the indicator of success. This avoids misjudgment caused by chips adhering to the tool tip, thus ensuring accuracy. Simultaneously, an image processing-based tool setting indentation recognition method is developed to guarantee the accuracy of the tool setting completion judgment. After tool setting, an automatic tool retraction program is added to further improve accuracy. Finally, automated control of the tool setting process is implemented through programming, completing the entire automated tool setting process design to significantly improve the repair efficiency of large-diameter optical components. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the large-diameter KDP crystal surface micro-defect repair device and automatic tool setting system in an embodiment of the present invention;

[0025] Figure 2 This is the user-facing crystal plane calibration interface in this embodiment of the invention;

[0026] Figure 3 These are gravity deformation cloud diagrams for different crystal types in embodiments of the present invention;

[0027] Figure 4 This is a diagram illustrating the process of identifying knife dents in an embodiment of the present invention.

[0028] Figure 5 This is a frequency distribution diagram of automatic blade cutting depth in an embodiment of the present invention. Detailed Implementation

[0029] In the description of this invention, it should be noted that the terms "first," "second," and "third" mentioned in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] This invention provides an automated tool setting method for repairing micro-defects on the surface of optical crystals based on dual-microscope collaboration, comprising the following steps:

[0032] Step 1: Install the large-aperture KDP crystal element, assemble and adjust the scanning microscope system and the restoration microscope system, and automatically return each axis of the crystal restoration machine tool system to zero;

[0033] Step 2: Establish a plane fitting equation for predicting the spatial position of the surface to be repaired of a large-diameter KDP crystal using the three-point "trial cutting method". Based on the established plane fitting equation, consider the gravitational deformation of the crystal element to determine the key points for dividing the fine cutting stage and the coarse cutting stage in the cutting stage, and hide and encapsulate them. Design an intuitive crystal plane calibration interface for users.

[0034] Step 3: Obtain the planar position information of micro-defects on the surface of the large-diameter KDP crystal element using a scanning microscope, move the tool below the location of the micro-defect to be repaired, and use a repair microscope to collect tool setting image information in real time. Calculate the actual distance between the tool and the crystal tool setting surface based on the "reflection method" to perform coarse tool setting.

[0035] Step 4: Use a scanning microscope to acquire real-time image information of the crystal tool surface, process the data of each frame of image, and capture the image changes of the local tool-setting area on the crystal surface before and after each tool-setting feed.

[0036] Step 5: Based on the actual distance from the tool tip to the tool setting surface estimated in Step 3, when the distance between the tool tip and the tool setting surface reaches the key point of the fine tool setting stage and the rough tool setting stage, set the program to perform fine tool setting.

[0037] Step 6: After the image of the tool-setting surface captured by the scanning microscope changes, the image processing method of "differential circle extraction" is used to process the acquired image of the tool-setting surface to obtain clear contour information of the tool-setting pit.

[0038] Step 7: Based on the image processing results of Step 6, when the minimum outer circle pixel radius of the tool setting pit reaches the preset threshold, it is used as a sign of successful tool setting, and an automatic tool retraction program is added after tool setting is completed.

[0039] like Figure 1As shown, the crystal repair machine tool mentioned in step 1 is a self-developed large-diameter KDP crystal surface micro-defect rapid search and micro-milling repair device (application number: 201310744691.1). The repair machine tool includes a scanning microscope system (X1, Y1, Z1 axes) for rapid search of crystal surface defect points and acquisition of real-time image information of the crystal tool surface during the repair process; a defect repair system (X2, Y2, Z2 axes) for three-axis linkage machining removal of defect points; and a repair microscope system (X3, Y3, Z3 axes) for acquisition of tool setting image information and calculation of the distance between the tool and the crystal tool surface. During the repair process, the tool axis is designed to be at a 45° angle with the horizontal plane, and the tool setting microscope optical axis is at a 15° angle with the horizontal plane. The tool setting process is the process of the tool being fed upward to the lower surface of the crystal.

[0040] The scanning microscope used in this repair machine is a JAI BM-500GE CCD with a resolution of 2456×2058, a maximum frame rate of 15fps, and a pixel size of 3.45μm×3.45μm. The microscope features a zoom ring (0.58X~7X) and allows manual adjustment of the zoom ring to change the microscope's magnification. The repair microscope is a Vision Imaging MV-VD200SC industrial CCD with a resolution of 1600×1200 and a maximum frame rate of 12fps. Its driver provides a C++ standard library function interface based on WDMIAT3.0, encapsulating 37 classes, 17 global functions, 4 structure types, and 25 variable types to achieve real-time image acquisition, simple image processing, and video stream processing.

[0041] The gravitational deformation of the crystal element in step 2 was obtained using the finite element simulation method.

[0042] This plane fitting equation can be used to calculate the distance between the tool and the surface to be repaired when repairing defects at different locations.

[0043] The "reflection method" described in step 3 uses the image contour detection function provided by OpenCV to determine the pixel distance between the tool entity and the reflection. Then, by calibrating the image pixel size obtained under different magnifications of the repair microscope, the visual distance between the tool and the crystal tool surface is calculated. Since there is a visual difference during the tool setting process, the image distance error caused by the visual difference is calculated by geometric relationship, so as to finally estimate the actual distance between the tool and the crystal tool surface.

[0044] In step 4, image processing and algorithm design are performed on the images acquired by the scanning microscope based on OpenCV.

[0045] In step 6, the image processing method of "subtraction and circle taking" is used to process the crystal tool surface image acquired by the scanning microscope. First, the images before and after each tool feed are subtracted and binarized. Then, the high grayscale areas of the crystal surface pits generated by the tool are subjected to dilation and erosion morphological processing to reduce noise and enhance features. Finally, the FindContours function is used to find the outer contour of the image and calculate the minimum circumcircle of the tool contour.

[0046] The method for determining the preset threshold of the minimum outer circle pixel radius of the tool setting pit in step 7 is as follows: Based on the magnification of the scanning microscope's zoom ring, calculate the theoretical size parameter c of the representative length of a single pixel. When the automatic tool setting depth of the micro-defects on the surface of the crystal element is 0.5μm, calculate the radius of the corresponding tool setting pit based on the diameter of the ball end mill, and further calculate its corresponding pixel radius, which is the pixel radius threshold of the minimum outer circle of the tool setting pit.

[0047] In this embodiment, the automatic tool setting process for micro-defects on the surface of the crystal element uses a ball end mill with a diameter of 0.5 mm. When the tool setting depth is 0.5 μm, the radius of the corresponding tool setting pit can be calculated to be 15.8 μm, which corresponds to a pixel radius of approximately 50 pixels. Therefore, when the radius of the tool setting pit after image processing is greater than 50 pixels, the tool setting is considered complete.

[0048] The method of the present invention was verified as follows:

[0049] Since this invention involves multiple process steps in its automatic tool setting method for repairing micro-defects on optical crystal surfaces based on dual-microscope collaboration, to ensure the feasibility of the solution and the effectiveness of defect detection, when testing the automatic tool setting process method according to the above steps, it is necessary to specifically implement the division of key point positions in the tool setting stage, consider the influence of crystal tilt during installation, crystal gravity deformation, and the determination of successful tool setting marks, as well as the identification of tool setting pits on the surface to be repaired.

[0050] 1) Tilting angle during crystal mounting

[0051] When a large-diameter KDP crystal is mounted on the fixture of a repair machine, it cannot be guaranteed that the surface of the crystal to be repaired is completely parallel to the scanning motion plane. Therefore, it is necessary to consider the inclination of the plane during installation, which can be determined by establishing a square equation. This invention uses a three-point calibration method outside the aperture to fit the plane equation of the lower surface of the crystal to be repaired. Three points are selected outside the aperture of the crystal element, and the three external coordinates are recorded as (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3). The plane equation is then obtained by the following formula, where A, B, C, and D are the equation coefficients.

[0052]

[0053] Figure 2 The calibration module for the crystal surface to be repaired, through manual tool setting at three points outside the aperture, can obtain the x and y values ​​of the current scanning motion system and the z value of the repair motion system. After calibration, the plane fitting equation of the crystal surface to be repaired is calculated. In the repair process of large-diameter KDP crystals, when a defect is in the repair state, the height value of the crystal surface corresponding to the current defect position coordinates can be calculated.

[0054] 2) Crystal deformation due to gravity

[0055] Commonly used large-diameter KDP crystals are mainly classified into three types based on their crystal planes: (001), Type I, and Type II. When considering gravitational deformation in simulation, material parameters, namely Poisson's ratio and elastic modulus, need to be input. Due to the anisotropy of KDP crystals, obtaining the elastic modulus is difficult. To meet the simulation requirements and obtain the material parameters, the stiffness matrix method is used. The stiffness matrix of the (001) crystal type is shown in Table 1, which represents the stiffness matrix of the (001) plane of the KDP crystal. Simultaneously, different crystals exhibit geometric angle differences. By transforming the stiffness matrix, the stiffness matrices of Type I and Type II crystal types can be obtained. Finite element simulation is performed in Workbench, yielding the results as shown below. Figure 3 The gravity deformation cloud diagram shown.

[0056] Table 1

[0057]

[0058] According to the obtained gravity deformation cloud map, the anisotropy of the crystal has a relatively small influence on the gravity deformation of the crystal. The maximum deformation of (001), Type I and Type II crystal types are 1.77 μm, 6.34 μm and 2.53 μm, respectively.

[0059] Based on existing automatic tool setting data, it can be concluded that the installation tilt difference between tool setting heights at different positions can reach 700μm. After fitting the data to a plane (goodness of fit R...), 2 =0.9989, then the fitting is considered effective. The distance z1 from the height of different tool setting positions to the fitting plane is only 14μm, which can effectively predict the tool setting height. Figure 3 b) The maximum deformation z2 caused by crystal gravity deformation is 6.34 μm. During the actual repair process, the workpiece platform moves horizontally on the machine tool. When the crystal is in different positions, the height of the same point on the crystal is not the same. Therefore, for the i-th defect point, the maximum distance difference between different tool setting positions and the fitted plane equation is... Therefore, entering the fine tool setting stage when the tool is 25μm away from the surface of the crystal to be repaired can improve tool setting efficiency and ensure the safety of the automatic tool setting stage.

[0060] 3) Determining the sign of successful tool setting

[0061] The zoom ring magnification range of a scanning microscope is 0.58–7X. To ensure accurate acquisition of the pixel radius corresponding to the tool-setting indentation in the image during automatic tool setting, a zoom ring magnification of 7X is selected for the automatic tool setting process. When the zoom ring magnification of the scanning microscope is 7X, pixel calibration yields an average pixel calibration value of 0.335 μm / pixel. Compared to the theoretical pixel calibration value of 0.328 μm / pixel, the calibration error is 0.2%, indicating that the error caused by pixel calibration is negligible. Furthermore, when processing images of the surface to be repaired, the radius of the tool setting pit obtained through image processing is generally smaller than the actual tool setting contour. This phenomenon is mainly due to the reduction in grayscale at the edge of the tool setting pit, which is filtered out. The maximum error of this process is 3.8 μm. After averaging, the error of the tool setting pit contour radius is approximately 2.11 μm. Subsequently, when measuring the depth of the tool setting pit, due to the unavoidable vibration of the tool during the tool setting process, the depth of the tool setting pit measured by the white light interferometer will be greater than the pit depth obtained from image processing, and its maximum error is 0.309 μm. Averaging the error results, the error of the tool setting pit depth is approximately 0.126 μm.

[0062] Based on the above error analysis of the radius and depth of the tool setting recess outline, the depth of the tool setting recess calculated using the radius of the circumcircle of the recess outline is compared with the actual depth of the tool setting recess measured by the white light morphology profile interferometer. The maximum error is 0.512 μm, and the average error is 0.178 μm after averaging the data. Considering the radius of curvature of the sphere, as the depth of the tool setting recess increases, the radius change of the recess becomes smaller, and the impact of the error on the result becomes greater. Therefore, the presence of a tool setting recess in the scanning microscope, with a pixel radius of 50 pixels for the circumcircle of the recess outline, can be effectively used as a marker that tool setting is complete.

[0063] 4) Development of an algorithm for identifying tool-setting pits on the surface to be repaired

[0064] Using the tool setting pit in the scanning microscope field of view as an indicator of successful tool setting, it is essential to accurately identify the tool setting pit from the scanning microscope field of view. KDP crystal element surface global micro-defect detection is a dark-field detection method, with low background grayscale and high grayscale of the tool setting pit. However, the reflection from the high-speed rotating micro-milling cutter irradiates the tool setting pit, creating a larger area of ​​high grayscale value near the pit, thus interfering with accurate pit identification. To address these issues, an OpenCV-based "subtraction and circle extraction" image processing algorithm was developed. The specific calculation process is as follows:

[0065] Step 1: During the fine tool setting stage, acquire an image of the tool setting surface after each feed motion. Images before and after the feed are shown below. Figure 4 a) and Figure 4 As shown in b), by subtracting and binarizing the two images, a clear image of the tool setting pit outline, unaffected by the tool and other unrepaired damage points, can be obtained, as shown in [example image]. Figure 4 As shown in c);

[0066] Step 2: Perform dilation and erosion morphological processing on the high-grayscale image of the tool-setting pit area, such as... Figure 4 As shown in e), this achieves the purpose of eliminating noise and enhancing object features;

[0067] Step 3: Use the FindContours function to find the outer contour of the image, such as... Figure 4 As shown in f), calculate the minimum circumcircle of the profile, as follows. Figure 4 As shown in g), the largest circumcircle is identified as the contour of the tool setting pit. When the pixel radius is greater than 50 pixels, the tool setting movement stops, and the current tool setting depth is calculated based on the pixel radius.

[0068] The above steps, using the process flow of this invention, realize the automatic tool setting function for the full-area micro-defect repair of large-aperture precision optical crystal surfaces based on dual-microscope collaboration. Experimental verification, using a white-light topography interferometer to measure the depth of the automatic tool setting pits, yielded results as shown... Figure 5 The diagram shows the frequency distribution of automatic tool cutting depth.

[0069] It can be seen that the maximum cutting depth does not exceed 2.5 μm, and the average cutting depth is 1.4 μm. Based on the above analysis, the error between the cutting pit depth calculated by scanning electron microscopy and the actual cutting pit depth does not exceed 0.512 μm. Adding a retraction motion after cutting to bring the tool back to the calculated element surface ensures that the actual distance between the tool and the element surface does not exceed 0.5 μm, meaning the cutting accuracy is better than 0.5 μm. This achieves the accuracy of automatic cutting for repairing micro-defects on the surface of large-diameter crystal elements while significantly improving the precision of automatic cutting.

[0070] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. An automatic tool setting method for repairing micro-defects on the surface of an optical crystal based on dual microscope cooperation, characterized in that, The method comprises the following steps: Step 1, install the large-diameter KDP crystal element, assemble and adjust the scanning microscope system and the repair microscope system, and automatically return the axes of the crystal repair machine tool system to zero; Step 2, establish a plane fitting equation for predicting the spatial position of the surface of the large-diameter KDP crystal to be repaired by a three-point "trial cutting method", determine the key points for dividing the fine tool setting stage and the coarse tool setting stage in the tool setting stage based on the established plane fitting equation considering the gravity deformation of the crystal element, and hide and encapsulate the key points, and design an intuitive crystal plane calibration interface for users; Step 3, acquire the plane position information of the surface micro-defects of the large-diameter KDP crystal element by the scanning microscope, move the tool to the position below the micro-defect point to be repaired, acquire the tool setting image information in real time by the repair microscope, calculate the actual distance between the tool and the tool setting surface based on the "inverted image method", and perform coarse tool setting; Step 4, acquire the real-time image information of the tool setting surface of the crystal by the scanning microscope, process the data of each frame of image, and capture the image changes of the local tool setting area of the crystal surface before and after each tool setting feed; Step 5, according to the actual distance between the tool tip and the tool setting surface estimated in step 3, when the distance between the tool tip and the tool setting surface reaches the key points of the fine tool setting stage and the coarse tool setting stage, set the program to perform fine tool setting; Step 6, after the tool setting surface image captured by the scanning microscope changes, process the acquired tool setting surface image by the "difference taking circle" image processing method to obtain clear tool setting pit contour information; Step 7, according to the result of the image processing in step 6, when the pixel radius of the minimum circumscribed circle of the tool setting pit reaches a preset threshold, the tool setting is successful, and an automatic tool retraction program is added after the tool setting is completed.

2. The automatic tool alignment method for repairing the micro-defects on the surface of the optical crystal based on the dual-microscope coordination according to claim 1, characterized in that, The crystal repair machine tool in step 1 comprises a scanning microscope system for quickly searching and acquiring real-time image information of the tool setting surface of the crystal during the repair machining process, a defect repair system for three-axis linkage machining removal of the defect point, and a repair microscope system for acquiring tool setting image information and calculating the distance between the tool and the tool setting surface of the crystal, and the tool setting process is the process of feeding the tool upward to the lower surface of the crystal.

3. The automatic tool alignment method for repairing the micro-defects on the surface of the optical crystal based on the dual-microscope coordination according to claim 2, characterized in that, The scanning microscope in step 3 is a BM-500GE type CCD of JAI, the resolution is 2456*2058, the maximum frame speed can reach 15fps, and the pixel size is 3.45μm*3.45μm; the repair microscope is an MV-VD200SC type industrial CCD of Vistek, the resolution is 1600*1200, the maximum frame speed can reach 12fps, and the driving program can provide C++ language standard library functions with WDMIAT3.0 as the interface.

4. The automatic tool alignment method for repairing the micro-defects on the surface of the optical crystal based on the dual-microscope coordination according to claim 1, characterized in that, The gravity deformation of the crystal element in step 2 is obtained by a finite element simulation method.

5. The automatic tool alignment method for repairing the micro-defects on the surface of the optical crystal based on the dual-microscope coordination according to claim 1, characterized in that, In step 6, the image processing method of "difference taking circle" is used to process the crystal tool surface image collected by the scanning microscope. First, the images before and after each tool alignment are subtracted and binarized, then the high gray area of the tool alignment generated crystal surface pit area is subjected to morphological processing of expansion and corrosion to reduce noise and enhance features, finally, the FindContours function is used to find the image external contour, and the minimum circumscribed circle of the tool alignment contour is calculated.

6. The automatic tool alignment method for repairing the micro-defects on the surface of the optical crystal based on the dual-microscope coordination according to claim 1, characterized in that, In step 7, the determination method of the preset threshold of the minimum circumscribed circle pixel radius of the tool alignment pit is as follows: according to the scanning microscope zoom ring magnification, the theoretical size parameter c of the representative length of a single pixel is calculated, when the automatic tool alignment depth of the crystal element surface micro-defect is 0.5 μm, the corresponding tool alignment pit radius is calculated according to the diameter of the ball head micro-milling cutter, and the corresponding pixel radius is further calculated, which is the pixel radius threshold of the minimum circumscribed circle of the tool alignment pit.

7. An automatic tool setting system for repairing micro-defects on the surface of an optical crystal based on the cooperation of two microscopes, characterized in that: The system has program modules corresponding to the steps of the automatic tool alignment method based on the cooperation of double microscopes for repairing optical crystal surface micro-defects according to any one of claims 1-6, and executes the steps of the automatic tool alignment method based on the cooperation of double microscopes for repairing optical crystal surface micro-defects.

8. A computer-readable storage medium, characterized in that: The computer readable storage medium stores a computer program configured to realize the steps of the automatic tool alignment method based on the cooperation of double microscopes for repairing optical crystal surface micro-defects according to any one of claims 1-6 when called by the processor.

Images