A distortion measurement device and method for a projection lens

Abstract

This application provides a distortion measurement device and method for a projection lens. The distortion measurement device includes: a controller, a first light source device, a pinhole mask, a movable stage, a wavefront analyzer, and an interferometer. A pinhole mask is spaced between the first light source device and the movable stage. A laser beam generated by the interferometer is projected onto the movable stage. The controller is connected to the first light source device, the movable stage, the wavefront analyzer, and the interferometer, respectively, and is used to control the movement of the first light source device and the movable stage in the horizontal and / or vertical directions. The controller determines the distortion and actual magnification of the projection lens under test based on the obtained object point coordinates, first image point coordinates, second image point coordinates, light energy values, and light deviation slopes of each pinhole. By introducing a pinhole mask for measuring the distortion and magnification of the projection lens, the testing process and device are simplified, thereby improving testing efficiency.

Description

Technical Field

[0001] This application relates to the field of performance testing technology for projection optical systems, and in particular to a distortion measurement device and method for a projection lens. Background Technology

[0002] With the rapid development of the integrated circuit industry, the requirements for device graphic resolution are constantly increasing, prompting projection lenses (which project objects illuminated by a light source onto a large screen) to continuously pursue smaller aberrations (spherical aberration, chromatic aberration, coma, and astigmatism) control. Among these, the distortion and magnification of the projection lens are important factors affecting image quality. Therefore, it is very important to perform offline measurement and calibration of the distortion and magnification of the projection lens.

[0003] Existing technologies involve testing for kit errors through processes such as coating, developing, exposure, and overlay to calculate the distortion and magnification of the projection lens. These technologies require complex and expensive equipment, and the testing process is cumbersome. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide at least one device and method for measuring the distortion of a projection lens. By introducing a pinhole mask to measure the distortion and magnification of the projection lens, the testing process and testing device are simplified, thereby improving the testing efficiency.

[0005] This application mainly includes the following aspects:

[0006] In a first aspect, a distortion measurement device for a projection lens is provided. The distortion measurement device includes: a controller, a first light source device, a pinhole mask, a movable stage, a wavefront analyzer, and an interferometer device. The first light source device and the movable stage are horizontally spaced apart, and the pinhole mask is spaced between the first light source device and the movable stage. The pinhole mask has multiple pinholes. Light emitted by the first light source device passes through the pinholes and the projection lens under test to form an image point corresponding to the pinhole. The wavefront analyzer is mounted on the movable stage, and the laser beam generated by the interferometer device is projected onto the movable stage. The controller and the first light source device are connected in series. The source device, movable stage, wavefront analyzer, and interferometer are connected respectively to control the movement of the first light source device and the movable stage in the horizontal and / or vertical directions, and to acquire the object point coordinates of each pinhole recorded by the first light source device, the first image point coordinates of each pinhole recorded by the movable stage, the second image point coordinates of each pinhole recorded by the interferometer, and the light energy value and light deviation slope collected by the wavefront analyzer. The controller determines the distortion and actual magnification of the projection lens under test based on the acquired object point coordinates, first image point coordinates, second image point coordinates, light energy value, and light deviation slope of each pinhole.

[0007] In one possible implementation, a plurality of pinholes on the pinhole mask form a rectangular pinhole array, and alignment holes are provided in the area between each edge of the pinhole mask and the edge of the rectangular pinhole array, the diameter of the alignment holes being larger than the diameter of the pinholes.

[0008] In one possible implementation, the distortion testing device further includes a first elongated mirror and a second elongated mirror disposed on a movable worktable. The first elongated mirror is positioned along the horizontal X-axis, and the second elongated mirror is positioned along the horizontal Y-axis. The interferometer device includes a laser head, an optical mirror group, a mediator, a first laser interferometer, and a second laser interferometer. The laser head is used to provide a laser beam, and the optical mirror group is used to receive the laser beam and obtain a first laser beam along the horizontal X-axis and a second laser beam along the horizontal Y-axis. The first laser interferometer is used to receive the first laser beam and incident it onto the first elongated mirror, and the second laser interferometer is used to receive the second laser beam and incident it onto the second elongated mirror. The first and second laser interferometers are respectively connected to the mediator, which is used to obtain the optical path values ​​of the first and second laser beams. The mediator is connected to a controller, which is used to determine the coordinates of the second image point of each pinhole based on the optical path values ​​of the first and second laser beams.

[0009] Secondly, embodiments of this application also provide a distortion measurement method for a projection lens. The distortion measurement method is applied to the distortion measurement device of any of the above embodiments, wherein the projection lens under test is fixed between a wavefront analyzer and a pinhole mask. The distortion measurement method includes: controlling a first light source device to move to the positions of any two alignment holes to achieve a first alignment between the first light source device and the pinhole mask, and between the movable stage and the pinhole mask; controlling the first light source device to move to the positions of at least three randomly selected pinholes, and obtaining the object point coordinates and first image point coordinates corresponding to the at least three randomly selected pinholes to achieve a second alignment between the first light source device and the pinhole mask, and between the movable stage and the pinhole mask; fitting the object point coordinates and first image point coordinates corresponding to the remaining pinholes (excluding the at least three randomly selected pinholes) and the object point coordinates and first image point coordinates of the center point of the rectangular pinhole array based on the obtained object point coordinates and first image point coordinates of the center point of the rectangular pinhole array; and fitting the object point coordinates and first image point coordinates of the center point of the rectangular pinhole array based on the object point coordinates and first image point coordinates of the center point of the rectangular pinhole array. The object point coordinates and first image point coordinates of the center point are used to control the movable stage to move to the location of the first image point coordinates of the center point of the rectangular pinhole array, and this location is used as the coordinate origin of the interferometer equipment to fit the theoretical image point coordinates of each pinhole. For each pinhole in the rectangular pinhole array, the first light source equipment is controlled to move to the location of the object point coordinates corresponding to the pinhole to obtain the image point formed by the light emitted by the first light source equipment through the pinhole on the movable stage. The movable stage is then controlled to move so that the wavefront analyzer reaches the location of the first image point coordinates corresponding to the pinhole. For each pinhole in the rectangular pinhole array, the light deviation slope of the image point corresponding to the pinhole is collected by the wavefront analyzer. Based on the light deviation slope corresponding to the pinhole, the second image point coordinates of the pinhole image point recorded by the interferometer equipment are obtained. For each pinhole in the rectangular pinhole array, the actual image point coordinates corresponding to the pinhole image point are obtained based on the second image point coordinates corresponding to the pinhole. Based on the actual image point coordinates and theoretical image point coordinates corresponding to each pinhole, the distortion and actual magnification of the projection lens under test are determined.

[0010] In one possible implementation, the distortion measurement system further includes a second light source device. The alignment holes are rectangular. The step of controlling the first light source device to move to the positions of any two alignment holes to achieve the first alignment between the first light source device and the pinhole mask, and between the movable stage and the pinhole mask, includes: for each of the two alignment holes, controlling the second light source device to move to the position of that alignment hole, so that the light emitted by the second light source device passes through the alignment hole and the projection lens under test to form a light spot; for each of the two alignment holes, controlling the movable stage to move so that the wavefront analyzer reaches the position of the light spot; for each of the two alignment holes, acquiring the ray tilt slope at the position of the light spot collected by the wavefront analyzer, and determining the coordinates of the first image point of the alignment hole based on the ray tilt slope collected by the wavefront analyzer at the position of the light spot; for each of the two alignment holes, controlling the workpiece stage to be stationary, while... The system controls the first light source device to move to the location of the alignment hole, so that the light emitted by the first light source device passes through the alignment hole and the projection lens under test to form a corresponding image point on the movable worktable; for each of any two alignment holes, the system controls the first light source device to move towards the edge of the alignment hole, and during the movement of the first light source device towards the edge of the alignment hole, the system controls the wavefront analyzer to collect the light energy value; for each of any two alignment holes, the position of the movable worktable corresponding to the light energy value that meets the preset conditions collected by the wavefront analyzer is determined as the edge position of the alignment hole; for each of any two alignment holes, the object point coordinates of the alignment hole are determined according to the obtained edge positions of the alignment hole; based on the obtained object point coordinates and first image point coordinates corresponding to any two alignment holes, the first alignment between the first light source device and the pinhole mask, and between the movable worktable and the pinhole mask, is achieved.

[0011] In one possible implementation, the step of controlling the first light source device to move to the locations of at least three randomly selected pinholes, and obtaining the object point coordinates and first image point coordinates corresponding to the at least three randomly selected pinholes to achieve a second alignment between the first light source device and the pinhole mask, and between the movable stage and the pinhole mask, includes: for each of the at least three randomly selected pinholes, controlling the first light source device to move to the location of that pinhole, so that the light emitted by the first light source device passes through the pinhole and the projection lens under test to form a corresponding image point on the movable stage; for each of the at least three randomly selected pinholes, controlling the movable stage to move so that the wavefront analyzer reaches the location of the image point of that pinhole, and obtaining the light energy value and light deviation slope of the image point corresponding to that pinhole collected by the wavefront analyzer; for each of the at least three randomly selected pinholes, determining the object point coordinates and first image point coordinates corresponding to that pinhole based on the light energy value and light deviation slope of the image point corresponding to that pinhole, thereby achieving a second alignment between the first light source device and the mask, and between the movable stage and the mask.

[0012] In one possible implementation, for each of at least three randomly selected pinholes, the steps of determining the object point coordinates and the first image point coordinates corresponding to the pinhole based on the ray energy value and ray deviation slope of the image point corresponding to the pinhole, and realizing the second alignment between the first light source device and the mask, and between the movable worktable and the mask, include: for each of at least three randomly selected pinholes, determining whether the ray energy value of the image point corresponding to the pinhole reaches a first threshold; for each of at least three randomly selected pinholes, if the ray energy value of the image point corresponding to the pinhole does not reach the first threshold, finely adjusting the position of the first light source device until the ray energy value of the image point corresponding to the pinhole reaches the first threshold, and determining the coordinates of the current position of the first light source device as the object point coordinates of the pinhole; for each of at least three randomly selected pinholes, if the pinhole... If the light energy value of the corresponding image point reaches the first threshold, determine whether the light deviation slope of the image point corresponding to the pinhole reaches the second threshold. For each of the at least three randomly selected pinholes, if the light deviation slope of the image point corresponding to the pinhole reaches the second threshold, determine the coordinates corresponding to the current position of the movable worktable as the first image point coordinates of the pinhole, and realize the second alignment between the first light source device and the mask, and between the worktable and the mask. For each of the at least three randomly selected pinholes, if the light deviation slope of the image point corresponding to the pinhole does not reach the second threshold, fine-tune the position of the movable worktable until the light deviation slope of the image point corresponding to the pinhole reaches the second threshold, determine the coordinates of the current position of the movable worktable as the first image point coordinates of the pinhole, and realize the second alignment between the first light source device and the mask, and between the movable worktable and the mask.

[0013] In one possible implementation, the step of controlling the movable stage to move to the location of the first image point coordinates of the center point of the rectangular pinhole array based on the object point coordinates and the first image point coordinates of the center point of the rectangular pinhole array, and using this location as the coordinate origin of the interferometer device, and fitting the theoretical image point coordinates of each pinhole includes: determining the pinhole closest to the center point of the rectangular pinhole array based on the object point coordinates of the center point of the rectangular pinhole array and the object point coordinates of each pinhole, and determining the pinhole closest to the center point of the rectangular pinhole array as the center pinhole of the rectangular pinhole array; controlling the first light source device to move towards the location of the center pinhole based on the object point coordinates of the center pinhole; controlling the movable stage to move to the location of the first image point coordinates corresponding to the center pinhole; and obtaining the image point coordinates of each pinhole using a wavefront analyzer. The ray deviation slope at the location of the first image point corresponding to the central pinhole is determined; it is then determined whether the ray deviation slope at the location of the first image point corresponding to the central pinhole reaches a second threshold; if the ray deviation slope at the location of the first image point corresponding to the central pinhole reaches the second threshold, the coordinates corresponding to the current position of the movable stage are determined as the coordinate origin of the interferometer, and the theoretical image point coordinates of each pinhole are fitted; if the ray deviation slope at the location of the first image point corresponding to the central pinhole does not reach the second threshold, the position of the movable stage is finely adjusted until the ray deviation slope at the location of the first image point corresponding to the central pinhole reaches the second threshold, the coordinates of the current position of the movable stage are determined as the coordinate origin of the interferometer, and the theoretical image point coordinates of each pinhole are fitted.

[0014] In one possible implementation, the second image point coordinates include the abscissa and ordinate of the second image point. For each pinhole in the rectangular pinhole array, the step of obtaining the actual image point coordinates of the pinhole based on its corresponding second image point coordinates includes: for each pinhole in the rectangular pinhole array, when the interferometer is positioned at the location of the second image point coordinates corresponding to the pinhole, obtaining the abscissa centroid tilt, ordinate centroid tilt, and focal length of the collimating lens in the wavefront analyzer for the pinhole's image point; calculating a first product of the abscissa centroid tilt and the focal length, and determining the sum of the first product and the abscissa of the pinhole's second image point as the abscissa of the pinhole's actual image point; calculating a second product of the ordinate centroid tilt and the focal length, and determining the sum of the second product and the ordinate of the pinhole's second image point as the ordinate of the pinhole's actual image point; and determining the actual image point coordinates based on the obtained abscissa and ordinate of the actual image point.

[0015] In one possible implementation, the step of determining the distortion and actual magnification of the projection lens under test based on the actual and theoretical image point coordinates corresponding to each pinhole includes: fitting a pre-established X-axis distortion fitting formula and a Y-axis distortion fitting formula to the actual and theoretical image point coordinates corresponding to each pinhole; determining the distortion parameters of the projection lens under test based on the fitting results; and determining the distortion and actual magnification of the projection lens under test based on the obtained distortion parameters.

[0016] In one possible implementation, the distortion parameters include the distortion level and magnification error of the projection lens under test. The step of determining the distortion and actual magnification of the projection lens under test based on the acquired distortion parameters includes: for each pinhole's theoretical image point, calculating the third product of the abscissa of the theoretical image point, the square of the abscissa of the theoretical image point, the square of the ordinate of the theoretical image point, and the distortion level; determining the maximum value among the multiple third products as the X-axis distortion of the projection lens under test; for each pinhole's theoretical image point, calculating the fourth product of the ordinate of the theoretical image point, the square of the abscissa of the theoretical image point, and the square of the ordinate of the theoretical image point, and the distortion level; determining the maximum value among the multiple fourth products as the Y-axis distortion of the projection lens under test; and determining the actual magnification of the projection lens under test as the sum of the magnification error and the standard magnification of the projection lens under test.

[0017] In one possible implementation, the fitting formula for the X-axis distortion of the projection lens under test is:

[0018] X act =X nr +T x +R×Y nr +M×X nr +X nr ×r 2 ×D+R x

[0019] In this formula, X act The x-coordinate of the actual image point of the pinhole, X nr The x-coordinate, Y, represents the theoretical image point of the pinhole. nr T represents the ordinate of the theoretical image point of the pinhole. x R represents the offset of the actual image point's x-coordinate relative to the theoretical image point's x-coordinate; M represents the magnification error; and r represents the rotation parameter of the actual image point relative to the theoretical image point. 2 The value of R represents the sum of the squares of the x-coordinate and y-coordinate of the theoretical image point of the pinhole, where D represents the distortion level and R represents the distortion level. x This represents the fitting residual along the X-axis.

[0020] The fitting formula for the Y-axis distortion of the projection lens under test is:

[0021] Y act =X nr +T y +R×X nr +M×Y nr +Y nr ×r 2 ×D+R y (2)

[0022] In this formula, Y ac t represents the ordinate of the actual image point of the pinhole, X nr The x-coordinate, Y, represents the theoretical image point of the pinhole. nr T represents the ordinate of the theoretical image point of the pinhole. y R represents the offset of the ordinate of the actual image point of the pinhole relative to the ordinate of the theoretical image point of the pinhole; M represents the fitting magnification error; and r represents the rotation parameter of the actual image point of the pinhole relative to the theoretical image point of the pinhole. 2 The value of R represents the sum of the squares of the x-coordinate and y-coordinate of the theoretical image point of the pinhole, where D represents the distortion level and R represents the distortion level. y This represents the fitting residual along the Y-axis.

[0023] This application provides a distortion measurement device and method for a projection lens. The distortion measurement device includes: a controller, a first light source device, a pinhole mask, a movable stage, a wavefront analyzer, and an interferometer. The first light source device and the movable stage are horizontally spaced apart, and a pinhole mask is spaced between them. The pinhole mask has multiple pinholes. Light emitted from the first light source device passes through the pinholes and the projection lens under test to form an image point corresponding to the pinhole. The wavefront analyzer is mounted on the movable stage, and the laser beam generated by the interferometer is projected onto the movable stage. The controller and the first light source device are connected in series. A light source device, a movable stage, a wavefront analyzer, and an interferometer are connected separately. These components control the movement of the first light source device and the movable stage in the horizontal and / or vertical directions. The controller acquires the object point coordinates of each pinhole recorded by the first light source device, the first image point coordinates of each pinhole recorded by the movable stage, the second image point coordinates of each pinhole recorded by the interferometer, and the light energy value and light deviation slope acquired by the wavefront analyzer. Based on the acquired object point coordinates, first image point coordinates, second image point coordinates, light energy value, and light deviation slope, the controller determines the distortion and actual magnification of the projection lens under test. By introducing a pinhole mask for measuring the distortion and magnification of the projection lens, the testing process and apparatus are simplified, thereby improving testing efficiency.

[0024] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This paper shows a schematic diagram of the structure of a distortion measurement device for a projection lens provided in an embodiment of this application;

[0027] Figure 2 An example diagram of a pinhole mask template provided in an embodiment of this application is shown;

[0028] Figure 3 A top view of the movable worktable provided in an embodiment of this application is shown;

[0029] Figure 4 This application illustrates the steps of a method for measuring the distortion of a projection lens according to an embodiment of the present application. Figure 1 ;

[0030] Figure 5 This application illustrates the steps of a method for measuring the distortion of a projection lens according to an embodiment of the present application. Figure 2 . Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0032] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] Existing technologies involve testing for kit errors through processes such as coating, developing, exposure, and overlay to calculate the distortion and magnification of the projection lens. These technologies require complex and expensive equipment, and the testing process is cumbersome.

[0034] Based on this, embodiments of this application provide a distortion measurement device and method for projection lenses. By introducing a pinhole mask template to measure the distortion and magnification of the projection lens, the testing process and device are simplified, thereby improving testing efficiency, as detailed below:

[0035] Please see Figure 1 , Figure 1 A schematic diagram of the structure of a distortion measurement device for a projection lens provided in an embodiment of this application is shown. Figure 1 As shown, the distortion measurement device includes a controller (not shown in the figure), a first light source device 1, a pinhole mask 2, a movable worktable 3, a wavefront analyzer 4, and an interferometer device 5. The first light source device 1 and the movable worktable 3 are horizontally spaced apart, and the pinhole mask 2 is spaced apart between the first light source device 1 and the movable worktable 3. The pinhole mask 2 has multiple pinholes. The wavefront analyzer 4 is mounted on the movable worktable 4, and the laser beam generated by the interferometer device 5 is projected onto the movable worktable 3.

[0036] Specifically, the light emitted by the first light source device 1 passes through the pinhole and the projection lens 6 under test to form the image point corresponding to the pinhole.

[0037] The controller is connected to the first light source device 1, the movable stage 3, the wavefront analyzer 4, and the interferometer device 5 respectively. It is used to control the movement of the first light source device 1 and the movable stage 3 in the horizontal and / or vertical directions, and to acquire the object point coordinates of each pinhole recorded by the first light source device 1, the first image point coordinates of each pinhole recorded by the movable stage 3, the second image point coordinates of each pinhole recorded by the interferometer device 5, and the light energy value and light deviation slope collected by the wavefront analyzer 4.

[0038] The controller determines the distortion and actual magnification of the projection lens 6 under test based on the obtained object point coordinates, first image point coordinates, second image point coordinates, light energy value, and light deviation slope of each pinhole.

[0039] In a preferred embodiment, a plurality of pinholes on the pinhole mask form a rectangular pinhole array. Alignment holes are provided in the region between each edge of the pinhole mask and the edge of the rectangular pinhole array. The diameter of the alignment holes is larger than the diameter of the pinholes. The shapes of the alignment holes and the pinholes can be rectangular.

[0040] Please see Figure 2 , Figure 2 An example diagram of a pinhole mask template provided in an embodiment of this application is shown. Figure 2 As shown, the multiple pinholes 21 on the pinhole mask 2 form a 7×8 rectangular pinhole array, and Figure 2 In the process, an alignment hole 22 is provided between the center position of each edge of the pinhole mask template 2 and the edge of the rectangular pinhole array, that is, four alignment holes 22 are provided on the pinhole mask template 2.

[0041] In one specific embodiment, please refer to Figure 3 , Figure 3 A top view of the movable worktable provided in an embodiment of this application is shown, as follows: Figure 3 As shown, the distortion testing device also includes a first long strip mirror 31 and a second long strip mirror 32 set on the movable worktable 3. The first long strip mirror 31 is placed along the horizontal X-axis direction, and the second long strip mirror 32 is placed along the horizontal Y-axis direction. The interferometer device 5 includes a laser head 51, an optical mirror group 52, a mediator 53, a first laser interferometer 54, and a second laser interferometer 55.

[0042] Laser head 51 is used to provide laser beam, and optical lens group 52 is used to receive laser beam and obtain a first laser beam along the horizontal X-axis direction and a second laser beam along the horizontal Y-axis direction.

[0043] The first laser interferometer 54 is used to receive the first laser beam and incident it onto the first long strip mirror 31, and the second laser interferometer 55 is used to receive the second laser beam and incident it onto the second long strip mirror 32.

[0044] The first laser interferometer 54 and the second laser interferometer 55 are respectively connected to the mediator 53, which is used to obtain the optical path values ​​of the first laser beam and the second laser beam respectively.

[0045] The mediator 53 is connected to the controller, which obtains the second image point coordinates of each pinhole based on the optical path values ​​of the first and second laser beams.

[0046] This application also provides a method for measuring the distortion of a projection lens. This distortion measurement method is applied to the distortion measurement device described in the above embodiments. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 This application illustrates the steps of a method for measuring the distortion of a projection lens according to an embodiment of the present application. Figure 1 Please see Figure 5 , Figure 5 This application illustrates the steps of a method for measuring the distortion of a projection lens according to an embodiment of the present application. Figure 2 ,like Figure 4 and Figure 5 As shown, distortion measurement methods include:

[0047] S100: Control the first light source device to move to the positions of any two alignment holes respectively, so as to achieve the first alignment between the first light source device and the pinhole mask, and between the movable worktable and the pinhole mask.

[0048] In a preferred embodiment, such as Figure 1 As shown, the projection objective 6 to be tested needs to be fixed between the wavefront analyzer 4 and the pinhole mask 2. The first light source device 1 is used to provide a point light source; specifically, the aperture of the point light source can be at the micrometer level. Preferably, two alignment holes that are relatively far apart can be selected from multiple alignment holes for the first alignment. Figure 2 As shown, two alignment holes 22 can be selected near the two parallel edges of the pinhole mask template 2.

[0049] In one specific embodiment, the distortion measurement system further includes a second light source device, wherein the radius of the point light source provided by the second light source device is much larger than the radius of the light source provided by the first light source device.

[0050] In a preferred embodiment, the step of controlling the first light source device to move to the positions of any two alignment holes to achieve the first alignment between the first light source device and the pinhole mask, and between the movable worktable and the pinhole mask, includes:

[0051] For any two alignment holes, control the second light source device to move to the position of the alignment hole so that the light emitted by the second light source device passes through the alignment hole and forms a light spot with the projection lens under test.

[0052] In one specific embodiment, the second light source device can be a flashlight. For each of the two alignment holes selected by the user, the user can directly move the flashlight to the location of the selected alignment hole by observing its position. Here, since the light source radius of the second light source device and the aperture of the alignment hole are relatively large, the light emitted by the second light source device will form a clear light spot on the movable worktable after passing through the alignment hole and the projection lens under test.

[0053] For each of the two alignment holes, the movable stage is controlled to move so that the wavefront analyzer reaches the location of the light spot.

[0054] In one specific embodiment, it is necessary to control the movable stage to move to the positions of any two alignment holes sequentially. Specifically, for each of the two alignment holes, the movable stage is controlled to move along the horizontal X-axis and the horizontal Y-axis so that the wavefront analyzer reaches the position of the light spot and can receive the light spot.

[0055] For any two alignment holes, obtain the ray tilt slope at the location of the light spot acquired by the wavefront analyzer, and determine the coordinates of the first image point of that alignment hole based on the ray tilt slope acquired by the wavefront analyzer at the location of the light spot.

[0056] In a preferred embodiment, the wavefront analyzer can capture the image point formed by the light emitted from the light source device after passing through a pinhole or alignment hole and the projection lens under test. The wavefront analyzer is equipped with a collimating lens and a Hartmann sensor. After the light emitted from the projection lens under test is received by the collimating lens, it will be focused onto the UV-CCD target surface of the Hartmann sensor by the microlens array of the Hartmann sensor. This allows the wavefront analyzer to calculate and obtain the centroid of the image point or light spot formed by the pinhole or alignment hole. Based on the deviation of the centroid of the obtained image point or light spot from the axis of the projection lens under test, the wavefront analyzer can obtain the ray tilt slope and ray energy value of the image point corresponding to the pinhole or alignment hole. In this embodiment, each time the first light source device moves to the position of an alignment hole or pinhole, it can only obtain one image point corresponding to that alignment hole or pinhole on the wavefront analyzer.

[0057] The process of determining the coordinates of the first image point of the alignment hole based on the tilt slope of the light rays collected by the wavefront analyzer at the location of the light spot includes: determining whether the tilt slope of the light rays collected by the wavefront analyzer at the location of the light spot reaches a second threshold; if the tilt slope of the light rays collected by the wavefront analyzer at the location of the light spot reaches the second threshold, determining the coordinates of the current position of the movable stage as the coordinates of the first image point of the alignment hole; if the tilt slope of the light rays collected by the wavefront analyzer at the location of the light spot does not reach the second threshold, fine-tuning the position of the movable stage until the light ray deviation slope of the image point corresponding to the pinhole reaches the second threshold, and determining the coordinates of the current position of the movable stage as the coordinates of the first image point of the alignment hole.

[0058] For any two alignment holes, the workpiece stage is kept stationary while the first light source device is moved to the position of the alignment hole, so that the light emitted by the first light source device passes through the alignment hole and the projection lens under test to form a corresponding image point on the movable worktable.

[0059] For any two alignment holes, the first light source device is controlled to move towards the position of each edge of the alignment hole. During the movement of the first light source device towards the position of each edge of the alignment hole, the wavefront analyzer is controlled to collect the light energy value.

[0060] For any two alignment holes, the position of the movable stage corresponding to the light energy value that meets the preset conditions collected by the wavefront analyzer is determined as the position of the edge of that alignment hole.

[0061] Specifically, the position of the first light source device can be determined by the light energy value collected by the wavefront analyzer. The preset condition is that the light energy value reaches a preset range. For any two alignment holes, the first light source device is controlled to move in the horizontal X direction. By judging whether the light energy value collected by the wavefront analyzer reaches the preset range, the position points on the two edges of the alignment hole that are parallel to the horizontal Y-axis can be determined. Similarly, the position points on the two edges of the alignment hole that are parallel to the horizontal X-axis can be determined.

[0062] For any two alignment holes, determine the object point coordinates of the alignment hole based on the obtained positions of each edge of the alignment hole.

[0063] Specifically, by adding the x-coordinates of the two points located on the two edges parallel to the horizontal Y-axis of the alignment hole and dividing by 2, the x-coordinate of the alignment hole can be obtained. Similarly, the y-coordinate of the alignment hole can be obtained.

[0064] Based on the obtained object point coordinates and first image point coordinates corresponding to any two alignment holes, the first alignment between the first light source device and the pinhole mask, and between the movable worktable and the pinhole mask, is achieved.

[0065] return Figure 4 S200, control the first light source device to move to the location of at least three randomly selected pinholes, and obtain the object point coordinates and the first image point coordinates corresponding to the at least three randomly selected pinholes, so as to achieve the second alignment between the first light source device and the pinhole mask template, and between the movable worktable and the pinhole mask template.

[0066] In a preferred embodiment, the step of controlling the first light source device to move to the locations of at least three arbitrarily selected pinholes, and obtaining the object point coordinates and the first image point coordinates corresponding to the at least three arbitrarily selected pinholes to achieve a second alignment between the first light source device and the pinhole mask, and between the movable worktable and the pinhole mask, includes:

[0067] For each of at least three randomly selected pinholes, the first light source device is controlled to move to the location of the pinhole, so that the light emitted by the first light source device passes through the pinhole and the projection lens under test to form a corresponding image point on the movable worktable.

[0068] Specifically, the user can arbitrarily select at least three pinholes from the rectangular pinhole array on the pinhole mask. Here, the movement of the first light source device can be controlled by the known row spacing and column spacing of the rectangular pinhole array, as well as the distance between the center of each alignment hole and the center of each pinhole.

[0069] For each of at least three randomly selected pinholes, the movable stage is controlled to move so that the wavefront analyzer reaches the image point of that pinhole, and the light energy value and light deviation slope of the image point corresponding to that pinhole are acquired by the wavefront analyzer.

[0070] In one specific embodiment, based on the standard magnification of the projection lens under test, the distance between the image points formed by the light emitted by the first light source device through each pinhole and the projection lens under test, as well as the distance between the image points of each alignment hole and the image points of each pinhole, can be obtained. This allows the movable stage to be moved so that the wavefront analyzer reaches the position of the image point of the pinhole.

[0071] For each of the at least three randomly selected pinholes, the coordinates of the object point and the coordinates of the first image point are determined based on the light energy value and light deviation slope of the image point corresponding to the pinhole, thereby achieving a second alignment between the first light source device and the mask, as well as between the movable worktable and the mask.

[0072] The steps for achieving a second alignment between the first light source device and the mask, and between the movable worktable and the mask, for each of at least three randomly selected pinholes, include: (1) Determining the object point coordinates and the first image point coordinates corresponding to the pinhole based on the ray energy value and ray deviation slope of the image point corresponding to the pinhole.

[0073] For each of at least three randomly selected pinholes, determine whether the light energy value of the image point corresponding to that pinhole reaches the first threshold.

[0074] For each of the at least three randomly selected pinholes, if the light energy value of the image point corresponding to the pinhole does not reach the first threshold, the position of the first light source device is finely adjusted until the light energy value of the image point corresponding to the pinhole reaches the first threshold, and the coordinates of the current position of the first light source device are determined as the object point coordinates of the pinhole.

[0075] In a preferred embodiment, for each of at least three randomly selected pinholes, a movable stage moves with a wavefront analyzer to the image point corresponding to that pinhole. After the movable stage with the wavefront analyzer reaches the image point corresponding to the pinhole, the light energy value of the current pinhole corresponding to the image point collected by the wavefront analyzer is obtained. The closer the light energy value is to 1, the closer the current location of the first light source device is to the pinhole. When the light energy value reaches a first threshold, the coordinates of the current location of the first light source device are determined as the object point coordinates of the pinhole.

[0076] For each of the at least three randomly selected pinholes, if the light energy value of the image point of the pinhole reaches the first threshold, it is determined whether the light deviation slope of the image point corresponding to the pinhole reaches the second threshold. If the light deviation slope of the image point corresponding to the pinhole reaches the second threshold, the coordinates corresponding to the current position of the movable worktable are determined as the coordinates of the first image point of the pinhole, thereby realizing the second alignment between the first light source device and the mask and between the worktable and the mask.

[0077] In a preferred embodiment, the ray deviation slope can represent the wavelet aberration of the image point. The smaller the wavelet aberration, the closer the position of the movable stage is to the actual position of each corresponding image point among the at least three randomly selected pinholes.

[0078] For each of the at least three randomly selected pinholes, if the light deviation slope does not reach the second threshold, the position of the movable stage is finely adjusted until the current light deviation slope reaches the second threshold. The coordinates of the current position of the movable stage are then determined as the coordinates of the first image point of the second alignment hole, thereby achieving the second alignment between the first light source device and the mask, as well as between the movable stage and the mask.

[0079] S300. Based on the obtained object point coordinates and first image point coordinates corresponding to at least three randomly selected pinholes, fit the object point coordinates and first image point coordinates corresponding to the remaining pinholes other than the at least three randomly selected pinholes, as well as the object point coordinates and first image point coordinates of the center point of the rectangular pinhole array.

[0080] In a preferred embodiment, after obtaining the object point coordinates corresponding to at least three randomly selected pinholes, the object point coordinates corresponding to the remaining pinholes in the rectangular pinhole array, excluding the at least three randomly selected pinholes, can be fitted based on the principle that three points determine a plane. The first light source device can be controlled to move to the position of each remaining pinhole based on the fitted object point coordinates of each remaining pinhole. At the same time, the first image point coordinates corresponding to the image points of the remaining pinholes can be fitted based on the obtained first image point coordinates corresponding to the at least three randomly selected pinholes. The movable worktable can be controlled to move to the position of the first image point coordinates of each remaining pinhole based on the fitted first image point coordinates of each remaining pinhole.

[0081] In one specific embodiment, the object point coordinates of the center point of the rectangular pinhole array can be determined based on the object point coordinates corresponding to at least three randomly selected pinholes and the object point coordinates of the remaining pinholes. The first image point coordinates of the center point of the rectangular pinhole array can be determined based on the first image point coordinates corresponding to at least three randomly selected pinholes and the first image point coordinates of the remaining pinholes.

[0082] S400. Based on the object point coordinates and the first image point coordinates of the center point of the rectangular pinhole array, control the movable stage to move to the position of the first image point coordinates of the center point of the rectangular pinhole array, and use this position as the coordinate origin of the interferometer device to fit the theoretical image point coordinates of each pinhole.

[0083] In a preferred embodiment, the step of controlling the movable stage to move to the position of the first image point coordinate of the center point of the rectangular pinhole array based on the object point coordinates and the first image point coordinates, and using this position as the coordinate origin of the interferometer device, and fitting the theoretical image point coordinates of each pinhole includes:

[0084] Based on the coordinates of the center point of the rectangular pinhole array and the coordinates of each pinhole, determine the pinhole that is closest to the center point of the rectangular pinhole array, and designate this pinhole as the center pinhole of the rectangular pinhole array.

[0085] In one specific embodiment, when the number of pinholes in both rows and columns of the rectangular pinhole array is odd, the pinhole at the very center of the rectangular pinhole array is the center point of the rectangular pinhole array. When the number of pinholes in either row or column of the rectangular pinhole array is odd, one pinhole can be arbitrarily selected from at least one pinhole closest to the center point of the rectangular pinhole array to be determined as the center point of the rectangular pinhole array.

[0086] Based on the object point coordinates of the central pinhole, the first light source device is controlled to move towards the location of the central pinhole; based on the first image point coordinates of the central pinhole, the movable stage is controlled to move to the location of the first image point coordinates corresponding to the central pinhole; the ray deviation slope at the location of the first image point coordinates corresponding to the central pinhole is obtained through a wavefront analyzer; it is determined whether the ray deviation slope at the location of the first image point coordinates corresponding to the central pinhole reaches a second threshold; if the ray deviation slope at the location of the first image point coordinates corresponding to the central pinhole reaches the second threshold, the coordinates corresponding to the current location of the movable stage are determined as the coordinate origin of the interferometer device, and the theoretical image point coordinates of each pinhole are fitted; if the ray deviation slope at the location of the first image point coordinates corresponding to the central pinhole does not reach the second threshold, the position of the movable stage is finely adjusted until the ray deviation slope at the location of the first image point coordinates corresponding to the central pinhole reaches the second threshold, the coordinates of the current location of the movable stage are determined as the coordinate origin of the interferometer device, and the theoretical image point coordinates of each pinhole are fitted.

[0087] In a preferred embodiment, the coordinate origin of the interferometer device is determined by the position of the image point formed by the central pinhole of the rectangular pinhole array. Therefore, it is necessary to control the first light source device to move to the position of the central pinhole according to the object point coordinates of the central pinhole obtained by fitting, and control the movable stage to move to the position of the first image point coordinates according to the first image point coordinates of the central pinhole obtained by fitting. At this time, it is necessary to align the image point of the central pinhole again, that is, to fine-tune the position of the movable stage so that the ray deviation slope of the image point of the central pinhole reaches the second threshold. When the ray deviation slope of the position of the first image point coordinates corresponding to the central pinhole reaches the second threshold, the coordinate position of the current movable stage is determined as the coordinate origin of the interferometer device.

[0088] In a preferred embodiment, the theoretical image point coordinates of each pinhole in the rectangular pinhole array can be fitted based on the coordinate origin of the interferometer device, the standard magnification of the projection lens under test, and the row spacing and column spacing of the rectangular pinhole array.

[0089] S500: For each pinhole in the rectangular pinhole array, control the first light source device to move to the position of the object point coordinates corresponding to the pinhole, and control the movable stage to move so that the wavefront analyzer reaches the position of the first image point coordinates corresponding to the pinhole.

[0090] Specifically, for each pinhole in the rectangular pinhole array, the first light source device is controlled to move to the position of the object point coordinates corresponding to that pinhole, so as to obtain the image point formed by the light emitted by the first light source device through that pinhole on the movable worktable.

[0091] In one specific embodiment, the first light source device is controlled to move to the location of one of the pinholes at a time, and the light emitted by the first light source device at the location of the pinhole passes through the pinhole mask and the projection lens under test, and can only form an image point corresponding to the pinhole on the worktable.

[0092] S600. For each pinhole in the rectangular pinhole array, the ray deviation slope of the corresponding image point is collected by the wavefront analyzer, and the coordinates of the second image point recorded by the interferometer device are obtained based on the ray deviation slope of the corresponding pinhole.

[0093] In one specific embodiment, for each pinhole in the rectangular pinhole array, after controlling the first light source to reach the pinhole's location according to the object point coordinates corresponding to the pinhole, it is also necessary to control the movable stage to move towards the pinhole's image point location according to the first image point coordinates corresponding to the pinhole, and determine whether the ray deviation slope corresponding to the pinhole reaches a second threshold. If the ray deviation slope corresponding to the pinhole does not reach the second threshold, the position of the movable stage is finely adjusted until the wavefront analyzer collects the ray deviation slope corresponding to the pinhole, which reaches the second threshold. The coordinates recorded by the interferometer at this time are then determined as the second image point coordinates corresponding to the pinhole. If the ray deviation slope corresponding to the pinhole reaches the second threshold, the coordinates recorded by the interferometer at this time are directly determined as the second image point coordinates corresponding to the pinhole.

[0094] S700. For each pinhole in the rectangular pinhole array, obtain the actual image point coordinates corresponding to the second image point coordinates of the pinhole.

[0095] The coordinates of the second image point include the x-coordinate of the second image point and the y-coordinate of the second image point.

[0096] In a preferred embodiment, the step of obtaining the actual image point coordinates corresponding to the image point of each pinhole in the rectangular pinhole array based on the second image point coordinates corresponding to the pinhole includes:

[0097] For each pinhole in the rectangular pinhole array, when the interferometer is located at the coordinates of the second image point corresponding to the pinhole, the abscissa centroid tilt, ordinate centroid tilt, and focal length of the collimating lens in the wavefront analyzer are obtained from the wavefront analyzer. The first product of the abscissa centroid tilt and the focal length is calculated, and the sum of the first product and the abscissa of the second image point of the pinhole is determined as the abscissa of the actual image point of the pinhole.

[0098] In one specific embodiment, the actual horizontal coordinate of the pinhole image point can be obtained using the following formula:

[0099] X act =X mea +Tiltx ×f (1)

[0100] In formula (1), X act The x-coordinate of the actual image point is represented by X. mea Tilt represents the x-coordinate of the second image point of the pinhole. x The x-coordinate of the image point of the pinhole represents the centroid tilt, and f represents the focal length of the collimating lens in the wavefront analyzer.

[0101] Calculate the second product of the centroid tilt of the vertical coordinate and the focal length value, and determine the sum of the second product and the vertical coordinate of the second image point of the pinhole as the vertical coordinate of the actual image point of the pinhole.

[0102] In one specific embodiment, the actual ordinate of the pinhole image point can be obtained using the following formula:

[0103] Y act =Y mea +Tilt y ×f (2)

[0104] In formula (2), Y act Y represents the actual image point's ordinate. mea Tilt represents the ordinate of the second image point of the pinhole. x The vertical coordinate of the pinhole image point represents the centroid tilt, and f represents the focal length of the collimating lens in the wavefront analyzer.

[0105] The coordinates of the actual image point are determined based on the obtained x-coordinate and y-coordinate of the actual image point.

[0106] S800. Based on the actual image point coordinates and theoretical image point coordinates corresponding to each pinhole, determine the distortion and actual magnification of the projection lens under test.

[0107] In one specific embodiment, the steps of determining the distortion and actual magnification of the projection lens based on the actual image point coordinates and theoretical image point coordinates corresponding to each pinhole include:

[0108] By using the actual and theoretical image point coordinates corresponding to each pinhole, the pre-established X-axis distortion fitting formula and Y-axis distortion fitting formula are fitted respectively. Based on the fitting results, the distortion parameters of the projection lens to be tested are determined.

[0109] Based on the obtained distortion parameters, the distortion and actual magnification of the projection lens under test are determined.

[0110] In one specific embodiment, the fitting formula for the X-axis distortion of the projection lens under test is:

[0111] X act =X nr +Tx +R×Y nr +M×X nr +X nr ×r 2 ×D+R x (3)

[0112] In formula (3), X act The x-coordinate of the actual image point of the pinhole, X nr The x-coordinate, Y, represents the theoretical image point of the pinhole. nr T represents the ordinate of the theoretical image point of the pinhole. x R represents the offset of the actual image point's x-coordinate relative to the theoretical image point's x-coordinate; M represents the magnification error; and r represents the rotation parameter of the actual image point relative to the theoretical image point. 2 The value of R represents the sum of the squares of the x-coordinate and y-coordinate of the theoretical image point of the pinhole, where D represents the distortion level and R represents the distortion level. x This represents the fitting residual along the X-axis.

[0113] In another preferred embodiment, the fitting formula for the Y-axis distortion of the projection lens under test is:

[0114] Y act =Y nr +T y +R×X nr +M×Y nr +Y nr ×r 2 ×D+R y (4)

[0115] In formula (4), Y act The ordinate of the actual image point of the pinhole, X nr The x-coordinate, Y, represents the theoretical image point of the pinhole. nr T represents the ordinate of the theoretical image point of the pinhole. y R represents the translation of the ordinate of the actual image point of the pinhole relative to the ordinate of the theoretical image point of the pinhole; M represents the fitting magnification error; and r represents the rotation parameter of the actual image point of the pinhole relative to the theoretical image point of the pinhole. 2 The value of R represents the sum of the squares of the x-coordinate and y-coordinate of the theoretical image point of the pinhole, where D represents the distortion level and R represents the distortion level. y This represents the fitting residual along the Y-axis.

[0116] The distortion parameters include the distortion level and magnification error of the projection lens under test. The steps for determining the distortion and actual magnification of the projection lens under test based on the obtained distortion parameters include: for each pinhole's theoretical image point, calculating the third product of the sum of the squares of the theoretical image point's x-coordinate and y-coordinate, and the distortion level; determining the maximum value among multiple third products as the X-axis distortion of the projection lens under test; for each pinhole's theoretical image point, calculating the fourth product of the sum of the squares of the theoretical image point's x-coordinate and y-coordinate, and the distortion level; determining the maximum value among multiple fourth products as the Y-axis distortion of the projection lens under test; and determining the actual magnification of the projection lens under test by summing the magnification error and the standard magnification of the projection lens under test.

[0117] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division; in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection may be through some communication interfaces; the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0118] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0119] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0120] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0121] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of measuring the distortion of a projection objective, characterized in that The distortion measurement method is applied to a controller in a distortion measurement device, and the distortion measurement device further comprises a first light source device, a pinhole mask, a movable workbench, a wavefront analyzer and an interferometer device, wherein the first light source device and the movable workbench are horizontally spaced apart, the pinhole mask is arranged between the first light source device and the movable workbench, the pinhole mask is provided with a rectangular pinhole array formed by a plurality of pinholes, and an alignment hole is arranged in a region between each edge of the pinhole mask and an edge of the rectangular pinhole array, light emitted by the first light source device passes through a pinhole and a to-be-measured projection objective lens to form an image point corresponding to the pinhole, the wavefront analyzer is arranged on the movable workbench, and a laser beam generated by the interferometer device is projected on the movable workbench, and the to-be-measured projection objective lens is fixed between the wavefront analyzer and the pinhole mask. The distortion measurement method comprises the following steps: controlling the first light source device to move to positions of any two alignment holes respectively, so as to realize first alignment between the first light source device and the pinhole mask and between the movable workbench and the pinhole mask; controlling the first light source device to move to positions of any selected at least three pinholes, and acquiring object point coordinates and first image point coordinates corresponding to the any selected at least three pinholes through the first light source device and the movable workbench, so as to realize second alignment between the first light source device and the pinhole mask and between the movable workbench and the pinhole mask; fitting object point coordinates and first image point coordinates corresponding to remaining pinholes except the any selected at least three pinholes and object point coordinates and first image point coordinates of a center point of the rectangular pinhole array according to the object point coordinates and the first image point coordinates corresponding to the any selected at least three pinholes; controlling the movable workbench to move to a position of the first image point coordinates of the center point of the rectangular pinhole array according to the object point coordinates and the first image point coordinates of the center point of the rectangular pinhole array, and taking the position as a coordinate origin of the interferometer device, and fitting theoretical image point coordinates of each pinhole; for each pinhole in the rectangular pinhole array, controlling the first light source device to move to a position of object point coordinates corresponding to the pinhole, so as to acquire an image point formed by light emitted by the first light source device and passing through the pinhole on the movable workbench, and controlling the movable workbench to move, so that the wavefront analyzer reaches a position of first image point coordinates corresponding to the pinhole; for each pinhole in the rectangular pinhole array, acquiring second image point coordinates of the pinhole image point recorded by the interferometer device according to a light deviation slope of the pinhole image point collected by the wavefront analyzer; for each pinhole in the rectangular pinhole array, acquiring actual image point coordinates corresponding to the pinhole image point according to the second image point coordinates of the pinhole; determining distortion and actual magnification of the to-be-measured projection objective lens according to the actual image point coordinates and the theoretical image point coordinates of each pinhole.

2. The distortion measurement method according to claim 1, characterized by, The alignment hole has a larger aperture than the pinhole.

3. The distortion measurement method according to claim 1, characterized by, The distortion measuring device further comprises a first long mirror and a second long mirror arranged on the movable workbench, the first long mirror is arranged along a horizontal X-axis direction, and the second long mirror is arranged along a horizontal Y-axis direction; The interferometer device comprises a laser head, an optical mirror group, a modulator, a first laser interferometer and a second laser interferometer, The laser head is configured to provide a laser beam, and the optical mirror group is configured to receive the laser beam and obtain a first laser beam along a horizontal X-axis direction and a second laser beam along a horizontal Y-axis direction; The first laser interferometer is configured to receive the first laser beam and make the first laser beam incident on the first long mirror, and the second laser interferometer is configured to receive the second laser beam and make the second laser beam incident on the second long mirror; The first laser interferometer and the second laser interferometer are respectively connected to the modulator, and the modulator is configured to obtain optical path values of the first laser beam and the second laser beam; The modulator is connected to the controller.

4. The distortion measurement method according to claim 1, characterized by, The distortion measuring device further comprises a second light source device, and the alignment hole is rectangular, The step of controlling the first light source device to move to a position of any two alignment holes to realize the first alignment between the first light source device and the pinhole mask plate and between the movable workbench and the pinhole mask plate comprises: For each of the any two alignment holes, the second light source device is controlled to move to a position of the alignment hole, so that light emitted by the second light source device forms a light spot via the alignment hole and the to-be-measured projection objective lens; For each of the any two alignment holes, the movable workbench is controlled to move, so that the wavefront analyzer reaches a position of the light spot; For each of the any two alignment holes, an optical line tilt slope of a position of the light spot collected by the wavefront analyzer is obtained, and a first image point coordinate of the alignment hole is determined according to the optical line tilt slope collected by the wavefront analyzer at the position of the light spot; For each of the any two alignment holes, the workpiece table is controlled to be in a stationary state, and the first light source device is controlled to move to a position of the alignment hole, so that light emitted by the first light source device forms a corresponding image point on the movable workbench via the alignment hole and the to-be-measured projection objective lens; For each of the any two alignment holes, the first light source device is controlled to move to a position of each edge of the alignment hole, and the wavefront analyzer is controlled to collect optical energy values in the process that the first light source device moves to the position of each edge of the alignment hole; For each of the any two alignment holes, a position of the movable workbench corresponding to an optical energy value that satisfies a preset condition and that is collected by the wavefront analyzer is determined as a position of each edge of the alignment hole; For each of the any two alignment holes, a subject point coordinate of the alignment hole is determined according to the obtained positions of each edge of the alignment hole; According to the obtained subject point coordinates and the first image point coordinates corresponding to any two alignment holes, the first alignment between the first light source device and the pinhole mask plate and between the movable workbench and the pinhole mask plate is realized.

5. The distortion measurement method according to claim 1, characterized by, The step of controlling the first light source device to move to positions of any selected at least three pinholes respectively, and acquiring object point coordinates and first image point coordinates corresponding to the any selected at least three pinholes, to realize the second alignment between the first light source device and the pinhole mask plate, and between the movable worktable and the pinhole mask plate, comprises: For each of the any selected at least three pinholes, the first light source device is controlled to move to a position of the pinhole, so that light emitted by the first light source device forms a corresponding image point on the movable worktable via the pinhole and the projection objective lens to be measured; For each of the any selected at least three pinholes, the movable worktable is controlled to move, so that the wavefront analyzer reaches a position of the image point of the pinhole, and the light energy value and the light deviation slope of the image point of the pinhole collected by the wavefront analyzer are acquired; For each of the any selected at least three pinholes, the object point coordinates and the first image point coordinates corresponding to the pinhole are determined according to the light energy value and the light deviation slope of the image point of the pinhole, to realize the second alignment between the first light source device and the mask plate, and between the movable worktable and the mask plate.

6. The distortion measurement method according to claim 5, wherein The step of controlling the first light source device to move to positions of any selected at least three pinholes respectively, and acquiring object point coordinates and first image point coordinates corresponding to the any selected at least three pinholes, to realize the second alignment between the first light source device and the pinhole mask plate, and between the movable worktable and the pinhole mask plate, comprises: For each of the any selected at least three pinholes, it is determined whether the light energy value of the image point of the pinhole reaches a first threshold value; For each of the any selected at least three pinholes, if the light energy value of the image point of the pinhole does not reach the first threshold value, the position of the first light source device is fine-tuned until the light energy value of the image point of the pinhole reaches the first threshold value, and the coordinates of the current position of the first light source device are determined as the object point coordinates of the pinhole; For each of the any selected at least three pinholes, it is determined whether the light deviation slope of the image point of the pinhole reaches a second threshold value; For each of the any selected at least three pinholes, if the light deviation slope of the image point of the pinhole reaches the second threshold value, the coordinates of the current position of the movable worktable are determined as the first image point coordinates of the pinhole, to realize the second alignment between the first light source device and the mask plate, and between the movable worktable and the mask plate; For each of the any selected at least three pinholes, if the light deviation slope of the image point of the pinhole does not reach the second threshold value, the position of the movable worktable is fine-tuned until the light deviation slope of the image point of the pinhole reaches the second threshold value, and the coordinates of the current position of the movable worktable are determined as the first image point coordinates of the pinhole, to realize the second alignment between the first light source device and the mask plate, and between the movable worktable and the mask plate.

7. The distortion measurement method according to claim 1, characterized by, According to the object point coordinates of the rectangular pinhole array center point and the first image point coordinates, the movable workbench is controlled to move to the position of the first image point coordinates of the rectangular pinhole array center point, and the position is taken as the coordinate origin of the interferometer device, and the step of fitting the theoretical image point coordinates of each pinhole includes: According to the object point coordinates of the rectangular pinhole array center point and the object point coordinates of each pinhole, the pinhole closest to the rectangular pinhole array center point is determined, and the pinhole closest to the rectangular pinhole array center point is determined as the center pinhole of the rectangular pinhole array; According to the object point coordinates of the center pinhole, the first light source device is controlled to move to the position of the center pinhole; The movable workbench is controlled to move to the position of the first image point coordinates corresponding to the center pinhole; The light deviation slope of the position of the first image point coordinates corresponding to the center pinhole is obtained through the wavefront analyzer; It is judged whether the light deviation slope of the position of the first image point coordinates corresponding to the center pinhole reaches a second threshold value; If the light deviation slope of the position of the first image point coordinates corresponding to the center pinhole reaches the second threshold value, the coordinates corresponding to the current position of the movable workbench are determined as the coordinate origin of the interferometer device, and the theoretical image point coordinates of each pinhole are fitted; If the light deviation slope of the position of the first image point coordinates corresponding to the center pinhole does not reach the second threshold value, the position of the movable workbench is fine-tuned until the light deviation slope of the position of the first image point coordinates corresponding to the center pinhole reaches the second threshold value, the coordinates of the current position of the movable workbench are determined as the coordinate origin of the interferometer device, and the theoretical image point coordinates of each pinhole are fitted.

8. The distortion measurement method according to claim 1, characterized by, The second image point coordinates include the horizontal coordinates of the second image point and the vertical coordinates of the second image point, For each pinhole in the rectangular pinhole array, the step of obtaining the actual image point coordinates of the pinhole according to the second image point coordinates corresponding to the pinhole includes: For each pinhole in the rectangular pinhole array, when the interferometer device is at the position of the second image point coordinates corresponding to the pinhole, the horizontal coordinate centroid tilt amount, the vertical coordinate centroid tilt amount of the image point of the pinhole, and the focal length value of the collimating lens in the wavefront analyzer are obtained from the wavefront analyzer; The first product of the horizontal coordinate centroid tilt amount and the focal length value is calculated, and the sum value between the first product and the horizontal coordinate of the second image point of the pinhole is determined as the horizontal coordinate of the actual image point of the pinhole; The second product of the vertical coordinate centroid tilt amount and the focal length value is calculated, and the sum value between the second product and the vertical coordinate of the second image point of the pinhole is determined as the vertical coordinate of the actual image point of the pinhole; According to the obtained horizontal coordinate of the actual image point and the vertical coordinate of the actual image point, the actual image point coordinates are determined.

9. The distortion measurement method according to claim 1, characterized by, According to the actual image point coordinates and the theoretical image point coordinates corresponding to each pinhole, the step of determining the distortion and the actual magnification of the to-be-measured projection objective lens includes: The pre-established X-axis distortion fitting formula and Y-axis distortion fitting formula are fitted respectively through the actual image point coordinates and the theoretical image point coordinates corresponding to each pinhole, and according to the fitting results, the distortion parameters of the to-be-measured projection objective lens are determined; According to the obtained distortion parameters, the distortion and the actual magnification of the to-be-measured projection objective lens are determined.

10. The distortion measurement method according to claim 9, wherein, The distortion parameters include a distortion level and a magnification error of the to-be-tested projection objective, The step of determining the distortion and the actual magnification of the to-be-tested projection objective according to the obtained distortion parameters includes: For each pinhole theoretical image point, a third product between a sum of squares of a horizontal coordinate of the pinhole theoretical image point, the horizontal coordinate of the pinhole theoretical image point and a vertical coordinate of the pinhole theoretical image point and the distortion level is calculated; A maximum value in the plurality of third products is determined as an X-axis distortion of the to-be-tested projection objective; For each pinhole theoretical image point, a fourth product between a sum of squares of a vertical coordinate of the pinhole theoretical image point, the horizontal coordinate of the pinhole theoretical image point and the vertical coordinate of the pinhole theoretical image point and the distortion level is calculated; A maximum value in the plurality of fourth products is determined as a Y-axis distortion of the to-be-tested projection objective; A sum of the magnification error and a standard magnification of the to-be-tested projection objective is determined as an actual magnification of the to-be-tested projection objective.

11. The distortion measurement method according to claim 9, wherein The X-axis distortion fitting formula of the to-be-tested projection objective is: In this formula, represents the horizontal coordinate of the actual image point of the pinhole, represents the horizontal coordinate of the theoretical image point of the pinhole, represents the vertical coordinate of the theoretical image point of the pinhole, represents the offset amount of the horizontal coordinate of the actual image point of the pinhole with respect to the horizontal coordinate of the theoretical image point of the pinhole, represents the rotation parameter of the actual image point of the pinhole with respect to the theoretical image point of the pinhole, represents the magnification error, represents the square sum between the square of the horizontal coordinate of the theoretical image point of the pinhole and the vertical coordinate of the theoretical image point, represents the distortion level, represents the X-axis fitting residual.

12. The distortion measurement method according to claim 9, wherein The Y-axis distortion fitting formula of the to-be-tested projection objective is: In this formula, represents a longitudinal coordinate of an actual image point of the pinhole, represents a lateral coordinate of a theoretical image point of the pinhole, represents a longitudinal coordinate of a theoretical image point of the pinhole, represents an offset amount of a longitudinal coordinate of an actual image point of the pinhole with respect to a longitudinal coordinate of a theoretical image point of the pinhole, represents a rotation parameter of an actual image point of the pinhole with respect to a theoretical image point of the pinhole, represents a fitting magnification error, represents a sum of squares between a square of a lateral coordinate of a theoretical image point of the pinhole and a longitudinal coordinate of the theoretical image point, represents a distortion level, represents a Y-axis fitting residual.

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