Calibration system and calibration method

Abstract

The embodiment of the invention provides a calibration system and a calibration method.The calibration system comprises a detection device, a beam splitter, a first optical element, a second optical element, a third optical element, a first camera and a second camera, and the second optical element and a measurement objective lens are used for obtaining a measurement light beam; the calibration mark is imaged to the first camera according to the measurement light beam to form a first image; the third optical element and the reference objective lens are used for acquiring a reference light beam and imaging the calibration mark to the second camera according to the reference light beam to form a second image, and the first image and the second image are used for adjusting the position of the reference objective lens or the measuring objective lens. The first optical element, the second optical element and the third optical element can calibrate the position of the reference objective lens or the measuring objective lens, so that the relative position between the reference objective lens and the measuring objective lens is small, the assembly precision is improved, interference fringes can be quickly adjusted subsequently, and the interference measurement efficiency and the measurement precision are improved.

Description

Technical Field

[0001] The present application relates to the field of interferometric measurement, and in particular to a calibration system and a calibration method. Background Art

[0002] Optical microscopy is a commonly used technique in semiconductor inspection and measurement, with advantages such as fast inspection speed and no pollution. With the development of semiconductor technology and the reduction of key dimensions, the requirements for the accuracy of wafer inspection and measurement are becoming higher and higher. This in turn places higher requirements on the performance of the optical system, especially the focusing accuracy.

[0003] The focusing device based on the Linnik type white light interference principle has the advantages of high focusing accuracy, fast speed, and unlimited working distance, and is widely used in high-power microscopic imaging systems. The Linnik type focusing device includes a measuring objective lens and a reference objective lens. The optical path difference is calculated based on the interference signal between the measuring light path and the reference light path, and then the defocus amount of the measuring objective lens at the distance of the object to be measured is obtained. Since the correlation length of white light interference is very short, usually only a few microns, the adjustment deviation between the two objective lenses will result in the inability to observe interference fringes, which brings great difficulties to the system adjustment. Therefore, how to improve the assembly accuracy of the objective lens in interferometric measurement and quickly adjust the interference fringes in interferometric measurement has become a technical problem that urgently needs to be solved. Summary of the invention

[0004] In view of this, the purpose of this application is to provide a calibration system and calibration method to improve the assembly accuracy of the reference objective lens and the measuring objective lens in interferometry, to quickly adjust the interference fringes, and to improve the efficiency and measurement accuracy of interferometry. The specific scheme is as follows:

[0005] In a first aspect, the present application provides a calibration system for calibrating the relative position of a measuring objective lens and a reference objective lens, comprising:

[0006] A detection device, the detection device is used to generate a calibration light and a calibration mark;

[0007] A beam splitter, the beam splitter being used to split the calibration light into a measurement light beam propagating toward a measurement light path where the measurement objective lens is located, and a reference light beam propagating toward a reference light path where the reference objective lens is located;

[0008] A first optical element, disposed on an optical path between the detection device and the beam splitter, and used for focusing the calibration light;

[0009] a second optical element and a first camera, the first camera being located at a focal plane of the second optical element, the second optical element and the measuring objective lens being used to acquire the measuring beam, and to image the calibration mark onto the first camera according to the measuring beam to form a first image;

[0010] a third optical element and a second camera, wherein the second camera is located at a focal plane of the third optical element, and the third optical element and the reference objective lens are used to acquire the reference beam and image the calibration mark to the second camera according to the reference beam to form a second image;

[0011] The first image and the second image are used to adjust the position of the reference objective lens and / or the measuring objective lens.

[0012] In a second aspect, an embodiment of the present application further provides a calibration method, which is applied to the calibration system, comprising:

[0013] When the first optical element, the measuring objective lens and the reference objective lens are configured to be out of the optical path, a first imaging position and a second imaging position are acquired; the first imaging position is an imaging position of the calibration mark in the first camera after passing through the beam splitter and the second optical element; the second imaging position is an imaging position of the calibration mark in the second camera after passing through the beam splitter and the third optical element;

[0014] When the first optical element, the measuring objective lens and the reference objective lens are arranged in the optical path, a third imaging position and a fourth imaging position are acquired; the third imaging position is an imaging position of the calibration mark in the first camera after the calibration mark passes through the first optical element, the beam splitter, the measuring objective lens and the second optical element; the fourth imaging position is an imaging position of the calibration mark in the second camera after the calibration mark passes through the first optical element, the beam splitter, the reference objective lens and the third optical element;

[0015] According to first relative offset information of the third imaging position relative to the first imaging position, and second relative offset information of the fourth imaging position relative to the second imaging position, the reference objective lens and the measuring objective lens are adjusted so that the first relative offset information is consistent with the second relative offset information.

[0016] The embodiments of the present application provide a calibration system and a calibration method. The calibration system is used to calibrate the relative position of a measuring objective lens and a reference objective lens. The calibration system includes a detection device, a beam splitter, a first optical element, a second optical element, a third optical element, a first camera, and a second camera. The detection device is used to generate calibration light and a calibration mark. The beam splitter is used to split the calibration light into a measurement light beam propagating in a measurement light path where the measuring objective lens is located, and a reference light beam propagating in a reference light path where the reference objective lens is located. The first optical element is arranged on the optical path between the detection device and the beam splitter, and is used to focus and adjust the calibration light. The first camera is located at the focal plane of the second optical element. The second optical element and the measuring objective lens are used to obtain the measuring light beam, and image the calibration mark to the first camera according to the measuring light beam to form a first image. The second camera is located at the focal plane of the third optical element. The third optical element and the reference objective lens are used to obtain the reference light beam, and image the calibration mark to the second camera according to the reference light beam to form a second image. The first image and the second image are used to adjust the position of the reference objective lens or the measuring objective lens. In this way, adding the first optical element, the second optical element and the third optical element can calibrate the position of the reference objective lens or the measuring objective lens, make the relative position between the reference objective lens and the measuring objective lens smaller, correct the installation error between the two objective lenses, improve the assembly accuracy of the reference objective lens and the measuring objective lens in the interference measurement, and be able to quickly adjust the interference fringes, thereby improving the efficiency and measurement accuracy of the interference measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic structural diagram of an interference measurement device provided in an embodiment of the present application is shown;

[0019] Figure 2 A schematic diagram of the structure of a calibration system provided in an embodiment of the present application is shown;

[0020] Figure 3 A schematic diagram of the structure of another calibration system provided in an embodiment of the present application is shown;

[0021] Figure 4 A schematic diagram of the structure of another calibration system provided in an embodiment of the present application is shown;

[0022] Figure 5 A flow chart of a calibration method provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0025] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0026] As described in the background technology, in a Linnik type focusing device, the adjustment deviation between the measuring objective lens and the reference objective lens will result in the inability to observe interference fringes, which brings great difficulties to the system adjustment. Therefore, how to improve the assembly accuracy of the objective lens in interferometric measurement and quickly adjust the interference fringes in interferometric measurement has become a technical problem that needs to be solved urgently.

[0027] Based on the above technical problems, an embodiment of the present application provides a calibration system and a calibration method. The calibration system is used to calibrate the relative positions of a measuring objective lens and a reference objective lens. The calibration system includes a detection device, a beam splitter, a first optical element, a second optical element, a third optical element, a first camera and a second camera. The detection device is used to generate calibration light and a calibration mark. The beam splitter is used to split the calibration light into a measurement light beam propagating in a measurement light path where the measuring objective lens is located, and a reference light beam propagating in a reference light path where the reference objective lens is located. The first optical element is arranged on the optical path between the detection device and the beam splitter, and is used to focus and adjust the calibration light. The first camera is located at the focal plane of the second optical element. The second optical element and the measuring objective lens are used to obtain the measuring light beam, and image the calibration mark to the first camera according to the measuring light beam to form a first image. The second camera is located at the focal plane of the third optical element. The third optical element and the reference objective lens are used to obtain the reference light beam, and image the calibration mark to the second camera according to the reference light beam to form a second image. The first image and the second image are used to adjust the position of the reference objective lens or the measuring objective lens. In this way, adding the first optical element, the second optical element and the third optical element can calibrate the position of the reference objective lens or the measuring objective lens, make the relative position between the reference objective lens and the measuring objective lens smaller, correct the installation error between the two objective lenses, improve the assembly accuracy of the reference objective lens and the measuring objective lens in the interference measurement, and be able to quickly adjust the interference fringes, thereby improving the efficiency and measurement accuracy of the interference measurement.

[0028] For ease of understanding, a calibration system and a calibration method provided in an embodiment of the present application are described in detail below with reference to the accompanying drawings.

[0029] In the embodiment of the present application, the objective lens in the interferometric measurement device can be calibrated by using the calibration system, Figure 1 As shown, it is a schematic diagram of the structure of an interferometer measurement device provided in an embodiment of the present application, and the interferometer measurement device includes a light source 101, two beam splitters 102 and 103, a measuring objective lens 104, a reference objective lens 105, a reference reflector 106, a camera 107, and a phase Doppler analyzer 108 (Phase Doppler Analysis, PDA). The optical path in the interferometer measurement device includes an illumination optical path from the light source 101 to the beam splitter 103, a measurement optical path from the beam splitter 103 to the object to be measured 110, a reference optical path from the beam splitter 103 to the reference reflector 106, and an interference optical path from the beam splitter 103 to the PDA 108.

[0030] Specifically, the illumination beam emitted by the light source 101 is divided into two parts through the beam splitter 103, namely, a measurement beam propagating in the measurement optical path where the measurement objective lens 104 is located, and a reference beam propagating in the reference optical path where the reference objective lens 105 is located; the measurement beam passes through the measurement objective lens 104 and irradiates the object to be measured 110, and the reflected light passes through the measurement objective lens 104 and passes through the beam splitter 103 to form a measurement reflected beam; the reference beam passes through the reference objective lens 105 and irradiates the reference reflector 106, and the reflected light passes through the reference objective lens 105 and is reflected 90 degrees in the beam splitter 103 to form a reference reflected beam. The measurement reflected beam and the reference reflected beam are superimposed and interfered, and the interference fringes are measured by the PDA 108 to form an interference image, and the back-end processor can judge the distance between the object to be measured 110 and the measurement objective lens 104 based on the interference image. When the installation error between the reference objective lens 104 and the measurement objective lens 105 is large, the interference fringes cannot be quickly adjusted, which wastes time.

[0031] refer to Figure 2 , which is a schematic diagram of the structure of a calibration system provided in an embodiment of the present application, the calibration system includes a detection device 201, a beam splitter 103, a first optical element 202, a second optical element 203, a third optical element 204, a first camera 205 and a second camera 206.

[0032] The detection device 201 is used to generate calibration light and calibration mark. The detection device 201 can be an autocollimator. The standard mark can be a cross mark. The beam splitter 103 is used to split the calibration light into two light beams. One light beam is a measurement light beam that propagates into a measurement light path where the measurement objective lens 104 is located, and the other light beam is a reference light beam that propagates into a reference light path where the reference objective lens 105 is located.

[0033] The first optical element 202 is arranged on the optical path between the detection device and the beam splitter, and can be used to adjust the focus of the calibration light, thereby changing the imaging state in the camera, such as adjusting the clarity of the calibration mark or the imaging position of the calibration mark.

[0034] The first camera 205 may be located at the focal plane of the second optical element 203 so as to focus the image in the first camera 205 . The second optical element 203 and the measuring objective lens 104 may acquire the measuring beam and image the calibration mark to the first camera 205 according to the measuring beam, thereby forming a first image.

[0035] The second camera 206 is located at the focal plane of the third optical element 204 so as to focus the image in the second camera 206. The third optical element 204 and the reference objective lens 105 are used to obtain the reference beam and image the calibration mark to the second camera 206 according to the reference beam, thereby forming a second image.

[0036] The first image and the second image are used to adjust the position of the reference objective lens 105 and / or the measuring objective lens 104. The position of the reference objective lens 105 or the measuring objective lens 104 can be reflected in many aspects. The first image and the second image can be used to adjust the inclination, eccentric displacement and axial displacement of the reference objective lens and / or the measuring objective lens. Please understand that the inclination is the inclination of the radial plane of the objective lens relative to the preset axis, the eccentric displacement is the radial movement of the optical axis center of the objective lens relative to the preset axis, and the axial displacement is the axial movement of the optical axis center of the objective lens on the preset axis; the preset axis here is the direction line of the measuring beam generated after the light beam of the autocollimator passes through the beam splitter, or the direction line of the reference beam generated. For example, since the reference beam is projected toward the reference objective lens, the inclination of the reference objective lens is the inclination of its own radial plane relative to the direction line of the reference beam.

[0037] Specifically, when the position of the measuring objective lens 104 is fixed, the position of the reference objective lens 105 can be adjusted according to the first image and the second image, such as adjusting the tilt, eccentric displacement and axial displacement of the reference objective lens 105. When the position of the reference objective lens 105 is fixed, the position of the measuring objective lens 104 can be adjusted according to the first image and the second image, such as adjusting the tilt, eccentric displacement and axial displacement of the measuring objective lens 104. When the positions of the reference objective lens 105 and the measuring objective lens 104 are not fixed, the positions of the measuring objective lens 104 and the reference objective lens 105 can be adjusted simultaneously according to the first image and the second image, that is, the tilt, eccentric displacement and axial displacement of the measuring objective lens 104 and the reference objective lens 105 can be adjusted simultaneously.

[0038] Specifically, the first image is an image formed in the first camera 205 after the light beam passes through the first optical element 202, the beam splitter 103, the measuring objective lens 104 and the second optical element 203. The second image is an image formed in the second camera 206 after the light beam passes through the first optical element 202, the beam splitter 103, the reference objective lens 105 and the third optical element 204. Based on the difference between the first image and the second image, the difference between the two light paths can be determined. Since the second optical element 203 and the third optical element 204 are used to focus the calibration light on the first camera 205 and the second camera 206 respectively, the positions of the second optical element 203 and the third optical element 204 have little effect on the optical path, and the difference between the two optical paths is mainly reflected in the relative position change between the measuring objective lens 104 and the reference objective lens 105. Therefore, the first optical element 202, the second optical element 203 and the third optical element 204 are added to focus and adjust the calibration light, thereby changing the imaging state of the light spot in the first image and the second image, and then according to the difference between the first image and the second image, the reference objective lens 105 or the measuring objective lens 104 can be calibrated more accurately, so that the relative position between the reference objective lens 105 and the measuring objective lens 104 is smaller, the installation error between the two objective lenses is corrected, and the assembly accuracy of the reference objective lens 105 and the measuring objective lens 104 in the interferometric measurement is improved, the interference fringes can be quickly adjusted, and the efficiency and measurement accuracy of the interferometric measurement are improved.

[0039] Among them, the first optical element 202, the second optical element 203, and the third optical element 204 can all be configured as lenses or lens barrels. The lens barrel is a lens group composed of multiple lenses. For example, the first optical element is a first lens or a first lens barrel, the second optical element is a second lens or a second lens barrel, and the third optical element is a third lens or a third lens barrel. The selection can be made according to actual application conditions.

[0040] In the embodiment of the present application, before installing the first optical element 202, the measuring objective lens 104 and the reference objective lens 105, the objective lens calibration system includes a detection device 201, a beam splitter 103, a second optical element 203, a third optical element 204, a first camera 205 and a second camera 206, and the reference objective lens 105 is installed. Figure 3 As shown, it is a schematic diagram of the structure of another calibration system provided in an embodiment of the present application, and a third image can be obtained in the first camera 205, and a fourth image can be obtained in the second camera. The third image is an image obtained when the light beam emitted by the detection device 201 passes through the beam splitter 103 and the second optical element 203 and is received by the first camera 205, and the fourth image is an image obtained when the light beam emitted by the autocollimator 201 passes through the beam splitter 103 and the third optical element 204 and is received by the second camera 206.

[0041] Specifically, the difference between the imaging position in the first image and the imaging position in the third image can be recorded as the first relative offset information, and the difference between the imaging position in the second image and the imaging position in the fourth image can be recorded as the second relative offset information. When the first relative offset information and the second relative offset information are consistent, it can be determined that the optical axis of the reference objective lens 105 and the optical axis of the measuring objective lens 104 are symmetrical relative to the beam splitter 103, and interference fringes can be quickly called out.

[0042] In the embodiment of the present application, it is possible to adjust only the position of the reference objective lens 105, or only the position of the measuring objective lens 104, or to adjust both the positions of the reference objective lens 105 and the measuring objective lens 104. In the following embodiment, the position of the measuring objective lens 104 is fixed and the position of the reference objective lens 105 is adjusted as an example. Of course, it is also possible to adjust the position of the measuring objective lens 104 by fixing the position of the reference objective lens 105, or to adjust both the reference objective lens 105 and the measuring objective lens 104 at the same time, which is not specifically limited here.

[0043] In an embodiment of the present application, if the first image and the second image are used to adjust the position of the reference objective lens 105, the optical axis of the detection device 201, the optical axis of the first optical element 202 and the optical axis of the measuring objective lens 104 can be located on the same axis, so that the imaging position in the first image and the imaging position in the third image can coincide, the first relative offset information is zero, the calculation process can be omitted, the relative position between the reference objective lens 105 and the measuring objective lens 104 can be adjusted faster, the installation error between the two objective lenses can be corrected, and the error generated when calculating the first relative offset information can be avoided, thereby improving the assembly accuracy.

[0044] Specifically, the difference between the first image and the third image lies in whether the first optical element 202 and the measuring objective lens 104 are present in the optical path. After the calibration light emitted by the detection device 201 passes through the beam splitter 103 and the second optical element 203, the third image is formed in the first camera 205. After the calibration light emitted by the detection device 201 passes through the first optical element 202, the beam splitter 103, the measuring objective lens 104 and the second optical element 203, the first image is formed in the first camera 205. After adjusting the position of the first optical element 202, the imaging position in the first image can be made to coincide with the imaging position in the third image. At this time, the optical axis of the detection device 201, the optical axis of the first optical element 202 and the optical axis of the measuring objective lens 104 are located in the same straight line, and the calibration light emitted by the detection device 201 can be incident on the center position of the optical axis of the measuring objective lens 104.

[0045] Specifically, the optical axis of the reference objective lens 105 and the optical axis of the measuring objective lens 104 can be symmetrical about the splitting plane of the beam splitter 103, so that the eccentric positions of the reference objective lens 105 and the measuring objective lens 104 can be consistent, and the consistency between the reference objective lens 105 and the measuring objective lens 104 can be determined from the eccentric position, thereby improving the assembly accuracy of the reference objective lens 105 and the measuring objective lens 104.

[0046] Specifically, the difference between the second image and the fourth image lies in whether the first optical element 202 and the reference objective lens 105 are present in the optical path. The calibration light emitted by the detection device 201 passes through the beam splitter 103 and the third optical element 204 in sequence, and then forms the fourth image in the second camera 206. The calibration light emitted by the detection device 201 passes through the first optical element 202, the beam splitter 103, the reference objective lens 105 and the third optical element 204 in sequence, and then forms the second image in the second camera 206. After adjusting the position of the reference objective lens, the imaging position in the second image can be made to coincide with the imaging position in the fourth image. At this time, the first relative offset information and the second relative offset information are both zero, so that the interference fringes can be adjusted more quickly, eliminating the process of calculating the relative offset information.

[0047] In an embodiment of the present application, if the first image and the second image are used to adjust the position of the reference objective lens 105, the focal plane of the first optical element 202 can coincide with the back focal plane of the measuring objective lens 104, so that the calibration light emitted by the detection device 201 can be clearly imaged in the first image, thereby avoiding large errors in the first relative offset information due to blurred imaging, and improving the assembly accuracy of the two objective lenses.

[0048] In one case, the back focal plane of the reference objective lens 105 and the back focal plane of the measuring objective lens 104 can be symmetrical about the splitting plane of the beam splitter 103, and the consistency between the reference objective lens 105 and the measuring objective lens 104 can be determined in the axial direction. At this time, the image of the light beam emitted by the autocollimator 201 in the second image is clear, avoiding large errors in the second relative offset information due to imaging blur, and improving the assembly accuracy of the two objective lenses.

[0049] In an embodiment of the present application, the objective lens calibration system may further include a measuring objective lens mounting position and a first reflector, wherein the measuring objective lens mounting position is used to mount the measuring objective lens, the first reflector is detachable, the first reflector is used to replace the measuring objective lens, and is arranged at the measuring objective lens mounting position, and the first reflector verifies the inclination of the measuring objective lens mounting position relative to the optical axis of the autocollimator by reflecting the measuring light beam.

[0050] Specifically, when the first optical element 202, the second optical element 203, the measuring lens 104 and the first camera 205 are configured to be out of the optical path, when the first reflector is located in the optical path, the first reflector is configured at the measuring lens installation position, and the inclination of the measuring lens installation position relative to the optical axis of the autocollimator is verified by reflecting the measuring light beam. When the propagation path of the reflected light beam of the first reflector coincides with the propagation path of the incident light beam incident on the first reflector, it indicates that the measuring lens installation position is perpendicular to the optical axis of the autocollimator. When the position of the measuring lens 104 is fixed, the measuring lens installation position is also fixed, and the inclination of the mirror surface of the first reflector is also fixed. The position of the detection device 201 can be adjusted according to the measuring lens installation position, so that the light beam emitted by the detection device 201 is perpendicular to the plane where the measuring lens installation position is located, thereby determining the installation position of the detection device 201.

[0051] Specifically, the detection device 201 can emit a cross-shaped laser beam, which reaches a first reflector pre-set on the mounting surface where the measuring objective lens 104 is located and is reflected. The reflected light forms a cross-shaped image in the detection device 201. When the imaging center coincides with the standard center, it means that the emitted laser is perpendicular to the plane where the measuring objective lens 104 is located.

[0052] In the embodiment of the present application, the objective lens calibration system may further include a measuring reflector 207 , which is disposed in the measuring optical path and is used to vertically reflect the measuring light beam at least when the first camera 205 is out of the optical path.

[0053] Specifically, when the first camera 205 and the first reflector are out of the optical path, and the measuring reflector 207 is in the optical path, the position of the measuring reflector 207 is the position of the fixed object to be measured, and the inclination of the measuring reflector 207 is the inclination of the object to be measured. The inclination of the measuring reflector 207 can be adjusted by using the autocollimator 201. Figure 4 , which is a schematic diagram of the structure of another calibration system provided in an embodiment of the present application, wherein the optical path includes a detection device 201 , a beam splitter 103 , a measurement reflector 207 and a reference reflector 106 .

[0054] Specifically, since the position of the detection device 201 has been determined, by adjusting the inclination of the measuring reflector 207, the calibration light emitted by the detection device 201 can be perpendicular to the mirror surface of the measuring reflector 207. In this way, the calibration light emitted by the detection device 201 is perpendicular to both the installation position of the measuring objective lens and the mirror surface of the measuring reflector 207, and the plane where the measuring objective lens 104 is located is parallel to the mirror surface of the measuring reflector 207, which meets the use requirements of using the measuring objective lens 104 to detect the object to be measured, and can call out interference fringes more quickly.

[0055] In the embodiment of the present application, the calibration system may further include a reference objective lens mounting position and a second reflector, the second reflector is detachable, and the second reflector is used to replace the reference objective lens, and is arranged at the reference objective lens mounting position, and verifies the inclination of the reference objective lens mounting position relative to the optical axis of the detection device by reflecting the reference beam. The second reflector can determine the inclination of the reference objective lens 105, so that the inclination of the reference objective lens 105 is consistent with the inclination of the measuring objective lens 104, and correct the installation error between the two objective lenses.

[0056] Specifically, when the first optical element 202, the third optical element 204, the reference objective lens 105 and the second camera 206 are configured to be out of the optical path, when the second reflector is located in the optical path, the second reflector is configured at the reference objective lens installation position, and the inclination of the reference objective lens installation position relative to the optical axis of the detection device is verified by reflecting the reference light beam. When the reflected light beam of the second reflector coincides with the propagation path of the incident light beam incident on the second reflector, it indicates that the reference objective lens installation position is perpendicular to the optical axis of the detection device. The calibration light emitted by the detection device 201 can be perpendicular to the plane where the reference objective lens installation position is located. In this way, the calibration light emitted by the detection device 201 is perpendicular to both the plane where the measurement objective lens 104 is located and the plane where the reference objective lens 105 is located, so that the inclination of the two objective lenses can be consistent.

[0057] In the embodiment of the present application, the calibration system may further include a reference reflector 106, which is disposed in the reference optical path and is used to vertically reflect the reference light beam at least when the second camera 206 is out of the optical path. Specifically, when the second camera 206 and the second reflector are not located in the optical path, so that the reference reflector 106 is located in the optical path, the light beam emitted by the detection device 201 is perpendicular to the mirror surface of the reference reflector 106, so that the mirror surface of the reference reflector 106 is parallel to the installation position of the reference objective lens, which meets the measurement requirements and can better adjust the interference fringes.

[0058] It is understandable that after the installation position of the detection device 201 is determined, the tilt degrees of the reference objective lens 105, the measuring reflector 207 and the reference reflector 106 can be determined by the detection device 201 so as to quickly call out the interference fringes.

[0059] An embodiment of the present application provides a calibration system, which is used to calibrate the relative position of a measuring objective lens and a reference objective lens. The calibration system includes a detection device, a beam splitter, a first optical element, a second optical element, a third optical element, a first camera, and a second camera. The detection device is used to generate calibration light and a calibration mark. The beam splitter is used to split the calibration light into a measurement light beam that propagates in a measurement light path where the measuring objective lens is located, and a reference light beam that propagates in a reference light path where the reference objective lens is located. The first optical element is arranged on the light path between the detection device and the beam splitter, and is used to focus the calibration light. The first camera is located at the focal plane of the second optical element. The second optical element and the measuring objective lens are used to obtain the measuring light beam, and image the calibration mark to the first camera according to the measuring light beam to form a first image. The second camera is located at the focal plane of the third optical element. The third optical element and the reference objective lens are used to obtain the reference light beam, and image the calibration mark to the second camera according to the reference light beam to form a second image. The first image and the second image are used to adjust the position of the reference objective lens or the measuring objective lens. In this way, adding the first optical element, the second optical element and the third optical element can calibrate the position of the reference objective lens or the measuring objective lens, make the relative position between the reference objective lens and the measuring objective lens smaller, correct the installation error between the two objective lenses, improve the assembly accuracy of the reference objective lens and the measuring objective lens in the interference measurement, and be able to quickly adjust the interference fringes, thereby improving the efficiency and measurement accuracy of the interference measurement.

[0060] Based on the above calibration system, the present application embodiment also provides a calibration method, which is applied to the calibration system, referring to Figure 5 As shown, it is a flow chart of a calibration method provided in an embodiment of the present application, and the method includes the following steps.

[0061] S101 , when the first optical element, the measuring objective lens, and the reference objective lens are configured to be out of the optical path, acquiring a first imaging position and a second imaging position.

[0062] In the embodiment of the present application, when the first optical element 202, the measuring objective lens 104 and the reference objective lens 105 are configured to be separated from the optical path, and the optical path includes the detection device 201, the beam splitter 103, the second optical element 203, the third optical element 204, the first camera 205 and the second camera 206, a first imaging position can be acquired in the first camera 205, and a second imaging position can be acquired in the second camera 206, the first imaging position being the imaging position of the calibration mark in the first camera 205 after passing through the beam splitter 103 and the second optical element 203; the second imaging position being the imaging position of the calibration mark in the second camera 206 after passing through the beam splitter 103 and the third optical element 204.

[0063] Specifically, the second optical element 203 can be configured to be located on the optical path between the beam splitter 103 and the first camera 205, and the second optical element 203 can converge the measuring light beam emitted from the detection device 201. The third optical element 204 is configured to be located on the optical path between the beam splitter 103 and the second camera 206, so as to converge the reference light beam, so that the light spot at the first imaging position and the light spot at the second imaging position are clearly imaged, thereby improving the accuracy of objective lens calibration.

[0064] At this time, the optical path does not include the measuring objective lens 104 and the reference objective lens 105, and the first imaging position and the second imaging position can be used as reference positions to determine the change in the imaging position after the measuring objective lens 104 and the reference objective lens 105 are subsequently added to the optical path, and then determine the adjustment method of the measuring objective lens 104 or the reference objective lens 105, so that the optical axis of the measuring objective lens 104 and the optical axis of the reference objective lens 105 are symmetrical about the beam splitter 103, so that interference fringes can be quickly adjusted.

[0065] In the embodiment of the present application, when the optical path includes the detection device 201, the first optical element 202, the beam splitter 103, the measuring objective lens 104, the reference objective lens 105, the second optical element 203, the third optical element 204, the first camera 205 and the second camera 206, Figure 2 As shown, the light beam emitted by the detection device 201 forms a first image in the first camera 205, and the third imaging position in the first image can be obtained. The third imaging position is the imaging position in the first image in the first camera 205 of the light beam emitted by the detection device 201 after passing through the first optical element 202, the beam splitter 103, the measuring objective lens 104 and the second optical element 203. After the first optical element 202 and the measuring objective lens 104 are added to the optical path, the imaging position in the first camera 205 changes from the first imaging position to the third imaging position.

[0066] S102, when the first optical element, the measuring objective lens, and the reference objective lens are arranged in the optical path, acquiring a third imaging position and a fourth imaging position.

[0067] In the embodiment of the present application, when the first optical element 202, the measuring objective lens 104 and the reference objective lens 105 are arranged in the optical path, the third imaging position and the fourth imaging position can be obtained, the third imaging position is the imaging position of the calibration mark in the first camera 205 after passing through the first optical element 202, the beam splitter 103, the measuring objective lens 104 and the second optical element 203, and the fourth imaging position is the imaging position of the calibration mark in the second camera 206 after passing through the first optical element 202, the beam splitter 103, the reference objective lens 105 and the third optical element 204. . After the first optical element 202 and the reference objective lens 105 are added to the optical path, the imaging position of the calibration mark in the second camera 206 changes from the second imaging position to the fourth imaging position.

[0068] S103, adjusting the reference objective lens and the measuring objective lens according to first relative offset information of the third imaging position relative to the first imaging position and second relative offset information of the fourth imaging position relative to the second imaging position, so that the first relative offset information is consistent with the second relative offset information.

[0069] In an embodiment of the present application, there is relative offset information between the two imaging positions, and the relative offset information may include an offset amount and an offset direction. The offset information of the third imaging position relative to the first imaging position may be recorded as first relative offset information, and the offset information of the fourth imaging position relative to the second imaging position may be recorded as second relative offset information.

[0070] Specifically, the first relative offset information may indicate the change in imaging position when the measuring objective lens 104 is added to the measuring optical path and when the measuring objective lens 104 is not added, and the second relative offset information indicates the change in imaging position when the reference objective lens 105 is added to the reference optical path and when the reference objective lens 105 is not added. The reference objective lens 105 or the measuring objective lens 104 may be adjusted according to the first relative offset information and the second relative offset information, so that the first relative offset information is consistent with the second relative offset information, that is, the offset amount and the offset direction are consistent, so that the influence of the measuring objective lens 104 on the measuring optical path is consistent with the influence of the reference objective lens 105 on the reference optical path, and the optical axis of the reference objective lens 105 and the optical axis of the measuring objective lens 104 are symmetrical about the beam splitter 103. The installation error between the two objective lenses can be corrected, the assembly accuracy of the reference objective lens 105 and the measuring objective lens 104 in the interferometric measurement is improved, the interference fringes can be quickly adjusted, and the efficiency and measurement accuracy of the interferometric measurement are improved.

[0071] In an embodiment of the present application, the first relative offset information can be zero, so that the first imaging position and the third imaging position coincide with each other, and when the second imaging position and the fourth imaging position also coincide with each other, it indicates that the optical axis of the reference objective lens 105 and the optical axis of the measuring objective lens 104 are symmetrical about the beam splitter 103, and the installation error between the two objective lenses can be corrected, and interference fringes can be quickly adjusted. Moreover, there is no need to calculate the relative offset information, so as to avoid errors in calculating the offset amount and the offset direction, which may affect the adjustment of the measuring objective lens 104 or the reference objective lens 105, and thus improve the assembly accuracy of the two objective lenses.

[0072] Specifically, S103 can be specifically as follows: when the first optical element 202, the measuring objective lens 104 and the reference objective lens 105 are located in the optical path, the first optical element 202 is configured to move in the axial direction (optical axis direction) until the light spot image at the third imaging position is clear, and it is determined that the focal plane of the first optical element coincides with the back focal plane of the measuring objective lens, thereby avoiding large errors in the relative offset information due to imaging blur, and improving the assembly accuracy of the reference objective lens 105 and the measuring objective lens 104.

[0073] In the direction of the optical axis, the first optical element 202 is moved forward and backward to change the imaging clarity of the light spot at the third imaging position. When the imaging clarity meets the requirement, the imaging is relatively clear. When the imaging clarity is the highest, the focal plane of the first optical element 202 coincides with the back focal plane of the measuring objective lens 104, and the calibration light emitted by the detection device 201 is focused on the focal plane of the first optical element 202, that is, the back focal plane of the measuring objective lens 104, through the first optical element 202, and then the light is changed into a parallel beam through the measuring objective lens 104.

[0074] Specifically, after the light spot at the third imaging position is clearly imaged, the first optical element 202 can be configured to move in a direction perpendicular to the optical axis until the third imaging position coincides with the first imaging position, and the measuring beam is determined to pass through the optical axis center of the measuring objective lens, at which time the first relative offset information is zero.

[0075] The first optical element 202 can be moved up and down or left and right in a plane perpendicular to the optical axis of the first optical element 202 so that the third imaging position coincides with the first imaging position, and the calibration light emitted by the detection device 201 is located at the center of the optical axis of the measuring objective lens 104. In this way, the addition of the measuring objective lens 104 has little effect on the imaging position of the measuring light path.

[0076] In the embodiment of the present application, after the third imaging position coincides with the first imaging position, the reference objective lens 105 can be configured to move in the axial direction when the first optical element 202, the measuring objective lens 104 and the reference objective lens 105 are located in the optical path until the light spot at the fourth imaging position is clearly imaged, and it is determined that the back focal planes of the measuring objective lens and the reference objective lens are symmetrical about the splitting plane of the beam splitter.

[0077] Specifically, in the reference optical path, the reference objective lens 105 is moved forward and backward along the optical axis direction, so that the imaging clarity of the second image in the second camera 206 is high, avoiding large errors in the second relative offset information due to imaging blur, and improving the assembly accuracy of the reference objective lens 105 and the measuring objective lens 104. When the imaging clarity is maximum, the back focal plane of the measuring objective lens 104 coincides with the back focal plane of the reference objective lens 105, and the consistency of the measuring objective lens 104 and the reference objective lens 105 can be maintained in the axial position.

[0078] In the embodiment of the present application, when the first relative offset information is zero and the second relative offset information is also zero, it can be indicated that the optical axis of the measuring objective lens 104 and the optical axis of the reference objective lens 105 are symmetrical about the beam splitter 103, and interference fringes can be quickly adjusted. At this time, in the optical path, the positions of the first optical element 202 and the measuring objective lens 104 have been determined, and the position of the reference objective lens 105 can be adjusted so that the fourth imaging position coincides with the second imaging position.

[0079] In an embodiment of the present application, after the light spot at the fourth imaging position is clearly imaged, the reference objective lens 105 can also be configured to move in a direction perpendicular to the optical axis until the fourth imaging position coincides with the second imaging position, thereby determining that the optical axes of the measuring objective lens and the reference objective lens are symmetrical about the beam splitter plane of the beam splitter.

[0080] Specifically, by moving the reference objective lens 105 up and down or left and right in a plane perpendicular to the optical axis of the third optical element 204, the fourth imaging position can be changed so that the fourth imaging position coincides with the second imaging position. In this way, the addition of the reference objective lens 105 has basically no effect on the imaging position of the reference light path.

[0081] In the embodiment of the present application, when the detection device 201 and the beam splitter 103 are included in the optical path, and the first optical element 202, the second optical element 203, the third optical element 204, the measuring objective lens 104, the reference objective lens 105, the first camera 205 and the second camera 206 are not located in the optical path, a first reflector can be added to the optical path to determine the installation position of the detection device 201. The first reflector is detachable, and after the position of the detection device 201 is determined, the first reflector can be moved out of the optical path.

[0082] In one possible implementation, before S101, the detection device 201 and / or the inclination of the measuring objective lens mounting position can be configured. For example, the measuring objective lens mounting position can be fixed and the inclination of the detection device 201 can be adjusted. The detection device 201 can also be fixed and the inclination of the measuring objective lens mounting position can be adjusted until the calibration light emitted by the detection device 201 is reflected by the first reflector through the beam splitter 103 and is imaged in the detection device 201. The imaging position is recorded as the fifth imaging position, so that the fifth imaging position coincides with the standard position.

[0083] Specifically, the first reflector is arranged at the measuring objective lens installation position, and the measuring objective lens installation position is used to install the measuring objective lens. The detection device 201 has a standard position inside, and the standard position is the spot imaging position of the calibration light emitted by the detection device 201 after returning along the original path in the detection device. If the reflector is not perpendicular to the calibration light emitted by the detection device 201, the calibration light deviates from the standard position after being reflected back. When the position of the measuring objective lens 104 is fixed, the measuring objective lens installation position is also fixed, and the inclination degree of the mirror surface of the first reflector is also fixed. The position of the detection device 201 can be adjusted according to the measuring objective lens installation position, so that the calibration light emitted by the detection device 201 is perpendicular to the plane where the measuring objective lens installation position is located, thereby determining the installation position of the detection device 201.

[0084] Specifically, the detection device 201 can emit a cross-shaped laser beam, which reaches a first reflector pre-set on the plane where the measuring objective lens 104 is located and is reflected. The reflected light forms a cross-shaped image in the detection device 201. When the imaging center coincides with the standard center, it means that the emitted laser is perpendicular to the plane where the measuring objective lens 104 is located.

[0085] In other possible implementations, the position of the detection device 201 may also be pre-set, such as being set at the position where the third camera is located, or may be determined by other methods, which are not specifically limited here.

[0086] In the embodiment of the present application, after the inclination of the detection device is configured, a measuring reflector 207 can be set in the measuring light path and a reference reflector 106 can be set in the reference light path, wherein the position of the measuring reflector 207 is fixed to the position of the object to be measured so as to quickly call out the interference fringes.

[0087] Specifically, the first reflector can be configured to be moved out of the optical path, and the inclination of the measuring reflector 207 can be adjusted until the sixth imaging position in the detecting device 201 coincides with the standard position after the calibration light emitted by the detecting device 201 is split by the beam splitter 103 to form a measuring beam which is reflected by the measuring reflector 207. By moving the first reflector out of the optical path and adding the measuring reflector 207 into the optical path, Figure 4 As shown, the inclination of the measuring reflector 207 is adjusted, so that the calibration light emitted by the detection device 201 is perpendicular to the plane where the measuring objective lens installation position is located, and also perpendicular to the mirror surface of the measuring reflector 207, so that the measuring objective lens installation position is parallel to the mirror surface of the measuring reflector 207, meeting the use requirements of using the measuring objective lens 104 to detect the object to be measured, and can call out interference fringes more quickly.

[0088] In an embodiment of the present application, the inclination of the reference reflector 106 can be adjusted until the calibration light emitted by the detection device 201 is split by the beam splitter 103 to form a reference beam which is reflected by the reference reflector 106, and the seventh imaging position in the detection device 201 coincides with the standard position, thereby making the reference reflector 106 perpendicular to the reference beam.

[0089] In an embodiment of the present application, for the reference optical path, a second reflector can be set at the reference objective lens mounting position so that the calibration light emitted by the detection device 201 is reflected, and the inclination of the second reflector is determined according to the position where the reflection enters the detection device 201, so that the inclination of the reference objective lens 105 is consistent with the inclination of the measurement objective lens 104, thereby correcting the installation error between the two objective lenses.

[0090] Specifically, after the inclination of the detection device 201 is configured, the inclination of the reference objective lens installation position is configured until the calibration light emitted by the detection device 201 passes through the beam splitter 103 and is reflected by the second reflector, and the eighth imaging position in the detection device coincides with the standard position, so that the calibration light emitted by the detection device 201 is perpendicular to both the reference objective lens installation position and the reference reflector 106, so that the reference reflector 106 is parallel to the reference objective lens installation position, so that interference fringes can be quickly called out. The reference objective lens installation position and the measurement objective lens installation position can also be made perpendicular, so that the inclination degrees of the two objective lenses can be consistent.

[0091] In the embodiment of the present application, after the reference objective lens and the measuring objective lens are adjusted, an interference fringe adjustment step can be performed, and other equipment can be installed to form an interference measurement device to perform interference measurement.

[0092] Specifically, the detection device 201, the first optical element 202, the second optical element 203, the third optical element 204, the first camera 205 and the second camera 206 are separated from the optical path, and the light source 101, the tube lens 109 and the third camera 107 are added to the optical path. The light source 101 and the third camera 107 can be configured on the same side optical path or on different sides of the beam splitter 103. The light source 101 is used to emit a light beam to the beam splitter 103, the third camera 107 is used for imaging, and the tube lens 109 is configured on the optical path between the third camera 107 and the beam splitter 103. The measuring reflector 207 or the object to be measured 110 is adjusted to the focal plane of the measuring objective lens 104, and the reference reflector 106 is adjusted to the focal plane of the reference objective lens 105, so that interference fringes appear in the third camera 107.

[0093] Specifically, the detection device 201, the first optical element 202, the second optical element 203, the third optical element 204, the first camera 205 and the second camera 206 can be moved out of the optical path, and the third camera 107 is added, and the position of the third camera 107 is the position of the detection device 201. The measuring reflector 207 and the reference reflector 106 are respectively adjusted to the focal planes of the measuring objective lens 104 and the reference objective lens 105, so that interference fringes appear in the third camera 107.

[0094] In the embodiment of the present application, the reference objective lens 105 can also be fine-tuned so that the width and the light-dark contrast of the interference fringes meet the requirements. Specifically, the interference adjustment step can include adjusting the reference objective lens 105 along the optical axis direction of the reference objective lens 105 so that the light-dark contrast of the interference fringes reaches a preset contrast, and adjusting the reference objective lens 105 in a plane perpendicular to the optical axis direction of the reference objective lens 105 so that the width of the interference fringes reaches a preset width.

[0095] An embodiment of the present application provides a calibration method, which is applied to a calibration system. When the first optical element, the measuring objective lens and the reference objective lens are configured to be out of the optical path, a first imaging position and a second imaging position are obtained; the first imaging position is the imaging position of the calibration mark in the first camera after passing through the beam splitter and the second optical element; the second imaging position is the imaging position of the calibration mark in the second camera after passing through the beam splitter and the third optical element; when the first optical element, the measuring objective lens and the reference objective lens are configured in the optical path, a third imaging position and a fourth imaging position are obtained; the third imaging position is the imaging position of the calibration mark in the first camera after passing through the first optical element, the beam splitter, the measuring objective lens and the second optical element; the fourth imaging position is the imaging position of the calibration mark in the second camera after passing through the first optical element, the beam splitter, the reference objective lens and the third optical element; according to the first relative offset information of the third imaging position relative to the first imaging position, and the second relative offset information of the fourth imaging position relative to the second imaging position, the reference objective lens and the measuring objective lens are adjusted so that the first relative offset information is consistent with the second relative offset information. By adding the first optical element, the second optical element and the third optical element, the position of the reference objective lens or the measuring objective lens can be calibrated, so that the relative position between the reference objective lens and the measuring objective lens is smaller, the installation error between the two objective lenses is corrected, and the assembly accuracy of the reference objective lens and the measuring objective lens in the interferometric measurement is improved. The interference fringes can be quickly adjusted, thereby improving the efficiency and measurement accuracy of the interferometric measurement.

[0096] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0097] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

Claims

1. A calibration system for calibrating the relative position of a measuring objective lens and a reference objective lens, characterized in that: include: A detection device, the detection device is used to generate a calibration light and a calibration mark; A beam splitter, the beam splitter being used to split the calibration light into a measurement light beam propagating toward a measurement light path where the measurement objective lens is located, and a reference light beam propagating toward a reference light path where the reference objective lens is located; A first optical element, disposed on an optical path between the detection device and the beam splitter, and used for focusing the calibration light; a second optical element and a first camera, the first camera being located at a focal plane of the second optical element, the second optical element and the measuring objective lens being used to acquire the measuring beam, and to image the calibration mark onto the first camera according to the measuring beam to form a first image; a third optical element and a second camera, wherein the second camera is located at a focal plane of the third optical element, and the third optical element and the reference objective lens are used to acquire the reference beam and image the calibration mark to the second camera according to the reference beam to form a second image; The first image and the second image are used to adjust the position of the reference objective lens and / or the measuring objective lens.

2. The system according to claim 1, characterized in that The optical axis of the reference objective lens and the optical axis of the measuring objective lens are symmetrical with respect to the beam splitting plane of the beam splitter.

3. The system according to claim 1, characterized in that If the first image and the second image are used to adjust the position of the reference objective lens, the focal plane of the first optical element coincides with the back focal plane of the measuring objective lens.

4. The system according to claim 1, characterized in that The objective lens calibration system also includes a measuring objective lens mounting position and a first reflector. When the first optical element, the second optical element, the measuring objective lens and the first camera are configured to be out of the optical path, the first reflector is configured at the measuring objective lens mounting position to verify the inclination of the measuring objective lens mounting position relative to the optical axis of the detection device by reflecting the measuring light beam.

5. The system according to claim 1, characterized in that The objective lens calibration system also includes a reference objective lens mounting position and a second reflector. When the first optical element, the third optical element, the reference objective lens and the second camera are configured to be out of the optical path, the second reflector is configured at the reference objective lens mounting position to verify the inclination of the reference objective lens mounting position relative to the optical axis of the detection device by reflecting the reference light beam.

6. The system according to claim 1, characterized in that The objective lens calibration system also includes a measuring reflector and a reference reflector; the measuring reflector is arranged in the measuring optical path, and is used to vertically reflect the measuring beam at least when the first camera is out of the optical path; the reference reflector is arranged in the reference optical path, and is used to vertically reflect the reference beam at least when the second camera is out of the optical path.

7. The system according to claim 1, characterized in that The first optical element, the second optical element, and the third optical element are all configured as lenses or lens barrels.

8. The system according to claim 1, characterized in that The first image and the second image are used to adjust the tilt, eccentric displacement and axial displacement of the reference objective lens and / or the measuring objective lens; The tilt amount is the inclination of the radial plane of the reference objective lens and / or the measuring objective lens relative to the preset axis detection device, the eccentric displacement amount is the radial movement of the optical axis center of the reference objective lens and / or the measuring objective lens relative to the preset axis detection device, and the axial displacement amount is the axial movement of the optical axis center of the reference objective lens and / or the measuring objective lens on the preset axis; The preset axis is a direction line of the measuring beam or a direction line of the reference beam.

9. A calibration method, characterized in that: The calibration system according to any one of claims 1 to 8 comprises: When the first optical element, the measuring objective lens and the reference objective lens are configured to be out of the optical path, a first imaging position and a second imaging position are acquired; the first imaging position is an imaging position of the calibration mark in the first camera after passing through the beam splitter and the second optical element; the second imaging position is an imaging position of the calibration mark in the second camera after passing through the beam splitter and the third optical element; When the first optical element, the measuring objective lens and the reference objective lens are arranged in the optical path, a third imaging position and a fourth imaging position are acquired; the third imaging position is an imaging position of the calibration mark in the first camera after the calibration mark passes through the first optical element, the beam splitter, the measuring objective lens and the second optical element; the fourth imaging position is an imaging position of the calibration mark in the second camera after the calibration mark passes through the first optical element, the beam splitter, the reference objective lens and the third optical element; According to first relative offset information of the third imaging position relative to the first imaging position, and second relative offset information of the fourth imaging position relative to the second imaging position, the reference objective lens and the measuring objective lens are adjusted so that the first relative offset information is consistent with the second relative offset information.

10. The method according to claim 9, characterized in that The adjusting the reference objective lens or the measuring objective lens according to the first relative offset information of the third imaging position relative to the first imaging position and the second relative offset information of the fourth imaging position relative to the second imaging position so that the first relative offset information is consistent with the second relative offset information comprises: When the first optical element, the measuring objective lens and the reference objective lens are located in the optical path, the first optical element is configured to move in the axial direction until the light spot at the third imaging position is clearly imaged, and it is determined that the focal plane of the first optical element coincides with the back focal plane of the measuring objective lens.

11. The method according to claim 10, characterized in that After the light spot imaging at the third imaging position is clear, the following steps are also included: The first optical element is configured to move in a direction perpendicular to the optical axis until the third imaging position coincides with the first imaging position, and it is determined that the measuring light beam passes through the optical axis center of the measuring objective lens.

12. The method according to claim 11, characterized in that After the third imaging position coincides with the first imaging position, the method further comprises: When the first optical element, the measuring objective lens and the reference objective lens are located in the optical path, the reference objective lens is configured to move in the axial direction until the light spot image at the fourth imaging position is clear, and the back focal planes of the measuring objective lens and the reference objective lens are determined to be symmetrical about the beam splitting plane of the beam splitter.

13. The method according to claim 12, characterized in that After the light spot image at the fourth imaging position is clear, the method further includes: The reference objective lens is configured to move in a direction perpendicular to the optical axis until the fourth imaging position coincides with the second imaging position, and the optical axes of the measuring objective lens and the reference objective lens are determined to be symmetric about the beam splitting plane of the beam splitter.

14. The method according to any one of claims 9 to 13, characterized in that: When the first optical element, the measuring objective lens, and the reference objective lens are configured to be out of the optical path, before acquiring the first imaging position and the second imaging position, the method further includes: The detection device and / or the inclination of the measuring objective lens mounting position are configured until the calibration light emitted by the detection device passes through the beam splitter and is reflected by the first reflector, and the fifth imaging position in the detection device coincides with the standard position; the first reflector is arranged at the measuring objective lens mounting position; the standard position is the spot imaging position of the calibration light emitted by the detection device after returning along the original path in the detection device.

15. The method according to claim 14, characterized in that After configuring the inclination of the detection device, the method further includes: The first reflector is configured to be moved out of the optical path, and a measuring reflector and a reference reflector are respectively provided in the measuring optical path and the reference optical path; Adjusting the inclination of the measuring reflector until the sixth imaging position in the detection device coincides with the standard position after the calibration light emitted by the detection device is split by the beam splitter to form a measuring light beam which is reflected by the measuring reflector; The inclination of the reference reflector is adjusted until the seventh imaging position in the detection device coincides with the standard position after the reference beam formed by the calibration light emitted by the detection device is split by the beam splitter and is reflected by the reference reflector.

16. The method according to claim 15, characterized in that After configuring the inclination of the detection device, the method further includes: The inclination of the reference objective lens mounting position is configured until the calibration light emitted by the detection device passes through the beam splitter and is reflected by the second reflector, and the eighth imaging position in the detection device coincides with the standard position; the second reflector is arranged at the reference objective lens mounting position.

17. The method according to any one of claims 9 to 13, characterized in that: After the reference objective lens and the measuring objective lens are adjusted, the method further comprises an interference fringe adjustment step, wherein the interference fringe adjustment step comprises: The detection device, the first optical element, the second optical element, the third optical element, the first camera and the second camera are configured to be separated from the optical path, and the light source, the tube lens and the third camera are configured to be added to the optical path, the light source and the third camera are configured on the same side optical path or on different sides optical paths of the beam splitter, the light source is used to emit a light beam to the beam splitter, the third camera is used for imaging, and the tube lens is configured on the optical path between the third camera and the beam splitter; The measuring reflector is adjusted to the focal plane of the measuring objective lens, and the reference reflector is adjusted to the focal plane of the reference objective lens, so that interference fringes appear in the third camera.

18. The method according to claim 17, characterized in that The interference fringe adjustment step comprises: Adjusting the reference objective lens along the optical axis direction of the reference objective lens so that the light-dark contrast of the interference fringes reaches a preset contrast; The reference objective lens is adjusted in a plane perpendicular to the optical axis direction of the reference objective lens so that the width of the interference fringes reaches a preset width.

Images