Novel high-precision self-calibration method for transverse distortion of white light interference vertical scanning system
By combining an optical two-dimensional planar target and a mapping model, high-precision self-calibration of lateral distortion in a white light interferometric vertical scanning system was achieved, solving the problems of low efficiency and high cost in existing technologies and improving calibration accuracy and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI UNIV OF AUTOMOTIVE TECH
- Filing Date
- 2026-01-09
- Publication Date
- 2026-05-01
AI Technical Summary
Existing methods for lateral distortion calibration in white light interferometric vertical scanning systems are inefficient, costly, and inaccurate, failing to effectively correct distortion and requiring expensive three-dimensional targets and multiple measurements.
By employing an optical two-dimensional planar target and constructing a mapping model for grid deformation registration, a mapping relationship between pixel coordinates and physical coordinates is established, enabling one-time high-precision self-calibration and avoiding expensive three-dimensional targets and multiple measurements.
It achieves high-precision lateral calibration across the entire field of view, simplifies operation, reduces costs, improves calibration accuracy and repeatability, and avoids accuracy decay in edge areas.
Smart Images
Figure CN121953902A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanostructure measurement or analysis, specifically relating to a novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system. Background Technology
[0002] Vertical Scanning Interferometry (VSI) is a high-precision three-dimensional topography measurement technique based on the principle of low-coherence interference. It has advantages such as nanometer-level vertical resolution, non-contact non-destructive testing, high measurement efficiency, and high data density. This method has been widely used in high-end manufacturing fields such as semiconductor wafer inspection, optical component surface analysis, micro-nano additive manufacturing, and precision industrial quality control.
[0003] The white-light interferometric vertical scanning system, based on the principle of low-coherence interference, can achieve nanometer-level measurement accuracy in longitudinal (Z-axis) height measurement. Lateral distortion is widespread in optical imaging systems. Due to the unavoidable introduction of radial, tangential, and more complex nonlinear distortions by the interferometric objective and imaging lens, the measured 3D point cloud exhibits nonlinear distortion in the lateral (XY) direction. Therefore, lateral (XY) distortion calibration of the white-light interferometric vertical scanning system is a crucial step in achieving high-precision 3D topography measurement, and is of great significance to the overall measurement accuracy and traceability of the system.
[0004] Existing methods for lateral (XY) distortion calibration are as follows: 1) A self-calibration method is used to resolve lateral distortion, and then an absolute scale is used to complete the traceability of calibration.
[0005] This method involves taking multiple measurements of the same rigid target (such as an uncalibrated mesh or arbitrary surface) in different postures (including rotation and translation), using an iterative self-calibration algorithm to separate the true geometry of the object's surface and the optical distortion of the measurement system from multiple sets of data, and finally introducing a one-dimensional traceable standard ruler (such as a grating) to determine the absolute physical scale, thereby achieving lateral (XY) distortion calibration and measurement.
[0006] 2) Lateral (XY) distortion calibration is performed using an artificial three-dimensional target with a square hole array structure.
[0007] The method first measures the true physical coordinates (i.e., the centroid of the square hole) of the control point in the three-dimensional target using a traceable measuring instrument; then it measures the three-dimensional target using a white light interferometric vertical scanning system to identify the square hole and calculate the control point (centroid).
[0008] Based on this, two methods are used for lateral (XY) distortion calibration: 1. By calculating the amplification factor and orthogonality based on the point set of the true coordinates of the square hole centroid and the measured coordinates of the white light interferometric vertical scanning system, linear calibration of lateral (XY) distortion is achieved. 2. A polynomial de-distortion model with self-calibration error separation is used to calculate the relationship between the observed values and the true values of the control points, thereby calibrating the lateral (XY) distortion of the system.
[0009] Both of the above methods are research theories proposed by foreign scholars and have not been practically applied in domestic white light interferometric vertical scanning systems. According to investigations, the lateral (XY) calibration of domestic white light interferometric vertical scanning systems all uses a single high-precision scale to calculate pixel length, achieving the dimensional conversion from pixel to physical dimensions through proportional calculations—that is, physical calibration.
[0010] This method has the following four problems: 1) The scale cannot completely correct lateral distortion; 2) It cannot guarantee that the scale and pixels are strictly level; 3) The scale resolution is limited; 4) The scale is expensive. Summary of the Invention
[0011] This invention aims to solve the technical problems of low efficiency, high cost, and low accuracy in the calibration process of existing vertical scanning systems, which require step-by-step calibration and multiple measurements at different attitudes. To address these problems, this invention provides a novel high-precision self-calibration method for lateral distortion in white light interferometric vertical scanning systems.
[0012] This invention provides a novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system, specifically including the following steps: S1: Place the optical two-dimensional planar target on the optical path alignment module and position it directly below the white light interference microscope objective; S2: Adjust the optical two-dimensional planar target to be perpendicular to the optical path of the interference system; S3: Obtain a white light interference microscopy image of the optical two-dimensional planar target; S4: Extract the pixel coordinates of the control points from the white light interference microscopy image; S5: Calculate the world coordinates of the control point in physical space; S6: Based on the correspondence between the pixel coordinates and the world coordinates, construct a mapping model for mesh deformation registration; S7: Use the mapping model to achieve distortion self-calibration in the lateral XY direction.
[0013] A lateral distortion self-calibration system for implementing the novel white light interferometric vertical scanning system with high-precision lateral distortion self-calibration method, comprising: The white light interference microscopy imaging system includes a white light source, a beam splitter, a white light interference microscopy objective lens, and an imaging lens; An optical two-dimensional planar target is a sequence pattern of non-collinear feature points with known physical coordinates. A support and alignment unit, used to support and adjust the attitude of the optical two-dimensional planar target, includes: The optical path alignment module is used to adjust the spatial angle of the optical two-dimensional planar target so that its plane is perpendicular to the optical axis of the white light interference microscope objective. The XY-axis horizontal displacement module is used to move the optical path alignment module and the optical two-dimensional planar target in the horizontal plane. Z-axis displacement module is used to move the white light interference microscope objective or the carrier and alignment unit along the optical axis; A computer, connected to the white light interferometric microscopy system, is used to acquire images, perform image processing and coordinate calculations, and construct the mapping model to complete calibration.
[0014] The technical solution provided by this invention has the following beneficial effects: This invention provides a novel high-precision self-calibration method for lateral (XY) distortion in a white light interferometric vertical scanning system. This method requires only one white light interferometric microscopy imaging with a two-dimensional target. By constructing a mapping model with grid deformation registration, a mapping relationship between pixel coordinates and physical coordinates in the entire field of view is established, realizing high-precision self-calibration of lateral (XY) distortion in the white light interferometric vertical scanning system. Through the mapping model with grid deformation registration, different degrees of distortion differences are corrected, enabling the system to maintain a uniform lateral (XY) calibration accuracy distribution in the entire field of view, improving the problem of accuracy attenuation in edge regions, and simultaneously completing the dimensional conversion. Compared with the method of lateral (XY) distortion calibration using a three-dimensional target, the proposed method uses a planar two-dimensional target, which has high calibration accuracy, simple operation, low computational load, and good repeatability. It eliminates the need for expensive three-dimensional target fabrication and avoids the use of traceable measuring instruments to measure the true value of control points, reducing the system calibration cost. Attached Figure Description
[0015] The present invention will be further described below with reference to the accompanying drawings and examples. In the accompanying drawings: Figure 1 This is a schematic diagram of the overall process of a novel white light interferometric vertical scanning system with high-precision self-calibration for lateral distortion according to the present invention. Figure 2 This is a schematic diagram of the system structure of the present invention; Figure 3 This is a schematic diagram of the optical two-dimensional planar target of the present invention. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.
[0017] Example 1 Please refer to Figure 1 This invention provides a novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system, the main steps of which are as follows: S1: Place the optical two-dimensional planar target on the optical path alignment module and position it directly below the white light interference microscope objective; It should be noted that the optical two-dimensional planar target is a sequence pattern of non-collinear feature points with known physical coordinates; the pattern includes a checkerboard, grid, or dot matrix pattern.
[0018] S2: Adjust the optical two-dimensional planar target to be perpendicular to the optical path of the interference system; It should be noted that step S2 is as follows: S21: Fix the optical two-dimensional planar target to the optical path alignment module; S22: Adjust the optical path alignment module to change the spatial orientation of the optical two-dimensional planar target; S23: Fine-tune to make the plane of the optical two-dimensional target perpendicular to the interference optical path; S24: Lock the optical path alignment module.
[0019] S3: Obtain a white light interference microscopy image of the optical two-dimensional planar target; It should be noted that step S3 is as follows: S31: Adjust the Z-axis displacement module and observe whether interference occurs; S32: At the position one moment before the start of interference or one moment after the end of interference, acquire a clear white light interference microscopic image of the optical two-dimensional planar target.
[0020] Specifically, the white light interferometric microscopy system is started; the coarse drive module in the Z-axis displacement module is adjusted to observe whether interference occurs in the system; when interference occurs, the adjustment is stopped and the coarse drive module is locked; the XY-axis horizontal displacement module is finely adjusted to distribute the optical two-dimensional planar target throughout the system, keeping the spatial angle and orientation of the target constant during adjustment; the fine drive module in the Z-axis displacement module is slowly adjusted to define point A as the moment before interference fringes appear and point B as the moment after they disappear, thus obtaining the interference range AB; at point A or point B, the exposure time and light source brightness are adjusted to obtain a clear white light interferometric microscopy image of the optical two-dimensional planar target.
[0021] S4: Extract the pixel coordinates of the control points from the white light interference microscopy image; It should be noted that step S4 is as follows: S41: Identify control points in the white light interference microscopy image; S42: Calculate the sub-pixel coordinates of the control point; S43: Use the sub-pixel coordinate value as the pixel coordinate.
[0022] Specifically, the control points are { P ij | i= 0,1,2 … ,n; j= 0,1,2 … ,n}, that is, the nth digit in the white light interference microscopy image. i line, number j Subpixel coordinates of the grid control points of the column P ij ( u ij , v ij (The unit is pixels).
[0023] S5: Calculate the world coordinates of the control point in physical space; It should be noted that step S5 is as follows: S51: Define the world coordinate system Z w The zero plane coincides with the optical two-dimensional plane target plane; S52: Calculate the world coordinates of each control point based on the known physical distance between the control points in the optical two-dimensional planar target.
[0024] Specifically, define control points { Q ij | i= 0,1,2 … ,n; j= 0,1,2 … ,n} is the nth integer in an optical two-dimensional planar target. i Column, No. j Control points on the line; define the world coordinate system Z w =0 plane coincides with the optical two-dimensional target plane; calculate control points. Q ij ( x ij , y ij The world coordinates of the symbol are expressed in micrometers.
[0025] S6: Based on the correspondence between the pixel coordinates and the world coordinates, construct a mapping model for mesh deformation registration; It should be noted that step S6 is as follows: S61: Establish a mapping function between the control point pixel coordinate set P and the world coordinate set Q; S62: The mapping function is a polynomial mapping function M, in the form of:
[0026] x ij , y ij and u ij and v ij The specific functional relationships are as follows:
[0027] in, a k and b k They are x ij and y ij The mapping coefficients, , , For pixel coordinates, Used as world coordinates.
[0028] Specifically, due to control points P ij With control points Q ij There exists a one-to-one correspondence; feature point groups are defined. L ij { P ij , Q ij}; In a white light interference microscopy imaging system, the control point is located at the upper left corner of the imaging plane. P 00 Based on this, traverse the corresponding control points in physical space in both column and row directions. Q ij This achieves matching between control points, ultimately resulting in a series of control point groups. L 00 { P 00 , Q 00}、 L 01 {P 01 , Q 01}、 L 02 { P 02 , Q 02}… L ij { P ij , Q ij}; In the control point group P 00 、P 01 、P 02 arrive P ij Let it be set P. Q 00 、Q 01 、Q 02 arrive Q ij Define it as set Q; Construct a mapping model for mesh deformation registration and establish a mapping function between set P and set Q. W Achieve high-precision calibration of lateral (XY) distortion in white light interferometric vertical scanning system; Among them, since the white light interference microscope objective is a high magnification objective with an extremely shallow depth of field, it is necessary to ensure that the optical two-dimensional plane target is perpendicular to the interference optical path in order to obtain a clear white light interference microscope image of the two-dimensional plane target. Among them, point A or point B is the scanning start position, where there is no interference from interference fringes, and the longitudinal (Z-axis) measurement data is acquired from the moment the interference fringes are generated. Therefore, the above two points are the optimal positions for acquiring the target image. Among them, the white light interference microscopy image of the optical two-dimensional planar target exhibits distortion; Among them, calculate control points Q ij ( x ij , y ij When determining the world coordinates, any control point can be set as the origin of the coordinate system. By determining the specific coordinates of any two control points in the X-axis and Y-axis directions, the physical coordinates of all control points can be assigned. Among them, control points P ij The calculation can be performed without being limited to computer algorithms; control points can be obtained in various ways.P ij Pixel coordinates; Wherein, the mapping function between set P and set Q M as follows; (1) In the above formula x ij , y ij and u ij and v ij The specific functional relationships are as follows: (2) in, a k and b k They are x ij and y ij The mapping coefficients, , .
[0029] S7: Use the mapping model to achieve distortion self-calibration in the lateral XY direction.
[0030] It should be noted that step S7 is as follows: S71: Substitute the pixel coordinates and the world coordinates into the mapping function to form a system of linear equations; S72: Solve for the mapping coefficients using the least squares method; S73: Substitute the obtained mapping coefficients into the mapping function to complete the construction of the lateral distortion calibration model.
[0031] Specifically, the mapping relationship of formula (2) can be expanded as follows: x ij and u ij and v ij Relationship: (3) y ij and u ij and v ij Relationship: (4) make = , = , = , = , = Formulas (3) and (4) can be simplified to: (5) (6) To calculate the matrix Multiply both sides of equation (5) by You can obtain: (7) Due to the matrix It is an invertible matrix. It can be obtained from formula (7): (8) Similarly, matrix It can be obtained by transforming formula (6): (9) Solve for the mapping coefficients; based on formulas (8) and (9), the mapping relationship is finally obtained. M middle ij , y ij mapping coefficients = and = Achieving high-precision self-calibration of lateral (XY) distortion in the white light interferometric vertical scanning system.
[0032] Example 2 A lateral distortion self-calibration system for implementing the novel white light interferometric vertical scanning system with high-precision lateral distortion self-calibration method, comprising: The white light interference microscopy imaging system includes a white light source, a beam splitter, a white light interference microscopy objective lens, and an imaging lens; An optical two-dimensional planar target is a sequence pattern of non-collinear feature points with known physical coordinates. A support and alignment unit, used to support and adjust the attitude of the optical two-dimensional planar target, includes: The optical path alignment module is used to adjust the spatial angle of the optical two-dimensional planar target so that its plane is perpendicular to the optical axis of the white light interference microscope objective. The XY-axis horizontal displacement module is used to move the optical path alignment module and the optical two-dimensional planar target in the horizontal plane. Z-axis displacement module is used to move the white light interference microscope objective or the carrier and alignment unit along the optical axis; A computer, connected to the white light interferometric microscopy system, is used to acquire images, perform image processing and coordinate calculations, and construct the mapping model to complete calibration.
[0033] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the self-calibration system structure of the present invention; This embodiment presents a novel high-precision self-calibration method for lateral (XY) distortion in a white light interferometric vertical scanning system, such as... Figure 2 As shown, it includes a white light interference microscopy imaging system 1, a computer 2, an imaging lens 3, a beam splitter 4, a white light source 5, a white light interference microscopy objective lens 6, an optical two-dimensional plane target 7, an optical path alignment module 8, an X-Y horizontal displacement module 9, a Z-displacement working module 10, a coarse-stage drive module 11, and a fine-stage drive module 12.
[0034] The optical two-dimensional planar target 7 is horizontally placed on the optical path alignment module 8, and the optical path alignment module 8 has a clamping device that can fix the optical two-dimensional planar target 7, forming a rigid connection between the two.
[0035] Among them, the optical two-dimensional planar target 7 is used for lateral (XY direction) distortion calibration in the white light interferometric vertical scanning system, and can be any sequence pattern of non-collinear feature points with known physical coordinates.
[0036] Among them, the optical path alignment module 10 is used to adjust the interference optical path to be perpendicular to the optical two-dimensional plane target plane. As a preferred embodiment, the optical path alignment module 10 can be composed of a spatial dual-axis tilting angular stage, which has dual-degree-of-freedom rotation adjustment and locking functions.
[0037] The Z-axis displacement working module consists of a coarse-stage Z-axis displacement drive module 11 and a fine-stage Z-axis displacement drive module 12. The coarse-stage drive module 11 can be composed of a stepper motor and a lead screw, while the fine-stage drive module 12 is composed of piezoelectric ceramics and a flexible hinge.
[0038] Computer 2 is used to acquire white light interferometric microscopic images of two-dimensional planar targets, extract the coordinates of control points, and after analysis and calculation, finally obtain the distortion calibration results.
[0039] Example 3 This invention provides a self-calibration method using this system as follows: 1. Place the optical two-dimensional planar target 7 horizontally on the optical path alignment module 10 and directly below the white light interference microscope objective 6, so that the optical two-dimensional planar target is located in the optical path of the interference system. The optical two-dimensional planar target 7 can be any sequence pattern of non-collinear feature points with known physical coordinates. In this embodiment, a checkerboard pattern is used as an example. 2. Adjust the optical two-dimensional planar target 7 to be perpendicular to the optical path of the interference system, including the following sub-steps: Fix the optical two-dimensional planar target (taking a checkerboard pattern as an example) 7 to the optical path alignment module 10 and lock the fixing fixture; Adjust the optical path alignment module 10 to change the spatial attitude of the optical two-dimensional planar target (taking the checkerboard pattern as an example). The optical path alignment module 10 is mainly composed of a spatial dual-axis tilting angle stage, which has dual-degree-of-freedom rotation adjustment and locking functions. Fine-tuning achieves perpendicularity between plane 7 of the optical two-dimensional planar target (taking a checkerboard pattern as an example) and the interference optical path, and locks the optical path alignment module 10; 3. Acquisition of white light interference microscopic images of a two-dimensional planar target, including the following sub-steps; Start the white light interference microscopy system 1; Adjust the coarse-stage drive module 11 in the Z-axis displacement working module 10 and observe whether interference occurs in the white light interferometric microscopy imaging system 1. When interference occurs, stop adjusting and lock the coarse-stage drive module 11. The XY horizontal displacement module 9 is fine-tuned to distribute the image of the optical two-dimensional planar target 7 throughout the white light interferometric microscopy system 1, while maintaining the spatial angle and orientation of the optical two-dimensional planar target 7 during fine-tuning. By slowly adjusting the precision drive module 12 in the Z-axis displacement working module, the position a moment before the interference fringes begin to appear is set as point A, and the position a moment after the interference fringes disappear is set as point B, thus obtaining the interference generation range AB. At point A or point B, adjust the exposure time and light source brightness to produce a clear optical two-dimensional planar target 7 white light interference microscopy image; 4. Calculate the pixel coordinates of the control points of the optical two-dimensional planar target (chessboard) in the white light interferometric microscopy imaging system 1, including the following sub-steps: The white light interference microscopy image of the two-dimensional planar optical target (checkerboard pattern) 7 acquired by computer 2 contains distortions due to the lack of any processing. Figure 3 As shown: Calculate the control points in a white light interferometry micrograph of a two-dimensional planar target (checkerboard pattern). P ij | i= 0,1,2 … ,n; j= 0,1,2 … ,n} (i.e., the nth element in a white light interference microscopy image) i line, number j Subpixel coordinates of the control points of the column P ij ( u ij , v ij (The unit is pixels. In this embodiment, the interior corner extraction algorithm in OpenCV is used to calculate the control points.) P ij The sub-pixel coordinates, such as Figure 3 As shown, the white light interference microscopy imaging plane o-uv The pixel coordinate system is defined with the top left corner of the image as the origin, and horizontal coordinates extending to the right. u The axis, vertically downwards is v axis, u ij and v ij These are feature points P ij In pixel coordinate system o-uv middle u , v The coordinates in the direction, in pixels; 5. Calculate the world coordinates of the optical two-dimensional plane target control points in physical space, including the following sub-steps: Definition point Q ij ( x ij , y ij ) is the first optical two-dimensional planar target (chessboard pattern) i Column, No. j Interior corners of a row, such as Figure 3 As shown; Define the world coordinate system Zw=0 plane to coincide with the optical calibration plate plane, realize the dimensionality reduction of the world coordinate values of the control points in the optical two-dimensional plane target in physical space, and transform the mapping between points on the two-dimensional plane and points in three-dimensional space into the mapping between points on the two-dimensional image plane and points on the two-dimensional physical plane. Calculate feature points Q ij ( x ij , y ij The world coordinates of ) are calculated as follows: (10) (11) in, xij and y ij These are control points Q ij In the world coordinate system O w -X w Y w middle x , y Coordinate values in the direction; w The width of the chessboard grid is expressed in micrometers. Among them, calculate control points Q ij ( x ij , y ij When determining the world coordinates of a feature point, any feature point can be set as the origin of the coordinate system. By determining the specific coordinates of any feature point in the X-axis and Y-axis directions, the physical coordinates of all control points can be assigned. 6. Construct a mapping model for grid deformation registration to achieve high-precision self-calibration of lateral (XY) distortion in the white light interferometric vertical scanning system, including the following sub-steps: Due to control points P ij With control points Q ij There is a one-to-one correspondence; define a control point group. L ij { P ij , Q ij}; In white light interference microscopy imaging systems, the imaging plane o-uv Top left control point P 00 Based on this, iterate through the corresponding control points in physical space in both column and row directions. Q ij This process achieves control point matching, ultimately resulting in a series of control point groups. L 00 { P 00 , Q 00}、 L 01 { P 01 , Q 01}、 L 02 { P 02 ,Q 02}… L ij { P ij , Q ij}; In the control point group P 00 , P 01 , P 02 arrive P ij Let it be set P. Q 00 , Q 01 , Q 02 arrive Q ij Define it as set Q; Construct a mapping model for mesh deformation matching and establish a mapping function between set P and set Q. M The function is as follows: (12) In the above formula x ij , y ij and u ij and v ij The specific functional relationships are as follows: (13) in, a k and b k They are x ij and y ij The mapping coefficients, , .
[0040] 7. Use the mapping model to achieve distortion self-calibration in the horizontal XY direction.
[0041] The mapping relationship is expanded as follows: x ij and u ij and v ij Relationship: (14) yij and u ij and v ij Relationship: (15) make = , = , = , = , = Formulas (14) and (15) can be simplified to: (16) (17) To calculate the matrix Multiply both sides of equation (16) by You can obtain: (18) Due to the matrix It is an invertible matrix. It can be obtained from formula (18): (19) Similarly, matrix It can be obtained by transforming formula (17): (20) Solve for the mapping coefficients; based on formulas (19) and (20), the mapping relationship is finally obtained. M middle x ij , y ij mapping coefficients = and = Achieving high-precision self-calibration of lateral (XY) distortion in the white light interferometric vertical scanning system.
[0042] The preferred embodiments of the present invention disclosed above are only for the purpose of illustrating the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation described herein. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention.
Claims
1. A novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system, characterized in that, Includes the following steps: S1: Place the optical two-dimensional planar target on the optical path alignment module and position it directly below the white light interference microscope objective; S2: Adjust the optical two-dimensional planar target to be perpendicular to the optical path of the interference system; S3: Obtain a white light interference microscopy image of the optical two-dimensional planar target; S4: Extract the pixel coordinates of the control points from the white light interference microscopy image; S5: Calculate the world coordinates of the control point in physical space; S6: Based on the correspondence between the pixel coordinates and the world coordinates, construct a mapping model for mesh deformation registration; S7: Use the mapping model to achieve distortion self-calibration in the lateral XY direction.
2. The novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system according to claim 1, characterized in that, The optical two-dimensional planar target is a sequence pattern of non-collinear feature points with known physical coordinates; the pattern includes a checkerboard, grid, or dot matrix pattern.
3. The novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system according to claim 1, characterized in that, Step S2 is as follows: S21: Fix the optical two-dimensional planar target to the optical path alignment module; S22: Adjust the optical path alignment module to change the spatial orientation of the optical two-dimensional planar target; S23: Fine-tune to make the plane of the optical two-dimensional target perpendicular to the interference optical path; S24: Lock the optical path alignment module.
4. The novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system according to claim 1, characterized in that, Step S3 is as follows: S31: Adjust the Z-axis displacement module and observe whether interference occurs; S32: At the position one moment before the start of interference or one moment after the end of interference, acquire a clear white light interference microscopic image of the optical two-dimensional planar target.
5. The novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system according to claim 1, characterized in that, Step S4 is as follows: S41: Identify control points in the white light interference microscopy image; S42: Calculate the sub-pixel coordinates of the control point; S43: Use the sub-pixel coordinate value as the pixel coordinate.
6. The novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system as described in claim 1, characterized in that, Step S5 is as follows: S51: Define the world coordinate system Z w The zero plane coincides with the optical two-dimensional plane target plane; S52: Calculate the world coordinates of each control point based on the known physical distance between the control points in the optical two-dimensional planar target.
7. A novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system as described in claim 1, characterized in that, Step S6 is as follows: S61: Establish a mapping function between the control point pixel coordinate set P and the world coordinate set Q; S62: The mapping function is a polynomial mapping function M, in the form of: x ij , y ij and u ij and v ij The specific functional relationships are as follows: in, a k and b k They are x ij and y ij The mapping coefficients, , , For pixel coordinates, s represents world coordinates, and s represents the model order parameter.
8. A novel high-precision self-calibration method for lateral distortion in a white light interferometric vertical scanning system as described in claim 7, characterized in that: Step S7 is as follows: S71: Substitute the pixel coordinates and the world coordinates into the mapping function to form a system of linear equations; S72: Solve for the mapping coefficients using the least squares method; S73: Substitute the obtained mapping coefficients into the mapping function to complete the construction of the lateral distortion calibration model.
9. A lateral distortion self-calibration system for implementing the novel white light interferometric vertical scanning system lateral distortion high-precision self-calibration method as described in any one of claims 1-8, characterized in that, include: The white light interference microscopy imaging system includes a white light source, a beam splitter, a white light interference microscopy objective lens, and an imaging lens; An optical two-dimensional planar target is a sequence pattern of non-collinear feature points with known physical coordinates. A support and alignment unit, used to support and adjust the attitude of the optical two-dimensional planar target, includes: The optical path alignment module is used to adjust the spatial angle of the optical two-dimensional planar target so that its plane is perpendicular to the optical axis of the white light interference microscope objective. The XY-axis horizontal displacement module is used to move the optical path alignment module and the optical two-dimensional planar target in the horizontal plane. Z-axis displacement module is used to move the white light interference microscope objective or the carrier and alignment unit along the optical axis; A computer, connected to the white light interferometric microscopy system, is used to acquire images, perform image processing and coordinate calculations, and construct the mapping model to complete calibration.