CN-116993650-B - Symmetry detection method and system for optical system, equipment and storage medium

Abstract

A symmetry detection method of an optical system comprises the steps of providing a target to be detected, wherein the target to be detected comprises a pattern to be detected, the pattern to be detected comprises a preset region of interest, the pattern to be detected of the preset region of interest is axisymmetric about a first symmetry axis extending along a specific direction, obtaining an image of the preset region of interest of the target to be detected by using the optical system, obtaining a second symmetry axis which is an axis of the first symmetry axis extending along the specific direction in the image of interest, and obtaining symmetry characterization values of the optical system along the specific direction according to the image of interest, wherein the symmetry characterization values are differences of detection values of two reference positions symmetrical about the second symmetry axis. The invention obtains the symmetry characterization value of the detection parameter of the optical system along the specific direction based on the axisymmetric interested image, thereby evaluating the symmetry of the optical system in real time and accurately.

Inventors

• CHEN LU
• WANG ZIYUAN
• LV SU
• HUANG YOUWEI
• ZHANG SONG

Assignees

• 深圳中科飞测科技股份有限公司

Dates

Publication Date

20260512

Application Date

20220425

Claims (16)

1. 1. A symmetry-detecting method of an optical system, comprising: Providing a target to be detected, wherein the target to be detected comprises a plurality of patterns to be detected which are periodically and repeatedly arranged, the patterns to be detected are provided with a preset region of interest, and the patterns to be detected of the preset region of interest are axisymmetric with respect to a first symmetry axis extending along a specific direction; Determining a first region of interest corresponding to each image to be measured, wherein the first region of interest is a region of a preset region of interest of the image to be measured in the image to be measured, and the image to be measured in the first region of interest is used as an image of interest of the image to be measured; The method comprises the steps of obtaining symmetry characterization values of the optical system along the specific direction for each image of interest, wherein the symmetry characterization values are differences of detection values of two reference positions symmetrical about the second symmetry axis, the detection values are positively correlated with gray values of the reference positions, the method comprises the steps of projecting the image of interest along a projection direction, obtaining correspondence between positions of a plurality of pixel points in the position arrangement direction and projection values as one-dimensional projection data, the position arrangement direction is perpendicular to the specific direction, the projection direction is parallel to the specific direction, the projection values are weighted values of the detection values of one or more pixel points along the projection direction, the detection values are positively correlated with gray values, selecting two reference positions which are axisymmetrical about the second symmetry axis in the position arrangement direction of the one-dimensional projection data, and obtaining the differences of the projection values of the two reference positions as symmetry characterization values according to the one-dimensional projection data; And obtaining symmetry distribution of the optical system in the specific direction by using symmetry characterization values corresponding to the patterns to be detected respectively.
2. 2. The method for detecting symmetry of an optical system according to claim 1, wherein the specific direction is plural, and the plural specific directions include a first direction and a second direction perpendicular to each other; Acquiring a symmetry-characterization value of the optical system along the particular direction for each of the images of interest includes acquiring a difference of detected values of two reference locations symmetrical about a second axis of symmetry extending along the second direction as a symmetry-characterization value in the first direction, and acquiring a difference of detected values of two reference locations symmetrical about the second axis of symmetry extending along the first direction as a symmetry-characterization value in the second direction.
3. 3. The symmetry detection method of an optical system according to claim 1, wherein in the process of obtaining symmetry distribution of the optical system in the specific direction by using symmetry characterization values corresponding to a plurality of patterns to be detected respectively, the symmetry distribution comprises one or more gray scale patterns, and each gray scale pattern is composed of symmetry characterization values of each pattern to be detected in the same specific direction; Or alternatively The specific directions are multiple, the specific directions comprise a first direction and a second direction which are perpendicular to each other, and the intersection point of a first symmetry axis of the first direction and the second direction is the symmetry center of the pattern to be detected; The symmetry distribution comprises a vector diagram, wherein the vector diagram consists of symmetry representation value vectors corresponding to the patterns to be tested, and each symmetry representation value vector of the patterns to be tested takes the corresponding symmetry center as an origin and the symmetry representation values in the first direction and the second direction which are corresponding to the symmetry representation value vector as coordinates of the vector.
4. 4. The method for detecting symmetry of an optical system according to claim 1, wherein selecting two reference positions which are axisymmetric with respect to the second symmetry axis in the direction of position arrangement of the one-dimensional projection data includes selecting two reference points which are axisymmetric with respect to the second symmetry axis in the direction of position arrangement of the one-dimensional projection data which are axisymmetric with respect to the second symmetry axis; according to the one-dimensional projection data, obtaining the difference value of the projection values of the two reference positions as a symmetry characterization value comprises obtaining the difference value of the projection values of the two reference points as the symmetry characterization value.
5. 5. The symmetry-detecting method for an optical system according to claim 4, wherein selecting two reference points which are axisymmetric with respect to the second symmetry axis in a positional arrangement direction of the one-dimensional projection data which is axisymmetric with respect to the second symmetry axis includes: When the one-dimensional projection data and the mirror image data corresponding to the one-dimensional projection data are subjected to cross-correlation calculation to obtain the maximum cross-correlation value, two reference points which are positioned at the same arrangement position in the projection direction in the one-dimensional projection data and the mirror image data, wherein the arrangement position is a position along the position arrangement direction; the method comprises the steps of obtaining the projection values of two reference points, calculating the difference value of the projection values of the two reference points, and obtaining the symmetry characterization value; Or alternatively The one-dimensional projection data comprises first projection data and second projection data which are respectively positioned at two sides of the second symmetry axis, and two reference points which are axisymmetric with respect to the second symmetry axis are selected in the position arrangement direction of the one-dimensional projection data which are axisymmetric with respect to the second symmetry axis; the method comprises the steps of obtaining the projection values of a first reference point and a second reference point, and calculating the difference value of the projection values of the first reference point and the second reference point to obtain the symmetry representation value.
6. 6. The method of claim 4, wherein in calculating the difference between the projection values of the two reference points, any one of the two reference points is a highest point of the one-dimensional projection data, and the highest point includes a lowest point or a highest point.
7. 7. The method for detecting symmetry of an optical system according to claim 4, wherein obtaining the difference between the projection values of the two reference points as the symmetry characterizing value comprises normalizing the difference between the projection values of the two reference points after calculating the difference between the projection values, and taking the normalized difference as the symmetry characterizing value; normalizing the difference of the projection values includes calculating a ratio of the difference of the projection values to a detected value of a background of the image of interest.
8. 8. The method of claim 1, wherein the detected value includes a gray level value, a light intensity value, or a charge value of a pixel.
9. 9. The method for detecting symmetry of an optical system according to claim 1, wherein determining the first region of interest corresponding to each image to be detected includes: Acquiring a template image of the pattern to be detected, wherein the template image has a detection range, and the template image comprises a preset position relation of a second region of interest relative to the detection range, and the second region of interest is a region of the preset region of interest of the pattern to be detected in the template image; Matching the target image with a template image, and acquiring a plurality of matching areas in the target image, wherein the matching areas are areas which are formed by pixel positions, wherein the similarity between the matching areas and the template image in the detection range is greater than or equal to a preset similarity threshold value, and the pixel positions are communicated with the matching areas; After the matching area is obtained, a first region of interest is determined in the image to be detected according to a preset position relation of a second region of interest in the template image relative to the detection range, and the relative position relation of the first region of interest and the matching area is the same as the preset position relation.
10. 10. The method for detecting symmetry of an optical system according to claim 9, wherein the pattern to be detected is a center symmetrical pattern, the pattern to be detected having a center of symmetry; The preset position relation of the second region of interest relative to the detection range is the position relation between the second region of interest and the center of the detection range; Determining a first region of interest in the image to be detected according to a preset position relation of a second region of interest in the template image relative to the detection range comprises the steps of obtaining the position of a matching center of the matching region, and determining the first region of interest in the image to be detected according to the preset position relation and the position of the matching center, so that the relative position relation between the center of the first region of interest and the matching center is the same as the preset position relation.
11. 11. The detection method according to claim 10, wherein obtaining the positions of the matching centers of the matching areas includes extracting the contour of each of the matching areas by a morphological algorithm, and obtaining the positions of the centers based on the contour, or extracting the positions of the similarity peaks thereof for each of the matching areas, respectively, to obtain the positions of the matching centers of the respective matching areas.
12. 12. The symmetry-detecting method of an optical system according to claim 10, wherein performing matching processing on the target image and the template image includes: Traversing the target image by using a matching window with the same size as the template image, and calculating a correlation score between the region of the matching window in the target image and the template image, wherein the correlation score is inversely related to the variance or standard deviation of gray scale of each pixel point of the region of the matching window and the template image; And acquiring a region where a matching window with the relevance score larger than or equal to a preset threshold value is located in the target image as the matching region, wherein the relevance score is used as the similarity.
13. 13. The method for detecting symmetry of an optical system according to claim 1, wherein the pattern to be detected includes at least one grid pattern, and the at least one grid pattern is center-symmetrical.
14. 14. A symmetry-detecting system for an optical system, comprising: The device comprises a target to be detected acquisition module, a target detection module and a target detection module, wherein the target to be detected acquisition module is used for providing a target to be detected, the target to be detected comprises a plurality of patterns to be detected which are periodically and repeatedly arranged, the patterns to be detected are provided with a preset region of interest, and the patterns to be detected of the preset region of interest are axisymmetric with respect to a first symmetry axis extending along a specific direction; The system comprises an interested image acquisition module, a first interested region, a second interested region, a first symmetrical axis and a second symmetrical axis, wherein the interested image acquisition module is used for acquiring a target image of the target to be detected by utilizing the optical system, and the target image comprises images to be detected corresponding to a plurality of patterns to be detected respectively; A symmetry-characterization-value obtaining module, configured to obtain, for each of the images of interest, a symmetry characterization value of the optical system along the specific direction, where the symmetry characterization value is a difference value between detected values of two reference positions symmetrical about the second symmetry axis, and the detected values are positively correlated with gray values of the reference positions; the symmetry distribution acquisition module is used for acquiring symmetry distribution of the optical system in the specific direction by utilizing symmetry characterization values corresponding to the patterns to be detected respectively; The symmetry characterization value acquisition module comprises a projection unit, a position arrangement unit and a gray value acquisition unit, wherein the projection unit is used for projecting an interested image along a projection direction, acquiring the corresponding relation between the positions of a plurality of pixel points in the position arrangement direction and the projection value as one-dimensional projection data, the position arrangement direction is perpendicular to the specific direction, the projection direction is parallel to the specific direction, the projection value is a weighted value of the detection value of one or a plurality of pixel points along the projection direction, and the detection value is positively correlated with the gray value; A reference position selecting unit for selecting two reference positions which are axisymmetric with respect to the second symmetry axis in the position arrangement direction of the one-dimensional projection data, wherein the reference positions are positions along the position arrangement direction; And the symmetry characterization value acquisition unit is used for acquiring the difference value of the projection values of the two reference positions as the symmetry characterization value according to the one-dimensional projection data.
15. 15. A terminal device comprising at least one memory and at least one processor, the memory storing one or more computer instructions, wherein the one or more computer instructions are executable by the processor to implement the symmetry-detecting method of the optical system of any one of claims 1 to 13.
16. 16. A storage medium storing one or more computer instructions for implementing a method of symmetry detection of an optical system according to any one of claims 1 to 13 when executed by a processor.

Description

Symmetry detection method and system for optical system, equipment and storage medium Technical Field The embodiment of the invention relates to the technical field of optical detection, in particular to a symmetry detection method and system of an optical system, equipment and a storage medium. Background An optical measurement device is a device that measures an object to be measured based on an optical principle. Optical measurement has the advantages of high measurement speed, no contact, no pollution and the like, and has become the most commonly used measurement means at present. When measuring, the optical measuring device obtains an image with a specific magnification of the object to be measured under a specific illumination condition through the illumination module and the imaging module, and processes the acquired image signal to obtain a measuring result based on the image. For this reason, in order to improve accuracy of measurement results, it is often required that the optical path system of the illumination module satisfies highly uniform illumination conditions (for example, intensity uniformity of illumination and angle uniformity of illumination), and that the imaging module satisfies alignment of each optical element and good conjugate relation of object side and image side. When the optical system has uneven illumination, off-axis, inclination or deviation from conjugation, the imaging signal is asymmetric, so that the measurement result is affected. Therefore, the symmetry of the optical system has a great influence on the accuracy of the measurement result. Disclosure of Invention The embodiment of the invention solves the problem of providing a symmetry detection method, a symmetry detection system, symmetry detection equipment and a symmetry detection storage medium for an optical system, which are beneficial to real-time and accurate evaluation of the symmetry of the optical system. In order to solve the problems, the embodiment of the invention provides a symmetry detection method of an optical system, which comprises the steps of providing a target to be detected, wherein the target to be detected comprises a pattern to be detected, the pattern to be detected is provided with a preset region of interest, the pattern to be detected of the preset region of interest is axisymmetric about a first symmetry axis extending along a specific direction, acquiring an image of the preset region of interest of the target to be detected by using the optical system, obtaining an image of interest, an axis of the first symmetry axis extending along the specific direction in the image of interest is a second symmetry axis, and acquiring a symmetry representation value of the optical system along the specific direction according to the image of interest, wherein the symmetry representation value is a difference value of detection values of two reference positions symmetrical about the second symmetry axis, and the detection value is positively correlated with a gray value of the reference position. Correspondingly, the embodiment of the invention also provides a symmetry detection system of the optical system, which comprises a target to be detected acquisition module, an interest image acquisition module and a symmetry characterization value acquisition module, wherein the target to be detected acquisition module is used for providing a target to be detected, the target to be detected comprises a pattern to be detected, the pattern to be detected is provided with a preset region of interest, the pattern to be detected of the preset region of interest is axisymmetric about a first symmetry axis extending along a specific direction, the image acquisition module is used for acquiring an image of interest of the preset region of interest of the target to be detected by using the optical system, the axis of the first symmetry axis extending along the specific direction in the image of interest is a second symmetry axis, and the symmetry characterization value acquisition module is used for acquiring symmetry characterization values of the optical system along the specific direction according to the image of interest, wherein the symmetry characterization values are differences of detection values of two reference positions symmetrical about the second symmetry axis, and the detection values are positively correlated with gray values of the reference positions. Correspondingly, the embodiment of the invention also provides equipment, which comprises at least one memory and at least one processor, wherein the memory stores one or more computer instructions, and the one or more computer instructions are executed by the processor to realize the symmetry detection method of the optical system. Correspondingly, the embodiment of the invention also provides a storage medium, wherein one or more computer instructions are stored in the storage medium, and the one or more computer instructions are used for real