Imaging compensation method, imaging compensation device and storage medium

Abstract

The invention discloses an imaging compensation method, an imaging compensation device and a storage medium, and the method comprises the steps: obtaining at least one detection image of a to-be-detected part in a first preset direction, and enabling the first preset direction to be parallel to a first coordinate axis in a scanning coordinate system of a scanning workbench; the surface of the to-be-tested piece is correspondingly provided with a first coordinate system, and the surface of the to-be-tested piece is provided with a plurality of preset features distributed along a third coordinate axis array of the first coordinate system; calculating a first included angle between the third coordinate axis and the first coordinate axis according to a preset characteristic imaged in the detection image to obtain a deviation angle of the first coordinate system relative to the scanning coordinate system; and according to the deviation angle, performing compensation processing on a preset scanning position of the to-be-measured piece on the image plane when the to-be-measured piece is scanned in the first preset direction according to the deviation angle. The preset scanning position can be compensated, and the dislocation problem caused by the deviation angle is reduced.

Description

Technical Field

[0001] The present invention relates to the field of image detection technology, and in particular to an imaging compensation method, an imaging compensation device and a storage medium. Background Art

[0002] In the field of small-size and high-precision image detection, the surface detection of the test piece (such as wafers, chips, masks, glass screens, etc.) requires the acquisition of multiple images and then stitching them together to obtain a complete image of the surface of the test piece. In general, the imaging coordinate system of the imaging area of ​​the image acquisition system and the scanning coordinate system of the scanning workbench can be aligned with high precision.

[0003] At present, after the workpiece to be tested is placed on the scanning workbench, due to the limited calibration accuracy of the placement position of the workpiece to be tested, there is a deviation angle between the first coordinate system of the surface of the workpiece to be tested and the scanning coordinate system of the scanning workbench. As a result, when the scanning workbench subsequently drives the image acquisition system and the workpiece to be tested to move relative to each other, there is a misalignment between the actual scanning position of the image acquisition system and the preset scanning position, and there is a misalignment between multiple images, which makes it difficult to stitch the images in the later stage. Summary of the invention

[0004] The main technical problem solved by the present invention is that there is a deviation angle between the first coordinate system of the surface of the object to be measured and the scanning coordinate system of the scanning workbench, which affects the difficulty of subsequent image stitching.

[0005] According to the first aspect, an embodiment provides an imaging compensation method, comprising:

[0006] Acquire at least one detection image of the object to be tested along a first preset direction, wherein the first preset direction is parallel to a first coordinate axis in a scanning coordinate system of a scanning workbench; a surface of the object to be tested corresponds to the first coordinate system, and the surface of the object to be tested has a plurality of preset features distributed in an array along a third coordinate axis of the first coordinate system;

[0007] Calculate a first angle between the third coordinate axis and the first coordinate axis according to the preset features imaged in the detection image, and obtain a deviation angle of the first coordinate system relative to the scanning coordinate system;

[0008] According to the deviation angle, when the object to be tested is scanned along the first preset direction, a compensation process is performed on a preset scanning position of the object to be tested on the image plane.

[0009] According to the second aspect, an imaging compensation device is provided in one embodiment, comprising: an image acquisition system, a compensation motion system, a scanning workbench, and a processing module;

[0010] The image acquisition system is configured to acquire a detection image of the object to be tested; the imaging area of ​​the image acquisition system has an imaging coordinate system; the surface of the object to be tested corresponds to a first coordinate system, and the surface of the object to be tested has a plurality of preset features distributed in an array along a third coordinate axis of the first coordinate system;

[0011] The compensating motion system is configured to drive the imaging area of ​​the image acquisition system to move relative to the object to be measured;

[0012] The scanning workbench is configured to drive the object to be tested to move on the scanning coordinate system of the scanning workbench, so as to realize the relative movement of the object to be tested relative to the imaging area of ​​the image acquisition system;

[0013] The processing module is configured to: calculate the deviation angle of the first coordinate system relative to the scanning coordinate system based on the preset features imaged in the detection image; and compensate for the preset scanning position of the test piece on the image plane based on the deviation angle to adjust the actual scanning position of the image acquisition system.

[0014] According to a third aspect, an embodiment provides a computer-readable storage medium, on which a program is stored, and the program can be executed by a processor to implement the method described in the first aspect.

[0015] According to the imaging compensation method, imaging compensation device and storage medium of the above-mentioned embodiment, by acquiring a detection image, angle calculation is performed according to preset features in the detection image to obtain the deviation angle of the first coordinate system relative to the scanning coordinate system. In subsequent scanning, the preset scanning position of the test piece on the image plane can be compensated according to the deviation angle, thereby reducing the misalignment of the subsequently acquired detection image and reducing the difficulty of subsequent image stitching. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a device under test and preset features provided in one embodiment of the present application;

[0017] Figure 2 A schematic diagram of the structure of an imaging compensation device provided in one embodiment of the present application (I);

[0018] Figure 3 A schematic diagram of a detection image provided by an embodiment of the present application;

[0019] Figure 4 A schematic diagram of a preset scanning position and a corresponding imaging area provided in an embodiment of the present application;

[0020] Figure 5 For the corresponding Figure 4 Schematic diagram of the detection image;

[0021] Figure 6A schematic diagram of an actual scanning position and a corresponding imaging area provided in an embodiment of the present application;

[0022] Figure 7 For the corresponding Figure 6 Schematic diagram of the detection image;

[0023] Figure 8 Corresponding to an embodiment of the present application Figure 6 A schematic diagram of a detection image after compensation;

[0024] Fig. 9 A schematic diagram of the structure of a processing module provided in one embodiment of the present application;

[0025] Fig.10 A schematic diagram of the structure of a compensating motion system and an image acquisition system provided in one embodiment of the present application;

[0026] Fig.11 A schematic diagram of the structure of an imaging compensation device provided in one embodiment of the present application (II);

[0027] Fig.12 A flowchart of an imaging compensation method provided by an embodiment of the present application;

[0028] Fig.13 A schematic diagram of a deviation angle calculation process provided in one embodiment of the present application (I);

[0029] Fig.14 A schematic diagram of a deviation angle calculation process provided in one embodiment of the present application (II);

[0030] Fig.15 A schematic diagram of a deviation angle calculation process provided in one embodiment of the present application (III);

[0031] Fig.16 A schematic diagram of a displacement deviation value provided in one embodiment of the present application.

[0032] Figure numerals: 10-image acquisition system; 11-image detector; 12-optical component; 20-compensation motion system; 21-displacement drive; 22-rotation drive; 30-scanning workbench; 40-processing module; 41-image acquisition module; 42-angle calculation module; 43-compensation processing module; 50-illumination system; 60-carrying system; 100-test piece. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0034] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0035] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0036] Taking the wafer that has been processed by patterning as an example, the front of the wafer has an array pattern after etching, deposition and other processing. When a wafer with such a pattern is subjected to bright field detection, it is necessary to obtain a complete image of the wafer by collecting multiple images and stitching them together. Due to system errors in the detection equipment, when the wafer is inspected, there is a deviation angle between the actual placement direction of the wafer and the theoretical placement direction, resulting in a deviation angle between the wafer and the imaging area of ​​the image acquisition system. When continuously collecting images in one direction, there is a misalignment between multiple images. This leads to certain difficulties in image stitching and an increase in the amount of image processing calculations.

[0037] The applicant's research found that the systematic deviation of the wafer image misalignment comes from the error of the wafer rotation system. After the wafer is rotated through the rotation calibration system (for example, it is rotated using the wafer supporting system), there is still an irremovable angular deviation between the wafer coordinate system and the scanning coordinate system of the scanning worktable. In theory, the wafer coordinate system is parallel to the scanning coordinate axis; among which: the scanning coordinate system is defined by the scanning direction of the scanning worktable; the wafer coordinate system is defined by the continuous direction of the repeated pattern on the wafer.

[0038] It should be noted that, although the present application uses a wafer as an example, in reality, the DUT 100 having the above-mentioned image misalignment problem is not limited to the wafer. Figure 1 As shown in (A), the test piece 100 can be a circular test piece such as a wafer, and the wafer has an array of preset features (such as cutting grooves, isolation grooves, chip patterns, overlay marks, etc.). Generally, the preset features are arrayed in two directions. At this time, the wafer corresponds to a wafer coordinate system (corresponding to the first coordinate system of the test piece 100). In theory, the first coordinate system is parallel to the scanning coordinate system, and the third coordinate axis of the first coordinate system (the horizontal axis in the figure) is parallel to the first coordinate system of the scanning coordinate system (the horizontal axis in the figure). When the wafer is scanned, the wafer is driven by the scanning workbench 30 to move along the first coordinate axis and scan a row, and then move left and right to scan the next row after moving a certain distance along the second coordinate axis (the vertical axis in the figure).

[0039] like Figure 1 As shown in (B), the DUT 100 may also be a rectangular DUT or a DUT of other shapes, such as a glass substrate or a display panel. Taking the display panel as an example, the light-emitting unit on the display panel corresponds to the preset feature of the DUT 100. The rectangular DUT 100 is placed on the scanning workbench 30, and there is also a problem of a deviation angle between the first coordinate system of the DUT 100 and the scanning coordinate system.

[0040] Since the imaging coordinate system of the image acquisition system 10 can be calibrated in advance so that the imaging coordinate system is aligned with the scanning coordinate system, the actual position of each pixel point in the detection image corresponding to the part to be tested 100 can be calculated by combining the corresponding relationship between the imaging coordinate system and the scanning coordinate system, and combining the parameters such as the pixel size of the image. However, after each part to be tested 100 is placed on the scanning workbench 30, the deviation angle is random. For the detection of each part to be tested 100, it is necessary to compensate for the deviation angle in a targeted manner. Therefore, the embodiment of the present application first performs a pre-scan, and the deviation angle of the current part to be tested 100 is calculated based on the pre-scanned detection image. During the formal scanning, the image acquisition system 10 for image acquisition is compensated in terms of spatial position or spatial and angular position, eliminating the image misalignment problem caused by the deviation angle and reducing the difficulty of subsequent image stitching.

[0041] like Figure 2 As shown, an embodiment of the present application provides an imaging compensation device, which may include: an image acquisition system 10, a compensation motion system 20, a scanning workbench 30 and a processing module 40.

[0042] The image acquisition system 10 is configured to acquire a detection image of the test piece 100; the image plane of the image acquisition system 10 has an imaging coordinate system; the surface of the test piece 100 corresponds to a first coordinate system, and the surface of the test piece 100 has a plurality of preset features distributed in an array along a third coordinate axis of the first coordinate system. The first coordinate system includes a third coordinate axis and a fourth coordinate axis. Figure 3 As shown, at least two preset features can be captured in the detection image. According to the size of the test piece 100 and the preset feature size, the size of the imaging area and the resolution of the image acquisition system 10 can be adjusted to ensure that the captured image has two preset features.

[0043] The compensating motion system 20 is configured to drive the imaging area of ​​the image acquisition system 10 to move relative to the object to be tested 100. For example, the imaging area can be driven to move in a two-dimensional direction parallel to the surface of the object to be tested 100, or to rotate axially perpendicular to the surface of the object to be tested 100.

[0044] The scanning table 30 is configured to drive the test piece 100 to move based on the scanning coordinate system of the scanning table 30, so as to realize the relative movement of the test piece 100 relative to the imaging area of ​​the image acquisition system 10. The scanning coordinate system includes a first coordinate axis and a second coordinate axis. Figure 4 As shown, the scanning workbench 30 can drive the test piece 100 to move in the left and right directions. Figure 4 Middle (A) Movement to Figure 4 The position of (B) in the middle.

[0045] The processing module 40 is configured to: calculate the deviation angle of the first coordinate system relative to the scanning coordinate system based on the preset features imaged in the detection image; and compensate for the preset scanning position of the test piece on the image plane based on the deviation angle to adjust the actual scanning position of the image acquisition system 10.

[0046] Through the above-mentioned imaging compensation device, the deviation angle can be calculated based on the detection image. During the formal scanning detection, the preset scanning position is compensated by the compensation motion system 20 to adjust the position or position and angle of the imaging area.

[0047] The calculation of the deviation angle and the compensation of the preset scanning position are further described below.

[0048] like Figure 4 As shown in FIG. 1 , in a theoretical state, there is no deviation angle between the first coordinate system and the scanning coordinate system. Figure 4 Middle (A) Movement to Figure 4 The position of (B) in the figure can be represented as follows: Figure 5 Assume that Figure 4When the image is in the middle (A) position, the center of the imaging area is aligned with the center of the preset feature "2". Assuming that the preset feature "2" is at the center of the object to be tested 100, when moving to Figure 4 When the image is in the middle (B) position, the center of the imaging area is aligned with the center of the preset feature "12".

[0049] Due to system errors, there is a deviation angle between the first coordinate system of the test piece 100 and the scanning coordinate system. Figure 4 , the test piece 100 from Figure 6 Middle (A) Movement to Figure 6 The position of (B) in the figure can be represented as follows: Figure 7 Assume that Figure 6 When the image is in the middle (A) position, the center of the imaging area is aligned with the center of the preset feature "2". Assuming that the preset feature "2" is at the center of the object to be tested 100, when moving to Figure 6 When the position is in (B), Figure 7 As shown in (B), the center of the imaging area cannot be aligned with the center of the preset feature "12". Figure 5 The center of the preset feature "12" in (B) is the preset scanning position, and Figure 7 The center of the preset feature "12" in (B) is the actual scanning position. Figure 5 The two detection images shown, Figure 7 The two detection images shown have problems of angle deviation and center misalignment.

[0050] This application needs to compensate for this deviation angle to ensure that the actual scanning position is as consistent as possible with the preset scanning position. The final compensation effect can be as follows: Figure 8 As shown, Figure 8 As shown in (A), the two-dimensional position deviation of the actual scanning position caused by the deviation angle is compensated so that the center of the imaging area is aligned with the preset scanning position; or as Figure 8 As shown in (B), the two-dimensional position deviation of the actual scanning position caused by the deviation angle is compensated and the imaging angle is compensated to eliminate the angular deviation between the imaging coordinate system and the first coordinate system.

[0051] The above is a description of the calculation of the deviation angle and the compensation of the preset scanning position. The following is a detailed description of the imaging compensation device.

[0052] In some embodiments, Fig. 9 As shown, the processing module 40 may include an image acquisition module 41, an angle calculation module 42, and a compensation processing module 43. The above submodules may be functional modules formed by one or more processors.

[0053] The image acquisition module 41 is configured to control the scanning workbench 30 to drive the test piece 100 to move along a first preset direction, and control the image acquisition system 10 to obtain at least one detection image of the test piece 100. The first preset direction is parallel to the first coordinate axis in the scanning coordinate system. The image acquisition module 41 performs a pre-scan in the formal scanning detection direction and acquires at least one detection image.

[0054] The angle calculation module 42 is configured to calculate a first angle between the third coordinate axis and the first coordinate axis according to the detection image, and obtain a deviation angle of the first coordinate system relative to the scanning coordinate system.

[0055] The compensation processing module 43 is configured to control the compensation motion system 20 to drive the imaging area of ​​the image acquisition system 10 to move when scanning the test piece 100 along the first preset direction according to the deviation angle, perform compensation processing on the preset scanning position of the test piece on the image plane, and adjust the actual scanning position of the image acquisition system 10 so that the center of each actual scanning position is on the same straight line, and the straight line is parallel to the third coordinate axis. Figure 7 and Figure 8 As shown, by controlling the movement of the imaging area of ​​the image acquisition system 10, the actual scanning position of the image acquisition system 10 (i.e., the center of the imaging area) is changed so that the centers of multiple detection images acquired along the first preset direction are all on the same straight line, thereby eliminating the image misalignment problem caused by the deviation angle.

[0056] In some embodiments, Fig.10 As shown, the image acquisition system 10 may include an image detector 11, and the compensation motion system 20 drives the image detector 11 to move so as to drive the imaging area of ​​the image acquisition system 10 to move. Fig.10 As shown in (A), the image acquisition system 10 may only include the image detector 11 without the optical component 12.

[0057] In these embodiments, the compensating motion system 20 is also configured to drive the image detector 11 to rotate; the processing module 40 is also configured to drive the compensating motion system 20 to adjust the angle of the imaging area of ​​the image acquisition system 10 according to the deviation angle, and rotate along the center of the imaging area so that the imaging coordinate system of the image acquisition system 10 is aligned with the first coordinate system.

[0058] In other embodiments, Fig.10 As shown in (B), the image acquisition system 10 may include an image detector 11 and an optical component 12. In this case, the adjustment of the imaging area may be achieved by adjusting at least one of the image detector 11 and the optical component 12. The compensating motion system 20 drives the imaging area of ​​the image acquisition system 10 to move by driving the image detector 11 and / or the optical component 12 to move.

[0059] In these embodiments, the compensating motion system 20 is also configured to drive the image detector 11 and / or the optical component 12 to rotate; the processing module 40 is also configured to drive the compensating motion system 20 to adjust the angle of the imaging area of ​​the image acquisition system 10 according to the deviation angle, and rotate along the center of the imaging area so that the imaging coordinate system of the image acquisition system 10 is aligned with the first coordinate system.

[0060] In some embodiments, such as Fig.10 As shown, the compensation motion system 20 may include a piezoelectric driver group, and the piezoelectric driver group may include at least one displacement driver 21, all displacement drivers 21 have axes in at least two displacement directions, and all displacement drivers 21 are configured to drive the imaging area of ​​the image acquisition system 10 to move, and the motion accuracy of the displacement driver 21 is at the nanometer level. For example, in wafer inspection, after the wafer is rotated by the rotation calibration system, the deviation angle between it and the scanning table 30 is very small, such as 0.01°, and the final two-dimensional deviation of the actual scanning position is at the nanometer or micrometer level. At this time, the two-dimensional deviation compensation can be achieved by the displacement driver 21 with nanometer-level accuracy. Among them, the displacement driver 21 can be a piezoelectric ceramic displacement driver 21.

[0061] In some embodiments, such as Fig.10 As shown, in order to achieve Figure 8 The compensation effect of (B) requires angle compensation in the imaging area so that the imaging coordinate system is aligned with the first coordinate system. The piezoelectric driver group may also include a rotation driver 22, which is configured to drive the imaging area of ​​the image acquisition system 10 to rotate, and the movement accuracy of the rotation driver 22 is at the nanometer level. For example, a piezoelectric ceramic rotation driver 22 may be used. It should be noted that the alignment of one coordinate system with another coordinate system described in this application may be that the origins of the two coordinate systems coincide, or that the horizontal / vertical axes of the two coordinate systems are parallel.

[0062] In some embodiments, such as Fig.11 As shown, the device may further include an illumination system 50, which is configured to provide detection light, the detection light is used to illuminate the test piece 100 and cause the test piece to generate imaging light, and the imaging light is acquired by the image acquisition system 10 to form a detection image. For example, the detection light may be white light or monochromatic light of other colors. The present application does not limit the specific form of the illumination system 50, and any implementation method that can provide bright field illumination is acceptable.

[0063] In some embodiments, such as Figure 2 and Fig.11As shown, the device may further include a carrying system 60, the carrying system 60 is configured to rotate the test piece 100, and the scanning table 30 is configured to drive the carrying system 60 to move; the carrying system 60 is configured to rotate the test piece 100, preliminarily straighten the test piece 100, and there is a deviation angle after the preliminarily straightening. When the test piece 100 is a circular test piece 100, such as a wafer, it is necessary to perform rotation correction through the carrying system 60 and preliminarily straighten the wafer for subsequent detection.

[0064] The specific process of the imaging compensation method system for the imaging compensation method is described below. Fig.12 As shown, the imaging compensation method includes the following steps:

[0065] Step 1, obtain at least one detection image of the test piece 100 along a first preset direction, where the first preset direction is parallel to the first coordinate axis in the scanning coordinate system of the scanning workbench 30; the surface of the test piece 100 corresponds to the first coordinate system, and the surface of the test piece 100 has multiple preset features distributed in an array along a third coordinate axis of the first coordinate system.

[0066] like Figure 6 and Figure 7 As shown, the device under test 100 is Figure 6 Move to the position of (A) Figure 6 In this process, at least one detection image can be collected, for example, Figure 7 The two detection images are shown.

[0067] Step 2: Calculate a first angle between the third coordinate axis and the first coordinate axis according to a preset feature imaged in the detection image, and obtain a deviation angle of the first coordinate system relative to the scanning coordinate system.

[0068] like Figure 6 As shown, there is a deviation angle θ between the first coordinate system and the scanning coordinate system. The first angle between the third coordinate axis and the first coordinate axis is calculated based on the preset features imaged in the detection image, which can be used as the deviation angle θ caused by the system error.

[0069] Step 3: According to the deviation angle, when scanning the object to be tested 100 along the first preset direction, the preset scanning position of the object to be tested on the image plane is compensated to adjust the actual scanning position of the image acquisition system 10 so that the center of each actual scanning position is on the same straight line, which is parallel to the third coordinate axis.

[0070] like Figure 8 As shown, by compensating the actual scanning position, the center position of the imaging area can be aligned with the preset scanning position.

[0071] In some embodiments, Fig.13As shown, the detection image may be one, and in step 2, calculating the first angle between the third coordinate axis and the first coordinate axis according to the detection image may include:

[0072] Step 201: perform image recognition on the detection image to identify at least two preset features; Fig.13 The preset features "1" and "3" in .

[0073] Step 202: Calculate the angle of the third coordinate axis relative to the detection image based on at least two preset features to obtain a first angle between the third coordinate axis and the first coordinate axis; and obtain a deviation angle of the first coordinate system relative to the scanning coordinate system based on the first angle.

[0074] For example, the first reference line is determined according to the midpoint of the preset features "1" and "3", and the second reference line is determined according to the imaging coordinate system of the detection image, and the second reference line is parallel to the horizontal axis of the imaging coordinate system; the first reference line is theoretically parallel to the third coordinate axis, and the second reference line is theoretically parallel to the first coordinate axis. The angle between the first reference line and the second reference line can be used as the angle of the third coordinate axis relative to the detection image, thereby obtaining the first angle between the third coordinate axis and the first coordinate axis.

[0075] Alternatively, there are at least two detection images, and in step 2, calculating the first angle between the third coordinate axis and the first coordinate axis according to the detection images may include:

[0076] Step 203: Perform image recognition on each detection image to identify at least two preset features.

[0077] Step 204: Calculate the angle of the third coordinate axis relative to the detection image based on at least two preset features to obtain a first angle between the third coordinate axis and the first coordinate axis. Fig.13 As shown, for example, the first reference line is determined according to the midpoint of the preset features "1" and "3", and the second reference line is determined according to the imaging coordinate system of the detection image, and the second reference line is parallel to the horizontal axis of the imaging coordinate system; the first reference line is theoretically parallel to the third coordinate axis, and the second reference line is theoretically parallel to the first coordinate axis. The angle between the first reference line and the second reference line can be used as the angle of the third coordinate axis relative to the detection image, thereby obtaining the first angle between the third coordinate axis and the first coordinate axis.

[0078] Step 205: For each detected image, a first angle between the third coordinate axis and the first coordinate axis is calculated. Figure 7 The two first angles can be calculated from (A) and (B).

[0079] Step 206: Calculate the deviation angle of the first coordinate system relative to the scanning coordinate system based on part or all of the calculated first angle. Figure 7The average of the two first angles calculated from the two detection images shown in (A) and (B) is taken as the deviation angle of the first coordinate system relative to the scanning coordinate system. When there are more than two detection images, the average or median of multiple first angles can be taken as the deviation angle.

[0080] In some embodiments, such as Fig.14 and Fig.15 As shown, there are at least two detection images. In step 2, calculating the first angle between the third coordinate axis and the first coordinate axis according to the detection images may include:

[0081] Step 210: select at least one reference point in each detection image using a preset rule, wherein the reference points at corresponding positions in each of the detection images are located on the same first reference line; the first reference line is parallel to the third coordinate axis.

[0082] In some embodiments, selecting at least one reference point in each detection image using a preset rule may include:

[0083] Step 211: perform image recognition on the detection image, and recognize at least one preset feature in a preset area in the detection image. For example, the preset area is an area near the center of the detection image.

[0084] Step 212: Select a midpoint or edge point of a preset feature as a reference point. In some embodiments, the preset rule may be to take a preset point of the preset feature closest to the preset position in the detection image as the reference point, for example, Fig.14 As shown, the center point of the preset feature closest to the center of the detection image is taken as the reference point. The preset point can also be the edge point of the preset feature or the midpoint of the edge. For the convenience of explanation, Fig.14 Only the preset features "2" and "12" are identified in the detection image.

[0085] Step 220: Obtain the distance of each reference point relative to a second reference line, where the second reference line is parallel to the first coordinate axis.

[0086] Step 230: Calculate a first angle between the third coordinate axis and the first coordinate axis based on the distances between all reference points and the corresponding second reference line.

[0087] At this time, according to the number of detection images and the number of selected reference points, the first angle between the third coordinate axis and the first coordinate axis can be calculated in a variety of ways. The following is an explanation for the case where there are two or more detection images.

[0088] In some embodiments, such as Fig.14As shown, there may be two detection images. In step 230, calculating the first angle between the third coordinate axis and the first coordinate axis according to the distances between all reference points and the corresponding second reference line may include:

[0089] Step 231, obtaining a first distance of a first reference point of a detection image relative to a second reference line, obtaining a second distance of a second reference point of another detection image relative to the second reference line; the distance between the two detection images is a first scanning distance; Fig.14 As shown, the two reference points can obtain the first distance D1 and the second distance D2. For example, since the deviation angle is very small, the first scanning distance corresponding to the two detection images can be used as the lateral distance between the two reference points, such as D0 in the figure.

[0090] Step 232: According to the first distance, the second distance and the first scanning distance, triangulation is used to calculate an angle between the first reference line and the second reference line as the first angle.

[0091] At this time, the first angle between the third coordinate axis and the first coordinate axis can be calculated by the first distance D1, the second distance D2 and D0. For example, when there are more than two reference points, a first angle is calculated for each two reference points as a group, and multiple first angles are calculated by multiple groups of reference points, and then the average or median is taken as the final first angle.

[0092] Or, if Fig.15 As shown, there may be at least three detection images, and there is a preset scanning interval D01 between every two detection images; in step 230, according to the distances of all reference points and the corresponding second reference line, calculating the first angle between the third coordinate axis and the first coordinate axis may include:

[0093] Step 233: According to the distances between all reference points and the second reference line and all preset scanning intervals, a straight line is fitted to serve as the actual first reference line.

[0094] Step 234: Calculate the actual angle between the first reference line and the second reference line as the first angle.

[0095] For example, multiple reference points can be fitted into a straight line, which is used as the first reference line to calculate the first angle between the third coordinate axis and the first coordinate axis. Fig.15In the figure, the three detected images are respectively taken as reference points with the midpoint of the preset feature closest to the midpoint of the image, such as the preset features "2", "7" and "12" in the figure, and the distances D1, D2 and D3 can be obtained respectively, and the corresponding preset scanning interval D01. One way is to fit a straight line based on the three reference points and use it as the first reference line to calculate the first angle. Another way is to calculate a first angle through two reference points and multiple groups of reference points as in the above step 232. For example, D1 and D2 are one group, D1 and D3 are one group, and D2 and D3 are another group.

[0096] Through the above multiple embodiments, the deviation angle can be calculated in different ways, and how to compensate is described below.

[0097] In some embodiments, in step 3, compensating the preset scanning position of the piece under test on the image plane may include: performing displacement compensation on the preset scanning position of the piece under test on the image plane, or performing angle compensation and displacement compensation on the preset scanning position of the piece under test on the image plane.

[0098] The displacement compensation process may include:

[0099] Step 310 : Calculate the displacement deviation value corresponding to each preset scanning position of the current image acquisition system 10 according to the deviation angle and each preset scanning position.

[0100] Step 320: Perform displacement compensation on each actual scanning position according to each displacement deviation value.

[0101] For example, Fig.16 As shown, before compensation is performed, assuming that the first preset direction is the direction of the first coordinate axis, there is a displacement deviation between each preset scanning position and the corresponding actual scanning position. The embodiment of the present application compensates each actual scanning position by calculating the deviation angle, so that during actual scanning, the actual scanning position after compensation is close to the preset scanning position.

[0102] In some embodiments, in step 320, performing displacement compensation on each preset scanning position according to each displacement deviation value may include:

[0103] Step 321 : Use the compensating motion system 20 to drive the image acquisition system 10 to move, so as to change the scanning position of the imaging area of ​​the image acquisition system 10 .

[0104] Step 322, control the compensating motion system 20 to drive the image acquisition system 10 to move according to the displacement deviation value to adjust the displacement of each actual scanning position so that the center of each actual scanning position is on the same straight line, which is parallel to the third coordinate axis.

[0105] like Figure 7 Middle (B) and Figure 8 As shown in (A), after the displacement compensation process, the center of the imaging area (actual scanning position) is aligned with the center of the preset feature "12" (preset scanning position).

[0106] The angle compensation process may include:

[0107] Step 303 : adjusting the angle of the imaging area of ​​the image acquisition system 10 according to the deviation angle, and rotating along the center of the imaging area so that the imaging coordinate system of the image acquisition system 10 is aligned with the first coordinate system of the object to be tested 100 .

[0108] like Figure 7 Middle (B) and Figure 8 As shown in (B), after displacement compensation and angle compensation, the center of the imaging area is aligned with the preset scanning position, and the imaging coordinate system of the image acquisition system 10 is aligned with the first coordinate system of the object to be tested 100. It can be seen that the detection image actually acquired at this time is Figure 5 The theoretical detection image shown in (B) is consistent in theory.

[0109] When scanning, the scanning workbench still drives the workpiece to move according to the preset motion parameters, and the compensation motion system performs compensation synchronously. For each preset scanning position, it drives the image acquisition system to perform synchronous compensation and change the actual scanning position so that the actual scanning position is the same as the preset scanning position, eliminating the misalignment problem.

[0110] To summarize, the imaging compensation method and device of the embodiments of the present application acquire a detection image, perform angle calculation based on preset features in the detection image, and obtain a deviation angle of the first coordinate system relative to the scanning coordinate system. In subsequent scans, the actual scanning position can be compensated based on the deviation angle, thereby reducing the misalignment of the subsequently acquired detection image and reducing the difficulty of subsequent image stitching.

[0111] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above-mentioned embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, and the storage medium can include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to implement the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above-mentioned functions can be implemented. In addition, when all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can also be stored in a storage medium such as a server, another computer, disk, optical disk, flash disk or mobile hard disk, and can be downloaded or copied and saved in the memory of the local device, or the system of the local device is updated, and when the program in the memory is executed by the processor, all or part of the functions in the above-mentioned embodiments can be implemented.

[0112] This document is described with reference to various exemplary embodiments. However, those skilled in the art will recognize that changes and modifications may be made to the exemplary embodiments without departing from the scope of this document. For example, various operating steps and components for performing the operating steps may be implemented in different ways (e.g., one or more steps may be deleted, modified, or incorporated into other steps) depending on the specific application or considering any number of cost functions associated with the operation of the system.

[0113] Although the principles of this invention have been shown in various embodiments, many modifications of structures, arrangements, proportions, elements, materials and components particularly suitable for specific environments and operational requirements can be used without departing from the principles and scope of this invention. The above modifications and other changes or amendments will be included in the scope of this invention.

[0114] The foregoing specific description has been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the present disclosure. Therefore, the consideration of the present disclosure will be illustrative rather than restrictive, and all these modifications will be included in its scope. Similarly, the advantages, other advantages and solutions to the problems of various embodiments have been described above. However, the benefits, advantages, solutions to the problems and any elements that can produce these, or make them more clear, should not be interpreted as critical, necessary or necessary. The term "include" and any other variants used in this article are all non-exclusive inclusions, so that the process, method, article or device including the list of elements not only includes these elements, but also includes other elements that are not explicitly listed or do not belong to the process, method, system, article or device. In addition, the term "coupled" and any other variants used in this article refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections and / or any other connections.

[0115] Those skilled in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the basic principles of the invention. Therefore, the scope of the present invention should be determined solely by the claims.

Claims

1. An imaging compensation method, characterized in that: include: Acquire at least one detection image of the object to be tested along a first preset direction, wherein the first preset direction is parallel to a first coordinate axis in a scanning coordinate system of the scanning workbench; The surface of the object to be tested corresponds to a first coordinate system, and the surface of the object to be tested has a plurality of preset features distributed in an array along a third coordinate axis of the first coordinate system; Calculating a first angle between the third coordinate axis and the first coordinate axis according to the preset feature imaged in the detection image, and obtaining a deviation angle of the first coordinate system relative to the scanning coordinate system; According to the deviation angle, when the piece to be tested is scanned along the first preset direction, a compensation process is performed on a preset scanning position of the piece to be tested on an image plane.

2. The method according to claim 1, characterized in that The detection image is one or more, and calculating the first angle between the third coordinate axis and the first coordinate axis according to the preset feature imaged in the detection image includes: Performing image recognition on at least one of the detection images to identify at least two of the preset features; Calculating the angle of the third coordinate axis relative to the detection image according to at least two of the preset features to obtain a first angle between the third coordinate axis and the first coordinate axis; If there are multiple first angles obtained, the deviation angle of the first coordinate system relative to the scanning coordinate system will be obtained by calculation based on some or all of the first angles.

3. The method according to claim 1, characterized in that There are at least two detection images, and calculating a first angle between the third coordinate axis and the first coordinate axis according to the preset features imaged in the detection images includes: At least one reference point is selected in each of the detection images using a preset rule, wherein the reference points at corresponding positions in the detection images are located on the same first reference line; the first reference line is parallel to the third coordinate axis; Obtaining a distance of each of the reference points relative to a second reference line, where the second reference line is parallel to the first coordinate axis; A first angle between the third coordinate axis and the first coordinate axis is calculated according to the distance between the reference point and the corresponding second reference line.

4. The method according to claim 3, characterized in that There are two detection images, and according to the distance between the reference point and the corresponding second reference line, a first angle between the third coordinate axis and the first coordinate axis is calculated, including: Acquire a first distance of a first reference point of one of the detection images relative to a second reference line, and acquire a second distance of a second reference point of another detection image relative to the second reference line; the distance between the two detection images is a first scanning distance; According to the first distance, the second distance and the first scanning distance, a trigonometric method is used to calculate an angle between the first reference line and the second reference line as the first angle; Alternatively, there are at least three detection images, and there is a preset scanning interval between every two detection images; and calculating the first angle between the third coordinate axis and the first coordinate axis according to the distance between the reference point and the corresponding second reference line includes: According to the distances between all the reference points and the second reference line and all the preset scanning intervals, a straight line is fitted to be used as the actual first reference line; An actual angle between the first reference line and the second reference line is calculated as the first angle.

5. The method according to claim 3 or 4, characterized in that Selecting at least one reference point in each of the detection images using a preset rule includes: Performing image recognition on the detection image, and identifying at least one of the preset features in a preset area in the detection image; A midpoint or edge point of the preset feature is selected as a reference point.

6. The method according to claim 1, characterized in that The preset scanning position of the test piece on the image plane is compensated, including: adjusting the actual scanning position of the image acquisition system on the image plane of the test piece so that the center of each actual scanning position is on the same straight line, which is parallel to the third coordinate axis.

7. The method according to claim 1, characterized in that Performing compensation processing on the preset scanning position of the piece to be tested on the image plane, including: performing displacement compensation processing on the preset scanning position of the piece to be tested on the image plane, or performing angle compensation processing and displacement compensation processing on the preset scanning position of the piece to be tested on the image plane; Wherein, the displacement compensation processing includes: According to the deviation angle and each preset scanning position, a displacement deviation value corresponding to each preset scanning position of the current image acquisition system is calculated; Perform displacement compensation on each preset scanning position according to each displacement deviation value; Wherein, the angle compensation processing includes: According to the deviation angle, the angle of the imaging area of ​​the image acquisition system is adjusted, and the imaging coordinate system of the image acquisition system is rotated along the center of the imaging area so that the imaging coordinate system of the image acquisition system is aligned with the first coordinate system of the object to be measured.

8. The method according to claim 7, characterized in that Displacement compensation is performed on each actual scanning position according to each displacement deviation value, including: Using a compensating motion system to drive the image acquisition system to move, so as to change the scanning position of the image acquisition system when imaging on an image plane; The compensating motion system is controlled to drive the image acquisition system to move according to the displacement deviation value, so as to achieve displacement compensation for the actual scanning position.

9. An imaging compensation device, characterized in that: include: Image acquisition system, compensation motion system, scanning table and processing module; The image acquisition system is configured to obtain a detection image of the object to be tested; The image plane imaged by the image acquisition system has an imaging coordinate system; the surface of the object to be tested has a corresponding first coordinate system, and the surface of the object to be tested has a plurality of preset features distributed in an array along a third coordinate axis of the first coordinate system; The compensating motion system is configured to drive the imaging area of ​​the image acquisition system to move relative to the object to be measured; The scanning workbench is configured to drive the object to be tested to move based on the scanning coordinate system of the scanning workbench, so as to achieve relative movement of the object to be tested relative to the imaging area of ​​the image acquisition system; The processing module is configured to: calculate the deviation angle of the first coordinate system relative to the scanning coordinate system based on the preset features imaged in the detection image; and compensate for the preset scanning position of the test piece on the image plane based on the deviation angle to adjust the actual scanning position of the image acquisition system.

10. The device according to claim 9, characterized in that The processing module includes an image acquisition module, an angle calculation module and a compensation processing module; The image acquisition module is configured to control the scanning workbench to drive the object to be tested to move along a first preset direction, and control the image acquisition system to acquire at least one detection image of the object to be tested, wherein the first preset direction is parallel to a first coordinate axis in the scanning coordinate system; The angle calculation module is configured to calculate a first angle between the third coordinate axis and the first coordinate axis according to the detection image, and obtain a deviation angle of the first coordinate system relative to the scanning coordinate system; The compensation processing module is configured to control the compensation motion system to drive the imaging area of ​​the image acquisition system to move according to the deviation angle when scanning the test piece along the first preset direction, so as to perform compensation processing on the preset scanning position of the test piece on the image plane.

11. The device according to claim 9, characterized in that The image acquisition system includes an image detector, and the compensation motion system drives the imaging area of ​​the image acquisition system to move by driving the image detector to move.

12. The device according to claim 11, characterized in that The compensatory motion system is also configured to drive the image detector to rotate; the processing module is also configured to drive the compensatory motion system to adjust the angle of the imaging area of ​​the image acquisition system according to the deviation angle, and rotate along the center of the imaging area so that the imaging coordinate system of the image acquisition system is aligned with the first coordinate system.

13. The device according to claim 9, characterized in that The image acquisition system includes an image detector and an optical component. The compensating motion system drives the imaging area of ​​the image acquisition system to move by driving the image detector and / or the optical component to move.

14. The device according to claim 13, characterized in that The compensatory motion system is also configured to drive the image detector and / or the optical component to rotate; the processing module is also configured to drive the compensatory motion system to adjust the angle of the imaging area of ​​the image acquisition system according to the deviation angle, and rotate along the center of the imaging area so that the imaging coordinate system of the image acquisition system is aligned with the first coordinate system.

15. The device according to claim 9, characterized in that The compensating motion system includes a piezoelectric driver group, which includes at least one displacement driver. All displacement drivers have axes in at least two displacement directions, and all displacement drivers are configured to drive the imaging area of ​​the image acquisition system to move.

16. The device according to claim 9, characterized in that The compensating motion system includes a piezoelectric drive group, wherein the piezoelectric drive group includes a rotation drive configured to drive an imaging region of the image acquisition system to rotate.

17. The device according to claim 9, characterized in that The device further includes an illumination system, which is configured to provide detection light, wherein the detection light is used to illuminate the test piece and cause the test piece to generate imaging light, and the imaging light is acquired by the image acquisition system to form a detection image.

18. A computer-readable storage medium, characterized in that: The medium stores a program, which can be executed by a processor to implement the method according to any one of claims 1 to 8.

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