A Distortion Correction System and Method for a Laser Self-Spatial Five-Dimensional Galvanometer

Abstract

The present invention discloses a distortion correction system and method for a laser self-spatial five-axis galvanometer, which includes an offset module, a beam expansion module, a scanning module and a focusing module; each module is sequentially installed inside the device at a certain distance, and the movement of the optical lens is used to focus the end laser beam on the working plane of the workbench to realize the movement in the five-dimensional space, that is, to realize 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; the offset module is used to realize the beam deviating from the optical axis by a certain distance in the X and Y dimensions; the beam expansion module is used to expand the beam diameter; the scanning module realizes the scanning of the beam in the XY plane; the focusing module is used to focus the beam and ensure that the inclination angle of the focused beam is small enough. The present invention adopts indirect correction of the processed pattern, designs different correction patterns for different dimensions of the beam movement, is convenient to operate and has low cost.

Description

Technical Field

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

[0002] The laser self-spatial five-axis galvanometer belongs to high-precision and advanced laser processing equipment. Its essence is to achieve the five-dimensional movement of the light beam in space (X, Y, Z, α, β) by adjusting the optical lenses in the system. Due to the installation errors in the system and the aberration caused by optical focusing, there will be deviations when the light beam scans in each dimension, which affects the processing results. Therefore, it is necessary to correct each dimension before using the system. Currently, the common corrections are for the X, Y, and Z dimensions;

[0003] For example, the publication number CN117139832A proposes a method for rapid correction of a two-axis galvanometer. However, this method is applicable to the case where the distortion in the XY plane is symmetric, and it has poor effects on other forms of distortion. Moreover, it can only correct the XY dimensions, and the correction for the α and β dimensions is currently blank. Summary of the Invention

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

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

[0006] A distortion correction system for a laser self-spatial five-axis galvanometer includes a displacement module, a beam expander module, a scanning module, and a focusing module installed in sequence;

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

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

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

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

[0011] By the movement of the optical lens, the laser beam at the end of the focusing module is focused on the working plane to achieve five-dimensional space movement, that is, to achieve 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.

[0012] The offset module 1 is composed of two sets of reflection / refraction modules. Each set of reflection modules consists of two parallel mirrors or flat plates; the mirrors or flat plates of the two sets of reflection modules are perpendicular to each other.

[0013] The number of parallel mirrors or parallel flat plates in each group is two. The incident laser beam is successively reflected by the first mirror or flat plate of the first set of reflection modules, the second mirror or flat plate of the first set of reflection modules, the first mirror or flat plate of the second set of reflection modules, and the second mirror or flat plate of the second set of reflection modules.

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

[0015] The two reflection modules are separated by D1 and are at a distance D2 from the working plane. The distance between the mirrors in each set of reflection modules is d1. The initial light beam is the vector P0=(0,0,1). By performing beam tracing using the vector method, we can obtain:

[0016]

[0017] The beam expander module consists of a lens group at a certain distance. The first lens is a dynamic lens, which forms a dynamic focusing module with the focusing module for regulating 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 and an electric connecting rod; the beam diameter is expanded to 8 mm or 9 mm to facilitate focusing. Generally, the output light beam is about 2 mm, so generally a 4-fold beam expander module is selected.

[0018] The scanning module includes two mutually perpendicular mirrors; the scanning module is equivalent to a set of two-dimensional galvanometers, and realizes planar scanning through the continuous deflection of the XY lenses; it is ensured that when the light beam enters the scanning module, the angle with the lens is 45°.

[0019] The focusing module is a telecentric field lens, and the beam expander system needs to be determined according to the entrance aperture of the imaging system; there is no specific requirement, as long as it is convenient for focusing and observation.

[0020] The surface of the workbench is the working plane. The initial distance D between the working plane and the focusing module is obtained by the rangefinder of the paraxial vision system, where the initial distance D is the initial focal position of the system; the measurement of the distortion in each dimension is carried out by an indirect method, and different processing patterns are used for different dimensions to indirectly reflect the amount of distortion. The position (amount of distortion) 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 coordinate transformation. The amount of distortion 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 correcting the Z dimension, it is corrected layer by layer. The same spacing d is selected for measurement according to the focus movement range of different theories. This spacing d is set to 0.5 mm or 1 mm according to the focus movement range of the system. The position of different actual foci is measured by a rangefinder to obtain the actual focus change amount 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 the correction coefficients of different layers, the correction coefficients of each layer are fitted by polynomial, and finally the correction coefficients at different focus displacements are obtained. The obtained correction coefficients are saved in the controller for calling.

[0030] A distortion correction method for a laser self - spatial five - dimensional galvanometer includes the following steps:

[0031] First, correct the error of the six - degree - of - freedom working plane. Place the calibration plate on the working plane, use the paraxial vision system to capture the position of the standard pattern on the calibration plate, and through the adjustment of the six - degree - of - freedom working plane, make the pattern on the calibration plate consistent with the pre - set coordinate system;

[0032] For the correction of the XY dimension, by marking an n*n grid pattern in the XY plane, the actual positions of the grid points are captured and recognized by the vision system, the difference between the actual position and the theoretical position of the grid points is determined. Based on the coordinate differences of each grid point in each row of the grid, the differences of multiple coordinates in each row are fitted to obtain a correction table composed of the actual coordinates of the grid points and the coordinate differences; or the corner point approximation method is adopted, using the coordinate differences of the surrounding grid points of the unknown marking point to calculate the coordinate difference of this unknown point, and obtaining a correction table constructed by each unknown marking point and its coordinate difference;

[0033] The change of the beam in the Z dimension mainly refers to the movement of the focus along the Z - axis. Build a test system. By placing a reflector at the beam output end of the system, and then using a beam expander system, a filter system, an imaging system, a beam quality analyzer, and a six - degree - of - freedom displacement workbench 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 focal point displacement is obtained. The moving distance of the dynamic lens at the initial position is 0, and the focal point displacement at this time is recorded as the initial position. The focal point is stratified by 0.5 mm or 1 mm according to the moving range of the focal point, so as to obtain the moving distance of the dynamic lens corresponding to different theoretical levels at this time. The moving distance command of the dynamic lens at different levels is sent to obtain the actual position of the focal point. The actual position is subtracted from the initial position for normalization processing. The difference between the data after normalization processing and the theoretical position is used to obtain the focal point difference of each level. A calibration table is established by polynomial fitting of the differences at different levels;

[0035] The two inclination angles α and β of the light beam need to be indirectly obtained through geometric relationships. Mark circles on different working planes, and by measuring the circle radii on different planes and the height differences between different planes, the inclination angles are solved using geometric relationships;

[0036] According to the motion range of the system, the maximum value of the inclination angle is determined. Subsequently, the inclination angle is stratified by 0.5° or 1°. The inclination angle is increased by 0.5° or 1° through control commands, and the actual angle values are measured. Different-level calibration coefficients are established based on the theoretical angle values and the actual angle values. A calibration table is established by polynomial fitting of the coefficients at each level.

[0037] During comprehensive calibration, the pattern used is a grid with circles interspersed. The distance between working plane 1 and working plane 2 (the working planes are both planes, but only moved a certain distance along the Z-axis through a six-degree-of-freedom workbench) to the working plane is the stratification distance for Z-axis focal point calibration. For the Z dimension, only the line thickness of different working planes needs to be judged. For the X and Y dimensions, the grid size is measured, and for the α and β dimensions, the circle radii of adjacent planes are measured. After measurement, calibration is performed using the calibration coefficients of different dimensions. To ensure the accuracy of comprehensive calibration, the final calibration coefficients are obtained by multiplying the influence of the calibration coefficients of different dimensions on the overall pattern distortion by the corresponding percentages, and the average value is taken after multiple measurements.

[0038] Advantages of the present invention:

[0039] The calibration 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 for five-dimensional regulation of the light beam space. In terms of XY two-dimensional plane calibration, the grid method adopted can significantly reduce the distortion generated during the scanning of the light beam. In terms of the Z dimension, through the measurement and calibration of the focal point displacement, the processing accuracy of three-dimensional components is significantly improved. In addition, through the measurement and calibration of the deflection angles α and β, the processing accuracy of the system when dealing with complex special-shaped structures is also greatly improved. This multi-dimensional calibration method of the light beam is mainly used for system calibration before processing, and can effectively correct inherent errors such as installation errors of the system and aberration of optical focusing. Description of the Drawings

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

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

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

[0043] Figure 4 It is a correction method for the Z dimension by the focusing module 4 of the present invention.

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

[0045] Figure 6 It is a correction method for 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 implementation mode

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

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

[0049] Each module is installed inside the device at a certain interval in sequence. The movement of the optical lens makes the end laser beam focus on the working plane of the workbench 5 to realize the movement in the five-dimensional space, that is, to realize 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; the offset module 1 is used to make the light beam deviate from the optical axis by a certain distance in the X and Y dimensions;

[0050] The offset module 1 is composed of two sets of mutually perpendicular parallel mirrors or parallel plates; the two parallel mirrors or parallel plates in the first set are parallel to each other, and the two parallel mirrors or parallel plates in the second set are parallel to each other;

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

[0052] As Figure 7 shown, the distance between the two reflection modules is D1, the distance from the working plane is D2, the distance between the mirrors in each set of reflection modules is d1, the initial light beam is the vector P0=(0,0,1), and the light beam tracing can be obtained by the vector method:

[0053]

[0054] The beam expander module 2 is composed of a lens group at a certain distance. The first lens is a dynamic lens, which forms a dynamic focusing module with the focusing module 4 for regulating 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 and an electric connecting rod. The beam diameter is expanded to 8 mm or 9 mm for easy focusing. Generally, the outgoing beam is about 2 mm, so a 4-fold beam expander module is generally selected.

[0055] The offset module 1, together with the beam expander module 2, the scanning module 3, and the focusing module 4, affects the inclination angles α and β at the end of the light beam. The beam expander module 2 is used to expand the beam diameter.

[0056] The beam expander module 2 is composed of a lens group at a certain distance. The first lens is a dynamic lens, which forms a dynamic focusing module with the focusing module 4 and can be used to regulate the Z dimension of the light beam. The scanning module 3 includes two mutually perpendicular reflectors, and their common action can realize the scanning of the light beam in the XY plane.

[0057] The focusing module 4 is composed of a lens group. In the system, the focusing module 4 here 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 it refers to Figure 1 the two reflecting lenses marked for the scanning module 3 Figure 4 The beam expander module marked in the system is a newly built beam expander module for measuring the focal point (a commonly available beam expander module).

[0059] The initial distance D between the surface of the workbench 5, i.e., the working plane, and the focusing module 4 is obtained by the rangefinder 7. The initial distance D is exactly the initial focal point position of the system. The measurement of the distortion in each dimension adopts an indirect method. Different processing patterns are used for different dimensions to indirectly reflect the distortion amount. The position (distortion amount) of the pattern is obtained by the CCD camera 6 and is converted into the actual position in the workpiece coordinate system according to coordinate transformation. 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-degree-of-freedom regulation ability, and its schematic diagram is as 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 laser is adjusted by the lens in the five-dimensional spatial galvanometer, the theoretical change value of the focal point in the Z dimension can be obtained through calculation. Among them, the beam expander module 2 and the focusing module 4 constitute a dynamic focusing module. After simplification, the relationship between the movement amount of the dynamic lens and the focal point displacement amount can be obtained using geometric optics. The actual change value is obtained from the beam quality analyzer 13 and the workbench 5. By comparing the two, the distortion value in the Z dimension can be obtained.

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

[0067] When correcting Z, it is corrected layer by layer. The same spacing d is selected for measurement according to different theoretical focal point movement ranges. This spacing d can be set to 0.5 mm or 1 mm according to the focal point movement range of the system. Using the rangefinder 7 to measure the positions of different actual focal points, the actual focal point change amounts at different levels can be obtained: D1 - D, D2 - D... D n -D.

[0068] Using the formula to obtain the correction coefficient of each layer: k1 = d / (D1 - D), k2 = d / (D2 - D)... k n = d / (D n -D), after establishing the correction coefficients of different layers, use polynomial fitting for the correction coefficients of each layer, and finally obtain the correction coefficients at different focal point displacements. Save the obtained correction coefficients in the controller for calling.

[0069] Figure 5It is the measurement of the inclination deviation. By utilizing the characteristics of laser inclination (the combined action of the offset module 1, beam expansion module 2, scanning module 3, and focusing module 4), circles with different radii are formed on different working planes. Using the geometric relationship α(β) = arctan((r2 - r1) / d), the size of the inclination angle can be obtained. At the same time, since the circles formed due to control errors and installation errors are not perfect circles, multi-equal division measurement is required, that is, n-equal division measurement. 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 method for correction is similar to the Z-dimension focus correction method. By dividing the maximum inclination angle into multiple equal parts, determining the maximum value of the inclination angle according to the motion range of the system, then stratifying the inclination angle by 0.5° or 1°, increasing the inclination angle by 0.5° or 1° through control commands, measuring the actual angle values, establishing correction coefficients for different levels based on the theoretical angle values and actual angle values, and using polynomial fitting of the coefficients at each level to establish a correction table. Figure 6 During comprehensive correction, for the measurement in the Z dimension, the thickness of the linear pattern of the engraving is used to judge the position of the focus. At this time, the engraved pattern is a grid with circles interspersed, and only the thickness of the linear pattern of these patterns needs to be judged, that is, the position of the focus is the place where the line is thinnest.

[0070] The pattern used during comprehensive correction is a grid with circles interspersed. The distance between the working plane 1 and the working plane 2 (the working planes are both planes, but only moved a certain distance along the Z axis by the six-degree-of-freedom workbench 5) to the working plane is the stratification distance during Z-focus correction. Therefore, at this time, in the Z dimension, only the thickness of the lines on different working planes needs to be judged. For the measurement of the grid size in the X and Y dimensions, and the circle radii of adjacent planes in the α and β dimensions are measured. After measurement, correction is performed using the correction coefficients of different dimensions. To ensure the accuracy of comprehensive correction, the influence of the correction coefficients of different dimensions on the overall pattern distortion is multiplied by the corresponding percentage to obtain the final correction coefficient, and the average value is taken for 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 with an enlarged diameter in the XY plane; The focusing module (4) is used to focus the laser beam and make the inclination angle of the focused beam sufficiently small; The end laser beam of the focusing module (4) is focused on the working plane through the movement of the optical lens to realize 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; The offset module (1) is composed of two groups of reflection or refraction modules, each group of reflection modules is composed of two parallel reflection mirrors; the reflection mirrors or plates of the two groups of reflection modules are perpendicular to each other; The number of each group of parallel reflectors is two, and the incident laser beam is reflected in sequence by the first reflector of the first reflector module, the second reflector of the first reflector module, the first reflector of the second reflector module, and the second reflector 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 S1, and the distance from the working plane is S2. 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: Where: d1—the distance between the first set of parallel reflectors / mm; d2—spacing of the second set of parallel reflectors / mm; θ1—rotation angle of the first set of parallel reflectors / °; θ2—rotation angle of the second set of parallel reflectors / °; Δx—the offset distance of the light beam after passing through the first set of parallel reflectors / mm; Δy—the offset distance of the light beam after passing through the second set of parallel reflectors / mm; 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.

2. The laser self-space five-dimensional galvanometer distortion correction system according to claim 1, characterized in that: The surface of the workbench (5) is the work plane, and the 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 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.

3. The laser self-space five-dimensional galvanometer distortion correction system according to claim 2, 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).

4. The laser self-space five-dimensional galvanometer distortion correction system according to claim 3, characterized in that: The grid method is used for the correction of XY dimensions. The distortion is measured by drawing an N*N grid. For the correction of distortion, the actual position of the grid points is captured and identified by the visual system. 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 difference between the actual coordinates and the theoretical coordinates of the grid points. 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 of the unknown marking point, and obtain a correction table constructed by each unknown marking point and its coordinate difference.

5. The laser self-space five-dimensional galvanometer distortion correction system according to claim 3, 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, and the relationship between the movement amount of the dynamic lens and the focus displacement amount 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 amount in the Z dimension can be obtained by comparing the two.

6. The laser self-space five-dimensional galvanometer distortion correction system according to claim 5, 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.

7. The laser self-space five-dimensional galvanometer distortion correction system according to claim 5, 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 distance meter (7) is used to measure the positions of different actual focuses, and the actual focus changes at different levels are obtained: D1-D, D2-D...D n -D; Use the formula to calculate the correction coefficient of each layer: 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.

8. A method for correcting distortion of a laser self-space five-dimensional galvanometer according to any one of claims 5 to 7, 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 grid points around the unknown marking point, 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.

9. The method for correcting the distortion of a laser self-space five-dimensional galvanometer according to claim 8, characterized in that: During comprehensive correction, the pattern used is a grid with mixed circles. For working plane one and working plane two formed by the working plane, the distance between working plane one and working plane two 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 can 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.

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