A calibration plate

Abstract

The utility model discloses a kind of calibration plate, for the calibration of semiconductor wafer defect detection equipment, including calibration plate base body and the calibration pattern group being set on calibration plate base body;Calibration pattern group includes first calibration pattern and second calibration pattern, first calibration pattern includes multiple interval settings stripe grating line, the line width of stripe grating line is equal with the line distance between adjacent stripe grating line;Second calibration pattern includes at least one first long straight line and at least three second short straight lines, first long straight line and second short straight line are mutually orthogonal, and the extension direction of stripe grating line is parallel with the extension direction of first long straight line.By the above structure, the calibration plate can be used for the evaluation of dark field illumination uniformity, and can be completed with line scanning camera posture and calibration plate azimuth angle debugging, reduce the repeated positioning error generated by replacing different calibration plate, improve the calibration efficiency and detection stability of wafer defect detection equipment.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor optical detection technology, and specifically relates to a calibration board. Background Technology

[0002] Semiconductor wafer defect inspection equipment is typically used for automated optical inspection of wafer surfaces to detect particles, scratches, contamination, film layer abnormalities, and pattern defects. As wafer manufacturing processes advance towards smaller linewidths and higher integration densities, wafer defect inspection equipment faces increasingly higher demands for accuracy, repeatability, and stability of inspection results. For high-speed scanning and high-precision mosaic wafer defect inspection equipment, the relative positions of the line scan camera, illumination optical path, and motion platform directly affect image acquisition quality. During long-term operation, the equipment may also be affected by mechanical vibrations, platform motion errors, and changes in light source posture. Therefore, regular calibration and excitation of the camera, illumination optical path, and motion mechanism are necessary to ensure the accuracy of the inspection data.

[0003] Existing automated optical inspection equipment for semiconductors typically includes two types of optical inspection methods: bright-field imaging and dark-field imaging. Bright-field imaging primarily relies on reflected light to form images, and the evaluation of bright-field illumination uniformity and the flat-field correction of the bright-field camera are relatively easy to implement. Dark-field imaging, on the other hand, usually utilizes ring light or obliquely incident light to acquire defect scattering signals. Its illumination uniformity is affected not only by the intensity distribution of the light source but also by factors such as the working distance of the dark-field ring light, the incident angle, the light source orientation, and the camera orientation. Especially when adapting to different defect characteristics, the illumination angle or working distance of the dark-field ring light may need to be adjusted, and changes in the working distance and illumination angle further affect the illumination uniformity across the entire field of view.

[0004] In dark field testing, without a suitable calibration pattern for evaluating the uniformity of dark field illumination, it is difficult to intuitively determine the grayscale distribution of the dark field ring light across the entire field of view, and it is also difficult to provide stable and effective raw image data for the flat field correction of dark field cameras. If only ordinary reflectors, bright field calibration plates, or single line patterns are used for debugging, it is often impossible to simultaneously meet multiple requirements such as evaluating the uniformity of dark field illumination, adjusting the azimuth angle of the line scan camera, adjusting the camera's levelness, and calibrating the optical magnification. This leads to the need to frequently change different calibration plates during equipment debugging, increasing clamping errors and repeatability errors, and reducing calibration efficiency. Utility Model Content

[0005] To address the aforementioned issues, this invention provides a calibration plate that enables the evaluation of dark field illumination uniformity through a specific pattern structure, while also accommodating camera attitude calibration, bright field flat field correction, and optical system magnification calibration, thereby improving the debugging efficiency and detection stability of wafer defect detection equipment.

[0006] The technical solution provided by this utility model is as follows: A calibration board for calibration of a semiconductor wafer defect detection equipment, comprising a calibration board substrate and a set of calibration patterns disposed on the calibration board substrate; The calibration pattern set includes a first calibration pattern and a second calibration pattern; The first calibration pattern includes multiple spaced striped grid lines, the line width of which is equal to the line spacing between adjacent striped grid lines; The second calibration pattern includes at least one first long straight line and at least three second short straight lines, wherein the first long straight line and the second short straight lines are orthogonal to each other; The extension direction of the striped grid lines in the first calibration pattern is parallel to the extension direction of the first long straight line in the second calibration pattern.

[0007] In some embodiments, the stripe grid lines, the first long straight line, and the second short straight line are all chromium lines formed on the surface of the calibration plate substrate.

[0008] In some implementations, the linewidth of the stripe grid corresponds to the minimum optical resolution of the optical system to be calibrated.

[0009] In some implementations, the width of the pattern area of ​​the first calibration pattern is greater than the ratio of the target surface size of the camera to be calibrated to the magnification of the optical system to be calibrated, so that the first calibration pattern covers the maximum single field of view of the camera to be calibrated.

[0010] In some implementations, the length of the first long straight line is not less than the diameter of the wafer to be tested, and the length of the second short straight line is not less than the single-frame field of view width of the camera to be calibrated.

[0011] In some implementations, the straightness of the first long straight line is better than half of the minimum optical resolution of the optical system to be calibrated.

[0012] In some implementations, the perpendicularity between the first long line and the second short line satisfies the condition that the horizontal jigsaw misalignment caused by the perpendicularity error is less than one pixel.

[0013] In some embodiments, the calibration pattern set further includes a third calibration pattern, which is a highly reflective film or a planar mirror layer disposed on the calibration plate substrate, and the size of the third calibration pattern covers a single field of view of the camera to be calibrated.

[0014] In some embodiments, the calibration pattern set further includes a fourth calibration pattern, which includes a dot array in which each dot has the same diameter and the spacing between adjacent dots is fixed.

[0015] In some implementations, the calibration plate substrate is a transparent glass substrate, a silicon substrate, or a ceramic substrate, and the surface flatness of the calibration plate substrate meets the depth-of-field requirements of the camera to be calibrated at its maximum magnification.

[0016] In summary, the beneficial effects of this utility model are as follows: (1) This utility model sets a first calibration pattern on the calibration plate substrate. The first calibration pattern includes multiple stripe grid lines with equal line width and spacing, enabling the camera to obtain periodic and resolvable scattering images under dark illumination conditions. As a result, the uniformity of illumination of dark ring light can be evaluated by the grayscale response of different field of view areas, and stable raw image data can be provided for the flat field correction of dark field cameras, thereby improving the accuracy and visualization of dark field illumination adjustment.

[0017] (2) This utility model provides a second calibration pattern on the calibration plate substrate. The second calibration pattern includes at least one first long straight line and at least three second short straight lines orthogonal to it, and the stripe grid lines in the first calibration pattern are parallel to the first long straight line. This allows the calibration plate to simultaneously perform dark field illumination uniformity evaluation and camera attitude calibration functions. With this structure, dark field optical path evaluation, calibration plate azimuth adjustment, and line scan camera attitude debugging can be completed under the same calibration reference, reducing the repeated positioning error caused by changing the calibration plate and improving the calibration efficiency and detection stability of the wafer defect detection equipment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is an enlarged view of the new calibration pattern set for this utility model.

[0019] The attached figures are labeled as follows: 1. Calibration plate substrate; 2. Calibration pattern group; 21. First calibration pattern; 211. Striped grid line; 22. Second calibration pattern; 221. First long straight line; 222. Second short straight line; 23. Third calibration pattern; 24. Fourth calibration pattern; 241. Dot. Detailed Implementation

[0020] To enhance understanding of this utility model, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. These embodiments are only used to explain the present utility model and do not constitute a limitation on the scope of protection of the present utility model.

[0021] like Figure 1 , Figure 2As shown, this embodiment provides a calibration board for semiconductor wafer defect inspection equipment, particularly suitable for calibration between a line scan camera, dark field ring light, bright field illumination optical path, and motion platform in a bright-field / dark-field dual-path wafer defect inspection equipment. The calibration board includes a calibration board substrate 1 and a calibration pattern group 2 disposed on the calibration board substrate 1. The calibration pattern group 2 includes a first calibration pattern 21 and a second calibration pattern 22, and may further include a third calibration pattern 23 and a fourth calibration pattern 24. By integrating multiple calibration patterns onto the same calibration board substrate 1, the calibration board can simultaneously meet the requirements of dark field illumination uniformity evaluation, camera attitude adjustment, bright field illumination uniformity evaluation, flat field correction, and optical system magnification calibration, reducing clamping errors and repetitive debugging steps caused by repeatedly changing calibration sheets between different calibration processes.

[0022] The calibration plate substrate 1 can be made of transparent glass, silicon, or ceramic. Preferably, the calibration plate substrate 1 can be made of transparent glass, silicon, ceramic, or other materials, and its upper and lower surfaces have a flatness that meets the depth-of-field requirements of the camera to be calibrated at its maximum magnification, to ensure pattern processing accuracy and operational stability. The upper and lower surfaces of the calibration plate substrate 1 are ground and polished, and its surface flatness meets the depth-of-field requirements of the camera to be calibrated at its maximum magnification, thereby avoiding distortion of focus evaluation results due to warping of the calibration plate itself or local height differences. During use, the calibration plate substrate 1 can be fixed on a mechanical mounting base, which can be adjusted for levelness and azimuth to establish a stable spatial reference relationship between the calibration plate substrate 1 and the XY motion guide rail, line scan camera, and illumination optical path in the wafer defect inspection equipment.

[0023] The first calibration pattern 21 is a striped grating pattern used for evaluating the uniformity of dark-field illumination and for dark-field camera flat-field correction. The first calibration pattern 21 includes multiple spaced striped grating lines 211, each arranged parallel to the others. The linewidth of each striped grating line 211 is equal to the line spacing between adjacent striped grating lines 211, forming a periodic stripe array in the first calibration pattern 21. Preferably, the striped grating lines 211 are chromium lines formed on the surface of the calibration plate substrate 1. Chromium lines can be formed through processes such as photolithography, coating, and etching, and have the characteristics of clear edges, stable linewidth, and good consistency in reflection and scattering properties.

[0024] The linewidth of the fringe grating 211 is determined based on the minimum optical resolution of the optical system to be calibrated. Specifically, the linewidth of the fringe grating 211 is equal to the minimum optical resolution of the optical system to be calibrated, and the line spacing between adjacent fringe grating lines 211 is equal to the linewidth of the fringe grating line 211. With this setting, after the camera clearly images the first calibration pattern 21, each fringe grating line 211 can be identified, and a scattering signal that can be used for dark-field imaging can be formed between adjacent fringe grating lines 211, enabling each pixel of the dark-field camera to obtain an effective grayscale response. Thus, the first calibration pattern 21 can provide raw image data for the flat field correction of the dark-field camera and be used to determine the illumination uniformity of the dark-field ring light.

[0025] The width of the pattern area of ​​the first calibration pattern 21 is greater than the ratio of the target surface size of the camera to be calibrated to the magnification of the optical system to be calibrated. In other words, the coverage area of ​​the first calibration pattern 21 on the object side is greater than the maximum single field of view of the camera to be calibrated, enabling the camera to obtain a striped grating image covering the entire field of view in a single imaging or scanning process. This setting avoids the lack of effective scattered signals in the edge areas of the field of view due to insufficient pattern area, thereby improving the completeness of the evaluation of dark field illumination uniformity.

[0026] When evaluating the uniformity of dark-field illumination using the first calibration pattern 21, the extension direction of the fringe grating 211 can be kept parallel to the scanning direction, while the fringe grating 211 can be perpendicular to the array direction of the line scan camera. After the camera achieves clear focusing, if each fringe grating 211 can be stably identified and no obvious moiré fringes appear in the image, it can be used as a visual criterion for the parallelism of the fringe grating 211 to the scanning direction. Furthermore, the camera's field of view can be divided into multiple sub-regions, for example, sub-regions composed of several pixels. The total gray value in each sub-region is counted, and the uniformity distribution of dark-field illumination is fitted based on the total gray value of each sub-region, thereby evaluating the illumination consistency of the dark-field ring light across the entire field of view.

[0027] The second calibration pattern 22 is an orthogonal long and short line pattern used for high-precision adjustment of camera attitude and calibration plate azimuth. The second calibration pattern 22 includes at least one first long straight line 221 and at least three second short straight lines 222, with the first long straight line 221 and the second short straight lines 222 being orthogonal to each other. Preferably, the first long straight line 221 and the second short straight lines 222 are both chromium lines formed on the surface of the calibration plate substrate 1 to ensure clear line edges and stable pattern morphology. The extension direction of the first long straight line 221 is parallel to the extension direction of the stripe grid lines 211 in the first calibration pattern 21, so that the first calibration pattern 21 and the second calibration pattern 22 establish a unified directional reference on the same calibration plate.

[0028] The length of the first long straight line 221 is not less than the diameter of the wafer under test, enabling it to cover the main motion stroke or scanning range of the wafer inspection equipment. The length of the second short straight line 222 is not less than the single-frame field of view width of the camera to be calibrated, allowing the line scan camera to obtain a complete line image when scanning the second short straight line 222. At least three second short straight lines 222 can be arranged at intervals along the length direction of the first long straight line 221, for example, near both ends and near the middle of the first long straight line 221, thereby facilitating the determination of the parallelism between the first long straight line 221 and the scanning direction of the motion guide rail by the image coordinate difference at multiple positions.

[0029] The straightness of the first long straight line 221 is better than half of the minimum optical resolution of the optical system to be calibrated, so as to reduce the influence of the shape error of the first long straight line 221 itself on the attitude calibration result. The perpendicularity between the first long straight line 221 and the second short straight line 222 satisfies the condition that the lateral mosaic misalignment caused by the perpendicularity error is less than one pixel. Through the above straightness and perpendicularity constraints, the second calibration pattern 22 can be applied to high-speed scanning and high-precision mosaic scenarios, reducing mosaic misalignment and attitude adjustment errors caused by the error of the calibration pattern itself.

[0030] In one usage method, the X-axis motion guide rail can be fixed, and only the Y-axis motion guide rail can be driven to scan, so that the camera sequentially acquires the image coordinates of different intersection positions formed by the second short straight line 222 and the first long straight line 221. By comparing the pixel coordinate differences of multiple intersection positions in the X-direction, the parallelism between the first long straight line 221 and the Y-direction scanning direction can be determined, and the azimuth angle of the calibration plate substrate 1 can be adjusted accordingly. If the pixel coordinate differences in the X-direction of multiple intersection positions meet the preset requirements, it indicates that the first long straight line 221 and the Y-direction scanning direction have a high degree of parallelism. At the same time, the maximum X-direction pixel deviation among multiple intersection positions can also be used as an evaluation basis for the straightness of the first long straight line 221.

[0031] In another application, the azimuth angle of the line scan camera can be adjusted using the horizontality index of the second short straight line 222 in the camera coordinate system. Since the first long straight line 221 and the second short straight line 222 are orthogonal to each other, and the first long straight line 221 is parallel to the direction of the stripe grid line 211, when the second short straight line 222 meets the predetermined horizontal or vertical requirements in the camera image, it can be considered that a high-precision angular correspondence has been established between the array direction of the line scan camera and the direction of the calibration plate pattern. For line scan cameras with a large number of horizontal pixels, this adjustment method can achieve azimuth angle adjustment accuracy close to the single-pixel level.

[0032] The third calibration pattern 23 is a highly reflective planar area used for evaluating the illumination uniformity and performing planar correction on bright-field cameras. The third calibration pattern 23 can be a highly reflective film set on the calibration plate substrate 1, or a planar mirror layer set on the calibration plate substrate 1. The surface of the third calibration pattern 23 is kept clean and has high reflectivity, and its size covers a single frame of the field of view of the camera to be calibrated. In use, bright-field illumination light shines on the third calibration pattern 23, and the camera to be calibrated acquires the reflected image of the third calibration pattern 23. The bright-field illumination uniformity is determined based on the grayscale distribution of different areas in the reflected image, and planar correction data for the bright-field camera can be further generated.

[0033] The fourth calibration pattern 24 is a dot array pattern used for calibrating the magnification and pixel accuracy of the optical system. The fourth calibration pattern 24 includes multiple dots 241, arranged in a predetermined row and column pattern to form a dot array. All dots 241 have the same diameter, and the spacing between adjacent dots 241 is fixed. Each dot 241 is a circular mark formed on the calibration plate substrate 1, with equal diameter and fixed spacing between adjacent dots 241. In use, the camera captures an image of the fourth calibration pattern 24. By identifying the center position of each dot 241 and the pixel distance between adjacent dots 241, and comparing this with the actual spacing of the dot array, the magnification, pixel size correspondence, and image measurement accuracy of the optical system can be obtained.

[0034] The first calibration pattern 21, the second calibration pattern 22, the third calibration pattern 23, and the fourth calibration pattern 24 are respectively disposed in different pattern areas of the calibration plate substrate 1, with a predetermined interval between each pattern area. Preferably, the predetermined interval between each calibration pattern is maintained to avoid mutual interference; at the same time, the relative positions of each calibration pattern on the calibration plate substrate 1 are pre-designed so that after the calibration plate is clamped once, the device can switch the camera field of view to different calibration pattern areas via the XY motion guide rail, thereby sequentially completing the evaluation of dark field illumination uniformity, camera attitude adjustment, bright field flat field correction, and magnification calibration.

[0035] In this embodiment, the calibration board is first mounted on a mechanical mounting base, which is then fixed to the support platform or calibration station of the wafer defect inspection equipment. Subsequently, using the XY motion guide rail as the calibration reference for the optical and motion systems, and with the aid of a ranging sensor or focusing detection mechanism in the equipment, the horizontality of the calibration board base 1 is initially adjusted to ensure that the working surface of the calibration board base 1 is substantially parallel to the camera imaging plane. Afterwards, the azimuth angle of the calibration board base 1 and the attitude of the line scan camera are finely adjusted using the second calibration pattern 22, ensuring that the first long straight line 221 satisfies a preset relationship with the scanning direction and the camera array direction.

[0036] After aligning the calibration plate substrate 1 with the camera in terms of horizontality and azimuth, the uniformity of dark-field illumination can be evaluated using the first calibration pattern 21. Specifically, the dark-field ring light is turned on and the camera acquires a fringe image of the first calibration pattern 21. Based on the scattering signals of the fringe grid lines 211 and their intervals, the grayscale uniformity across the entire field of view is determined. If the grayscale in a certain area is significantly higher or lower, the attitude, working distance, or illumination angle of the dark-field ring light can be adjusted accordingly to make the dark-field illumination more uniform across the entire field of view. After the dark-field ring light is adjusted, dark-field camera flat-field correction parameters can be generated based on the image data of the first calibration pattern 21 to further compensate for grayscale unevenness within the field of view.

[0037] For adjusting the camera's tilt in the X direction, the stripe image of the first calibration pattern 21 can be used for regional focus evaluation. Specifically, the camera's field of view is divided into a left region, a middle region, and a right region. The contrast score for each region is calculated, and the Z-axis focus position when each region achieves the optimal contrast score is recorded. If the optimal Z-axis focus positions for the left, middle, and right regions are inconsistent, it indicates a tilt between the camera and the calibration plate in the X direction. This can be addressed by adjusting the levelness of the camera or the calibration plate base 1 to make the optimal Z-axis focus positions for all regions of the field of view more consistent.

[0038] To adjust the tilt of the TDI line scan camera in the Y direction, the contrast scores under different integration modes can be compared using the first calibration pattern 21. Specifically, images of the first calibration pattern 21 are acquired and contrast scores are calculated when the camera is in first-order integration mode and highest-order integration mode, respectively. By adjusting the tilt angle of the TDI line scan camera in the Y direction, the contrast score in the highest-order integration mode is made closer to the contrast score in the first-order integration mode. When the difference between the two meets a preset range, it can be considered that the TDI line scan camera and the calibration plate substrate 1 have a good parallel relationship in the Y direction.

[0039] Subsequently, the third calibration pattern 23 can be used to evaluate the uniformity of bright-field illumination and perform bright-field camera flat-field correction. Since the third calibration pattern 23 is a highly reflective planar region and its size covers a single frame of the camera's field of view, the bright-field image acquired by the camera can reflect the intensity distribution of the bright-field illumination light within the field of view. Based on the grayscale distribution of this image, it can be determined whether there are vignetting, local bright spots, or intensity gradients in the bright-field illumination, and accordingly, the bright-field illumination components can be adjusted or bright-field flat-field correction data can be generated.

[0040] Finally, the fourth calibration pattern 24 can be used to calibrate the magnification and pixel accuracy of the optical system. After the camera acquires an image of the dot array of the fourth calibration pattern 24, the center coordinates of each dot 241 are extracted using an image processing algorithm, and the pixel distance between adjacent dots 241 is calculated. Since the actual spacing between the dots 241 is a fixed value, the magnification and pixel equivalent of the optical system can be calculated based on the correspondence between the actual spacing and the pixel distance. This calibration result can be used for wafer defect size measurement, image stitching position correction, and detection coordinate transformation.

[0041] As can be seen from the above embodiments, the calibration board of this embodiment integrates a first calibration pattern 21, a second calibration pattern 22, a third calibration pattern 23, and a fourth calibration pattern 24 on the same calibration board substrate 1. This enables it not only to be used for the visual evaluation of dark field illumination uniformity, but also for camera attitude calibration, bright field illumination uniformity evaluation, camera flat field correction, and optical system magnification calibration. Compared to using multiple single-function calibration boards, this embodiment can reduce the number of calibration board replacements, reduce repeated clamping errors, and improve the debugging efficiency and calibration consistency of semiconductor wafer defect detection equipment.

[0042] It should be noted that implementations not shown or described in the accompanying drawings or the main text of the specification are all forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the elements and methods described above are not limited to the various specific structures, shapes, or methods mentioned in the embodiments.

[0043] It should also be noted that this document may provide examples of parameters containing specific values, but these parameters need not be exactly equal to the corresponding values, but can approximate the corresponding values ​​within acceptable error tolerances or design constraints. Directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," "right," "inner," and "outer," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this application.

[0044] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or related technical or knowledge. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A calibration board for calibrating semiconductor wafer defect detection equipment, characterized in that, It includes a calibration plate substrate (1) and a calibration pattern group (2) disposed on the calibration plate substrate (1); The calibration pattern group (2) includes a first calibration pattern (21) and a second calibration pattern (22); The first calibration pattern (21) includes multiple striped grid lines (211) arranged at intervals, and the line width of the striped grid lines (211) is equal to the line spacing between adjacent striped grid lines (211); The second calibration pattern (22) includes at least one first long straight line (221) and at least three second short straight lines (222), wherein the first long straight line (221) and the second short straight lines (222) are orthogonal to each other; The extension direction of the stripe grid line (211) in the first calibration pattern (21) is parallel to the extension direction of the first long straight line (221) in the second calibration pattern (22).

2. The calibration plate according to claim 1, characterized in that, The striped grid lines (211), the first long straight line (221), and the second short straight line (222) are all chromium lines formed on the surface of the calibration plate substrate (1).

3. The calibration plate according to claim 1, characterized in that, The linewidth of the stripe grid line (211) corresponds to the minimum optical resolution of the optical system to be calibrated.

4. The calibration plate according to claim 1, characterized in that, The width of the pattern area of ​​the first calibration pattern (21) is greater than the ratio of the target surface size of the camera to be calibrated to the magnification of the optical system to be calibrated, so that the first calibration pattern (21) covers the maximum single field of view of the camera to be calibrated.

5. The calibration plate according to claim 1, characterized in that, The length of the first long straight line (221) is not less than the diameter of the wafer to be tested, and the length of the second short straight line (222) is not less than the single-frame field of view width of the camera to be calibrated.

6. The calibration plate according to claim 1, characterized in that, The straightness of the first long straight line (221) is better than half of the minimum optical resolution of the optical system to be calibrated.

7. The calibration plate according to claim 1, characterized in that, The perpendicularity between the first long straight line (221) and the second short straight line (222) satisfies the condition that the horizontal jigsaw puzzle misalignment caused by the perpendicularity error is less than one pixel.

8. The calibration plate according to claim 1, characterized in that, The calibration pattern group (2) also includes a third calibration pattern (23), which is a highly reflective film or a flat mirror layer disposed on the calibration plate substrate (1), and the size of the third calibration pattern (23) covers the single field of view of the camera to be calibrated.

9. The calibration plate according to claim 1, characterized in that, The calibration pattern group (2) further includes a fourth calibration pattern (24), which includes an array of dots (241). Each dot (241) in the array of dots (241) has the same diameter, and the spacing between adjacent dots (241) is fixed.

10. The calibration plate according to claim 1, characterized in that, The calibration plate substrate (1) is a transparent glass substrate, a silicon substrate or a ceramic substrate, and the surface flatness of the calibration plate substrate (1) meets the depth of field requirements of the camera to be calibrated at the maximum magnification.

Images