A near-zero gap measuring device, method and apparatus

Abstract

The application discloses a kind of near-zero gap measuring device, method and equipment, including micro vision displacement mechanism, alignment rectification platform, precision moving slide, marble platform, frame platform, base plate moving slide and host computer;Two ends of frame platform are fixedly connected with the upper surface two sides of marble platform;Precision moving slide is fixedly arranged in the recess of marble platform, and alignment rectification platform is movably installed on precision moving slide;Two ends of base plate moving slide are movably arranged on the upper surface two sides of marble platform, and are located between alignment rectification platform and frame platform;Micro vision displacement mechanism is arranged on the side of frame platform;Micro vision displacement mechanism acquires image and imaging position in response to instruction;Host computer carries out imaging position search to image and imaging position, and determines near-zero gap value;Solve the technical problem that existing near-zero gap measuring method is susceptible to environmental noise, resulting in that the precision of gap measurement result is not ideal.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and in particular to a near-zero gap measurement device, method and apparatus. Background Technology

[0002] With the continuous development of third-generation display technology, Mini / Micro LED display devices have become a research hotspot in display technology due to their excellent current saturation density, higher quantum efficiency, and high reliability. A crucial process in the production of Mini / Micro LED display devices is chip mass transfer, which requires the efficient and precise transfer of a large number of chips onto a circuit board.

[0003] During the Mini / Micro LED transfer and repair process, Mini / Micro LED chips need to be transferred from the carrier plate to the substrate using methods such as lasers. When the gap between the carrier plate and the substrate is large, laminar flow is easily generated during the transfer process, causing the transfer path of the MicroLED / MiniLED chip to drift and reducing the yield of the display panel. At this time, it is necessary to correct the transfer path, and quickly and accurately obtaining the gap between the carrier plate and the substrate is the prerequisite for achieving precise correction.

[0004] Most existing near-zero gap measurement methods are based on capacitive sensors, which measure the gap by detecting changes in capacitance between gaps. Three capacitive sensors can be embedded in the surface of the carrier plate and the substrate. The gap can be obtained by the values ​​of the three capacitive sensors and help with leveling. However, the range of capacitive sensors is limited and they are easily affected by environmental noise, resulting in unsatisfactory accuracy of gap measurement results. Summary of the Invention

[0005] This invention provides a near-zero gap measurement device, method, and apparatus, which solves the technical problem that most existing near-zero gap measurement methods are based on capacitive sensors to measure gaps by detecting changes in capacitance between gaps. However, capacitive sensors have limited ranges and are easily affected by environmental noise, resulting in unsatisfactory accuracy of gap measurement results.

[0006] The first aspect of the present invention provides a near-zero gap measuring device, the device comprising a microscopic visual displacement mechanism, an alignment and correction platform, a precision moving slide, a marble platform, a frame platform, a substrate moving slide, and a host computer.

[0007] The two ends of the frame platform are fixedly connected to the two sides of the upper surface of the marble platform;

[0008] The precision moving slide is fixedly disposed in the groove of the marble platform, and the alignment and correction platform is movably mounted on the precision moving slide.

[0009] The two ends of the substrate moving slide are movably disposed on both sides of the upper surface of the marble platform and are located between the alignment and correction platform and the frame platform.

[0010] The microscopic visual displacement mechanism is disposed on the side of the frame platform;

[0011] The microscopic visual displacement mechanism is communicatively connected to the host computer.

[0012] The microscopic visual displacement mechanism is used to respond to the first instruction sent by the host computer, acquire multiple substrate images of the substrate moving slide and the first imaging position corresponding to each substrate image and send them to the host computer, and then respond to the second instruction sent by the host computer to acquire multiple carrier images of the alignment and correction platform and the second imaging position corresponding to each carrier image and send them to the host computer.

[0013] The host computer is used to perform imaging position search on each of the received substrate images, each of the first imaging positions, each of the carrier plate images and each of the second imaging positions based on the improved discrete differential operator and hill climbing search algorithm, output the first target imaging position and the second target imaging position, and determine the near-zero gap value between the alignment and correction platform and the substrate moving slide.

[0014] Optionally, the microscopic vision displacement mechanism includes a microscopic vision mechanism and a nanoscale displacement stage;

[0015] The nanostage is equipped with an objective lens interface;

[0016] The nanostage is disposed on the side of the frame platform, and the microscopic vision mechanism is movably connected to the nanostage through the objective lens interface.

[0017] Both the microscopic vision mechanism and the nano-displacement stage are communicatively connected to the host computer.

[0018] The microscopic vision mechanism is used to respond to the first instruction sent by the host computer, acquire multiple substrate images of the substrate moving slide and send them to the host computer, and then respond to the second instruction sent by the host computer, acquire multiple carrier board images of the alignment and correction platform and send them to the host computer.

[0019] The nano-displacement stage is used to respond to a first instruction sent by the host computer, acquire the first imaging position corresponding to each substrate image and send it to the host computer, and then respond to a second instruction sent by the host computer, acquire the second imaging position corresponding to each carrier plate image and send it to the host computer.

[0020] Optionally, the first instruction includes a first sub-instruction and a second sub-instruction; the substrate image includes a first substrate image and a second substrate image; the second instruction includes a third sub-instruction and a fourth sub-instruction; the carrier plate image includes a first carrier plate image and a second carrier plate image; the microscopic vision mechanism is specifically used for:

[0021] In response to the first sub-instruction sent by the host computer, the first substrate image of the substrate moving slide is acquired according to a preset first step length and sent to the host computer. In response to the second sub-instruction sent by the host computer, multiple second substrate images of the substrate moving slide are acquired according to a preset second step length and sent to the host computer.

[0022] In response to the third sub-instruction sent after the host computer outputs the first target imaging position, the first carrier plate image of the alignment and correction platform is acquired according to the preset first step length and sent to the host computer. In response to the fourth sub-instruction sent by the host computer, multiple second carrier plate images of the alignment and correction platform are acquired according to the preset second step length and sent to the host computer.

[0023] Optionally, the nanoscale displacement stage is specifically used for:

[0024] In response to the second sub-instruction sent by the host computer, the system acquires the first imaging position corresponding to each of the second substrate images and sends it to the host computer. Then, in response to the fourth sub-instruction sent by the host computer, the system acquires the second imaging position corresponding to each of the second carrier board images and sends it to the host computer.

[0025] The host computer is specifically used for:

[0026] An improved discrete difference operator is used to perform convolution operation on the received first substrate image, outputting multiple grayscale values, which are then substituted into a preset first formula to output multiple center pixel values.

[0027] The average value of each center pixel is calculated to determine a first sharpness evaluation value, which is then compared with a preset sharpness threshold.

[0028] If the first sharpness evaluation value is greater than the preset sharpness threshold, the hill-climbing search algorithm and the improved discrete difference operator are used to normalize each received second substrate image, output the first sharpness trend chart and the second sharpness evaluation value corresponding to each second substrate image, and count the number of times the second substrate image is collected in real time.

[0029] When the number of acquisitions of the second substrate image reaches the preset number of acquisitions and the first clarity trend map meets the preset trend conditions, the first imaging position corresponding to the largest second clarity evaluation value is selected as the first target imaging position.

[0030] The improved discrete difference operator is used to evaluate the sharpness of the received first carrier image, and a third sharpness evaluation value is determined and compared with the preset sharpness threshold.

[0031] If the third sharpness evaluation value is greater than the preset sharpness threshold, the hill-climbing search algorithm and the improved discrete difference operator are used to normalize each received second carrier board image, output the second sharpness trend chart and the fourth sharpness evaluation value corresponding to each second carrier board image, and count the number of times the second carrier board image is collected in real time.

[0032] When the number of acquisitions of the second carrier image reaches the preset number of acquisitions and the second sharpness trend map meets the preset trend condition, the second imaging position corresponding to the largest fourth sharpness evaluation value is selected as the second target imaging position.

[0033] The difference between the first target imaging position and the second target imaging position is calculated to determine the near-zero gap value between the alignment and correction platform and the substrate moving slide.

[0034] Optionally, the calculation formula for the improved discrete difference operator is as follows:

[0035]

[0036] In the formula, for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operator.

[0037] Optionally, the host computer is further used for:

[0038] In response to a measurement request, after generating the first sub-instruction and sending it to the microscopic vision mechanism, when the first sharpness evaluation value is greater than the preset sharpness threshold, the second sub-instruction is generated and sent to the microscopic vision mechanism.

[0039] When the first imaging position corresponding to the largest second sharpness evaluation value is selected as the first target imaging position, the third sub-instruction is generated and sent to the microscopic vision mechanism.

[0040] When the third sharpness evaluation value is greater than the preset sharpness threshold, the fourth sub-instruction is generated and sent to the microscopic vision mechanism.

[0041] A near-zero gap measurement method provided by a second aspect of the present invention includes:

[0042] When multiple substrate images and the first imaging position corresponding to each substrate image are received from the microscopic visual displacement mechanism, an improved discrete difference operator and hill-climbing search algorithm are used to search for the imaging position of each substrate image and each first imaging position, and the first target imaging position is output.

[0043] When multiple carrier images and the second imaging position corresponding to each carrier image are received from the microscopic visual displacement mechanism, the improved discrete difference operator and the hill-climbing search algorithm are used to search for the imaging position of each carrier image and each second imaging position, and the second target imaging position is output.

[0044] The difference between the first target imaging position and the second target imaging position is calculated, and the near-zero gap value between the alignment correction platform and the substrate moving slide is output.

[0045] Optionally, the calculation formula for the improved discrete difference operator is as follows:

[0046]

[0047] In the formula, for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operator.

[0048] A third aspect of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the near-zero gap measurement method as described in any of the preceding claims.

[0049] As can be seen from the above technical solutions, the present invention has the following advantages:

[0050] The first aspect of the above-described technical solution of the present invention provides a near-zero gap measuring device, which includes a microscopic visual displacement mechanism, an alignment and correction platform, a precision moving slide, a marble platform, a frame platform, a substrate moving slide, and a host computer; wherein, the two ends of the frame platform are fixedly connected to the two sides of the upper surface of the marble platform; the precision moving slide is fixedly disposed in the groove of the marble platform, and the alignment and correction platform is movably mounted on the precision moving slide; the two ends of the substrate moving slide are movably disposed on the two sides of the upper surface of the marble platform and located between the alignment and correction platform and the frame platform; the microscopic visual displacement mechanism is disposed on the side of the frame platform; the microscopic visual displacement mechanism is communicatively connected to the host computer; the microscopic visual displacement mechanism is used to respond to a first instruction sent by the host computer, acquire multiple substrate images of the substrate moving slide and the first imaging position corresponding to each substrate image and send them to the host computer, and then respond to a second instruction sent by the host computer, acquire the images of the alignment and correction platform. Multiple substrate images and their corresponding second imaging positions are sent to a host computer. The host computer uses an improved discrete differential operator and hill-climbing search algorithm to search for the imaging positions of the received substrate images, first imaging positions, substrate images, and second imaging positions, outputs the first target imaging position and the second target imaging position, and determines the near-zero gap value between the alignment correction platform and the substrate moving slide. The above scheme first acquires multiple substrate images, multiple first imaging positions, multiple substrate images, and multiple second imaging positions through a microscopic visual displacement mechanism. Then, the host computer uses an improved discrete differential operator and hill-climbing search algorithm to search for the imaging positions of the received substrate images, first imaging positions, substrate images, and second imaging positions, and determines the near-zero gap value between the alignment correction platform and the substrate moving slide. This process is not affected by environmental noise and can improve the accuracy of the gap measurement results.

[0051] The second aspect of the above-described technical solution of the present invention provides a near-zero gap measurement method. When multiple substrate images and corresponding first imaging positions of each substrate image are received from a microscopic visual displacement mechanism, an improved discrete differential operator and a hill-climbing search algorithm are first used to search for imaging positions of each substrate image and each first imaging position, and a first target imaging position is output. Then, when multiple carrier plate images and corresponding second imaging positions of each carrier plate image are received from the microscopic visual displacement mechanism, an improved discrete differential operator and a hill-climbing search algorithm are used to search for imaging positions of each carrier plate image and each second imaging position. The second target imaging position is output; finally, the difference between the first target imaging position and the second target imaging position is calculated, and the near-zero gap value between the alignment correction platform and the substrate moving slide is output. In the above scheme, the process of searching for the imaging position of the image and position by using an improved discrete differential operator and a hill-climbing search algorithm, and outputting the near-zero gap value between the alignment correction platform and the substrate moving slide, is different from the existing near-zero gap measurement method which completes the gap measurement process by detecting the change in capacitance between the gaps. It does not rely on a capacitance sensor and is not affected by environmental noise, thus improving the accuracy of the gap measurement results. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of a near-zero gap measuring device provided in Embodiment 1 of the present invention;

[0054] Figure 2 This is a front view of a near-zero gap measuring device provided in Embodiment 1 of the present invention;

[0055] Figure 3 This is a top view of a near-zero gap measuring device provided in Embodiment 1 of the present invention;

[0056] Figure 4 This is a schematic diagram of the structure of the nano-displacement stage provided in Embodiment 1 of the present invention;

[0057] Figure 5 A schematic diagram of a template for a conventional Sobel gradient operator provided in Embodiment 1 of the present invention.

[0058] Figure 6 This is a schematic diagram of a 5*5 image region of a grayscale image provided in Embodiment 1 of the present invention;

[0059] Figure 7 This is a schematic diagram of the normalized sharpness trend chart provided in Embodiment 1 of the present invention;

[0060] Figure 8 A schematic diagram of a simplified model of micro-visual imaging provided in Embodiment 1 of the present invention;

[0061] Figure 9 This is a schematic diagram of the experimental setup for a near-zero gap measuring device provided in Embodiment 1 of the present invention;

[0062] Figure 10 This is a schematic diagram illustrating the coarse focusing and fine focusing process of a near-zero gap measuring device provided in Embodiment 1 of the present invention.

[0063] Figure 11 This is a flowchart illustrating the steps of a near-zero gap measurement method provided in Embodiment 2 of the present invention.

[0064] The meanings of the labels in the attached figures are as follows:

[0065] 1. Microscopic vision mechanism; 2. Nanoscale displacement stage; 3. Alignment and correction platform; 4. Precision moving slide; 5. Marble platform; 6. Substrate moving slide; 7. Frame platform; 8. Objective lens interface. Detailed Implementation

[0066] This invention provides a near-zero gap measurement device, method, and apparatus to address the technical problem that most existing near-zero gap measurement methods are based on capacitive sensors to measure gaps by detecting changes in capacitance between gaps. However, capacitive sensors have limited ranges and are easily affected by environmental noise, resulting in unsatisfactory accuracy of gap measurement results.

[0067] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0068] Please see Figures 1-3 , Figure 1 This is a schematic diagram of a near-zero gap measuring device provided in Embodiment 1 of the present invention.

[0069] This invention provides a near-zero gap measuring device, comprising a microscopic visual displacement mechanism, an alignment and correction platform 3, a precision moving slide 4, a marble platform 5, a frame platform 7, a substrate moving slide 6, and a host computer; both ends of the frame platform 7 are fixedly connected to the upper surface of the marble platform 5; the precision moving slide 4 is fixedly disposed in a groove of the marble platform 5, and the alignment and correction platform 3 is movably mounted on the precision moving slide 4; both ends of the substrate moving slide 6 are movably disposed on the upper surface of the marble platform 5, and are located between the alignment and correction platform 3 and the frame platform 7; the microscopic visual displacement mechanism is disposed on the side of the frame platform 7; the microscopic visual displacement mechanism is communicatively connected to the host computer; The micro-visual displacement mechanism is used to respond to the first command sent by the host computer, acquire multiple substrate images and the first imaging position corresponding to each substrate image of the substrate moving slide 6 and send them to the host computer, and then respond to the second command sent by the host computer, acquire multiple carrier images and the second imaging position corresponding to each carrier image of the alignment and correction platform 3 and send them to the host computer; the host computer is used to perform imaging position search on each received substrate image, each first imaging position, each carrier image and each second imaging position based on the improved discrete differential operator and hill climbing search algorithm, output the first target imaging position and the second target imaging position, and determine the near-zero gap value between the alignment and correction platform 3 and the substrate moving slide 6.

[0070] It should be noted that the installation of the microscopic vision mechanism 1 and the nano-displacement stage 2 in the microscopic vision displacement mechanism with the alignment and correction platform 3 requires strict adherence to ensure the vertical installation of the microscopic vision lens of the microscopic vision mechanism 1, and it is bolted to the marble platform 5. The frame platform 7 is made of marble and is also a type of marble platform. It is fixedly connected to both sides of the upper surface of the marble platform 5, allowing sufficient space in the center between the frame platform 7 and the marble platform 5 to install the other components. The precision moving slide 4 is an XY precision moving slide, which is equipped with the alignment and correction platform 3 and can measure the position of multiple points. Leveling and correction; the substrate moving slide 6 is a precision moving slide with a substrate, which can first allow the microscopic vision mechanism 1 to focus on the substrate and record the best imaging position (first target imaging position), and then the precision moving slide 4 is equipped with the alignment and correction platform 3 to focus on the point on the alignment and correction platform 3 and record the best imaging position (second target imaging position). The host computer calculates the difference between the best imaging position of the substrate and the best imaging position of the alignment and correction platform 3 to determine the position difference, which can be used as the measurement value of the near-zero gap between the two. By using the measurement value of the near-zero gap, the alignment and correction platform can be controlled to perform the leveling and correction process.

[0071] As a further improvement, the microscopic vision displacement mechanism includes a microscopic vision mechanism 1 and a nanostage 2; the nanostage 2 is provided with an objective lens interface 8; the nanostage 2 is disposed on the side of the frame platform 7, and the microscopic vision mechanism 1 is movably connected to the nanostage 2 through the objective lens interface 8; both the microscopic vision mechanism 1 and the nanostage 2 are communicatively connected to a host computer; the microscopic vision mechanism 1 is used to respond to a first command sent by the host computer, acquire multiple substrate images of the substrate moving slide 6 and send them to the host computer, and then respond to a second command sent by the host computer, acquire multiple carrier plate images of the alignment and correction platform 3 and send them to the host computer; the nanostage 2 is used to respond to the first command sent by the host computer, acquire the first imaging position corresponding to each substrate image and send it to the host computer, and then respond to the second command sent by the host computer, acquire the second imaging position corresponding to each carrier plate image and send it to the host computer.

[0072] Please see Figure 4 The nano-displacement stage 2 is a mechanical device containing one or more piezoelectric ceramics. These ceramics generate single-axis or multi-axis motion. It integrates a grating ruler sensing system and a capacitive sensing system, enabling real-time position feedback for micro-displacement measurement. The nano-displacement stage 2 can be divided into open-loop and closed-loop control. The open-loop control is determined by the piezoelectric ceramics, flexible structure, and mechanical structure; while this measurement technology relies more on closed-loop control. Combined with the precision sensors built into the nano-displacement stage 2, closed-loop control can achieve nanometer-level and sub-nanometer-level resolution while ensuring the linearity of the sensor technology.

[0073] Furthermore, by employing a nano-displacement stage 2 with its own sensor, the camera position can be precisely located and focused by a small step, thereby determining the position of the "ideal focusing plane". Regarding the microscopic vision mechanism 1, both the camera and the lens are mounted on the aforementioned nano-displacement stage, thereby realizing the camera's Z-axis focusing process. The microscopic vision mechanism 1 can be equipped with an MPlan Apo 10× objective lens, a TS5MSGV-36M / C camera, and a SOD-200-22C tube lens. No specific limitations are made here, as long as the system as a whole has a small depth of field (to better find the ideal focusing plane) and the microscopic vision mechanism 1 has a suitable working distance.

[0074] As a further improvement, the first instruction includes a first sub-instruction and a second sub-instruction; the substrate image includes a first substrate image and a second substrate image; the second instruction includes a third sub-instruction and a fourth sub-instruction; the carrier plate image includes a first carrier plate image and a second carrier plate image; the microscopic vision mechanism 1 is specifically used for:

[0075] In response to the first sub-instruction sent by the host computer, the first substrate image of the substrate moving slide 6 is acquired according to the preset first step length and sent to the host computer. In response to the second sub-instruction sent by the host computer, multiple second substrate images of the substrate moving slide 6 are acquired according to the preset second step length and sent to the host computer.

[0076] After responding to the third sub-instruction sent by the host computer after outputting the first target imaging position, the first carrier plate image of the alignment and correction platform 3 is acquired according to the preset first step length and sent to the host computer. Then, in response to the fourth sub-instruction sent by the host computer, multiple second carrier plate images of the alignment and correction platform 3 are acquired according to the preset second step length and sent to the host computer.

[0077] Optionally, the nanometer displacement stage is specifically used to: respond to a second sub-instruction sent by the host computer, acquire the first imaging position corresponding to each second substrate image and send it to the host computer, and respond to a fourth sub-instruction sent by the host computer, acquire the second imaging position corresponding to each second carrier plate image and send it to the host computer.

[0078] Optionally, the host computer is also used for:

[0079] In response to the measurement request, after generating the first sub-instruction and sending it to the microscopic vision mechanism 1, when the first sharpness evaluation value is greater than the preset sharpness threshold, a second sub-instruction is generated and sent to the microscopic vision mechanism 1.

[0080] When the first imaging position corresponding to the largest second sharpness evaluation value is selected as the first target imaging position, a third sub-instruction is generated and sent to the microscopic vision mechanism 1.

[0081] When the third sharpness evaluation value is greater than the preset sharpness threshold, a fourth sub-instruction is generated and sent to the microscopic vision mechanism 1.

[0082] It should be noted that when it is necessary to measure the near-zero gap value, the host computer generates a first sub-instruction and sends it to the microscopic vision mechanism 1. The microscopic vision mechanism 1 responds to the first sub-instruction and performs a coarse focusing process on the substrate moving slide 6. It moves up and down in large steps (preset first step length), stopping image acquisition after each step length is completed. The host computer evaluates the sharpness and obtains a score, which is then compared with a preset threshold. If the score is higher than the threshold, it indicates that coarse focusing is complete. That is, the first substrate image of the substrate moving slide 6 is acquired with the preset first step length and sent to the host computer. The host computer uses an improved discrete differential operator to evaluate the sharpness of the received first substrate image, determines a first sharpness evaluation value, and compares it with a preset sharpness threshold. If it is greater than the preset sharpness threshold, it indicates that the coarse focusing process on the substrate moving slide 6 is complete, and a second sub-instruction is generated and sent to the microscopic vision mechanism 1. The sensing mechanism 1 responds to the second sub-instruction and, based on the completion of the coarse focusing process, performs a fine focusing process on the substrate moving slide 6. It moves in one direction with a small step size (preset second step size) and stops image acquisition after each step size is completed. That is, based on the completion of the coarse focusing process, it acquires multiple second substrate images of the substrate moving slide 6 with a preset second step size and sends them to the host computer. The host computer normalizes each received second substrate image using a hill-climbing search algorithm and an improved discrete difference operator, outputs a first sharpness trend map and a second sharpness evaluation value corresponding to each second substrate image, and counts the number of times the second substrate images are acquired in real time. If the number of times the second substrate images are acquired reaches the preset number of acquisitions and the first sharpness trend map meets the preset trend conditions, then the first imaging position corresponding to the largest second sharpness evaluation value is selected as the first target imaging position. Thus, the fine focusing process of the substrate moving slide 6 is completed.

[0083] Furthermore, the focusing process needs to be performed once for surface 1 (substrate moving slide 6) and once for surface 2 (alignment and correction platform 3). Finally, the difference between the optimal imaging positions fed back by the two nano-displacement stages 2 is calculated as the near-zero gap distance between surface 1 and surface 2, thereby realizing the measurement of near-zero gap.

[0084] Specifically, after the fine focusing process of the substrate moving slide 6 is completed, the host computer will generate the third sub-instruction and the fourth sub-instruction in sequence, thereby starting the coarse focusing and fine focusing of the alignment and correction platform 3. The coarse focusing and fine focusing processes of the alignment and correction platform 3 are consistent with the coarse focusing and fine focusing processes of the substrate moving slide 6. First, the sharpness of the first carrier plate image is evaluated by the improved discrete difference operator. If the output sharpness value is greater than the threshold, the hill climbing search algorithm and the improved discrete difference operator are used to normalize each second carrier plate image until the second target imaging position is output.

[0085] Furthermore, the hill-climbing search algorithm starts from a point in the solution space and continuously moves towards adjacent points until a local optimum is reached where no further movement is possible. According to the background of this method, the implementation process involves using the sharpness evaluation score as a basis while the nano-displacement stage 2 moves, resulting in a series of discrete point coordinates. When the discrete points show an increasing trend, the movement direction of the nano-displacement stage 2 is determined, and the sharpness evaluation scores of its neighboring positions are continuously judged. The maximum sharpness value is determined through continuous iteration of the hill-climbing algorithm. As the camera position changes, the trend of the sharpness evaluation score shows a unimodal characteristic. Simultaneously, the fine focusing process is performed based on the coarse focusing process, thereby obtaining a local optimum.

[0086] As a further improvement, the host computer is specifically used for:

[0087] An improved discrete difference operator is used to perform convolution operation on the received first substrate image, outputting multiple grayscale values, which are then substituted into a preset first formula to output multiple center pixel values.

[0088] The average value of each center pixel is calculated to determine the first sharpness evaluation value and compared with the preset sharpness threshold;

[0089] If the first sharpness evaluation value is greater than the preset sharpness threshold, the hill-climbing search algorithm and the improved discrete difference operator are used to normalize each received second substrate image, output the first sharpness trend chart and the second sharpness evaluation value corresponding to each second substrate image, and count the number of times the second substrate image is collected in real time.

[0090] When the number of acquisitions of the second substrate image reaches the preset number of acquisitions and the first sharpness trend chart meets the preset trend conditions, the first imaging position corresponding to the largest second sharpness evaluation value is selected as the first target imaging position.

[0091] An improved discrete difference operator is used to evaluate the sharpness of the received first carrier image, and a third sharpness evaluation value is determined and compared with a preset sharpness threshold.

[0092] If the third sharpness evaluation value is greater than the preset sharpness threshold, the hill-climbing search algorithm and the improved discrete difference operator are used to normalize each received second carrier board image, output the second sharpness trend chart and the fourth sharpness evaluation value corresponding to each second carrier board image, and count the number of times the second carrier board image is collected in real time.

[0093] When the number of acquisitions of the second carrier image reaches the preset number of acquisitions and the second sharpness trend map meets the preset trend conditions, the second imaging position corresponding to the largest fourth sharpness evaluation value is selected as the second target imaging position.

[0094] The difference between the imaging positions of the first target and the imaging positions of the second target is calculated to determine the near-zero gap value between the alignment and correction platform and the substrate moving slide.

[0095] Optionally, the calculation formula for the improved discrete difference operator is as follows:

[0096]

[0097] In the formula, for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operator.

[0098] It should be noted that you should refer to [link / reference]. Figure 5 Traditional sharpness evaluation operators, such as the Roberts operator and the Prewitt operator, have limitations. The Sobel gradient operator, as a traditional evaluation operator, is constructed based on the classic Pascal's triangle. Figure 5 The template shown serves as a mask, and convolution processing of the image yields the image contour. The quality of the contour is then used as the basis for sharpness evaluation, demonstrating good evaluation performance. However, the traditional Sobel gradient operator is limited to the X and Y directions, and its processing effect is not ideal for images whose contours are not horizontal or vertical. Therefore, this invention improves the traditional Sobel operator by expanding and extending the 3*3 template of the original Sobel operator, making multi-directional improvements, and introducing multiple directional gradients to obtain an improved discrete difference operator (improved Sobel operator). This can obtain more accurate edges and improve the sensitivity and accuracy of the sharpness evaluation system.

[0099] Further, please refer to Figure 6During the coarse focusing process of the image, the host computer first uses an improved discrete difference operator to perform convolution operations on the received image, outputting multiple grayscale values. The convolution process of the image can be regarded as a convolution template moving on an image. Then, the corresponding positions of the area covered by each convolution template are multiplied and summed to obtain the output value of the center pixel. The grayscale image is displayed in the form of pixel grids. The image is scanned and divided into 5*5 areas, where f represents the grayscale value of each position and the subscript (11, 12, ..., 55) represents the position. The convolution process involves multiplying the gray values ​​of a 5x5 image region with the corresponding positions of the improved Sobel operator template and summing the results to output the center pixel value. Specifically, it uses eight discrete difference operators from the improved discrete difference operator to perform convolution operations on the image, outputting eight gray sum values. These eight gray sum values ​​are then substituted into a preset first formula to calculate the eight center pixel values. Finally, the mean of the eight center pixel values ​​is calculated to output a sharpness evaluation value. The gray sum values ​​include the first gray sum value, the second gray sum value, the third gray sum value, and the fourth gray sum value.

[0100] Specifically, the computational principles of the eight discrete difference operators in the improved discrete difference operator are consistent; the difference lies in the matrix elements in each discrete difference operator. Discrete difference operators For example, using The discrete difference operator convolves the image using a template, outputting the first, second, third, and fourth gray-level sum values. The specific calculation process is as follows:

[0101] , , , ;

[0102] In the formula, A is the first grayscale sum; B is the second grayscale sum; C is the third grayscale sum; D is the fourth grayscale sum; f 11 f is the grayscale value of the first row and first column of the image; 12 This represents the grayscale value of the first row and second column in the image.

[0103] Next, the sum of the first, second, third, and fourth gray levels is substituted into the preset first formula to output the center pixel value. The specific calculation process is as follows:

[0104]

[0105] In the formula, A is the center pixel value; B is the first grayscale value; C is the second grayscale value; D is the third grayscale value; and D is the fourth grayscale value.

[0106] The first preset formula is as follows:

[0107]

[0108] In the formula, For the first The center pixel value output by the discrete difference operator; For the first The first gray level and value output by the discrete difference operator; For the first The second grayscale value output by the discrete difference operator; For the first The third gray level and value output by the discrete difference operator; For the first The fourth gray level value output by the discrete difference operator.

[0109] For example, the coarse focusing process is as follows: the nanoscale displacement stage 2 with the microscopic vision mechanism 1 moves up and down in large steps and stops to acquire images after each step. The host computer performs a sharpness evaluation and obtains a score, which is then compared with a previously preset threshold. If the score is higher than the threshold, it indicates that coarse focusing is complete. The sharpness evaluation process is as follows: the image is acquired through the imaging mechanism of the focusing plane; the image is processed by spatial convolution using the improved sharpness evaluation function; the spatial convolution result is calculated using a newly proposed calculation method; and the gray values ​​of the obtained contour image are averaged to obtain the sharpness evaluation result.

[0110] Further, please refer to Figure 7 After the initial coarse focusing of the image, the next step is fine focusing. The host computer uses an improved discrete difference operator to evaluate image sharpness and also employs a hill-climbing search algorithm to determine the trend of the sharpness score. As the amount of acquired image data increases, it will output results such as... Figure 7 The image sharpness trend chart is shown. For example, taking the results of 10 image acquisitions as an example, let's assume F... n-1 F n The sharpness evaluation value is calculated based on the sharpness evaluation values ​​of two adjacent images acquired within the search range. The effective factor C is then determined accordingly. fn If C fn The preset sharpness change trend judgment factor e (which can be set as needed, without specific limitations here) describes the sharpness function evaluation value as "effectively increased" and the number of "effectively increased" Up. n Then increase by 1, when Up n If the value is >6, the sharpness function evaluation value is considered to be on an upward trend, and the search direction is correct; if C fn<-e, indicates the "effective decrease" in the sharpness function evaluation value, and the number of "effective decreases" in the DOM. n Then increase by 1, when the DOM n If the value is >6, the sharpness function evaluation value is considered to be on a downward trend, indicating an incorrect search direction; if Up n With DOM n If all values ​​are less than 6, then follow Up. n With DOM n The value of Up is used to determine the trend of clarity changes, thereby determining the search direction. n DOM n If the sharpness function evaluation value is on an upward trend, then the search direction is correct. n <DOM n If the sharpness function evaluation value is considered to be decreasing, then the search direction is incorrect; proceed to the next interval according to the determined direction, repeat the above judgment strategy to determine the sharpness change trend again, and thus output a sharpness trend map; when the number of image acquisitions reaches the preset number of acquisitions and the sharpness trend map meets the preset trend conditions, then the imaging position corresponding to the highest sharpness evaluation value is selected as the target imaging position. The preset trend condition is that the score value in the sharpness trend map shows an increasing trend, indicating that the condition is met; effective factor C fn The calculation formula is as follows:

[0111]

[0112] In the formula, C fn F is the effective factor. n F represents the image sharpness evaluation value for the nth acquisition number; n-1 This is the image sharpness evaluation value for the (n-1)th acquisition of the image; n is the number of times the image has been acquired.

[0113] For example, the fine focusing process is as follows: the nanostage 2 with the microscopic vision mechanism 1 moves in a single direction with small steps and stops to acquire images after each step. The host computer evaluates the sharpness, obtains a score, and judges the trend of the score. If the score value increases with the increase of acquired data, the nanostage 2 moves in this direction; if the score value decreases with the increase of acquired data, the nanostage 2 moves in the opposite direction (which can be considered part of the hill-climbing search algorithm process). In addition to acquiring images and evaluating sharpness, it is necessary to determine whether the sharpness score is the maximum value. If the sharpness score is the maximum value, the position fed back by the nanostage 2 is recorded as the best imaging position on the object surface; if the sharpness score is not the maximum value, the movement direction of the nanostage is determined by the hill-climbing search algorithm to continue searching for the best imaging position.

[0114] Please see Figure 8 In the process of imaging in an optical microscopy vision system, when the object under test is within the depth of field, the sharpness of the CCD / CMOS image will change as the focal plane moves along the axis; the plane that captures the sharpest image is defined as the "ideal focal plane". Figure 8 The simplified model of microscopic vision imaging is shown in the image below. The range in which the image can be clearly imaged is called the depth of field, which is divided into the foreground depth of field and the background depth of field. The "ideal focal plane" is theoretically located at the boundary between the foreground depth of field and the background depth of field. When the object being measured deviates from the reference plane and is located at position P1 or P2, leaving the "focal plane", it will cause a circular diffusion range to appear on the CMOS / CCD, and the image will become blurry, and the sharpness evaluation score will decrease.

[0115] Further, please refer to Figure 9 After coarse and fine focusing are completed on the substrate moving slide 6 and the alignment and correction platform 3, respectively, based on the aforementioned focusing plane formation mechanism, the distance between the ideal focusing plane and the imaging plane is fixed, meaning it is not affected by any environmental factors. Therefore, the role of the microscopic vision mechanism 1 in near-zero gap measurement can be considered as a "sensor." The near-zero gap distance can be read from the feedback value of the nanometer displacement stage. That is, when the camera can clearly image the object surface, the working distance L can be considered constant. Therefore, only the difference between the two camera positions needs to be considered. The positional difference between surfaces 1 and 2 can be obtained by measurement. Specifically, through the aforementioned host computer calculation process, the camera focuses on surface 1 (substrate moving slide 6) and surface 2 (alignment and correction platform 3) respectively, thus completing the coarse focusing process of substrate moving slide 6 and fine focusing process of alignment and correction platform 3. Furthermore, the optimal imaging positions Z1 (first target imaging position) and Z2 (second target imaging position) are obtained from the values ​​fed back by the sensing system of nanometer displacement stage 2. Therefore, the optimal imaging positions can be obtained by calculating the position difference (near-zero gap value) of the camera in the two scenarios. .

[0116] For example, please refer to Figure 10First, a coarse focusing process is performed. The camera (microscopic vision mechanism 1) takes pictures to acquire images of surface 1 (substrate moving slide 6) (substrate image). Then, the image sharpness is evaluated by the improved discrete differential operator of the host computer. If the score is less than the threshold, the microscopic vision mechanism 1 continues to acquire substrate images with a large step size. If the score is greater than the threshold, the fine focusing process is entered. The microscopic vision mechanism 1 acquires substrate images with a small step size. The substrate image is scored by using an improved discrete differential operator, and the scoring trend is predicted by a hill climbing search algorithm. If the number of acquisitions reaches the threshold and the scoring trend meets the preset conditions, the target position is output. The coarse and fine focusing processes of surface 2 (alignment correction platform 3) are the same as those of surface 1 (substrate moving slide 6).

[0117] In this embodiment of the invention, a near-zero gap measuring device is provided. The device includes a microscopic visual displacement mechanism, an alignment and correction platform, a precision moving slide, a marble platform, a frame platform, a substrate moving slide, and a host computer. The frame platform is fixedly connected at both ends to the upper surface of the marble platform. The precision moving slide is fixedly disposed within a groove in the marble platform, and the alignment and correction platform is movably mounted on the precision moving slide. The substrate moving slide is movably disposed at both ends on the upper surface of the marble platform and located between the alignment and correction platform and the frame platform. The microscopic visual displacement mechanism is disposed on the side of the frame platform. The microscopic visual displacement mechanism is communicatively connected to the host computer. In response to a first command sent by the host computer, the microscopic visual displacement mechanism acquires multiple substrate images from the substrate moving slide and the first imaging position corresponding to each substrate image, and sends these to the host computer. Then, in response to a second command sent by the host computer, it acquires multiple substrate images from the alignment and correction platform. Each substrate image and its corresponding second imaging position are sent to the host computer. The host computer uses an improved discrete differential operator and hill-climbing search algorithm to search for the imaging positions of each received substrate image, each first imaging position, each substrate image, and each second imaging position, outputs the first target imaging position and the second target imaging position, and determines the near-zero gap value between the alignment correction platform and the substrate moving slide. The above scheme first acquires multiple substrate images, multiple first imaging positions, multiple substrate images, and multiple second imaging positions through a microscopic visual displacement mechanism, and then uses the host computer to search for the imaging positions of each received substrate image, each first imaging position, each substrate image, and each second imaging position based on an improved discrete differential operator and hill-climbing search algorithm to determine the near-zero gap value between the alignment correction platform and the substrate moving slide. This process is not affected by environmental noise and can improve the accuracy of the gap measurement results.

[0118] Please see Figure 11 , Figure 11 This is a flowchart illustrating the steps of a near-zero gap measurement method provided in Embodiment 2 of the present invention.

[0119] The present invention provides a near-zero gap measurement method, comprising:

[0120] Step 1101: When multiple substrate images and the first imaging position corresponding to each substrate image are received from the microscopic visual displacement mechanism, the improved discrete differential operator and hill-climbing search algorithm are used to search for the imaging position of each substrate image and each first imaging position, and the first target imaging position is output.

[0121] Optionally, the calculation formula for the improved discrete difference operator is as follows:

[0122]

[0123] In the formula, for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operators; for Discrete difference operator.

[0124] In this embodiment, when multiple substrate images and the first imaging position corresponding to each substrate image are received from the microscopic visual displacement mechanism, an improved discrete differential operator and hill-climbing search algorithm are used to search for the imaging position of each substrate image and each first imaging position, and the first target imaging position is output.

[0125] Step 1102: When multiple carrier images and the corresponding second imaging positions of each carrier image are received from the microscopic visual displacement mechanism, the improved discrete difference operator and hill-climbing search algorithm are used to search for the imaging positions of each carrier image and each second imaging position, and the second target imaging position is output.

[0126] In this embodiment, when multiple carrier images and corresponding second imaging positions of each carrier image are received from the microscopic visual displacement mechanism, an improved discrete difference operator and hill-climbing search algorithm are used to search for imaging positions of each carrier image and each second imaging position, and the second target imaging position is output.

[0127] Step 1103: Perform a difference calculation on the imaging positions of the first target and the second target, and output the near-zero gap value between the alignment correction platform and the substrate moving slide.

[0128] In this embodiment, the difference between the imaging positions of the first target and the imaging positions of the second target is calculated, and the near-zero gap value between the alignment correction platform and the substrate moving slide is output.

[0129] In this embodiment of the invention, a near-zero gap measurement method is provided. When multiple substrate images and corresponding first imaging positions are received from a microscopic visual displacement mechanism, an improved discrete difference operator and hill-climbing search algorithm are first used to search for imaging positions of each substrate image and each first imaging position, outputting a first target imaging position. Then, when multiple carrier plate images and corresponding second imaging positions are received from the microscopic visual displacement mechanism, an improved discrete difference operator and hill-climbing search algorithm are used to search for imaging positions of each carrier plate image and each second imaging position, outputting a first target imaging position. The second target imaging position is determined; finally, the difference between the first target imaging position and the second target imaging position is calculated, and the near-zero gap value between the alignment correction platform and the substrate moving slide is output. In the above scheme, the process of searching for the imaging position of the image and position by using an improved discrete differential operator and a hill-climbing search algorithm, and outputting the near-zero gap value between the alignment correction platform and the substrate moving slide, is different from the existing near-zero gap measurement method which completes the gap measurement process by detecting the change in capacitance between the gaps. It does not rely on a capacitance sensor and is not affected by environmental noise, thus improving the accuracy of the gap measurement results.

[0130] This invention also provides an electronic device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor performs the near-zero gap measurement method as described in Embodiment 2 above.

[0131] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0132] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0133] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A near-zero gap measuring device, characterized in that, The device includes a microscopic visual displacement mechanism, an alignment and correction platform, a precision moving slide, a marble platform, a frame platform, a substrate moving slide, and a host computer. The two ends of the frame platform are fixedly connected to the two sides of the upper surface of the marble platform; The precision moving slide is fixedly disposed in the groove of the marble platform, and the alignment and correction platform is movably mounted on the precision moving slide. The two ends of the substrate moving slide are movably disposed on both sides of the upper surface of the marble platform and are located between the alignment and correction platform and the frame platform. The microscopic visual displacement mechanism is disposed on the side of the frame platform; The microscopic visual displacement mechanism is communicatively connected to the host computer. The microscopic visual displacement mechanism is used to respond to the first instruction sent by the host computer, acquire multiple substrate images of the substrate moving slide and the first imaging position corresponding to each substrate image and send them to the host computer, and then respond to the second instruction sent by the host computer to acquire multiple carrier images of the alignment and correction platform and the second imaging position corresponding to each carrier image and send them to the host computer. The host computer is used to perform imaging position search on each of the received substrate images, each of the first imaging positions, each of the carrier images and each of the second imaging positions based on the improved discrete differential operator and hill climbing search algorithm, output the first target imaging position and the second target imaging position, and determine the near-zero gap value between the alignment and correction platform and the substrate moving slide. When multiple substrate images and the first imaging position corresponding to each substrate image are received from the microscopic visual displacement mechanism, an improved discrete difference operator and hill-climbing search algorithm are used to search for the imaging position of each substrate image and each first imaging position, and the first target imaging position is output. When multiple carrier images and the second imaging position corresponding to each carrier image are received from the microscopic visual displacement mechanism, the improved discrete difference operator and the hill-climbing search algorithm are used to search for the imaging position of each carrier image and each second imaging position, and the second target imaging position is output. The difference between the first target imaging position and the second target imaging position is calculated, and the near-zero gap value between the alignment correction platform and the substrate moving slide is output.

2. The near-zero gap measuring device according to claim 1, characterized in that, The microscopic vision displacement mechanism includes a microscopic vision mechanism and a nano-displacement stage; The nanostage is equipped with an objective lens interface; The nanostage is disposed on the side of the frame platform, and the microscopic vision mechanism is movably connected to the nanostage through the objective lens interface. Both the microscopic vision mechanism and the nano-displacement stage are communicatively connected to the host computer. The microscopic vision mechanism is used to respond to the first instruction sent by the host computer, acquire multiple substrate images of the substrate moving slide and send them to the host computer, and then respond to the second instruction sent by the host computer, acquire multiple carrier board images of the alignment and correction platform and send them to the host computer. The nano-displacement stage is used to respond to a first instruction sent by the host computer, acquire the first imaging position corresponding to each substrate image and send it to the host computer, and then respond to a second instruction sent by the host computer, acquire the second imaging position corresponding to each carrier plate image and send it to the host computer.

3. The near-zero gap measuring device according to claim 2, characterized in that, The first instruction includes a first sub-instruction and a second sub-instruction; the substrate image includes a first substrate image and a second substrate image; the second instruction includes a third sub-instruction and a fourth sub-instruction; the carrier plate image includes a first carrier plate image and a second carrier plate image; the microscopic vision mechanism is specifically used for: In response to the first sub-instruction sent by the host computer, the first substrate image of the substrate moving slide is acquired according to a preset first step length and sent to the host computer. In response to the second sub-instruction sent by the host computer, multiple second substrate images of the substrate moving slide are acquired according to a preset second step length and sent to the host computer. In response to the third sub-instruction sent after the host computer outputs the first target imaging position, the first carrier plate image of the alignment and correction platform is acquired according to the preset first step length and sent to the host computer. In response to the fourth sub-instruction sent by the host computer, multiple second carrier plate images of the alignment and correction platform are acquired according to the preset second step length and sent to the host computer.

4. The near-zero gap measuring device according to claim 3, characterized in that, The nanoscale displacement stage is specifically used for: In response to the second sub-instruction sent by the host computer, the system acquires the first imaging position corresponding to each of the second substrate images and sends it to the host computer. Then, in response to the fourth sub-instruction sent by the host computer, the system acquires the second imaging position corresponding to each of the second carrier board images and sends it to the host computer.

5. The near-zero gap measuring device according to claim 4, characterized in that, The host computer is specifically used for: An improved discrete difference operator is used to perform convolution operation on the received first substrate image, outputting multiple grayscale values, which are then substituted into a preset first formula to output multiple center pixel values. The average value of each center pixel is calculated to determine a first sharpness evaluation value, which is then compared with a preset sharpness threshold. If the first sharpness evaluation value is greater than the preset sharpness threshold, the hill-climbing search algorithm and the improved discrete difference operator are used to normalize each received second substrate image, output the first sharpness trend chart and the second sharpness evaluation value corresponding to each second substrate image, and count the number of times the second substrate image is collected in real time. When the number of acquisitions of the second substrate image reaches the preset number of acquisitions and the first clarity trend map meets the preset trend conditions, the first imaging position corresponding to the largest second clarity evaluation value is selected as the first target imaging position. The improved discrete difference operator is used to evaluate the sharpness of the received first carrier image, and a third sharpness evaluation value is determined and compared with the preset sharpness threshold. If the third sharpness evaluation value is greater than the preset sharpness threshold, the hill-climbing search algorithm and the improved discrete difference operator are used to normalize each received second carrier board image, output the second sharpness trend chart and the fourth sharpness evaluation value corresponding to each second carrier board image, and count the number of times the second carrier board image is collected in real time. When the number of acquisitions of the second carrier image reaches the preset number of acquisitions and the second sharpness trend map meets the preset trend condition, the second imaging position corresponding to the largest fourth sharpness evaluation value is selected as the second target imaging position. The difference between the first target imaging position and the second target imaging position is calculated to determine the near-zero gap value between the alignment and correction platform and the substrate moving slide.

6. The near-zero gap measuring device according to claim 5, characterized in that, The calculation formula for the improved discrete difference operator is as follows: In the formula, It is a 0° discrete difference operator; It is a 45° discrete difference operator; It is a 90° discrete difference operator; It is a 135° discrete difference operator; It is a 180° discrete difference operator; It is a 225° discrete difference operator; It is a 270° discrete difference operator; It is a 315° discrete difference operator.

7. The near-zero gap measuring device according to claim 5, characterized in that, The host computer is also used for: In response to a measurement request, after generating the first sub-instruction and sending it to the microscopic vision mechanism, when the first sharpness evaluation value is greater than the preset sharpness threshold, the second sub-instruction is generated and sent to the microscopic vision mechanism. When the first imaging position corresponding to the largest second sharpness evaluation value is selected as the first target imaging position, the third sub-instruction is generated and sent to the microscopic vision mechanism. When the third sharpness evaluation value is greater than the preset sharpness threshold, the fourth sub-instruction is generated and sent to the microscopic vision mechanism.

Images