High-precision guide rail angle swing error measuring device and measuring method based on pen type interference principle

Abstract

The invention discloses a high-precision guide rail angle swing error measuring device and method based on a pen type interference principle, and relates to the technical field of ultra-precision machining and detection. The beam splitter prism is arranged in front of the monochromatic laser, the linear polarizer is arranged between the beam splitter prism and the monochromatic laser, the two cube-corner prisms are arranged on a reflection light path and a transmission light path of the beam splitter prism, the half-wave plate is arranged on an emergent light path of the beam splitter prism, the polarizing beam splitter is arranged behind a light path of the half-wave plate, and the quarter-wave plates are arranged on the reflection light path and the transmission light path of the polarizing beam splitter respectively. One light path is selected as a laser emergent window direction to arrange the plane optical flat, the reference mirror is arranged on the other light path, the Fourier lens is arranged on an emergent light path of the polarizing beam splitter, and the photoelectric detector is arranged on a focal plane. The angle swing error of the guide rail can be measured in real time in place, the measurement resolution not lower than 5 arc seconds and the RMS repeated measurement precision of 10 nm are achieved, the overall structure is simple, and installation, adjustment and maintenance are convenient.

Description

Technical Field

[0001] This invention relates to the field of ultra-precision machining and testing technology, specifically a high-precision guide rail angular pendulum error measuring device and method based on the pen-type interference principle. Background Technology

[0002] In the fields of precision machining and high-end equipment manufacturing, high-precision linear guides serve as the core motion reference for high-end equipment such as precision machine tools, lithography machines, and coordinate measuring machines. Their angular pendulum errors (roll angle error around the X-axis and pitch angle error around the Y-axis) directly determine the positioning accuracy and machining / measurement accuracy of the equipment. Especially in fields such as semiconductor manufacturing and aerospace component processing, arc-second-level angular pendulum errors can accumulate during the processing, leading to micron-level terminal errors. Therefore, high-precision measurement of angular pendulum errors has become a key link in equipment manufacturing and maintenance.

[0003] Currently, the mainstream methods for measuring the error of guide rail angular pendulum are mainly divided into two categories: contact measurement and non-contact measurement. However, both of them have technical bottlenecks that make it difficult to balance measurement accuracy, environmental adaptability, real-time performance, and cost.

[0004] Contact-type measuring devices, such as levels and electronic levels, indirectly calculate the guide rail angular pendulum error by detecting the angle between the direction of gravity and the device's reference plane. This method suffers from two major problems: First, being an indirect measurement method, it requires a secondary derivation of the angular pendulum error from the guide rail straightness data, which easily introduces accumulated errors during the conversion process, resulting in low slope error resolution. Second, the measuring head is in direct contact with the guide rail surface, which not only easily causes scratches but is also significantly affected by the surface roughness and oil contamination, limiting repeatability accuracy to only 50 nm RMS or higher, making stable measurement difficult. Furthermore, contact-type measurements require shutdown, failing to meet the real-time monitoring needs of in-situ equipment maintenance.

[0005] The measurement of angular pendulum error based on laser interferometers often adopts the "straightness-angular pendulum conversion" mode. This involves collecting straightness data of the guide rail using two laser interferometer probes spaced at intervals, and then calculating the angular pendulum error based on the probe spacing. This method has three limitations: First, the indirect nature of the measurement results in a long error propagation chain, making it difficult to meet arc-second level accuracy requirements due to probe spacing calibration errors and laser beam collimation errors. Second, the rigid connection between the measurement frame and the machine tool under test means that machine tool vibration and temperature deformation are directly transmitted to the measurement reference, leading to reference drift and poor stability. Third, data processing requires complex difference calculations and error compensation, demanding high processor performance and requiring a dedicated laboratory environment with constant temperature, humidity, and vibration isolation, making it unsuitable for in-situ measurement scenarios in ordinary industrial settings.

[0006] Measurement systems employing self-collimators and laser collimators use a far-field laser beam as a reference, calculating the angular pendulum error by receiving signals through a reflector. However, the reference stability of such devices depends on an external optical platform. If the reference component and the measurement device are integrated and mounted on the same frame, they are susceptible to frame deformation. If an external independent reference is used, a complex calibration process is required, and the device structure includes multiple sets of reflectors and lens adjustment components, making assembly and adjustment difficult and requiring several hours for a single maintenance, resulting in high operation and maintenance costs. Furthermore, its measurement resolution is limited by the pixel accuracy of the photodetector, making it difficult to meet the requirements of high-precision measurement.

[0007] In summary, existing guide rail angular pendulum error measurement technologies suffer from problems such as lack of direct measurement, poor reference stability, weak environmental adaptability, complex structure, and high cost. They cannot meet the in-situ measurement requirements of precision equipment, which demand "high precision, real-time performance, low cost, and easy maintenance." Therefore, it is urgent to develop a high-precision guide rail angular pendulum error measurement device that can overcome the above bottlenecks. Summary of the Invention

[0008] To address the shortcomings of the prior art, this invention provides a high-precision guide rail angular pendulum error measuring device and method based on the pen-type interference principle. It can measure the angular pendulum error of the guide rail in real time, achieving a measurement resolution of no less than 5 arcseconds and an RMS repeatability of 10nm. The overall structure is simple and easy to assemble, adjust and maintain.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A high-precision guide rail angle pendulum error measurement device based on the pen-type interference principle includes a reference flat crystal module and a laser emission module, a dual beam generation module, an interference optical path module, and an imaging module arranged with the central propagation axis of the pen-type interference optical path as the optical axis.

[0011] The laser emission module includes a two-dimensional laser attitude adjustment frame and a monochromatic laser mounted thereon; the dual-beam generation module includes a linear polarizer, a beam splitter, a half-wave plate, and two cornerstone prisms. The beam splitter is arranged in front of the monochromatic laser along the optical axis, with the linear polarizer positioned between them. The two cornerstone prisms are supported by the two-dimensional displacement adjustment frame and are respectively positioned on the reflected and transmitted light paths of the beam splitter. The half-wave plate is positioned on the emitted light path of the beam splitter. The interference optical path module includes a polarizing beam splitter, a reference mirror, a Fourier lens, and two quarter-wave plates. A reference mirror is positioned behind the half-wave plate optical path. A quarter-wave plate is positioned on both the reflected and transmitted optical paths of the polarizing beam splitter, and one optical path is selected as the laser emission window. The reference mirror is supported by a reference mirror three-dimensional pose adjustment frame and positioned on the remaining optical path of the polarizing beam splitter. The Fourier lens is positioned on the emission optical path of the polarizing beam splitter. The imaging module uses a photodetector, which is positioned behind the Fourier lens optical path and located on the focal plane of the Fourier lens. The reference flat crystal module uses a planar flat crystal, which is positioned in the direction of the laser emission window.

[0012] Furthermore, the laser emitting module, dual-beam generating module, interference optical path module, and imaging module are all integrated and mounted on the surface of the mounting panel, and the surface of the mounting panel is configured with positioning holes adapted to the positions of each module.

[0013] Furthermore, the monochromatic laser is an experimental-grade monochromatic laser or a combination of laser, fiber, and collimator.

[0014] Furthermore, the two cornerstone prisms can be radially adjusted by their respective two-dimensional displacement adjustment frames to change the displacement of their central axes relative to the reflected or transmitted optical axes of the beam splitter.

[0015] A high-precision method for measuring the error of a guide rail angular pendulum based on the pen-type interferometry principle includes the following steps:

[0016] First, a test platform was built. The laser emission module, dual-beam generation module, interference optical path module, and imaging module were mounted on the slide of the guide rail machine tool. The reference flat crystal module was mounted on the surface of the guide rail machine tool adjacent to the slide, with the flat crystal parallel to the direction of movement of the guide rail. Then, the following measurements were taken:

[0017] S1. The monochromatic laser emits laser light, and the laser two-dimensional attitude adjustment frame adjusts the beam emission direction so that the beam emission direction coincides with the optical axis, and then enters the dual beam generation module.

[0018] S2. In the dual-beam generation module, the beam is formed into two laser beams by a linear polarizer and a beam splitter. The two laser beams are reflected back along the original direction by two corner prisms, and then transmitted and reflected by the beam splitter to form two parallel beams. The two parallel beams are transmitted into the interference optical path module by a half-wave plate.

[0019] In the S3 interference optical path module, two parallel beams are transmitted and reflected by a polarizing beam splitter to form a set of transmitted double beams and a set of reflected double beams, which ultimately form two focused spots on the photodetector. The reference mirror corresponds to the reference focused spot, and the flat crystal corresponds to the measurement focused spot.

[0020] S4. After obtaining the distance between the two focused light spots on the photodetector, the tilt angle of the flat crystal can be obtained based on the pen interference principle. This tilt angle is the angular pendulum error of the guide rail.

[0021] Furthermore, in step S4, if the reference focused spot is not located at the focal point, the tilt angle is the relative angular swing error of the guide rail relative to the initial measured position; if the reference mirror three-dimensional pose adjustment frame is adjusted so that the reference focused spot is located at the focal point, with the optical axis as the reference, the tilt angle is the absolute angular swing error of the guide rail.

[0022] Furthermore, the distance between the two focused light spots is calculated as follows:

[0023]

[0024] That is:

[0025]

[0026] In the formula, This indicates the distance between the reference focused spot and the measurement focused spot. and These represent the absolute tilt angles of the reference mirror and the measured surface relative to the optical axis normal plane, respectively. This indicates the yaw angle of the guide rail, i.e., the angular yaw error. This indicates the focal length of the Fourier lens.

[0027] Furthermore, the linear polarizer and half-wave plate can be rotated to adjust the intensity distribution of the reference beam and the measurement beam, and combined with the polarizing beam splitter, they can form an optical isolator to reduce the influence of stray light in the system.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention directly measures the guide rail angular pendulum error based on the pen-type interference principle, with high slope error resolution, low data processing requirements, and can achieve in-situ real-time measurement in ordinary industrial environments. The planar flat crystal is independently installed on the guide rail machine tool, and an independent measurement frame is adopted to improve measurement accuracy and stability. It can achieve a measurement resolution of not less than 5 arcseconds and an RMS repeatability of 10nm. The overall structure is simple, easy to assemble, adjust and maintain, and helps to control costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the measuring device of the present invention;

[0030] Figure 2 This is a schematic diagram of the optical path of the measuring device of the present invention;

[0031] Figure 3 This is a schematic diagram illustrating the application of the measuring device of the present invention on a guide rail machine tool.

[0032] In the diagram: 1. Mounting panel; 2. Monochromatic laser; 3. Laser 2D attitude adjustment frame; 4. Linear polarizer; 5. Beam splitter; 6. Pyramidal prism I; 7. 2D displacement adjustment frame I; 8. Pyramidal prism II; 9. 2D displacement adjustment frame II; 10. Half-wave plate; 11. Polarizing beam splitter; 12. Quarter-wave plate I; 13. Quarter-wave plate II; 14. Reference mirror; 15. Reference mirror 3D pose adjustment frame; 16. Planar optical disc; 17. Optical disc mounting frame; 18. Fourier lens; 19. Photodetector; 20. Slide table; 21. Guide rail; 22. Guide rail machine tool. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] This invention provides a high-precision guide rail angular pendulum error measurement device. Its optical axis, centered on the central propagation axis of the pen-type interference optical path, serves as the optical reference axis passing through the laser emission module, dual-beam generation module, interference optical path module, reference flat module, and imaging module. Essentially, it acts as the central reference for the optical path, enabling stable output of the interference signal between the measurement beam and the reference beam. It allows for real-time measurement of the guide rail angular pendulum error, achieving a measurement resolution of at least 5 arcseconds and an RMS repeatability accuracy of 10 nm (1 mm lateral resolution). The overall structure is simple, easy to assemble, adjust, and maintain. The specific solution is described below:

[0035] like Figures 1-3 As shown, a high-precision guide rail angular pendulum error measurement device based on the pen-type interference principle includes a mounting panel 1, a monochromatic laser 2, a laser two-dimensional attitude adjustment frame 3, a linear polarizer 4, a beam splitter 5, a corner bevel prism 6, a two-dimensional displacement adjustment frame 7, a corner bevel prism 8, a two-dimensional displacement adjustment frame 9, a half-wave plate 10, a polarizing beam splitter (PBS) 11, a quarter-wave plate 12, a quarter-wave plate 13, a reference mirror 14, a reference mirror three-dimensional pose adjustment frame 15, a planar flat crystal 16, a flat crystal mounting frame 17, a Fourier lens 18, and a photodetector 19.

[0036] The structural components of the measuring device are combined Figure 1 As shown, specifically:

[0037] The mounting panel 1 is used to integrate and load the laser emission module, the dual beam generation module, the interference optical path module and the imaging module. The surface of the mounting panel 1 is provided with positioning holes that are adapted to the positions of each module to facilitate assembly.

[0038] The laser emitting module includes a monochromatic laser 2 and a laser two-dimensional attitude adjustment frame 3. The monochromatic laser 2 is a conventional experimental-grade monochromatic laser, or a combination structure of laser, optical fiber and collimator can be used. The laser two-dimensional attitude adjustment frame 3 carries the monochromatic laser 2 to achieve attitude adjustment.

[0039] The dual-beam generation module includes a linear polarizer 4, a beam splitter 5, a first cornerstone prism 6, a first two-dimensional displacement adjustment frame 7, a second cornerstone prism 8, a second two-dimensional displacement adjustment frame 9, and a half-wave plate 10. The beam splitter 5 is arranged in front of the monochromatic laser 2 along the optical axis. The linear polarizer 4 is arranged between the beam splitter 5 and the monochromatic laser 2. The first cornerstone prism 6 and the second cornerstone prism 8 are respectively arranged in the reflected and transmitted optical paths of the beam splitter 5. The first two-dimensional displacement adjustment frame 7 and the second two-dimensional displacement adjustment frame 9 respectively support the first cornerstone prism 6 and the second cornerstone prism 8, and are used to adjust the displacement of their central axes relative to the reflected and transmitted optical axes. The half-wave plate 10 is arranged on the other side of the beam splitter 5 opposite to the first cornerstone prism 6.

[0040] The interference optical path module includes a polarizing beam splitter 11, a first quarter-wave plate 12, a second quarter-wave plate 13, a reference mirror 14, a three-dimensional pose adjustment frame 15 for the reference mirror, and a Fourier lens 18. The polarizing beam splitter 11 is positioned behind the optical path of the half-wave plate 10. One of the reflected and transmitted optical paths of the polarizing beam splitter 11 is selected as the laser emission window and subsequently engages with the planar flat crystal 16. The first quarter-wave plate 12 is positioned along this optical path. The reference mirror 14 is positioned along the remaining optical path of the polarizing beam splitter 11. The three-dimensional pose adjustment frame 15 supports the reference mirror 14 to achieve attitude adjustment to compensate for environmental interference in the optical path. The second quarter-wave plate 13 is positioned between the polarizing beam splitter 11 and the reference mirror 14. The Fourier lens 18 is positioned along the emission optical path of the polarizing beam splitter 11.

[0041] The imaging module includes a photodetector 19, which is arranged behind the optical path of the Fourier lens 18. The photodetector 19 is arranged in parallel with the monochromatic laser 2 and is located on the focal plane of the Fourier lens 18.

[0042] The reference flat crystal module includes a flat crystal 16 and a flat crystal mounting bracket 17. The flat crystal 16 is arranged adjacent to the mounting panel 1 in the direction of the laser emission window, and the flat crystal mounting bracket 17 is used for the installation and positioning of the flat crystal 16.

[0043] The optical path of the measuring device is combined with Figure 2 As shown, specifically:

[0044] The laser emission module emits laser light through a monochromatic laser 2. Simultaneously, the laser two-dimensional attitude adjustment frame 3 adjusts the beam's emission direction to align with the optical axis before it enters the dual-beam generation module. In the dual-beam generation module, the beam passes through a linear polarizer 4 and is reflected and transmitted by a beam splitter 5, forming two laser beams. These two beams are reflected back along their original directions by a first corner prism 6 and a second corner prism 8, respectively. They are then transmitted and reflected again by the beam splitter 5 to form two parallel beams. (The distance between the two parallel beams is determined by the radial displacement of corner prisms 6 and 8 adjusted by two-dimensional displacement adjustment frames 7 and 9. This can be considered as mirroring corner prism 6 along the beam splitter 5 onto the space containing corner prism 8. Twice the distance between their central axes is the distance between the two parallel beams, which is the lateral resolution of the measuring device. This lateral resolution determines the spatial frequency band to which the angular pendulum error measured by the measuring device belongs.) The two parallel beams are transmitted through a half-wave plate 10 into the interference optical path module. Two parallel beams of light pass through the interference optical path module, and after being transmitted and reflected by the polarizing beam splitter 11, they form a set of transmitted double beams and a set of reflected double beams (the double beams of the transmitted double beams and the reflected double beams are parallel). Taking the reflected optical path of the polarizing beam splitter 11 as the laser emission window as an example, the reflected double beam of the polarizing beam splitter 11 is transmitted through the quarter-wave plate 12, reflected by the flat crystal 16, and then transmitted back through the quarter-wave plate 12, the polarizing beam splitter 11, and the Fourier lens 18 before forming a measurement focused spot on the photodetector 19. The transmitted double beam of the polarizing beam splitter 11 is transmitted through the quarter-wave plate 13, reflected by the reference mirror 14, and then transmitted back through the quarter-wave plate 13, the polarizing beam splitter 11, and the Fourier lens 18 before forming a reference focused spot on the photodetector 19.

[0045] Among them, the linear polarizer 4 and the half-wave plate 10 can be rotated to adjust the intensity distribution of the reference beam and the measurement beam, and can be combined with the polarizing beam splitter 11 to form an optical isolator to reduce the influence of stray light in the system.

[0046] The application of this measuring device in guideway machine tools combines... Figure 3 As shown, specifically:

[0047] The laser emission module, dual-beam generation module, interference optical path module and imaging module integrated on the mounting panel 1 and its surface are fixedly mounted on the slide table 20 of the guide rail machine tool 22. The planar flat crystal 16 of the reference flat crystal module is fixedly mounted on the surface of the guide rail machine tool 22 adjacent to the slide table 20 through the flat crystal mounting bracket 17, so that the planar flat crystal 16 is parallel to the movement direction of the guide rail 21 and located in the direction of the laser emission window of the interference optical path module.

[0048] The method for measuring the guide rail 21 by setting up the testing platform of the measuring device and the guide rail machine tool 22 of the present invention includes the following steps:

[0049] S1. The monochromatic laser 2 emits laser light, and the laser two-dimensional attitude adjustment frame 3 adjusts the beam emission direction so that the beam emission direction coincides with the optical axis and enters the dual beam generation module.

[0050] S2. In the dual-beam generation module, the beam is formed into two laser beams by the linear polarizer 4 and the beam splitter 5. The two laser beams are reflected back along the original direction by the first corner prism 6 and the second corner prism 8 respectively. They are then transmitted and reflected by the beam splitter 5 to form two parallel beams. The two parallel beams are transmitted into the interference optical path module by the half-wave plate 10.

[0051] S3. In the interference optical path module, two parallel beams are transmitted and reflected by the polarizing beam splitter 11 to form a set of transmitted double beams and a set of reflected double beams, which finally form two focused spots on the photodetector 19. Among them, the reference mirror 14 corresponds to the reference focused spot, and the flat crystal 16 corresponds to the measurement focused spot.

[0052] S4. After obtaining the distance between the two focused spots on the photodetector 19, the tilt angle of the planar flat crystal 16 can be obtained based on the pen interference principle. This tilt angle is the angular swing error of the guide rail 21. If the reference focused spot is not located at the focal point, the tilt angle is the relative angular swing error of the guide rail 21 relative to the initial measured position. If the reference mirror three-dimensional pose adjustment frame 15 is adjusted so that the reference focused spot is located at the focal point, with the optical axis as the reference, the tilt angle is the absolute angular swing error of the guide rail 21.

[0053] The distance between the two focused light spots can be calculated as follows:

[0054]

[0055] That is:

[0056]

[0057] In the formula, This indicates the distance between the reference focused spot and the measurement focused spot. and These represent the absolute tilt angles of the reference mirror and the measured surface relative to the optical axis normal plane, respectively. This indicates the yaw angle of the guide rail, i.e., the angular yaw error. This indicates the focal length of the Fourier lens.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-precision guide rail angular pendulum error measuring device based on the pen-type interference principle, characterized in that: It includes a reference flat crystal module and a laser emission module, a dual beam generation module, an interference optical path module, and an imaging module arranged with the central propagation axis of the pencil interference optical path as the optical axis; The laser emission module includes a two-dimensional laser attitude adjustment frame and a monochromatic laser mounted thereon; the dual-beam generation module includes a linear polarizer, a beam splitter, a half-wave plate, and two cornerstone prisms. The beam splitter is arranged in front of the monochromatic laser along the optical axis, with the linear polarizer positioned between them. The two cornerstone prisms are supported by the two-dimensional displacement adjustment frame and are respectively positioned on the reflected and transmitted light paths of the beam splitter. The half-wave plate is positioned on the emitted light path of the beam splitter. The interference optical path module includes a polarizing beam splitter, a reference mirror, a Fourier lens, and two quarter-wave plates. A reference mirror is positioned behind the half-wave plate optical path. A quarter-wave plate is positioned on both the reflected and transmitted optical paths of the polarizing beam splitter, and one optical path is selected as the laser emission window. The reference mirror is supported by a reference mirror three-dimensional pose adjustment frame and positioned on the remaining optical path of the polarizing beam splitter. The Fourier lens is positioned on the emission optical path of the polarizing beam splitter. The imaging module uses a photodetector, which is positioned behind the Fourier lens optical path and located on the focal plane of the Fourier lens. The reference flat crystal module uses a planar flat crystal, which is positioned in the direction of the laser emission window.

2. The high-precision guide rail angular pendulum error measuring device based on the pen-type interference principle according to claim 1, characterized in that: The laser emitting module, dual-beam generating module, interference optical path module, and imaging module are all integrated and mounted on the surface of the mounting panel, which is equipped with positioning holes adapted to the positions of each module.

3. The high-precision guide rail angular pendulum error measuring device based on the pen-type interference principle according to claim 1, characterized in that: The monochromatic laser is an experimental-grade monochromatic laser or a combination of laser, fiber, and collimator.

4. The high-precision guide rail angular pendulum error measuring device based on the pen-type interference principle according to claim 1, characterized in that: The two corner prisms can be radially adjusted using their respective two-dimensional displacement adjustment frames, so that their central axes are displaced relative to the reflected or transmitted optical axes of the beam splitter.

5. A high-precision method for measuring the error of a guide rail angular pendulum based on the pen-type interference principle, characterized in that: The measuring device according to claim 1, wherein the measuring method comprises the following steps: First, a test platform was built. The laser emission module, dual-beam generation module, interference optical path module, and imaging module were mounted on the slide of the guide rail machine tool. The reference flat crystal module was mounted on the surface of the guide rail machine tool adjacent to the slide, with the flat crystal parallel to the direction of movement of the guide rail. Then, the following measurements were taken: S1. The monochromatic laser emits laser light, and the laser two-dimensional attitude adjustment frame adjusts the beam emission direction so that the beam emission direction coincides with the optical axis, and then enters the dual beam generation module. S2. In the dual-beam generation module, the beam is formed into two laser beams by a linear polarizer and a beam splitter. The two laser beams are reflected back along the original direction by two corner prisms, and then transmitted and reflected by the beam splitter to form two parallel beams. The two parallel beams are transmitted into the interference optical path module by a half-wave plate. In the S3 interference optical path module, two parallel beams are transmitted and reflected by a polarizing beam splitter to form a set of transmitted double beams and a set of reflected double beams, which ultimately form two focused spots on the photodetector. The reference mirror corresponds to the reference focused spot, and the flat crystal corresponds to the measurement focused spot. S4. After obtaining the distance between the two focused light spots on the photodetector, the tilt angle of the flat crystal can be obtained based on the pen interference principle. This tilt angle is the angular pendulum error of the guide rail.

6. The high-precision guide rail angular pendulum error measurement method based on the pen-type interference principle according to claim 5, characterized in that: In step S4, if the reference focused spot is not located at the focal point, the tilt angle is the relative angular swing error of the guide rail relative to the initial measured position; if the reference mirror three-dimensional pose adjustment frame is adjusted so that the reference focused spot is located at the focal point, with the optical axis as the reference, the tilt angle is the absolute angular swing error of the guide rail.

7. The high-precision guide rail angular pendulum error measurement method based on the pen-type interference principle according to claim 5, characterized in that: The distance between the two focused light spots is calculated as follows: That is: In the formula, This indicates the distance between the reference focused spot and the measurement focused spot. and These represent the absolute tilt angles of the reference mirror and the measured surface relative to the optical axis normal plane, respectively. This indicates the yaw angle of the guide rail, i.e., the angular yaw error. This indicates the focal length of the Fourier lens.

8. The high-precision guide rail angular pendulum error measurement method based on the pen-type interference principle according to claim 5, characterized in that: The linear polarizer and half-wave plate can be rotated to adjust the intensity distribution of the reference beam and the measurement beam. Combined with a polarizing beam splitter, they can form an optical isolator to reduce the influence of stray light in the system.

Images