Method for correcting the field curvature of a microscope and correcting device therefor

Abstract

The present disclosure describes a method for correcting the field curvature of a microscope and a correcting device thereof, the method comprising: placing a standard workpiece on a bearing platform, the standard workpiece having a standard surface; positioning the standard surface at the focal plane of a microscope objective; positioning the image plane of the standard surface as an initial image plane, obtaining a plurality of initial imaging points in the initial image plane, and taking the spatial position coordinates of the plurality of initial imaging points as a plurality of first coordinates, the plurality of initial imaging points corresponding one-to-one to each to-be-measured point in the standard surface; mapping the plurality of initial imaging points to a reference plane and obtaining a plurality of target imaging points matched with the plurality of initial imaging points, the plurality of target imaging points corresponding one-to-one to the plurality of initial imaging points; taking the spatial position coordinates of the plurality of target imaging points as a plurality of second coordinates; and correcting the field curvature of the microscope based on the plurality of first coordinates and the plurality of second coordinates during the measurement process. According to the present disclosure, a method for correcting the field curvature and a correcting device thereof are provided, which can improve the measurement accuracy of the to-be-measured workpiece.

Description

Technical Field

[0001] This disclosure generally relates to an intelligent manufacturing equipment industry, specifically to a field curvature correction method and device for microscopes. Background Technology

[0002] In the field of optical measurement, optical imaging systems are commonly used to measure the object under test. To obtain measurement information more accurately and intuitively, new optical imaging systems with high photosensitivity and high resolution have emerged. Taking confocal microscopy as an example, it uses the principle of three points—the light source, the object under test, and the microscope objective—conjugated to perform mechanical scanning to measure the object and reconstruct its three-dimensional morphology.

[0003] Ideally, when the object under test is located at the focal plane of the microscope objective, the optimal imaging focal points formed by the reflected light beams from each of the individual pixels under test lie on the same plane, thus enabling a clear image of the object. However, like ordinary imaging instruments, confocal microscopes also experience phase differences during the imaging process, leading to poor imaging results for the object under test. For example, due to the limitations of the microscope objective's structure, the optimal imaging focal points of each pixel under test scanned by the microscope objective may not be on the same plane. This causes field curvature in the image of the object under test, resulting in an unclear image and inaccurate measurements.

[0004] In the existing technology, multiple lenses are usually used in combination to adjust the beam of light passing through the microscope objective and thus correct the field curvature of the microscope. However, the selection and installation of lenses usually consume a lot of time and manpower. Summary of the Invention

[0005] This disclosure is made in view of the above-mentioned state of the prior art, and its purpose is to provide a field curvature correction method and device that is simple in procedure and can correct the field curvature of a microscope, thereby improving the measurement accuracy of the workpiece under test.

[0006] To this end, the first aspect of this disclosure provides a field curvature correction method for a microscope, the microscope including a support platform for supporting a workpiece and a microscope objective for scanning the workpiece, the correction method including: placing a standard workpiece on the support platform, the standard workpiece having a standard surface with a roughness not greater than a first preset value; positioning the standard surface at the focal plane of the microscope objective; setting the image plane of the standard surface as an initial image plane, acquiring a plurality of initial imaging points in the initial image plane, setting the spatial position coordinates of the plurality of initial imaging points as a plurality of first coordinates, the plurality of initial imaging points corresponding one-to-one with each test point in the standard surface; mapping the plurality of initial imaging points to a reference plane to obtain a plurality of target imaging points matching the plurality of initial imaging points, the plurality of target imaging points corresponding one-to-one with the plurality of initial imaging points; setting the spatial position coordinates of the plurality of target imaging points as a plurality of second coordinates; and correcting the field curvature of the microscope based on the plurality of first coordinates and the plurality of second coordinates during the measurement process.

[0007] According to the field curvature correction method disclosed herein, multiple correction values ​​for the field curvature of the microscope can be obtained in advance based on a standard workpiece with a standard surface having a roughness not greater than a first preset value through a simple preprocessing step. When measuring the workpiece to be measured, the measurement error caused by the field curvature of the microscope during the measurement process can be corrected based on the multiple correction values ​​obtained in advance. Thus, the measurement efficiency and measurement accuracy can be improved during the measurement of the workpiece to be measured.

[0008] Furthermore, in the field curvature correction method according to the first aspect of this disclosure, optionally, the first preset value is not greater than 1 nanometer. In this case, the standard surface can be made smoother, thereby enabling the standard surface to be ideally imaged as a regular and flat image surface, which facilitates the subsequent calculation of the correction value.

[0009] Additionally, in the field curvature correction method according to the first aspect of this disclosure, optionally, the microscope includes an imaging module for receiving the reflected light beam from the standard workpiece, and the reference plane is conjugate to the photosensitive surface of the imaging module. In this case, it is convenient to obtain multiple second coordinates that can reflect the corrected initial image plane, thereby facilitating the acquisition of a target image plane that matches the standard plane.

[0010] Furthermore, in the field curvature correction method according to the first aspect of this disclosure, optionally, reference coordinates are obtained based on a plurality of the first coordinates, and the position of the reference plane is set based on the reference coordinates. This facilitates the setting of the reference plane.

[0011] Furthermore, in the field curvature correction method according to the first aspect of this disclosure, optionally, the average value of the plurality of first coordinates is obtained as the reference coordinate. In this case, using the average value of the plurality of first coordinates as the reference coordinate can minimize the possibility that the subsequent obtained plurality of second coordinates may have large errors due to the measurement error of a single point to be measured.

[0012] Furthermore, in the field curvature correction method according to the first aspect of this disclosure, optionally, a straight line perpendicular to the photosensitive surface and passing through the initial imaging point is designated as an auxiliary mapping line, and the target imaging point is the intersection of the auxiliary mapping line and the reference plane. Thus, the target imaging point can be obtained.

[0013] Furthermore, in the field curvature correction method according to the first aspect of this disclosure, optionally, the differences between a plurality of first coordinates and a plurality of second coordinates are used as a plurality of correction values, and the field curvature of the microscope is corrected based on the correction values ​​during the measurement process. In this case, the field curvature of the microscope in subsequent measurement processes can be corrected using a plurality of correction values ​​obtained when measuring a standard workpiece, thereby improving the measurement accuracy of the microscope.

[0014] Furthermore, in the field curvature correction method according to the first aspect of this disclosure, optionally, during the measurement process, the second coordinate is obtained by subtracting the first coordinate from the correction value. In this case, the field curvature of the microscope can be quickly corrected so that the initial image plane of the workpiece under test is corrected to the target image plane, thereby making the image of the object under test clearer and further improving the measurement accuracy of the microscope.

[0015] Furthermore, a second aspect of this disclosure provides a field curvature correction device for a microscope. The microscope includes a support platform for supporting a workpiece and a microscope objective for scanning the workpiece. The correction device includes a recording module, a processing module, a storage module, and a correction module. The recording module is used to record multiple first coordinates and multiple second coordinates when measuring a standard surface with a roughness not greater than a first preset value. The multiple first coordinates are the spatial position coordinates of multiple initial imaging points on an initial image plane, and the multiple second coordinates are the spatial position coordinates of multiple target imaging points on a reference plane. The multiple target imaging points correspond one-to-one with the multiple initial imaging points. The processing module is configured to obtain multiple correction values ​​based on the multiple first coordinates and multiple second coordinates. The storage module is configured to store the multiple correction values. The correction module is configured to correct the field curvature of the microscope based on the multiple correction values ​​during the measurement process of the microscope.

[0016] According to the calibration device provided in this disclosure, a recording module records multiple first coordinates and multiple second coordinates when measuring a standard workpiece, and a processing module processes the multiple first coordinates and multiple second coordinates to obtain multiple calibration values. Thus, the calibration module can correct the measurement error caused by field curvature during the microscope measurement of the workpiece based on the multiple calibration values. Therefore, the measurement efficiency and measurement accuracy can be improved during the measurement of the workpiece.

[0017] Furthermore, in the field curvature correction apparatus according to the first aspect of this disclosure, optionally, the processing module obtains the plurality of correction values ​​based on the differences between the plurality of first coordinates and the plurality of second coordinates. In this case, the processing module can use the plurality of correction values ​​obtained when measuring a standard workpiece to correct the field curvature of the microscope in subsequent measurement processes, thereby improving the measurement accuracy of the microscope.

[0018] According to the field curvature correction method and field curvature correction device disclosed herein, a field curvature correction method and correction device with simple steps can be used to correct the field curvature of a microscope and thus improve the measurement accuracy of the workpiece to be measured. Attached Figure Description

[0019] This disclosure will now be explained in further detail by way of example only with reference to the accompanying drawings, in which:

[0020] Figure 1 This is a three-dimensional schematic diagram of the microscope involved in the example of this disclosure.

[0021] Figure 2 This is a flowchart illustrating the correction method involved in the example of this disclosure.

[0022] Figure 3 This is a schematic diagram illustrating the standard workpiece involved in the examples of this disclosure.

[0023] Figure 4 This is a simplified schematic diagram illustrating the measurement principle involved in the example of this disclosure.

[0024] Figure 5 This is a flowchart illustrating the process of obtaining multiple first coordinates (step S300) as described in this disclosure example.

[0025] Figure 6 This is a simplified schematic diagram illustrating the acquisition of the initial image plane as described in the examples of this disclosure.

[0026] Figure 7 This is a flowchart illustrating the process of obtaining multiple second coordinates (step S500) as described in this disclosure example.

[0027] Figure 8 This is a simplified schematic diagram illustrating the acquisition of target imaging points as described in the examples of this disclosure.

[0028] Figure 9 This is a structural block diagram illustrating the correction device involved in the example of this disclosure. Detailed Implementation

[0029] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are used for the same components, and repeated descriptions are omitted. Furthermore, the drawings are merely schematic diagrams, and the proportions of the components or the shapes of the components may differ from actual figures.

[0030] It should be noted that the terms "comprising" and "having" and any variations thereof in this disclosure, such as a process, method, system, product, or device that includes or has a series of steps or units, are not necessarily limited to those steps or units that are explicitly listed, but may include or have other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0031] Furthermore, the subheadings and similar terms used in the following description of this disclosure are not intended to limit the content or scope of this disclosure; they are merely intended to serve as reading prompts. Such subheadings should not be construed as dividing the content of the article, nor should the content under a subheading be limited to the scope of that subheading.

[0032] The first aspect of this disclosure relates to a field curvature correction method for a microscope (hereinafter referred to as the field curvature correction method or correction method), which can be used to correct the field curvature of the microscope image. This enables clear imaging of the object under test and improves the measurement accuracy of the object.

[0033] The microscope field curvature correction method disclosed herein may also be referred to as, for example, microscope correction method, aberration correction method, microscope field curvature calibration method, microscope calibration method, or aberration calibration method, etc. It should be noted that these names are for illustrative purposes only and should not be construed as limiting.

[0034] The second aspect of this disclosure relates to a field curvature correction device for a microscope (hereinafter referred to as a field curvature correction device or correction device), which can be used to implement the above-described correction method to correct the imaging of the microscope to correct the field curvature of the microscope.

[0035] The microscopes involved in this disclosure can be any microscope that involves optical imaging, such as a white light interferometer or a confocal microscope.

[0036] The present disclosure will now be described in detail using a confocal microscope as an example, in conjunction with the accompanying drawings. Figure 1 This is a three-dimensional schematic diagram of the microscope involved in the example of this disclosure.

[0037] In some examples, microscope 1 can be used to measure the workpiece to reconstruct its three-dimensional shape. See also Figure 1 In some examples, microscope 1 may include a support platform 110 and a microscope objective 121. The support platform 110 can be used to support a workpiece. The microscope objective 121 can be used to scan the workpiece. This enables measurement of the workpiece.

[0038] In some examples, the workpiece may be referred to as a sample. The workpiece can be an ultra-precise device such as a semiconductor, a 3C electronic glass screen, micro / nano materials, automotive parts, or MEMS devices. In some examples, the sample can be a device used in fields such as aerospace. In other examples, the sample can be a tissue or cell slice from the biological field.

[0039] Figure 2 This is a flowchart illustrating the correction method involved in the example of this disclosure. Figure 3 This is a schematic diagram illustrating the standard workpiece 2 involved in the example of this disclosure.

[0040] In this disclosure, the field curvature correction value of the microscope 1 is obtained by preprocessing the measurement of the microscope 1 using a standard workpiece 2. Subsequently, when measuring the workpiece to be measured, the field curvature of the microscope 1 can be corrected based on the field curvature correction value to improve the measurement accuracy of the microscope 1.

[0041] See Figure 2 The correction method disclosed herein may include placing a standard workpiece 2 on a support platform 110 (step S100), obtaining a plurality of first coordinates (step S300), obtaining a plurality of second coordinates (step S500), and correcting the field curvature of the microscope 1 based on the plurality of first coordinates and the plurality of second coordinates (step S700).

[0042] In some examples, standard workpiece 2 may be a precision-machined workpiece. See also Figure 3 In some examples, the standard workpiece 2 may have a standard surface 21. In some examples, the roughness of the standard surface 21 may not exceed a first preset value. This simplifies subsequent correction calculations.

[0043] In some examples, the first preset value may not be greater than 1 nanometer (nm). For example, the first preset value may be 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, or 1nm. In this case, the standard surface 21 can be made smoother, thus enabling the standard surface 21 to be ideally imaged as a regular and flat image surface, which facilitates the subsequent calculation of correction values.

[0044] In step S100, the standard workpiece 2 can be placed on the support platform 110. In some examples, when the standard workpiece 2 is placed on the support platform 110, the standard surface 21 can face the microscope objective 121 and be within the measurement range of the microscope objective 121. Thus, the standard workpiece 2 can be measured. In some examples, the standard surface 21 can be perpendicular to the optical axis B0 of the microscope objective 121.

[0045] In some examples, the material of the support platform 110 can be marble. Generally, marble has a fine and uniform texture, a smooth surface, and a low roughness value, allowing for high manufacturing precision, such as maintaining a manufacturing precision between 1 micrometer and 10 micrometers. In this case, the standard workpiece 2 can be placed more stably on the support platform 110, thereby improving the measurement accuracy of the standard workpiece 2.

[0046] Figure 4 This is a simplified schematic diagram illustrating the measurement principle involved in the example of this disclosure.

[0047] See Figure 4 In some examples, the microscope 1 may further include an illumination module 130, an imaging module 140, a scanning module 120, and an adjustment module 150. The scanning module 120 may include the aforementioned microscope objective 121. In some examples, the illumination module 130 may be used to emit an illumination beam L1, and the imaging module 140 may be used to receive the reflected beam L11 from the standard workpiece 2. Specifically, the illumination beam L1 may be emitted from the scanning module 120 to the standard workpiece 2 and reflected by the standard workpiece 2 to form a reflected beam L11. The reflected beam L11 is emitted from the scanning module 120 and its propagation direction is adjusted by the adjustment module 150 so that the reflected beam L11 is propagated to the imaging module 140. The imaging module 140 may be used to receive the reflected beam L11 reflected by the standard workpiece 2 to obtain an image of the standard surface 21. Thus, measurement of the standard surface 21 can be achieved.

[0048] See Figure 1 When the microscope objective 121 scans the standard workpiece 2 in the preset direction D1, it can realize the longitudinal measurement of the standard workpiece 2. When the standard surface 21 of the standard workpiece 2 is located at the focal plane of the microscope objective 121, the measurement result of the standard surface 21 can be obtained based on the reflected beam L11 of the standard surface 21 at this time.

[0049] In some examples, the preset direction D1 can be a direction perpendicular to the support platform 110.

[0050] In some examples, the microscope 1 may also include a drive module and a grating ruler. The drive module can be used to drive the microscope objective 121 to move in a preset direction D1. The grating ruler can be used to record the moving distance of the microscope objective 121 and reflect the measurement results of the standard plane 21. Thus, the measurement results of the standard plane 21 can be obtained based on the information fed back by the grating ruler.

[0051] In some examples, the measurement results described above can be height information reflected by the intensity of the reflected beam L11 of the standard surface 21. In some examples, when the intensity of the reflected beam L11 of the standard surface 21 is at its maximum, the information fed back by the grating ruler at this time can be considered as the height information of the standard surface 21.

[0052] Figure 5 This is a flowchart illustrating the process of obtaining multiple first coordinates (step S300) as described in this disclosure example.

[0053] See Figure 5 In some examples, obtaining multiple first coordinates (step S300) may include placing the standard plane 21 on the focal plane of the microscope objective 121 (step S310), obtaining multiple initial imaging points in the initial image plane P1 (step S330), and using the spatial coordinates of the multiple initial imaging points as multiple first coordinates (step S350).

[0054] In step S310, the microscope objective 121 can be driven to move in a preset direction D1 so that the standard surface 21 is located at the focal plane of the microscope objective 121. In some examples, when the microscope objective 121 moves in the preset direction D1, the standard surface 21 can be located in the negative defocus region, the focus region, and the positive defocus region of the microscope objective 121, respectively, or the standard surface 21 can be located in the positive defocus region, the focus region, and the negative defocus region of the microscope objective 121, respectively. When the standard surface 21 is located in the focus region of the microscope objective 121, a clear image of the standard surface 21 can be obtained through the microscope objective 121. In this context, the negative defocusing region of the standard surface 21 of the microscope objective 121 can mean that the standard surface 21 is located above the focal plane of the microscope objective 121, the focusing region of the standard surface 21 of the microscope objective 121 can mean that the standard surface 21 is located on the focal plane of the microscope objective 121, and the positive defocusing region of the standard surface 21 of the microscope objective 121 can mean that the standard surface 21 is located below the focal plane of the microscope objective 121.

[0055] Figure 6 This is a simplified schematic diagram illustrating the acquisition of the initial image plane P1 as described in the example of this disclosure. It will be understood that some elements have been omitted from the diagram for clarity.

[0056] As described above, in step S330, multiple initial imaging points in the initial image plane P1 can be obtained. In this disclosure, the image plane of the standard plane 21 can be designated as the initial image plane P1. In some examples, the initial image plane P1 may refer to the image plane obtained by imaging the standard plane 21 through the microscope objective 121 without processing. Figure 6 As shown, in the actual measurement process, due to the limitations of the structure of the microscope objective 121, the image of the standard plane 21 is a curved image plane. This phenomenon is called field curvature.

[0057] In some examples, the standard surface 21 can be divided into multiple test points (e.g. Figure 6 Multiple test points A0, A1, and A2 in the standard plane 21 are imaged as multiple initial imaging points (e.g., ...). Figure 6 By fitting multiple initial imaging points (A01, A11, and A21) to the standard plane 21, an initial image plane P1 matching the standard plane 21 can be obtained. Thus, multiple initial imaging points of the initial image plane P1 can be obtained, and the initial image plane P1 can be obtained based on these multiple imaging points.

[0058] In some examples, multiple initial imaging points can correspond one-to-one with each test point in the standard plane 21. Thus, the initial image plane P1 obtained by fitting multiple initial imaging points can match the standard plane 21. In some examples, the initial imaging point can refer to the point formed by the focused reflection beam L11 after passing through the microscope objective 121. Therefore, the relative height of the test point matching the initial imaging point can be obtained.

[0059] Ideally, multiple initial imaging points could all be located precisely on the back focal plane of the microscope objective 121, meaning they could lie in the same plane (hereinafter referred to as the ideal image plane P0). However, due to field curvature, the actual multiple initial imaging points are not all located on the ideal image plane P0. The further the initial imaging point is from the optical axis B0 of the microscope objective 121, the greater the deviation in distance from the ideal image plane P0. For example, the standard plane 21 is a plane, while... Figure 6 The initial image plane P1 shown is a curved surface, which will cause the image plane received by the imaging module 140 to exhibit a phenomenon where the center is clear but the edges are blurry. In other words, due to the field curvature, a clear image of the entire standard plane 21 cannot be obtained, resulting in measurement errors in the standard plane 21. Therefore, it is necessary to correct this measurement error.

[0060] In some examples, in step S350, the spatial coordinates of multiple initial imaging points can be used as multiple first coordinates. In some examples, the microscope 1 may also include a detector for detecting the intensity of the reflected beam L11, which can be used to detect the spatial position of each initial imaging point. In some examples, after obtaining the spatial position of each initial imaging point, the spatial position coordinates of each initial imaging point can be calculated using methods such as the point spread function of the optical system and Gaussian fitting localization algorithms. Thus, the spatial position coordinates of multiple initial imaging points can be obtained as multiple first coordinates.

[0061] Figure 7 This is a flowchart illustrating the process of obtaining multiple second coordinates (step S500) as described in this disclosure example. Figure 8 This is a simplified schematic diagram illustrating the acquisition of target imaging points as described in the examples of this disclosure. Figure 8 include Figure 6 An enlarged schematic diagram of the initial image plane P1 in the image.

[0062] As described above, the correction method disclosed herein may further include obtaining multiple second coordinates (step S500). See also Figure 7 In some examples, obtaining multiple second coordinates may include defining a reference plane P2 (step S510), mapping multiple initial imaging points to the reference plane P2 to obtain target imaging points (step S530), and setting the spatial position coordinates of multiple target imaging points as multiple second coordinates (step S550).

[0063] In some examples, a reference plane P2 can be predefined before obtaining multiple second coordinates. In some examples, the reference plane P2 can be the basis for obtaining multiple second coordinates. In some examples, the reference plane P2 can be any plane perpendicular to the optical axis B0 of the microscope objective 121.

[0064] In some examples, the imaging module 140 may have a photosensitive surface for receiving the reflected beam L11. In some examples, the reference plane P2 may be conjugate with the photosensitive surface of the imaging module 140. In this case, it is convenient to obtain multiple second coordinates that reflect the corrected initial image plane P1, thereby facilitating the acquisition of a target image plane that matches the standard plane 21. In some examples, the target image plane can be obtained after the initial image plane P1 is corrected.

[0065] In some examples, the reference plane P2 can coincide with the photosensitive surface of the imaging module 140. In this case, the final image of the initial imaging point can fall directly on the imaging module 140, thereby facilitating correction calculations.

[0066] In some examples, reference coordinates can be obtained based on multiple first coordinates, and the position of reference plane P2 can be set based on these reference coordinates. This facilitates the setting of reference plane P2. In some examples, obtaining reference coordinates based on multiple first coordinates can be based on the specific values ​​of these first coordinates in a preset direction D1. In other examples, reference plane P2 can coincide with the ideal image plane P0.

[0067] In some examples, the average of multiple first coordinates can be obtained as the reference coordinates. In this case, using the average of multiple first coordinates as the reference coordinates can minimize the possibility that the measurement error of a single point will lead to large errors in the subsequent obtained second coordinates.

[0068] In some examples, if the average of multiple first coordinates is obtained as the reference coordinate, then the reference plane P2 can be as follows: Figure 8 As shown. See also Figure 8 In some examples, in step S530, multiple initial imaging points (e.g., multiple initial imaging points A01, A11, and A21) can be mapped to the reference plane P2 to obtain multiple target imaging points (e.g., multiple target imaging points A02, A12, and A22). In some examples, the multiple target imaging points can correspond one-to-one with the multiple initial imaging points. Thus, a target image plane matching the standard plane 21 can be fitted based on the multiple target imaging points.

[0069] In some examples, a straight line perpendicular to the photosensitive surface and passing through the initial imaging point can be designated as an auxiliary mapping line, and the target imaging point can be the intersection of the auxiliary mapping line and the reference plane P2. This allows the target imaging point to be obtained.

[0070] In some examples, in step S550, the spatial coordinates of multiple target imaging points can be set to multiple second coordinates. In some examples, the coordinates of multiple target imaging points and the reference plane P2 in the beam propagation direction can be the same. In other words, the values ​​of the multiple second coordinates and the reference coordinates in the beam propagation direction can be the same.

[0071] In some examples, the target image plane can be fitted based on multiple second coordinates to correct the field curvature of microscope 1. This allows for more accurate measurement results of the workpiece under test.

[0072] Return to reference Figure 2 In step S700, during the measurement process, the field curvature of microscope 1 can be corrected based on multiple first coordinates and multiple second coordinates. In some examples, multiple correction values ​​can be obtained based on multiple first coordinates and multiple second coordinates, and the field curvature of microscope 1 can be corrected based on multiple correction values. This improves the measurement accuracy of microscope 1.

[0073] In some examples, the differences between multiple first coordinates and multiple second coordinates can be used as multiple correction values. That is, the distances between multiple initial imaging points and the reference plane P2 can be used as multiple correction values. In this case, multiple correction values ​​obtained when measuring the standard workpiece 2 can be used to correct the field curvature of the microscope 1 in subsequent measurement processes, thereby improving the measurement accuracy of the microscope 1.

[0074] In some examples, the correction value can be greater than 0; for example, see [link to relevant documentation]. Figure 8 The difference between the initial imaging point A01 and the target imaging point A02 can be greater than 0. In some examples, the correction value can be less than 0; for example, see [link to relevant documentation]. Figure 8 The difference between the initial imaging point A21 and the target imaging point A22, or the difference between the initial imaging point A11 and the target imaging point A12, can be less than 0. In some examples, the correction value can be 0.

[0075] In some examples, when multiple correction values ​​are obtained, it indicates that the preprocessing is complete. When measuring the workpiece in the subsequent process, the measurement results can be corrected for field curvature based on the multiple correction values ​​obtained in the preprocessing to improve the measurement accuracy.

[0076] In some examples, multiple correction values ​​can be used for field curvature correction of microscope 1 in each measurement process. This improves both measurement accuracy and efficiency.

[0077] In some examples, during the measurement process (i.e., while measuring the workpiece), the coordinates of multiple initial imaging points on the workpiece can be corrected based on multiple correction values. This reduces the possibility of poor measurement accuracy due to field curvature errors.

[0078] In some examples, when measuring the workpiece, the imaging of the test point can be corrected based on the initial imaging point and the correction value of the initial imaging point. In some examples, during the measurement process, the second coordinate can be obtained by subtracting the first coordinate from the correction value. In this case, the field curvature of microscope 1 can be quickly corrected so that the initial image plane P1 of the workpiece is corrected to the target image plane, thereby making the imaging of the test object clearer and further improving the measurement accuracy of microscope 1.

[0079] According to the correction method disclosed herein, multiple correction values ​​for the field curvature of the microscope 1 can be obtained in advance based on a standard workpiece 2 with a standard surface 21 having a roughness not greater than a first preset value through a simple preprocessing step. When measuring the workpiece to be measured, the measurement error caused by the field curvature of the microscope 1 during the measurement process can be corrected based on the multiple correction values ​​obtained in advance. Thus, the measurement efficiency and measurement accuracy can be improved during the measurement of the workpiece to be measured.

[0080] Figure 9 This is a block diagram illustrating the structure of the correction device 20 involved in the example of this disclosure.

[0081] As described above, this disclosure also provides a field curvature correction device 20 for a microscope 1 (hereinafter referred to as correction device 20), which can implement the above-described correction method to correct the field curvature of the microscope 1. In some examples, the microscope 1 may include a support platform 110 for supporting a workpiece and a microscope objective 121 for scanning the workpiece. See also Figure 9 In some examples, the correction device 20 may include a recording module 210, a processing module 220, a storage module 230, and a correction module 240. In some examples, the recording module 210 may be used to record multiple first coordinates and multiple second coordinates when measuring a standard surface 21 with a roughness not greater than a first preset value. The multiple first coordinates may be the spatial coordinates of multiple initial imaging points on the initial image plane P1, and the multiple second coordinates may be the spatial coordinates of multiple target imaging points on the reference plane P2. The multiple target imaging points may correspond one-to-one with the multiple initial imaging points.

[0082] In some examples, the processing module 220 can be configured to obtain multiple correction values ​​based on multiple first coordinates and multiple second coordinates. Specifically, the processing module 220 can obtain multiple correction values ​​based on the differences between multiple first coordinates and multiple second coordinates. In this case, the processing module 220 can use the multiple correction values ​​obtained when measuring the standard workpiece 2 to correct the field curvature of the microscope 1 in subsequent measurement processes, thereby improving the measurement accuracy of the microscope 1.

[0083] In some examples, storage module 230 can be configured to store multiple correction values. In some examples, correction module 240 can be configured to correct the field curvature of microscope 1 based on multiple correction values ​​during the measurement process of microscope 1. This improves the measurement accuracy of microscope 1.

[0084] According to the calibration device 20 provided in this disclosure, multiple first coordinates and multiple second coordinates are recorded by the recording module 210 when measuring the standard workpiece 2, and multiple first coordinates and multiple second coordinates are processed by the processing module 220 to obtain multiple calibration values. Then, the calibration module 240 can correct the measurement error caused by field curvature during the measurement of the workpiece under the microscope 1 based on the multiple calibration values. Thus, the measurement efficiency and measurement accuracy can be improved during the measurement of the workpiece under the test.

[0085] While the present disclosure has been specifically described above in conjunction with the accompanying drawings and examples, it is to be understood that the foregoing description does not limit the present disclosure in any way. Those skilled in the art can make modifications and variations to the present disclosure as needed without departing from its essential spirit and scope, and all such modifications and variations shall fall within the scope of the present disclosure.

Claims

1. A method for field curvature correction of a microscope, the microscope comprising a support platform for supporting a workpiece and a microscope objective for scanning the workpiece, characterized in that, The correction method includes: placing a standard workpiece on the support platform, the standard workpiece having a standard surface with a roughness not greater than a first preset value, the first preset value being not greater than 1 nanometer; positioning the standard surface at the focal plane of the microscope objective; setting the image plane of the standard surface as the initial image plane, acquiring multiple initial imaging points in the initial image plane, the microscope including a detector for detecting the intensity of reflected light beams, using the detector to detect the spatial position of each of the multiple initial imaging points, calculating the spatial position coordinates of each of the multiple initial imaging points using the point spread function or Gaussian fitting localization algorithm of the optical system, setting the spatial position coordinates of the multiple initial imaging points as multiple first coordinates, the multiple initial imaging points corresponding one-to-one with each test point in the standard surface; mapping the multiple initial imaging points to a reference plane to obtain multiple target imaging points matching the multiple initial imaging points, the multiple target imaging points corresponding one-to-one with the multiple initial imaging points; setting the spatial position coordinates of the multiple target imaging points as multiple second coordinates; during the measurement process, correcting the field curvature of the microscope based on the multiple first coordinates and the multiple second coordinates.

2. The field curvature correction method as described in claim 1, characterized in that: The microscope includes an imaging module for receiving the reflected light beam from the standard workpiece, and the reference plane is conjugate to the photosensitive surface of the imaging module.

3. The field curvature correction method as described in claim 2, characterized in that: A reference coordinate is obtained based on multiple first coordinates, and the position of the reference plane is set based on the reference coordinate.

4. The field curvature correction method as described in claim 3, characterized in that: The average value of the plurality of first coordinates is obtained as the reference coordinate.

5. The field curvature correction method as described in claim 2, characterized in that: Let the straight line perpendicular to the photosensitive surface and passing through the initial imaging point be the auxiliary mapping line, and the target imaging point be the intersection of the auxiliary mapping line and the reference plane.

6. The field curvature correction method as described in claim 1, characterized in that: The differences between multiple first coordinates and multiple second coordinates are used as multiple correction values. During the measurement process, the field curvature of the microscope is corrected based on the correction values.

7. The field curvature correction method as described in claim 6, characterized in that: During the measurement process, the difference between the first coordinate and the correction value is used to obtain the second coordinate.

8. A field curvature correction device for a microscope, the microscope comprising a support platform for supporting a workpiece and a microscope objective for scanning the workpiece, characterized in that: The correction device includes a recording module, a processing module, a storage module, and a correction module. The recording module records multiple first coordinates and multiple second coordinates when measuring a standard surface with a roughness not greater than a first preset value, where the first preset value is not greater than 1 nanometer. The microscope includes a detector for detecting the intensity of the reflected light beam. The microscope uses the detector to detect the spatial position of each of the multiple initial imaging points and calculates the spatial position coordinates of each of the multiple initial imaging points using the point spread function or Gaussian fitting localization algorithm of the optical system. The multiple first coordinates are the spatial position coordinates of multiple initial imaging points on the initial image plane, and the multiple second coordinates are the spatial position coordinates of multiple target imaging points on the reference plane. The multiple target imaging points correspond one-to-one with the multiple initial imaging points. The processing module is configured to obtain multiple correction values ​​based on the multiple first coordinates and the multiple second coordinates. The storage module is configured to store the plurality of correction values; The correction module is configured to correct the field curvature of the microscope based on the plurality of correction values ​​during the measurement process of the microscope.

9. The field curvature correction device as described in claim 8, characterized in that: The processing module obtains the plurality of correction values ​​based on the differences between the plurality of first coordinates and the plurality of second coordinates.

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