Distortion correction system and method for laser self-space five-dimensional galvanometer

Abstract

The invention discloses a distortion correction system and method for a laser self-space five-dimensional galvanometer. The distortion correction system comprises an offset module, a beam expanding module, a scanning module and a focusing module. All the modules are sequentially installed in the equipment according to a certain interval, and a laser beam at the tail end is focused on a working plane on a workbench through movement of an optical lens to achieve movement in a five-dimensional space, namely scanning in the X dimension and the Y dimension, movement of a focus in the Z dimension and deflection in the alpha dimension and the beta dimension are achieved. The offset module is used for enabling the light beam to deviate from the optical axis by a certain distance in the X dimension and the Y dimension; the beam expanding module is used for expanding the beam diameter; the scanning module is used for scanning the light beam in an XY plane; the focusing module is used for focusing the light beam and can ensure that the inclination angle of the focused light beam is small enough. Indirect correction of the processing pattern is adopted, different correction patterns are designed according to different dimensions of light beam movement, operation is convenient, and cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of laser self-space five-dimensional galvanometers, and in particular to a distortion correction system and method for a laser self-space five-dimensional galvanometer. Background Art

[0002] The laser self-space five-dimensional galvanometer is a high-precision laser processing equipment. Its essence is to achieve the five-dimensional movement of the light beam space (X, Y, Z, α, β) by adjusting the optical lens in the system. Due to the installation error of the system and the aberration caused by optical focusing, there will be deviations when the light beam is scanned in each dimension, which will affect the processing results. Therefore, each dimension needs to be calibrated before the system is used. At present, the most common calibration is the calibration of the X, Y and Z dimensions;

[0003] For example, the publication number CN117139832A proposes a method for rapid correction of a two-dimensional galvanometer, but this method is only applicable to distortion in the XY plane and has symmetry, and is not effective for other forms of distortion. It can only correct the XY dimensions, and the correction of the α and β dimensions is currently blank. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a distortion correction system and method for a laser self-space five-dimensional galvanometer. The distortion correction method adopts indirect correction of processing patterns and designs different correction patterns for different dimensions of light beam movement. It is easy to operate and has low cost.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A laser self-space five-dimensional galvanometer distortion correction system comprises an offset module, a beam expansion module, a scanning module and a focusing module which are installed in sequence;

[0007] The offset module is used to make the laser beam deviate from the optical axis by a certain distance in the X dimension and the Y dimension;

[0008] The beam expansion module is used to expand the diameter of the laser beam transmitted by the offset module 1;

[0009] The scanning module realizes scanning of the laser beam in the XY plane after the diameter is expanded;

[0010] The focusing module is used to focus the laser beam and make the inclination angle of the focused beam small enough;

[0011] Through the movement of the optical lens, the terminal laser beam of the focusing module is focused on the working plane to realize five-dimensional spatial movement, namely, scanning in the X and Y dimensions, movement of the focus in the Z dimension, and deflection in the α and β dimensions.

[0012] The offset module 1 is composed of two groups of reflection / refractive modules, each group of reflection modules is composed of two parallel reflection mirrors or flat plates; the reflection mirrors or flat plates of the two groups of reflection modules are perpendicular to each other;

[0013] The number of each group of parallel reflectors or parallel plates is two, and the incident laser beam is reflected in sequence by the first reflector or plate of the first reflector module, the second reflector or plate of the first reflector module, the first reflector or plate of the second reflector module, and the second reflector or plate of the second reflector module.

[0014] The first set of reflective modules is set at a certain angle to the incident laser beam, and the angle is less than 90 degrees. (The initial angle of the first set of reflectors is 45° to the incident light, ensuring that the incident light can be emitted in parallel to the second set of reflectors after passing through the first set of reflectors.)

[0015] The distance between the two reflection modules is D1, and the distance from the working plane is D2. The distance between the reflectors in each group of reflection modules is d1. The initial light beam is vector P0 = (0, 0, 1). By tracing the light beam using the vector method, we can get:

[0016]

[0017] The beam expansion module is composed of a lens group at a certain distance, wherein the first lens is a dynamic lens, which forms a dynamic focusing module with the focusing module, and is used to control the Z dimension of the light beam; the dynamic lens is a concave lens, which is directly driven by a voice coil motor or indirectly driven by a rotary motor electric connecting rod; the beam diameter is expanded to 8mm or 9mm for easy focusing. Generally, the output beam is about 2mm, so the beam expansion module is generally selected to be 4 times;

[0018] The scanning module includes two mutually perpendicular reflectors; the scanning module is equivalent to a set of two-dimensional galvanometer mirrors, which realizes plane scanning through the continuous deflection of the XY lens; when the light beam enters the scanning module, it is ensured that the angle between it and the lens is 45°

[0019] The focusing module is a telecentric field mirror, and the beam expansion system needs to be determined based on the entrance aperture of the imaging system; there are no specific requirements, as long as it is convenient for focusing observation.

[0020] The surface of the workbench is the work plane, and the initial distance D between the work plane and the focusing module is obtained by the rangefinder of the paraxial vision system, wherein the initial distance D is the initial focus position of the system; the distortion of each dimension is measured by an indirect method, and different processing patterns are used for different dimensions to indirectly reflect the distortion amount, wherein the position (distortion amount) of the pattern is obtained by the CCD camera of the paraxial vision system, and is converted into the actual position in the workpiece coordinate system according to the coordinate transformation, and the distortion amount is the difference between the theoretical position and the actual position in the workpiece coordinate system;

[0021] The workbench is an electric workbench with six-degree-of-freedom control capability, capable of reciprocating movement in X, Y, and Z dimensions and rotation around these three dimensions.

[0022] The operation method of the electric workbench is:

[0023] First, place the correction plate on the work plane. The pattern on the correction plate is composed of circles with a radius of 0.5mm, and the circles have a center line. The multiple circles on the correction plate form an n*n grid according to the size of the correction plate, where the spacing between the circles is 1mm. The position deviation of the center line of the circle in the correction plate is observed by a CCD camera, where the center line represents the XY direction. According to the gap between the center line and the X-axis and the gap between the center line and the Y-axis, the six-degree-of-freedom workbench is used to adjust the position of the correction plate on the X-axis and the Y-axis respectively, and finally the center line of the circle is made to coincide with the XY axis of the workbench, thereby eliminating the error of the workbench.

[0024] For the correction of XY dimensions, the grid method is used. The distortion value is measured by depicting an N*N grid. For the correction of distortion, the actual position of the grid point is captured and identified by the visual system, and the difference between the actual position and the theoretical position of the grid point is determined. Based on the coordinate difference of each grid point in each row of the grid, the difference of multiple coordinates of each row is fitted to obtain a correction table consisting of the actual coordinates of the grid point and the coordinate difference. Alternatively, the corner point approximation method is used to calculate the coordinate difference of the unknown marking point using the coordinate difference of the surrounding grid points, and obtain a correction table constructed by each unknown marking point and its coordinate difference.

[0025] For the measurement of the Z-dimensional focus, a new test system is arranged between the focusing module and the workbench, and the spot size is measured using a beam quality analyzer, with the smallest spot size being regarded as the focus position; first, the focusing module beam is reflected by reflector 1 to the beam expansion system to expand the beam diameter, and then reflected by reflector 2 to the filter system. After passing through the filter system, the beam energy is reduced, and then it is refocused by the imaging system;

[0026] As the lens in the laser self-space five-dimensional galvanometer is adjusted, the theoretical change value of the focus in the Z dimension can be obtained by calculation. The beam expansion module and the focusing module constitute a dynamic focusing module. After simplifying it, the relationship between the movement of the dynamic lens and the focus displacement can be obtained using geometric optics. The actual change value is obtained by the beam quality analyzer and the workbench. By comparing the two, the distortion value in the Z dimension can be obtained.

[0027] The focus displacement causes the movement of the laser focus through the reciprocating motion of the dynamic lens of the expansion module. The relationship between the lens displacement Δs and the focus displacement Δz of the moving lens is obtained through geometric optics, and the lens displacement Δs and the focus displacement Δz are simplified to a linear relationship of Δs=aΔz+b.

[0028] When calibrating the Z dimension, it is layered and calibrated. According to different theoretical focus movement ranges, the same spacing d is selected for measurement. This spacing d is set to 0.5mm or 1mm according to the focus movement range of the system. The position of different actual focal points is measured using a rangefinder to obtain the actual focus change at different levels: D1-D, D2-D...D n -D;

[0029] The correction coefficient of each layer is obtained by using the formula: k1 = d / (D1-D), k2 = d / (D2-D)...k n =d / (D n -D), after establishing correction coefficients of different levels, use polynomials to fit the correction coefficients of each level, and finally obtain the correction coefficients at different focus displacements, and save the obtained correction coefficients in the controller for calling.

[0030] A method for correcting distortion of a laser self-space five-dimensional galvanometer comprises the following steps:

[0031] First, the error of the six-degree-of-freedom working plane is corrected. The correction plate is placed on the working plane. The position of the standard pattern on the correction plate is captured by the paraxial vision system. The pattern on the correction plate is made consistent with the preset coordinate system by adjusting the six-degree-of-freedom working plane.

[0032] For the correction of XY dimension, an n*n grid pattern is marked on the XY plane, and the actual position of the grid point is captured and identified by the visual system, and the difference between the actual position and the theoretical position of the grid point is determined. Based on the coordinate difference of each grid point in each row of the grid, the difference of multiple coordinates of each row is fitted to obtain a correction table consisting of the actual coordinates of the grid point and the coordinate difference; or the corner point approximation method is used to calculate the coordinate difference of the unknown point using the coordinate difference of the surrounding grid points of the unknown marking point, and obtain a correction table constructed by each unknown marking point and its coordinate difference;

[0033] The change of the Z dimension of the beam mainly refers to the movement of the focus along the Z axis. The test system is built by placing a reflector at the end of the system beam output, and then using the beam expansion system, filter system, imaging system, beam quality analyzer, and six-degree-of-freedom displacement table to measure the position of the focus.

[0034] According to the dynamic focusing principle of the system, the relationship between the moving distance of the dynamic lens and the focus displacement is obtained. The dynamic lens moving distance at the initial position is 0, and the focus displacement at this time is recorded as the initial position; according to the moving range of the focus, it is layered by 0.5mm or 1mm, so as to obtain the dynamic lens moving distance corresponding to different theoretical levels at this time, send the moving distance instructions of the dynamic lens at different levels to obtain the actual position of the focus, subtract the initial position from the actual position for normalization, use the normalized data and the theoretical position to make a difference, obtain the focus difference of each level, and establish a correction table by fitting the differences of different levels through polynomials;

[0035] The two inclination angles α and β of the light beam need to be obtained indirectly through geometric relationships. Mark circles on different working planes, measure the circle radius of different planes and the height difference of different planes, and use geometric relationships to solve the inclination angles.

[0036] The maximum inclination angle is determined according to the system's range of motion, and then the inclination angle is layered by 0.5° or 1°. The inclination angle is increased by 0.5° or 1° through control instructions, and the actual angle value is measured. Correction coefficients of different levels are established based on the theoretical angle value and the actual angle value, and a correction table is established by fitting the coefficients of each level using polynomials.

[0037] During comprehensive correction, the pattern used is a grid with mixed circles. The distance from working plane 1 and working plane 2 (the working planes are all one plane, but they are moved a certain distance along the Z axis through the six-degree-of-freedom worktable) to the working plane is the layered distance during Z focus correction. The Z dimension only needs to judge the thickness of the lines of different working planes. For the X and Y dimensions, the grid size is measured, and the α and β dimensions measure the circle radius of the adjacent planes. After measurement, correction coefficients of different dimensions are used for correction. To ensure the accuracy of the comprehensive correction, the final correction coefficient is obtained by multiplying the influence of the correction coefficients of different dimensions on the overall pattern distortion by the corresponding percentage, and the average value is taken after multiple measurements.

[0038] Beneficial effects of the present invention:

[0039] The correction method of the present invention is not only applicable to traditional two-dimensional or three-dimensional galvanometer systems, but also can play a role in a five-dimensional galvanometer system with five-dimensional control of the light beam space. In terms of XY two-dimensional plane correction, the adopted grid method can significantly reduce the distortion of the light beam during the scanning process. In the Z dimension, the processing accuracy of three-dimensional parts can be significantly improved through the measurement and correction of the focus displacement. In addition, through the measurement and correction of the deflection angles α and β, the processing accuracy of the system when processing complex special-shaped structures is also greatly improved. This multi-dimensional correction method of the light beam is mainly used for system calibration before processing, and can effectively correct the inherent errors such as the installation error of the system and the aberration of optical focusing. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of a distortion correction system of a laser self-space five-dimensional galvanometer of the present invention.

[0041] Figure 2 It is a schematic diagram and function of the workbench 5 of the present invention.

[0042] Figure 3 This is the correction method for the X and Y dimensions of the present invention.

[0043] Figure 4 This is the Z-dimension correction method of the focusing module 4 of the present invention.

[0044] Figure 5 This is the correction method of the α and β dimensions of the present invention.

[0045] Figure 6 It is the correction method of the overall dimension of the present invention.

[0046] Figure 7 It is a motion relationship diagram of the offset module of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with embodiments.

[0048] Figure 1 A laser self-space five-dimensional galvanometer distortion correction system includes an offset module 1, a beam expansion module 2, a scanning module 3 and a focusing module 4;

[0049] Each module is installed in the device in sequence at a certain distance. Through the movement of the optical lens, the terminal laser beam is focused on the working plane on the workbench 5 to realize the movement in five-dimensional space, that is, the scanning in the X and Y dimensions, the movement of the focus in the Z dimension, and the deflection in the α and β dimensions are realized; the offset module 1 is used to realize the light beam deviating from the optical axis by a certain distance in the X and Y dimensions;

[0050] The offset module 1 is composed of two groups of mutually perpendicular parallel reflectors or parallel plates; the two parallel reflectors or parallel plates of the first group are parallel to each other, and the two parallel reflectors or parallel plates of the second group are parallel to each other;

[0051] The first group is set at a certain angle with the incident light of the light beam, and is set less than 90 degrees. (The initial angle of the first group of reflectors is 45° with the incident light, ensuring that the incident light can be emitted parallel to the second group of reflectors after passing through the first group of reflectors).

[0052] like Figure 7 As shown, the distance between the two reflection modules is D1, and the distance from the working plane is D2. The spacing between the reflectors in each group of reflection modules is d1. The initial light beam is vector P0 = (0, 0, 1). By tracing the light beam using the vector method, we can obtain:

[0053]

[0054] The beam expansion module 2 is composed of a lens group at a certain distance, wherein the first lens is a dynamic lens, which forms a dynamic focusing module with the focusing module 4, and is used to adjust the Z dimension of the light beam; the dynamic lens is a concave lens, which is directly driven by a voice coil motor or indirectly driven by a rotary motor electric connecting rod; the beam diameter is expanded to 8mm or 9mm, which is convenient for focusing. Generally, the output beam is about 2mm, so the beam expansion module is generally selected to be 4 times;

[0055] The offset module 1, the beam expansion module 2, the scanning module 3, and the focusing module 4 jointly affect the inclination angles α and β at the end of the light beam; the beam expansion module 2 is used to expand the diameter of the light beam;

[0056] The beam expansion module 2 is composed of a lens group at a certain distance, wherein the first lens is a dynamic lens, which together with the focusing module 4 constitutes a dynamic focusing module, which can be used to control the Z dimension of the light beam; the scanning module 3 includes two mutually perpendicular reflectors, which can work together to realize the scanning of the light beam in the XY plane;

[0057] The focusing module 4 is composed of a lens group. The focusing module 4 in the system is a telecentric field lens, which is not only used for focusing the light beam but also can ensure that the inclination angle of the focused light beam is small enough.

[0058] The scanning module 3 includes two mutually perpendicular reflectors; (here refers to Figure 1 The two reflective lenses marked with scanning module 3, Figure 4 The beam expander module marked in the system is a newly built beam expander module used as the measurement focus (a common commercially available beam expander module).

[0059] The initial distance D between the surface of the workbench 5, i.e., the work plane, and the focusing module 4 is obtained by the rangefinder 7, wherein the initial distance D is exactly the initial focus position of the system; the distortion of each dimension is measured by an indirect method, and different processing patterns are used for different dimensions to indirectly reflect the distortion amount, wherein the position of the pattern (distortion amount) is obtained by the CCD camera 6, and is converted into the actual position in the workpiece coordinate system according to the coordinate transformation, and the distortion amount is the difference between the theoretical position and the actual position in the workpiece coordinate system;

[0060] The workbench 5 in the system is an electric workbench 5 with six degrees of freedom control capability, as shown in the schematic diagram. Figure 2As shown, it has reciprocating movement in the X, Y, and Z dimensions and rotation around these three dimensions. First, the correction plate is placed on the work plane. The pattern on the correction plate is composed of a circle with a radius of 0.5 mm, and the circle has a center line. The multiple circles on the correction plate form an n*n grid according to the size of the correction plate, and the spacing between the circles is 1 mm. The position deviation of the center line of the circle in the correction plate is observed by the CCD camera 6, where the center line represents the XY direction. According to the gap between the center line and the X axis and the gap between the center line and the Y axis, the six-degree-of-freedom workbench 5 is used to adjust the position of the correction plate on the X axis and the Y axis respectively, and finally the center line of the circle coincides with the XY axis of the workbench 5, thereby eliminating the error of the workbench 5.

[0061] Figure 3 For the correction of XY dimensions, the grid method is used. The distortion value is measured by drawing an N*N grid. For the correction of distortion, the actual position of the grid point is captured and identified by the visual system, and the difference between the actual position and the theoretical position of the grid point is determined. Based on the coordinate difference of each grid point in each row of the grid, the difference of multiple coordinates of each row is fitted to obtain a correction table consisting of the actual coordinates of the grid point and the coordinate difference. Alternatively, the corner point approximation method is used to calculate the coordinate difference of the unknown marking point using the coordinate difference of the surrounding grid points, and obtain a correction table constructed by each unknown marking point and its coordinate difference.

[0062] Figure 4 For the measurement of the Z-dimensional focus, a new test system is arranged between the focusing module 4 and the workbench 5. The principle adopted is to use the beam quality analyzer 13 to measure the spot size and regard the minimum spot size as the focus position. Since the energy of the laser focus is large, the beam quality analyzer 13 cannot withstand large energy, so a smaller focused beam energy is required.

[0063] First, the light beam from the focusing module 4 is reflected by the reflector 1 8 to the beam expansion system 9 to expand the beam diameter, and then is reflected by the reflector 2 10 to the filtering system 11. After passing through the filtering system 11, the beam energy is reduced, and then it is refocused by the imaging system 12. Since the laser beam has been expanded again, the focal radius finally focused on the beam quality analyzer 13 is smaller.

[0064] Reflector 1 8 , beam expansion system 9 , reflector 2 10 , filter system 11 , imaging system 12 and beam quality analyzer 13 are optical paths built after focusing module 4 to assist in measurement.

[0065] As the lens in the laser self-space five-dimensional galvanometer is adjusted, the theoretical change value of the focus in the Z dimension can be obtained by calculation, where the beam expansion module 2 and the focusing module 4 constitute a dynamic focusing module, which can be simplified and the relationship between the movement of the dynamic lens and the focus displacement can be obtained by using geometric optics. The actual change value is obtained by the beam quality analyzer 13 and the workbench 5, and the distortion value of the Z dimension can be obtained by comparing the two.

[0066] Figure 4 The principle of focal point displacement is that the reciprocating motion of the dynamic lens of the expansion module causes the movement of the laser focus. The relationship between the lens displacement Δs of the moving lens and the focal point displacement Δz can be obtained through geometric optics. Since the movement of the moving lens is a high-speed reciprocating motion in the actual movement process, the lens displacement Δs and the focal point displacement Δz are simplified to a linear relationship of Δs=aΔz+b in actual control. The specific value needs to be determined according to the specific parameters of the lenses in the beam expansion module 2 and the focusing module 4 in the system.

[0067] When calibrating Z, it is calibrated in layers, and the same spacing d is selected for measurement according to different theoretical focus movement ranges. This spacing d can be set to 0.5mm or 1mm according to the focus movement range of the system. The actual focus change at different levels can be obtained by measuring the positions of different actual focuses using the rangefinder 7: D1-D, D2-D...D n -D.

[0068] The correction coefficient of each layer is obtained by using the formula: k1 = d / (D1-D), k2 = d / (D2-D)...k n =d / (D n -D), after establishing correction coefficients of different levels, use polynomials to fit the correction coefficients of each level, and finally obtain the correction coefficients at different focus displacements, and save the obtained correction coefficients in the controller for calling.

[0069] Figure 5It is a measurement of the inclination deviation. The characteristics of laser inclination (offset module 1, beam expansion module 2, scanning module 3, and focusing module 4 work together) are used to form circles of different radii on different working planes. The size of the inclination angle can be obtained by using the geometric relationship α(β)=arctan(r2-r1 / d). At the same time, the circle formed by the control error and the installation error is not a perfect circle, so it is necessary to perform multi-equal measurement, that is, n-equal measurement. In order to accurately obtain the circle radius, n can be taken as 8 or 16, and the circle radius is obtained by fitting the coordinates of n points. The correction method is similar to the Z-dimension focus correction method. By dividing the maximum inclination angle into multiple equal parts, the maximum inclination angle is determined according to the system's range of motion, and then the inclination angle is layered by 0.5° or 1°. The control command allows the inclination angle to increase by 0.5° or 1°, and the actual angle value is measured. According to the theoretical angle value and the actual angle value, the correction coefficients of different levels are established, and the correction table is established by fitting the coefficients of each level using polynomials. Figure 6 During comprehensive calibration, for the measurement of the Z dimension, the linear thickness of the pattern is used to determine the focal position. At this time, the pattern is a grid with circles interspersed in it. It is only necessary to determine the linear thickness of these patterns, that is, the focal position is where the line is the thinnest.

[0070] The pattern used for comprehensive calibration is a grid with mixed circles. The distance between working plane 1 and working plane 2 (the working planes are all one plane, but they are moved a certain distance along the Z axis by the six-degree-of-freedom workbench 5) and the working plane is the layered distance during Z focus calibration. Therefore, at this time, the Z dimension only needs to judge the thickness of the lines of different working planes. For the X and Y dimensions, the grid size is measured, and the α and β dimensions measure the circle radius of the adjacent planes. After measurement, the correction coefficients of different dimensions are used for calibration. To ensure the accuracy of the comprehensive calibration, the final correction coefficient is obtained by multiplying the influence of the correction coefficients of different dimensions on the overall pattern distortion by the corresponding percentage, and the average value is obtained by multiple measurements.

Claims

1. A laser self-space five-dimensional galvanometer distortion correction system, characterized in that: It comprises an offset module (1), a beam expansion module (2), a scanning module (3) and a focusing module (4) which are installed in sequence; The offset module (1) is used to make the laser beam deviate from the optical axis by a certain distance in the X dimension and the Y dimension; The beam expansion module (2) is used to expand the diameter of the laser beam transmitted by the offset module (1); The scanning module (3) realizes scanning of the laser beam in the XY plane after the diameter is expanded; The focusing module (4) is used to focus the laser beam and make the inclination angle of the focused beam sufficiently small; Through the movement of the optical lens, the laser beam at the end of the focusing module (4) is focused on the working plane to achieve five-dimensional spatial movement, that is, scanning in the X and Y dimensions, movement of the focus in the Z dimension, and deflection in the α and β dimensions.

2. The laser self-space five-dimensional galvanometer distortion correction system according to claim 1, characterized in that: The offset module (1) consists of two groups The reflection / refractive modules are composed of two parallel reflectors or flat plates; the reflectors or flat plates of the two reflector modules are perpendicular to each other; The number of each group of parallel reflectors or parallel plates is two, and the incident laser beam is sequentially reflected by the first reflector or plate of the first reflector module, the second reflector or plate of the first reflector module, the first reflector or plate of the second reflector module, and the second reflector or plate of the second reflector module; The first group of reflection modules is arranged at a certain angle with the incident laser beam, and the angle is less than 90 degrees; The distance between the two reflection modules is D1, and the distance from the working plane is D2. The distance between the reflectors in each group of reflection modules is d1. The initial light beam is vector P0 = (0, 0, 1). By tracing the light beam using the vector method, we can get: The beam expansion module (2) is composed of a lens group at a certain distance, wherein the first lens is a dynamic lens, and together with the focusing module (4) forms a dynamic focusing module for regulating the Z dimension of the light beam; The dynamic lens is a concave lens, driven directly by a voice coil motor or indirectly by a rotary motor electric linkage; The scanning module (3) comprises two mutually perpendicular reflectors; The focusing module (4) is a telecentric field mirror, and the beam expansion system (9) needs to be determined according to the entrance aperture of the imaging system.

3. The laser self-space five-dimensional galvanometer distortion correction system according to claim 2, characterized in that: The surface of the workbench (5) is a work plane, and an initial distance D between the work plane and the focusing module (4) is obtained by a rangefinder (7) of a paraxial vision system, wherein the initial distance D is the initial focus position of the system; an indirect method is used to measure the distortion of each dimension, and different processing patterns are used for different dimensions to indirectly reflect the distortion amount, wherein the position of the pattern (distortion amount) is obtained by a CCD camera (6) of the paraxial vision system and converted into an actual position in a workpiece coordinate system according to coordinate transformation, and the distortion amount is the difference between a theoretical position and an actual position in the workpiece coordinate system.

4. The laser self-space five-dimensional galvanometer distortion correction system according to claim 3, characterized in that: The workbench (5) is an electric workbench (5) with six-degree-of-freedom control capability, capable of reciprocating movement in the X, Y, and Z dimensions and rotation around these three dimensions; The operating method of the electric workbench (5) is as follows: A correction plate is placed on a working plane, wherein the pattern on the correction plate is composed of circles with a radius of 0.5 mm, and the circles have a center line. The multiple circles on the correction plate form an n*n grid according to the size of the correction plate, wherein the spacing between the circles is 1 mm. The position deviation of the center line of the circle in the correction plate is observed by a CCD camera (6), wherein the center line represents the XY direction. According to the difference between the center line and the X axis and the difference between the center line and the Y axis, the position of the correction plate on the X axis and the Y axis is adjusted respectively by using a six-degree-of-freedom workbench (5), and finally the center line of the circle is made to coincide with the XY axis of the workbench (5), thereby eliminating the error of the workbench (5).

5. The laser self-space five-dimensional galvanometer distortion correction system according to claim 4, characterized in that: The grid method is used for the correction of XY dimensions. The distortion value is measured by drawing an N*N grid. For the correction of distortion, the actual position of the grid point is captured and identified by the visual system, and the difference between the actual position and the theoretical position of the grid point is determined. Based on the coordinate difference of each grid point in each row of the grid, the difference of multiple coordinates of each row is fitted to obtain the correction table consisting of the actual coordinates of the grid point and the coordinate difference. Alternatively, the corner point approximation method is used to calculate the coordinate difference of the unknown marking point using the coordinate difference of the surrounding grid points, and obtain a correction table constructed by each unknown marking point and its coordinate difference.

6. The laser self-space five-dimensional galvanometer distortion correction system according to claim 4, characterized in that: For the measurement of the focus in the Z dimension, a new test system is arranged between the focusing module (4) and the workbench (5), and the spot size is measured using a beam quality analyzer (13), and the spot with the smallest size is regarded as the focus position; First, the light beam of the focusing module (4) is reflected by a first reflector (8) to a beam expansion system (9) to expand the diameter of the light beam, and then is reflected by a second reflector (10) to a filter system (11). After passing through the filter system (11), the energy of the light beam is reduced, and then it is refocused by passing through an imaging system (12); As the lens in the laser self-space five-dimensional galvanometer is adjusted, the theoretical change value of the focus in the Z dimension can be obtained by calculation, wherein the beam expansion module (2) and the focusing module (4) constitute a dynamic focusing module, which can be simplified and the relationship between the movement amount of the dynamic lens and the focus displacement can be obtained by using geometric optics. The actual change value is obtained by the beam quality analyzer (13) and the workbench (5), and the distortion value in the Z dimension can be obtained by comparing the two.

7. The laser self-space five-dimensional galvanometer distortion correction system according to claim 6, characterized in that: The focus displacement causes the movement of the laser focus through the reciprocating motion of the dynamic lens of the expansion module. The relationship between the lens displacement Δs and the focus displacement Δz of the moving lens is obtained through geometric optics, and the lens displacement Δs and the focus displacement Δz are simplified to a linear relationship of Δs=aΔz+b.

8. The laser self-space five-dimensional galvanometer distortion correction system according to claim 6, characterized in that: When calibrating the Z dimension, it is calibrated in layers. According to different theoretical focus movement ranges, the same spacing d is selected for measurement. This spacing d is set to 0.5 mm or 1 mm according to the focus movement range of the system. The positions of different actual focuses are measured using a rangefinder (7) to obtain the actual focus changes at different levels: D1-D, D2-D...D n -D; The correction coefficient of each layer is obtained by using the formula: k1 = d / (D1-D), k2 = d / (D2-D)...k n =d / (D n -D), after establishing correction coefficients of different levels, use polynomials to fit the correction coefficients of each level, and finally obtain the correction coefficients at different focus displacements, and save the obtained correction coefficients in the controller for calling.

9. A method for correcting distortion of a laser self-space five-dimensional galvanometer according to any one of claims 1 to 8, characterized in that: The following steps are involved: First, the error of the six-degree-of-freedom working plane is corrected. The correction plate is placed on the working plane. The position of the standard pattern on the correction plate is captured by the paraxial vision system. The pattern on the correction plate is made consistent with the preset coordinate system by adjusting the six-degree-of-freedom working plane. For the correction of XY dimension, an n*n grid pattern is marked on the XY plane, and the actual position of the grid points is captured and identified by the visual system, and the difference between the actual position and the theoretical position of the grid points is determined. Based on the coordinate difference of each grid point in each row of the grid, the difference of multiple coordinates of each row is fitted to obtain a correction table consisting of the actual coordinates of the grid points and the coordinate difference; Alternatively, a corner point approximation method is used to calculate the coordinate difference of the unknown marking point using the coordinate difference of the surrounding grid points, and a correction table constructed by each unknown marking point and its coordinate difference is obtained; The change in the Z dimension of the light beam mainly refers to the movement of the focus along the Z axis. A test system is built, and a reflector is placed at the light beam output end of the system, and then the focus position is measured using a beam expansion system (9), a filter system (11), an imaging system (12), a beam quality analyzer (13), and a six-degree-of-freedom displacement table (5); According to the dynamic focusing principle of the system, the relationship between the moving distance of the dynamic lens and the focus displacement is obtained. The dynamic lens moving distance at the initial position is 0, and the focus displacement at this time is recorded as the initial position; according to the moving range of the focus, it is layered by 0.5mm or 1mm, so as to obtain the dynamic lens moving distance corresponding to different theoretical levels at this time, send the moving distance instructions of the dynamic lens at different levels to obtain the actual position of the focus, subtract the initial position from the actual position for normalization, use the normalized data and the theoretical position to make a difference, obtain the focus difference of each level, and establish a correction table by fitting the differences of different levels through polynomials; The two inclination angles α and β of the light beam are indirectly obtained through geometric relationships. Circles are marked on different working planes. The inclination angles are solved using geometric relationships by measuring the circle radius and height difference of different planes. The maximum inclination angle is determined according to the system's range of motion, and then the inclination angle is layered by 0.5° or 1°. The inclination angle is increased by 0.5° or 1° through control instructions, and the actual angle value is measured. Correction coefficients of different levels are established based on the theoretical angle value and the actual angle value, and a correction table is established by fitting the coefficients of each level using polynomials.

10. The method for correcting distortion of a laser self-space five-dimensional galvanometer according to claim 9, characterized in that: During comprehensive correction, the pattern used is a grid with mixed circles. For working plane 1 and working plane 2 formed by the working plane, the distance between working plane 1 and working plane 2 to the working plane is the layered distance during Z focus correction. The Z dimension only needs to judge the thickness of the lines of different working planes. For the X and Y dimensions, the grid size is measured, and the α and β dimensions measure the circle radius of the adjacent planes. After measurement, correction coefficients of different dimensions are used for correction. To ensure the accuracy of the comprehensive correction, the final correction coefficient is obtained by multiplying the influence of the correction coefficients of different dimensions on the overall pattern distortion by the corresponding percentage, and the average value is taken after multiple measurements.

Images