A biaxial zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection

Abstract

A dual-axis zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection belongs to the field of optical measurement technology. It addresses the problem of developing a compact and easily integrated dual-axis zero-difference laser interferometer. This invention includes a single-frequency laser source, an interferometer group, a first measuring mirror, a second measuring mirror, and a signal processing board. The interferometer group includes a polarizing beam splitter, a first quarter-wave plate, a first reference mirror, a second quarter-wave plate, a second reference mirror, a first photodetector, a first pyramidal prism, a third quarter-wave plate, a second photodetector, a second pyramidal prism, a fourth quarter-wave plate, and a fifth quarter-wave plate. This invention enables synchronous and dynamic measurement of target displacement and angle. The dual-axis measurement results are based on the same wavelength reference and are highly consistent with the effects of laser frequency and power fluctuations, exhibiting better reliability and consistency.

Description

Technical Field

[0001] This invention belongs to the field of optical measurement technology, specifically relating to a biaxial zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection. Background Technology

[0002] Zero-difference laser interferometers, as core tools for nanometer and sub-nanometer precision displacement measurement, are widely used in key fields such as high-end equipment manufacturing, ultra-precision metrology, integrated circuit lithography machines, and precision positioning platform calibration. With technological advancements, the requirements for measurement systems are increasingly stringent: on the one hand, the trend towards miniaturization and integration of equipment demands that the measuring head structure be as compact as possible to adapt to limited space layouts; on the other hand, many application scenarios (such as multi-degree-of-freedom error measurement of workpiece stages and distance calibration of displacement stages) place higher demands on the measurement of target motion posture, requiring not only higher precision displacement detection but also urgent measurement of angle deflection during motion.

[0003] To achieve displacement and angle measurement of a motion stage, one common method is step-by-step measurement. Taking the Renishaw XL80 interferometer and the Zhongtu Instruments SJ6800 interferometer as examples, high-precision displacement and angle measurements can be performed separately by changing different optical components. However, this method typically only supports static testing, requiring point-by-point measurement of the stage error, which significantly limits its application in dynamic continuous measurement.

[0004] Another approach is to combine two independent single-axis interferometers to achieve simultaneous displacement and angle measurements. For example, Renishaw's RLE laser ruler uses a dedicated measuring bracket to mount two RLD10 transmitters, forming a dual-axis structure that can calculate angle information while acquiring displacement data along both axes. While this combination offers flexibility and adjustability, it also results in a large system size, complex assembly and adjustment, and high cost. In particular, beam parallelism and spacing are highly dependent on the assembly accuracy of the transmitters and brackets, often requiring subsequent calibration, making long-term stability and measurement accuracy difficult to guarantee. A major improvement involves using optical elements such as beam splitters and waveplates to split the same input beam, forming dual measuring axes, and then cementing the mirror assembly together. While this method reduces measurement scalability somewhat, it effectively improves the overall stability of the system.

[0005] Currently, the most mature commercially available biaxial interferometer is SIOS's SP 5000 DS. Its mirror assembly design is a trade secret, and detailed information is not publicly available. In relevant literature, such as the common biaxial interferometer (Ellis J D. Field guide to displacement measuring interferometry[M]. Online-Ausg. Bellingham, Washington: SPIE Press, 2014: 60-65.) and the dual-beam interferometer proposed by Sun Yat-sen University (Yan H, Mao Q, Xie S, et al. Highly linear sub-nanoradian tilt measurement based on dual-beam interferometry[J]. Optics Letters, 2020, 45(10): 2792-2795.), although the integrated mirror assembly ensures stability and accuracy, the multiple beam splitters often result in a large mirror assembly size, which is not conducive to the miniaturization and integration of the measuring head.

[0006] In summary, biaxial zero-difference interferometers are in high demand for measurement and calibration in high-end equipment manufacturing due to their advantages such as simultaneous displacement and angle measurement and real-time error calibration. However, given the limitations of step-by-step measurement (inability to perform simultaneous and dynamic measurements), the instability and accuracy issues of beam parallelism and spacing in combined measurements, and the often bulky nature of integrated structures, there is an urgent need to research and design a biaxial zero-difference laser interferometer that is highly stable, has a small number of beam splitters, a compact structure, and is easy to integrate and assemble. Summary of the Invention

[0007] The problem to be solved by this invention is to design a dual-axis zero-difference laser interferometer with high stability, few beam splitting surfaces, compact structure and easy integration and assembly, and to propose a dual-axis zero-difference interferometer that simultaneously measures positioning accuracy and motion deflection.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A dual-axis zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection includes a single-frequency laser source, an interferometer group, a first measuring mirror, a second measuring mirror, and a signal processing board;

[0010] The interference mirror group includes a polarizing beam splitter, a first quarter-wave plate, a first reference mirror, a second quarter-wave plate, a second reference mirror, a first photodetector, a first corner cube prism, a third quarter-wave plate, a second photodetector, a second corner cube prism, a fourth quarter-wave plate, and a fifth quarter-wave plate.

[0011] The polarizing beam splitter has a first quarter-wave plate and a second quarter-wave plate attached to its left end face, a third quarter-wave plate attached to its rear end face, a fourth quarter-wave plate attached to its right end face, and a fifth quarter-wave plate attached to its front end face.

[0012] A first reference mirror is attached to the left end face of the first quarter-wave plate; a second reference mirror is attached to the left end face of the second quarter-wave plate; a first corner bevel prism is attached to the rear end face of the third quarter-wave plate; a second corner bevel prism is attached to the right end face of the fourth quarter-wave plate; a first photodetector is disposed on the output optical path of the rear end face of the polarizing beam splitter; a second photodetector is disposed on the output optical path of the right end face of the polarizing beam splitter; a second measuring mirror and a first measuring mirror are disposed sequentially from left to right on the output optical path of the fifth quarter-wave plate.

[0013] The output light from the single-frequency laser source is incident perpendicularly on the left end face of the polarization beam splitter, and the signal processing board receives the detection signals from the first photodetector and the second photodetector.

[0014] Furthermore, the polarizing beam splitter transmits light in a horizontally polarized state and reflects light in a vertically polarized state; the fast axis of the first, second, and fifth quarter-wave plates forms a 45° angle with the horizontal direction. ° The included angle; the fast axis direction of the third and fourth quarter-wave plates forms a 22.5° angle with the horizontal direction. ° included angle;

[0015] The single-frequency laser source outputs a polarization direction to the polarization beam splitter at a 45° angle to the horizontal direction. ° Linearly polarized or circularly polarized light with an included angle;

[0016] The first reference mirror, the second reference mirror, the first measuring mirror, and the second measuring mirror are plane mirrors coated with a reflective film.

[0017] Furthermore, after the single-frequency laser source is incident perpendicularly on the polarization beam splitter, transmitted light and reflected light are obtained respectively. The reflected light is set as the first axis input beam, and the polarization state of the first axis input beam is vertically polarized; the transmitted light is set as the second axis input beam, and the polarization state of the second axis input beam is horizontally polarized.

[0018] Furthermore, the optical path process of the first axis input beam in the interferometer mirror group is as follows:

[0019] The first axis input beam first passes through the third quarter-wave plate, then is reflected by the first cornerstone prism, passes through the third quarter-wave plate again, and then is incident on the polarizing beam splitter. The reflected beam is used as the first reference beam, and the transmitted beam is used as the first measurement beam.

[0020] After the first reference beam passes through the second quarter-wave plate, it is reflected by the second reference mirror and then passes through the second quarter-wave plate again. It then propagates to the beam-splitting surface of the polarizing beam splitter and is transmitted again, resulting in the propagated first reference beam, which is then incident on the second photodetector.

[0021] After the first measuring beam passes through the fifth quarter-wave plate, it is reflected by the first measuring mirror carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate again. It then propagates to the beam splitting surface of the polarizing beam splitter and is reflected to obtain the propagated first measuring beam, which is then incident on the second photodetector.

[0022] The propagated first reference beam and the propagated first measurement beam coincide at the photosensitive surface of the second photodetector and interfere. The change in the intensity of the interference light is detected by the second photodetector and converted into an interference signal, which is output to the signal processing board. After signal processing, the first phase difference between the target and the measurement zero position is obtained. The displacement L1 of the first measuring mirror relative to the zero position, measured by the first axis, is obtained as follows:

[0023]

[0024] Where n is the refractive index of the medium and λ is the input laser vacuum wavelength.

[0025] Furthermore, the optical path process of the second axis input beam in the interferometer mirror group is as follows:

[0026] The second axis input beam is transmitted through the fourth quarter-wave plate, reflected by the second cornerstone prism, transmitted through the fourth quarter-wave plate again, and then incident on the polarizing beam splitter. The transmitted beam is used as the second reference beam, and the reflected beam is used as the second measurement beam.

[0027] After the second reference beam is transmitted through the first quarter-wave plate, it is reflected by the first reference mirror and then transmitted through the first quarter-wave plate again. It then propagates to the beam-splitting surface of the polarizing beam splitter and is reflected to obtain the propagated second reference beam, which is then incident on the first photodetector.

[0028] The second measuring beam, after passing through the fifth quarter-wave plate, is reflected by the second measuring mirror carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate again. It then propagates to the beam-splitting surface of the polarizing beam splitter and is transmitted to obtain the propagated second measuring beam, which is then incident on the first photodetector.

[0029] The propagated second reference beam and the propagated second measurement beam coincide on the photosensitive surface of the first photodetector and interfere with each other. The change in the intensity of the interference light is detected by the first photodetector and converted into an interference signal, which is output to the signal processing board. After signal processing, the second phase difference between the target and the measurement zero position is obtained. The displacement L2 of the second measuring mirror relative to the zero measuring position, obtained from the second axis measurement, is:

[0030] .

[0031] Furthermore, when the first and second measuring mirrors are fixedly mounted on the same target, the average displacement L of the target relative to the zero measurement position and the horizontal angular displacement α of the target relative to the zero measurement position are obtained by the following formulas:

[0032]

[0033]

[0034] Among them, L b The distance between the first and second measurement beams in the interferometer group is denoted as .

[0035] A dual-axis zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection includes a single-frequency laser source, an interferometer group, a first measuring mirror, a second measuring mirror, and a signal processing board;

[0036] The interference mirror group includes a polarizing beam splitter, a first quarter-wave plate, a first reference mirror, a second quarter-wave plate, a second reference mirror, a first photodetector, a first pyramidal prism, a third quarter-wave plate, a second photodetector, a second pyramidal prism, a fourth quarter-wave plate, a fifth quarter-wave plate, a third pyramidal prism, and a fourth pyramidal prism.

[0037] The polarizing beam splitter has a first quarter-wave plate and a second quarter-wave plate attached to its left end face, a third quarter-wave plate and a third pyramidal prism attached to its rear end face, a fourth quarter-wave plate and a fourth pyramidal prism attached to its right end face, and a fifth quarter-wave plate attached to its front end face.

[0038] A first reference mirror is attached to the left end face of the first quarter-wave plate; a second reference mirror is attached to the left end face of the second quarter-wave plate; a first corner bevel prism is attached to the rear end face of the third quarter-wave plate; a second corner bevel prism is attached to the right end face of the fourth quarter-wave plate; a second photodetector is disposed on the output optical path of the rear end face of the polarizing beam splitter, and a first photodetector is disposed on the output optical path of the right end face of the polarizing beam splitter; a second measuring mirror and a first measuring mirror are disposed sequentially from left to right on the output optical path of the fifth quarter-wave plate.

[0039] The output light from the single-frequency laser source is incident perpendicularly on the left end face of the polarization beam splitter, and the signal processing board receives the detection signals from the first photodetector and the second photodetector.

[0040] Furthermore, the polarizing beam splitter transmits light in a horizontally polarized state and reflects light in a vertically polarized state; the fast axis of the first, second, and fifth quarter-wave plates forms a 45° angle with the horizontal direction. ° The included angle; the fast axis direction of the third and fourth quarter-wave plates forms a 22.5° angle with the horizontal direction. ° included angle;

[0041] The single-frequency laser source outputs a polarization direction to the polarization beam splitter at a 45° angle to the horizontal direction. ° Linearly polarized or circularly polarized light with an included angle;

[0042] The first reference mirror, the second reference mirror, the first measuring mirror, and the second measuring mirror are plane mirrors coated with a reflective film.

[0043] Furthermore, after the single-frequency laser source is incident perpendicularly on the polarization beam splitter, transmitted light and reflected light are obtained respectively. The reflected light is set as the first axis input beam, and the polarization state of the first axis input beam is vertically polarized; the transmitted light is set as the second axis input beam, and the polarization state of the second axis input beam is horizontally polarized.

[0044] The beneficial effects of this invention are:

[0045] The present invention discloses a biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection. It utilizes a quarter-wave plate and a single polarizing beam splitter to construct dual measurement axes. Compared to the step-by-step measurement of traditional single-axis interferometers, it enables synchronous and dynamic measurement of target displacement and angle. The biaxial measurement results are based on the same wavelength reference and are highly consistent with the effects of laser frequency and power fluctuations, exhibiting better reliability and consistency.

[0046] The present invention discloses a biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection. Based on a single polarizing beam splitter prism, it achieves biaxial integration and integrated lens assembly. Compared with the combined measurement of two independent single-axis interferometers, it significantly reduces system complexity and assembly accuracy dependence, and can more effectively ensure the stability and accuracy of beam parallelism and spacing between the two measurement beams, without the need for repeated calibration. Structurally, it adopts a single polarizing beam splitter prism, which is more compact and easier to integrate and assemble.

[0047] The present invention discloses a dual-axis zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection, which supports high-precision synchronous measurement of displacement and angle, and is suitable for synchronous measurement and differential measurement of dual-target errors. By adapting optical components, it can be extended to synchronous detection of multi-degree-of-freedom errors. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the composition of a dual-axis zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection as described in this invention. Figure 2 This is a schematic diagram of the interferometer mirror group corresponding to Embodiment 1 of the present invention; Figure 3 This is the optical path diagram of the interference mirror group corresponding to Embodiment 1 of the present invention; Figure 4 This is a two-dimensional unfolded diagram of the internal optical path of the interference mirror group corresponding to Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the interference mirror group corresponding to Embodiment 3 of the present invention; Figure 6 This is the optical path diagram of the interference mirror group corresponding to Embodiment 3 of the present invention; Figure 7 This is a two-dimensional unfolded diagram of the internal optical path of the interference mirror group corresponding to Embodiment 3 of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0050] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0051] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 - Appendix Figure 7 Detailed explanation is as follows:

[0052] Example 1:

[0053] A dual-axis zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection includes a single-frequency laser source 1, an interferometer group 2, a first measuring mirror 3, a second measuring mirror 4, and a signal processing board 5;

[0054] The interference mirror group 2 includes a polarizing beam splitter 6, a first quarter-wave plate 7, a first reference mirror 8, a second quarter-wave plate 9, a second reference mirror 10, a first photodetector 11, a first cornerstone prism 12, a third quarter-wave plate 13, a second photodetector 14, a second cornerstone prism 15, a fourth quarter-wave plate 16, and a fifth quarter-wave plate 17.

[0055] The polarizing beam splitter 6 has a first quarter-wave plate 7 and a second quarter-wave plate 9 attached to its left end face, a third quarter-wave plate 13 attached to its rear end face, a fourth quarter-wave plate 16 attached to its right end face, and a fifth quarter-wave plate 17 attached to its front end face.

[0056] A first reference mirror 8 is attached to the left end face of the first quarter-wave plate 7; a second reference mirror 10 is attached to the left end face of the second quarter-wave plate 9; a first cornerstone prism 12 is attached to the rear end face of the third quarter-wave plate 13; a second cornerstone prism 15 is attached to the right end face of the fourth quarter-wave plate 16; a first photodetector 11 is disposed on the output optical path of the rear end face of the polarizing beam splitter 6; a second photodetector 14 is disposed on the output optical path of the right end face of the polarizing beam splitter 6; a second measuring mirror 4 and a first measuring mirror 3 are disposed sequentially from left to right on the output optical path of the fifth quarter-wave plate 17.

[0057] The output light of the single-frequency laser source 1 is incident perpendicularly on the left end face of the polarization beam splitter 6, and the signal processing board 5 receives the detection signals from the first photodetector 11 and the second photodetector 14.

[0058] Furthermore, the polarizing beam splitter 6 transmits light in a horizontally polarized state and reflects light in a vertically polarized state; the fast axis of the first quarter-wave plate 7, the second quarter-wave plate 9, and the fifth quarter-wave plate 17 forms a 45° angle with the horizontal direction. ° The included angle; the fast axis direction of the third quarter-wave plate 13 and the fourth quarter-wave plate 16 forms a 22.5-degree angle with the horizontal direction. ° included angle;

[0059] The single-frequency laser source 1 outputs a polarization direction at a 45° angle to the horizontal direction to the polarization beam splitter 6. ° Linearly polarized or circularly polarized light with an included angle;

[0060] The first reference mirror 8, the second reference mirror 10, the first measuring mirror 3, and the second measuring mirror 4 are plane mirrors coated with a reflective film.

[0061] Furthermore, after the single-frequency laser source 1 is incident perpendicularly on the polarization beam splitter 6, transmitted light and reflected light are obtained respectively. The reflected light is set as the first axis input beam, and the polarization state of the first axis input beam is vertically polarized; the transmitted light is set as the second axis input beam, and the polarization state of the second axis input beam is horizontally polarized.

[0062] Furthermore, the optical path process of the first axis input beam in the interferometer group 2 is as follows:

[0063] The first axis input beam first passes through the third quarter-wave plate 13, then is reflected by the first corner bevel prism 12, passes through the third quarter-wave plate 13 again, and then is incident on the polarizing beam splitter 6. The reflected beam is used as the first reference beam and the transmitted beam is used as the first measurement beam.

[0064] After the first reference beam passes through the second quarter-wave plate 9, it is reflected by the second reference mirror 10 and then passes through the second quarter-wave plate 9 again. It then propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted to obtain the propagated first reference beam, which is then incident on the second photodetector 14.

[0065] After the first measuring beam passes through the fifth quarter-wave plate 17, it is reflected by the first measuring mirror 3 carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate 17 again. It then propagates to the beam splitting surface of the polarizing beam splitter 6 and is reflected to obtain the propagated first measuring beam, which is then incident on the second photodetector 14.

[0066] The propagated first reference beam and the propagated first measurement beam coincide on the photosensitive surface of the second photodetector 14 and interfere. The change in the intensity of the interference light is detected by the second photodetector 14 and converted into an interference signal, which is output to the signal processing board 5. After signal processing, the first phase difference between the target and the measurement zero position is obtained. The displacement L1 of the first measuring mirror 3 relative to the zero position, measured by the first axis, is:

[0067]

[0068] Where n is the refractive index of the medium and λ is the input laser vacuum wavelength.

[0069] Furthermore, the optical path process of the second axis input beam in the interference mirror group 2 is as follows:

[0070] The second axis input beam is transmitted through the fourth quarter-wave plate 16, reflected by the second corner bevel prism 15, transmitted through the fourth quarter-wave plate 16 again, and then incident on the polarizing beam splitter 6. The transmitted beam is used as the second reference beam, and the reflected beam is used as the second measurement beam.

[0071] After the second reference beam passes through the first quarter-wave plate 7, it is reflected by the first reference mirror 8 and then passes through the first quarter-wave plate 7 again. It then propagates to the beam-splitting surface of the polarizing beam splitter 6 and is reflected to obtain the propagated second reference beam, which is then incident on the first photodetector 11.

[0072] The second measuring beam, after passing through the fifth quarter-wave plate 17, is reflected by the second measuring mirror 4 carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate 17 again. It then propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted to obtain the propagated second measuring beam, which is then incident on the first photodetector 11.

[0073] The propagated second reference beam and the propagated second measurement beam coincide on the photosensitive surface of the first photodetector 11 and interfere with each other. The change in interference light intensity is detected by the first photodetector 11 and converted into an interference signal, which is output to the signal processing board 5. After signal processing, the second phase difference between the target and the measurement zero position is obtained. The displacement L2 of the second measuring mirror 4 relative to the zero measuring position, obtained from the second axis measurement, is:

[0074] .

[0075] Furthermore, when the first measuring mirror 3 and the second measuring mirror 4 are fixedly installed on the same target, the average displacement L of the target relative to the zero measurement position and the horizontal angular displacement α of the target relative to the zero measurement position are obtained by the following formulas:

[0076]

[0077]

[0078] Among them, L b The distance between the first and second measurement beams in the interferometer group is denoted as .

[0079] Furthermore, PBS represents a polarizing beam splitter; RR represents a cornerstone prism; QWP represents a quarter-wave plate; and PD represents a photodetector.

[0080] Example 2:

[0081] The measurement method of a dual-axis zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to Example 1 includes the following steps:

[0082] S1. Turn on the single-frequency laser source 1, outputting a single stable frequency with a polarization direction at a 45° angle to the horizontal direction. ° Linearly or circularly polarized light with an angle is split into transmitted and reflected light after being incident perpendicularly on polarizing beam splitter 6.

[0083] The reflected light serves as the first axis input beam, with a vertical polarization state; the transmitted light serves as the second axis input beam, with a horizontal polarization state.

[0084] S2. The reflected beam, after being reflected by the polarizing beam splitter 6, is transmitted through the third quarter-wave plate 13, reflected by the first cornerstone prism 12, and transmitted again through the third quarter-wave plate 13. At this time, after the first-axis input beam has been acted upon twice by the third quarter-wave plate 13, its polarization state changes from vertical polarization to a 45° angle with the horizontal direction. ° Linear polarization at the included angle.

[0085] The polarization state of the first axis input beam changes from vertical polarization to polarization at a 45° angle to the horizontal direction. ° After linear polarization at the included angle, the beam is incident on the polarizing beam splitter 6, and the resulting reflected beam is used as the first reference beam and the transmitted beam is used as the first measurement beam.

[0086] The first reference beam, which is vertically polarized, is transmitted through the second quarter-wave plate 9 and then reflected by the second reference mirror 10 before being transmitted through the second quarter-wave plate 9 again. After passing through the second quarter-wave plate 9 twice, the polarization state of the first reference beam changes from vertical to horizontal.

[0087] After the first reference beam is polarized to horizontal, it propagates to the beam-splitting surface of the polarization beam splitter 6 and is transmitted, and then enters the second photodetector 14.

[0088] The first measuring beam is horizontally polarized. After passing through the fifth quarter-wave plate 17, it is reflected by the first measuring mirror 3 carrying the target displacement information and then passed through the fifth quarter-wave plate 17 again. At this time, after the first measuring beam has been acted on by the fifth quarter-wave plate 17 twice, its polarization state changes from horizontal to vertical.

[0089] The first measuring beam, after its polarization state changes to vertical polarization, propagates to the beam-splitting surface of the polarization beam splitter 6 and is reflected, then enters the second photodetector 14.

[0090] The first reference beam and the first measurement beam corresponding to the first axis coincide on the photosensitive surface of the second photodetector 14 and interfere; the second photodetector 14 detects the interference light field, obtains the interference signal, and outputs it to the signal calculation board 5; after signal processing, the displacement information of the first measurement reflector 3 relative to the measurement zero position is obtained.

[0091] S3. The transmitted beam, after being transmitted by the polarizing beam splitter 6, passes through the fourth quarter-wave plate 16, is reflected by the second pyramidal prism 15, and is transmitted through the fourth quarter-wave plate 16 again. At this time, after the second-axis input beam has been acted upon twice by the fourth quarter-wave plate 16, its polarization state changes from horizontal polarization to polarization at a 45° angle to the horizontal direction. ° Linear polarization at the included angle.

[0092] The polarization state of the second-axis input beam changes from horizontal polarization to polarization at a 45° angle to the horizontal direction. ° After being linearly polarized at the included angle, the beam is incident on the polarizing beam splitter 6, and the resulting transmitted beam is used as the second reference beam and the reflected beam is used as the second measurement beam.

[0093] The second reference beam is horizontally polarized. After passing through the first quarter-wave plate 7 and being reflected by the first reference mirror 8, it passes through the first quarter-wave plate 7 again. At this time, after passing through the first quarter-wave plate 7 twice, the polarization state of the first reference beam changes from horizontal to vertical.

[0094] After the second reference beam changes to vertical polarization, it propagates to the beam-splitting surface of the polarization beam splitter 6 and is reflected, then enters the first photodetector 11.

[0095] The second measuring beam, which is vertically polarized, passes through the fifth quarter-wave plate 17 and is reflected by the second measuring mirror 4 carrying the target displacement information. It then passes through the fifth quarter-wave plate 17 again. At this time, after the second measuring beam has been acted on by the fifth quarter-wave plate 17 twice, its polarization state changes from vertical to horizontal.

[0096] The second measuring beam, after its polarization state changes to vertical polarization, propagates to the beam-splitting surface of the polarization beam splitter 6 and is transmitted, then enters the first photodetector 11.

[0097] The second reference beam and the second measurement beam corresponding to the second axis coincide on the photosensitive surface of the first photodetector 11 and interfere; the first photodetector 11 detects the interference light field, obtains the interference signal, and outputs it to the signal calculation board 5; after signal processing, the displacement information of the second measurement reflector 4 relative to the measurement zero position is obtained.

[0098] The second photodetector 14 acquires the interference signal, which is then processed by the signal processing board 5 to calculate the phase difference relative to the measurement zero position. Then, the displacement L1 of the first measuring mirror 3 relative to the zero measuring position, measured by the first axis, is:

[0099]

[0100] The first photodetector 11 obtains the interference signal, which is then processed by the signal processing board 5 to calculate the phase difference relative to the measurement zero position. Then, the displacement L2 of the second measuring mirror 4 relative to the zero measuring position, measured by the first axis, is:

[0101]

[0102] Where n is the refractive index of the medium and λ is the input laser vacuum wavelength.

[0103] Furthermore, when the first and second measuring mirrors are fixedly mounted on the same target, the average displacement L of the target relative to the zero measurement position is:

[0104] ;

[0105] Furthermore, when the first measuring mirror 3 and the second measuring mirror 4 are fixedly installed on the same target, the horizontal angular displacement α of the target relative to the zero measurement position is:

[0106]

[0107] Among them, L b The distance between the first and second measurement beams in the interferometer group is denoted as .

[0108] Example 3:

[0109] A dual-axis zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection includes a single-frequency laser source 1, an interferometer group 2, a first measuring mirror 3, a second measuring mirror 4, and a signal processing board 5;

[0110] The interference mirror group 2 includes a polarizing beam splitter 6, a first quarter-wave plate 7, a first reference mirror 8, a second quarter-wave plate 9, a second reference mirror 10, a first photodetector 11, a first corner bevel prism 12, a third quarter-wave plate 13, a second photodetector 14, a second corner bevel prism 15, a fourth quarter-wave plate 16, a fifth quarter-wave plate 17, a third corner bevel prism 18, and a fourth corner bevel prism 19.

[0111] The polarizing beam splitter 6 has a first quarter-wave plate 7 and a second quarter-wave plate 9 attached to its left end face, a third quarter-wave plate 13 and a third pyramidal prism 18 attached to its rear end face, a fourth quarter-wave plate 16 and a fourth pyramidal prism 19 attached to its right end face, and a fifth quarter-wave plate 17 attached to its front end face.

[0112] A first reference mirror 8 is attached to the left end face of the first quarter-wave plate 7; a second reference mirror 10 is attached to the left end face of the second quarter-wave plate 9; a first cornerstone prism 12 is attached to the rear end face of the third quarter-wave plate 13; a second cornerstone prism 15 is attached to the right end face of the fourth quarter-wave plate 16; a second photodetector 14 is disposed on the output optical path of the rear end face of the polarizing beam splitter 6, and a first photodetector 11 is disposed on the output optical path of the right end face of the polarizing beam splitter 6; a second measuring mirror 4 and a first measuring mirror 3 are disposed sequentially from left to right on the output optical path of the fifth quarter-wave plate 17.

[0113] The output light of the single-frequency laser source 1 is incident perpendicularly on the left end face of the polarization beam splitter 6, and the signal processing board 5 receives the detection signals from the first photodetector 11 and the second photodetector 14.

[0114] Furthermore, the polarizing beam splitter 6 transmits light in a horizontally polarized state and reflects light in a vertically polarized state; the fast axis of the first quarter-wave plate 7, the second quarter-wave plate 9, and the fifth quarter-wave plate 17 forms a 45° angle with the horizontal direction. ° The included angle; the fast axis direction of the third quarter-wave plate 13 and the fourth quarter-wave plate 16 forms a 22.5-degree angle with the horizontal direction. ° included angle;

[0115] The single-frequency laser source 1 outputs a polarization direction at a 45° angle to the horizontal direction to the polarization beam splitter 6. ° Linearly polarized or circularly polarized light with an included angle;

[0116] The first reference mirror 8, the second reference mirror 10, the first measuring mirror 3, and the second measuring mirror 4 are plane mirrors coated with a reflective film.

[0117] Furthermore, after the single-frequency laser source 1 is incident perpendicularly on the polarization beam splitter 6, transmitted light and reflected light are obtained respectively. The reflected light is set as the first axis input beam, and the polarization state of the first axis input beam is vertically polarized; the transmitted light is set as the second axis input beam, and the polarization state of the second axis input beam is horizontally polarized.

[0118] Furthermore, the optical path process of the first axis input beam in the interferometer group 2 is as follows:

[0119] The first axis input beam is transmitted through the third quarter-wave plate 13, reflected by the first corner bevel prism 12, transmitted through the third quarter-wave plate 13 again, and incident on the polarizing beam splitter 6. The resulting reflected beam is used as the first reference beam and the transmitted beam is used as the first measurement beam.

[0120] After the first reference beam is transmitted through the second quarter-wave plate 9, it is reflected by the second reference mirror 10, and then transmitted through the second quarter-wave plate 9 again. After propagating to the beam-splitting surface of the polarizing beam-splitting prism 6, it is reflected by the fourth pyramidal prism 19, and then transmitted again to the beam-splitting surface of the polarizing beam-splitting prism 6. Subsequently, it is transmitted through the second quarter-wave plate 9, reflected by the second reference mirror 10, and then transmitted through the second quarter-wave plate 9 again. After propagating to the beam-splitting surface of the polarizing beam-splitting prism 6, it is reflected and then incident on the second photodetector 14 to obtain the propagated first reference beam.

[0121] After the first measuring beam passes through the fifth quarter-wave plate 17, it is reflected by the first measuring mirror 3 carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate 17 again. It then propagates to the beam-splitting surface of the polarizing beam-splitting prism 6 and is reflected. It then enters the fourth pyramidal prism 19 and is reflected again. It then propagates to the beam-splitting surface of the polarizing beam-splitting prism 6 and is reflected again. After passing through the fifth quarter-wave plate 17, it is reflected a second time by the first measuring mirror 3 carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate 17 again. The polarization state changes from vertical polarization to horizontal polarization. It then propagates to the beam-splitting surface of the polarizing beam-splitting prism 6 and is projected. It enters the second photodetector 14 to obtain the propagated first measuring beam.

[0122] The propagated first reference beam and the propagated first measurement beam coincide on the photosensitive surface of the second photodetector 14 and interfere. The second photodetector 14 detects the interference light field, obtains the interference signal, and outputs it to the signal processing board 5. After signal processing, the first phase difference between the target and the measurement zero position is obtained. The displacement L1 of the first measuring mirror 3 relative to the zero position, measured by the first axis, is:

[0123]

[0124] Where n is the refractive index of the medium and λ is the input laser vacuum wavelength.

[0125] Furthermore, the optical path process of the second axis input beam in the interference mirror group 2 is as follows:

[0126] The second axis input beam is transmitted through the polarizing beam splitter 6 and then through the fourth quarter-wave plate 16. After being reflected by the second pyramidal prism 15, it is transmitted through the fourth quarter-wave plate 16 again and then incident on the polarizing beam splitter 6. The transmitted beam is used as the second reference beam and the reflected beam is used as the second measurement beam.

[0127] After the second reference beam passes through the first quarter-wave plate 7 and is reflected by the first reference mirror 8, it passes through the first quarter-wave plate 7 again and then propagates to the beam-splitting surface of the polarizing beam splitter 6, where it is reflected. It then enters the third corner prism 18 and is reflected again, maintaining a vertical polarization state. It then enters the beam-splitting surface of the polarizing beam splitter 6 and is reflected again. After passing through the first quarter-wave plate 7 and being reflected by the first reference mirror 8, it passes through the first quarter-wave plate 7 again. After passing through the first quarter-wave plate 7 twice, the polarization state changes from vertical to horizontal polarization. It then enters the beam-splitting surface of the polarizing beam splitter 6 and is transmitted, entering the first photodetector 11 to obtain the propagated second reference beam.

[0128] After the second measuring beam passes through the fifth quarter-wave plate 17, it is reflected by the second measuring mirror 4 carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate 17 again. It propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted. It is then incident on the third corner prism 18 and is reflected, and then propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted again. After passing through the fifth quarter-wave plate 17, it is reflected a second time by the second measuring mirror 4 carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate 17 again. After being acted on by the fifth quarter-wave plate 17 twice, the polarization state changes from horizontal polarization to vertical polarization. It then propagates to the beam-splitting surface of the polarizing beam splitter 6 and is reflected, and then incident on the first photodetector 11 to obtain the propagated second measuring beam.

[0129] The propagated second reference beam and the propagated second measurement beam coincide on the photosensitive surface of the first photodetector 11 and interfere. The first photodetector 11 detects the interference light field and obtains the interference signal, which is input into the signal processing board 5. After signal processing, the second phase difference between the target and the measurement zero position is obtained. The displacement L2 of the second measuring mirror 4 relative to the zero measuring position, obtained from the second axis measurement, is:

[0130]

[0131] When the first measuring mirror 3 and the second measuring mirror 4 are fixedly installed on the same target, the average displacement L of the target relative to the zero measurement position is:

[0132]

[0133] When the first measuring mirror 3 and the second measuring mirror 4 are fixedly installed on the same target, the horizontal angular displacement α of the target relative to the zero measurement position is:

[0134]

[0135] Among them, L b The distance between the first and second measurement beams in the interferometer group is denoted as .

[0136] Example 4:

[0137] The measurement method of a biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to Embodiment 3 includes the following steps:

[0138] S1. Turn on the single-frequency laser source 1, outputting a single stable frequency with a polarization direction at a 45° angle to the horizontal direction. ° Linearly or circularly polarized light with an angle is split into transmitted and reflected light after being incident perpendicularly on polarizing beam splitter 6.

[0139] The reflected light serves as the first axis input beam, with a vertical polarization state; the transmitted light serves as the second axis input beam, with a horizontal polarization state.

[0140] S2. The reflected beam, after being reflected by the polarizing beam splitter 6, is transmitted through the third quarter-wave plate 13, reflected by the first cornerstone prism 12, and transmitted again through the third quarter-wave plate 13. At this time, after the first-axis input beam has been acted upon twice by the third quarter-wave plate 13, its polarization state changes from vertical polarization to a 45° angle with the horizontal direction. ° Linear polarization at the included angle.

[0141] The polarization state of the first axis input beam changes from vertical polarization to polarization at a 45° angle to the horizontal direction. ° After linear polarization at the included angle, the beam is incident on the polarizing beam splitter 6, and the resulting reflected beam is used as the first reference beam and the transmitted beam is used as the first measurement beam.

[0142] The first reference beam, which is vertically polarized, is transmitted through the second quarter-wave plate 9 and then reflected by the second reference mirror 10 before being transmitted through the second quarter-wave plate 9 again. After passing through the second quarter-wave plate 9 twice, the polarization state of the first reference beam changes from vertical to horizontal.

[0143] After the first reference beam changes its polarization state to horizontal polarization, it propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted. It is then incident on the fourth corner prism 19 and reflected, maintaining its horizontal polarization state. It propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted again. Subsequently, it is transmitted through the second quarter-wave plate 9, reflected by the second reference mirror 10, and transmitted through the second quarter-wave plate 9 again. At this time, after the first reference beam has been acted upon twice by the second quarter-wave plate 9, its polarization state changes from horizontal polarization to vertical polarization.

[0144] After the first reference beam is polarized to vertical polarization, it propagates to the beam-splitting surface of the polarization beam splitter 6 and is reflected, and then enters the second photodetector 14.

[0145] The first measuring beam is horizontally polarized. After passing through the fifth quarter-wave plate 17, it is reflected by the first measuring mirror 3 carrying the target displacement information and then passed through the fifth quarter-wave plate 17 again. At this time, after the first measuring beam has been acted on by the fifth quarter-wave plate 17 twice, its polarization state changes from horizontal to vertical.

[0146] The first measuring beam, after its polarization state changes to vertical polarization, is reflected at the beam-splitting surface of the polarizing beam splitter 6. It is then reflected by the fourth corner prism 19, maintaining its vertical polarization state. It is reflected again at the beam-splitting surface of the polarizing beam splitter 6. After passing through the fifth quarter-wave plate 17, it is reflected a second time by the first measuring mirror 3 carrying the target displacement information and then passed through the fifth quarter-wave plate 17 again. At this time, after being acted upon twice by the fifth quarter-wave plate 17, the polarization state of the first reference beam changes from vertical polarization to horizontal polarization.

[0147] After the first measuring beam changes to horizontal polarization, it propagates to the beam-splitting surface of the polarization beam splitter 6 and is projected onto the second photodetector 14.

[0148] The first reference beam and the first measurement beam corresponding to the first axis coincide on the photosensitive surface of the second photodetector 14 and interfere; the second photodetector 14 detects the interference light field, obtains the interference signal, and inputs it into the signal calculation board 5; after signal processing, the displacement information of the first measurement reflector 3 relative to the measurement zero position is obtained.

[0149] S3. The transmitted beam, after being transmitted by the polarizing beam splitter 6, passes through the fourth quarter-wave plate 16, is reflected by the second pyramidal prism 15, and is transmitted through the fourth quarter-wave plate 16 again. At this time, after the second-axis input beam passes through the fourth quarter-wave plate 16, its polarization state changes from horizontal polarization to polarization at a 45° angle to the horizontal direction. ° Linear polarization at the included angle.

[0150] The polarization state of the second-axis input beam changes from horizontal polarization to polarization at a 45° angle to the horizontal direction. ° After being linearly polarized at the included angle, the beam is incident on the polarizing beam splitter 6, and the resulting transmitted beam is used as the second reference beam and the reflected beam is used as the second measurement beam.

[0151] The second reference beam is horizontally polarized. After passing through the first quarter-wave plate 7 and being reflected by the first reference mirror 8, it passes through the first quarter-wave plate 7 again. At this time, after passing through the first quarter-wave plate 7 twice, the polarization state of the first reference beam changes from horizontal to vertical.

[0152] The second reference beam, after its polarization state changes to vertical polarization, propagates to the beam-splitting surface of the polarizing beam-splitting prism 6 and is reflected. It is then incident on the third corner prism 18 and reflected again, maintaining its vertical polarization state. It propagates to the beam-splitting surface of the polarizing beam-splitting prism 6 and is reflected again. After passing through the first quarter-wave plate 7, it is reflected by the first reference mirror 8 and then passed through the first quarter-wave plate 7 again. At this time, after the first reference beam has been acted upon twice by the first quarter-wave plate 7, its polarization state changes from vertical polarization to horizontal polarization.

[0153] After the second reference beam changes to horizontal polarization, it propagates to the beam-splitting surface of the polarization beam splitter 6 and is transmitted, then enters the first photodetector 11.

[0154] The second measuring beam, which is vertically polarized, passes through the fifth quarter-wave plate 17 and is reflected by the second measuring mirror 4 carrying the target displacement information. It then passes through the fifth quarter-wave plate 17 again. At this time, after the second measuring beam has been acted on by the fifth quarter-wave plate 17 twice, its polarization state changes from vertical to horizontal.

[0155] The second measuring beam, after its polarization state changes to horizontal polarization, propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted. It is then incident on the third corner prism 18 and reflected, maintaining its horizontal polarization state. It propagates to the beam-splitting surface of the polarizing beam splitter 6 and is transmitted again. After passing through the fifth quarter-wave plate 17, it is reflected a second time by the second measuring mirror 4 carrying the target displacement information and is transmitted through the fifth quarter-wave plate 17 again. At this time, after the first reference beam has been acted upon twice by the fifth quarter-wave plate 17, its polarization state changes from horizontal polarization to vertical polarization.

[0156] The second measuring beam, after its polarization state changes to vertical polarization, propagates to the beam-splitting surface of the polarization beam splitter 6 and is reflected, then enters the first photodetector 11.

[0157] The second reference beam and the second measurement beam corresponding to the second axis coincide on the photosensitive surface of the first photodetector 11 and interfere; the first photodetector 11 detects the interference light field, obtains the interference signal, and inputs it into the signal calculation board 5; after signal processing, the displacement information of the second measurement reflector 4 relative to the measurement zero position is obtained.

[0158] The first photodetector 11 obtains the interference signal, which is then processed by the signal processing board 5 to calculate the phase difference relative to the measurement zero position. Then, the displacement L1 of the first measuring mirror 3 relative to the zero measuring position, measured by the first axis, is:

[0159]

[0160] The second photodetector 14 acquires the interference signal, which is then processed by the signal processing board 5 to calculate the phase difference relative to the measurement zero position. Then, the displacement L2 of the second measuring mirror 4 relative to the zero measuring position, measured by the first axis, is:

[0161]

[0162] Where n is the refractive index of the medium and λ is the input laser vacuum wavelength. Since the first measurement beam travels back and forth twice between the polarizing beam splitter prism 6 and the second measurement mirror 4, optical four-part subdivision of the interferometric measurement is achieved.

[0163] Furthermore, when the first and second measuring mirrors are fixedly mounted on the same target, the average displacement L of the target relative to the zero measurement position is:

[0164]

[0165] Furthermore, when the first measuring mirror 3 and the second measuring mirror 4 are fixedly installed on the same target, the horizontal angular displacement α of the target relative to the zero measurement position is:

[0166]

[0167] Among them, L b The distance between the first and second measurement beams in the interferometer group is denoted as .

[0168] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0169] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A biaxial zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection, characterized in that, Includes a single-frequency laser source (1), an interferometer group (2), a first measuring mirror (3), a second measuring mirror (4), and a signal processing board (5); The interference mirror group (2) includes a polarizing beam splitter (6), a first quarter-wave plate (7), a first reference mirror (8), a second quarter-wave plate (9), a second reference mirror (10), a first photodetector (11), a first cornerstone prism (12), a third quarter-wave plate (13), a second photodetector (14), a second cornerstone prism (15), a fourth quarter-wave plate (16), and a fifth quarter-wave plate (17). The polarizing beam splitter (6) has a first quarter-wave plate (7) and a second quarter-wave plate (9) attached to its left end face, a third quarter-wave plate (13) attached to its rear end face, a fourth quarter-wave plate (16) attached to its right end face, and a fifth quarter-wave plate (17) attached to its front end face. A first reference mirror (8) is attached to the left end face of the first quarter-wave plate (7); a second reference mirror (10) is attached to the left end face of the second quarter-wave plate (9); a first corner bevel prism (12) is attached to the rear end face of the third quarter-wave plate (13); a second corner bevel prism (15) is attached to the right end face of the fourth quarter-wave plate (16); a first photodetector (11) is provided on the output optical path of the rear end face of the polarizing beam splitter (6); a second photodetector (14) is provided on the output optical path of the right end face of the polarizing beam splitter (6); a second measuring mirror (4) and a first measuring mirror (3) are arranged sequentially from left to right on the output optical path of the fifth quarter-wave plate (17). The output light of the single-frequency laser source (1) is incident perpendicularly on the left end face of the polarization beam splitter (6), and the signal processing board (5) receives the detection signals of the first photodetector (11) and the second photodetector (14).

2. The biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 1, characterized in that, The polarizing beam splitter (6) transmits light in a horizontal polarization state and reflects light in a vertical polarization state; the fast axis of the first quarter-wave plate (7), the second quarter-wave plate (9), and the fifth quarter-wave plate (17) forms a 45° angle with the horizontal direction. ° The included angle; the fast axis direction of the third quarter-wave plate (13) and the fourth quarter-wave plate (16) forms a 22.5° angle with the horizontal direction. ° included angle; The single-frequency laser source (1) outputs a polarization direction to the polarization beam splitter (6) at a 45° angle to the horizontal direction. ° Linearly polarized or circularly polarized light with an included angle; The first reference mirror (8), the second reference mirror (10), the first measuring mirror (3), and the second measuring mirror (4) are plane mirrors coated with a reflective film.

3. The biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 2, characterized in that, A single-frequency laser source (1) is incident perpendicularly onto a polarizing beam splitter (6) to obtain transmitted light and reflected light respectively. The reflected light is set as the first axis input beam, and the polarization state of the first axis input beam is vertically polarized. The transmitted light is set as the second axis input beam, and the polarization state of the second axis input beam is horizontally polarized.

4. The biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 3, characterized in that, The optical path of the first axis input beam in the interference mirror group (2) is as follows: The first axis input beam first passes through the third quarter-wave plate (13), then is reflected by the first corner bevel prism (12), and then passes through the third quarter-wave plate (13) again. The reflected beam obtained by the polarizing beam splitter (6) is used as the first reference beam, and the transmitted beam is used as the first measurement beam. After the first reference beam is transmitted through the second quarter-wave plate (9), it is reflected by the second reference mirror (10) and then transmitted through the second quarter-wave plate (9) again. It then propagates to the beam splitting surface of the polarizing beam splitter (6) and is transmitted to obtain the propagated first reference beam, which is then incident on the second photodetector (14). After the first measuring beam passes through the fifth quarter-wave plate (17), it is reflected by the first measuring mirror (3) carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate (17) again. It then propagates to the beam splitting surface of the polarizing beam splitter (6) and is reflected to obtain the propagated first measuring beam, which is then incident on the second photodetector (14). The propagated first reference beam and the propagated first measurement beam coincide on the photosensitive surface of the second photodetector (14) and interfere. The change in interference light intensity is detected by the second photodetector (14) and converted into an interference signal, which is output to the signal calculation board (5). After signal processing, the first phase difference between the target and the measurement zero position is obtained. The displacement L1 of the first measuring mirror (3) relative to the zero position, measured by the first axis, is: ； Where n is the refractive index of the medium and λ is the input laser vacuum wavelength.

5. A biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 4, characterized in that, The optical path of the second axis input beam in the interference mirror group (2) is as follows: The second axis input beam is transmitted through the fourth quarter-wave plate (16), reflected by the second corner bevel prism (15), and transmitted through the fourth quarter-wave plate (16) again. The transmitted beam obtained by the incident beam onto the polarizing beam splitter (6) is used as the second reference beam, and the reflected beam is used as the second measurement beam. After the second reference beam is transmitted through the first quarter-wave plate (7), it is reflected by the first reference mirror (8), and then transmitted through the first quarter-wave plate (7) again. It then propagates to the beam splitting surface of the polarizing beam splitter (6) and is reflected to obtain the propagated second reference beam, which is then incident on the first photodetector (11). The second measuring beam, after passing through the fifth quarter-wave plate (17), is reflected by the second measuring mirror (4) carrying displacement information of the target relative to the zero position of the measurement, and then passes through the fifth quarter-wave plate (17) again. It then propagates to the beam splitting surface of the polarizing beam splitter (6) and is transmitted to obtain the propagated second measuring beam, which is then incident on the first photodetector (11). The propagated second reference beam and the propagated second measurement beam coincide on the photosensitive surface of the first photodetector (11) and interfere; the change in interference light intensity is detected by the first photodetector (11) and converted into an interference signal, which is output to the signal calculation board (5); the second phase difference between the target and the measurement zero position is obtained after signal processing. The displacement L2 of the second measuring mirror (4) relative to the zero position, measured by the second axis, is: 。 6. A biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 5, characterized in that, When the first measuring mirror (3) and the second measuring mirror (4) are fixedly installed on the same target, the average displacement L of the target relative to the zero measurement position and the horizontal angular displacement α of the target relative to the zero measurement position are obtained by the following formula: ； ； Among them, L b The distance between the first and second measurement beams in the interferometer group is denoted as .

7. A biaxial zero-difference interferometer for simultaneously measuring positioning accuracy and motion deflection, characterized in that, Includes a single-frequency laser source (1), an interferometer group (2), a first measuring mirror (3), a second measuring mirror (4), and a signal processing board (5); The interference mirror group (2) includes a polarizing beam splitter (6), a first quarter-wave plate (7), a first reference mirror (8), a second quarter-wave plate (9), a second reference mirror (10), a first photodetector (11), a first corner prism (12), a third quarter-wave plate (13), a second photodetector (14), a second corner prism (15), a fourth quarter-wave plate (16), a fifth quarter-wave plate (17), a third corner prism (18), and a fourth corner prism (19). The polarizing beam splitter (6) has a first quarter-wave plate (7) and a second quarter-wave plate (9) attached to its left end face, a third quarter-wave plate (13) and a third corner prism (18) attached to its rear end face, a fourth quarter-wave plate (16) and a fourth corner prism (19) attached to its right end face, and a fifth quarter-wave plate (17) attached to its front end face. A first reference mirror (8) is attached to the left end face of the first quarter-wave plate (7); a second reference mirror (10) is attached to the left end face of the second quarter-wave plate (9); a first corner prism (12) is attached to the rear end face of the third quarter-wave plate (13); a second corner prism (15) is attached to the right end face of the fourth quarter-wave plate (16); a second photodetector (14) is provided on the output optical path of the rear end face of the polarizing beam splitter (6), and a first photodetector (11) is provided on the output optical path of the right end face of the polarizing beam splitter (6); a second measuring mirror (4) and a first measuring mirror (3) are arranged sequentially from left to right on the output optical path of the fifth quarter-wave plate (17). The output light of the single-frequency laser source (1) is incident perpendicularly on the left end face of the polarization beam splitter (6), and the signal processing board (5) receives the detection signals of the first photodetector (11) and the second photodetector (14).

8. A biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 7, characterized in that, The polarizing beam splitter (6) transmits light in a horizontal polarization state and reflects light in a vertical polarization state; the fast axis of the first quarter-wave plate (7), the second quarter-wave plate (9), and the fifth quarter-wave plate (17) forms a 45° angle with the horizontal direction. ° The included angle; the fast axis direction of the third quarter-wave plate (13) and the fourth quarter-wave plate (16) forms a 22.5° angle with the horizontal direction. ° included angle; The single-frequency laser source (1) outputs a polarization direction to the polarization beam splitter (6) at a 45° angle to the horizontal direction. ° Linearly polarized or circularly polarized light with an included angle; The first reference mirror (8), the second reference mirror (10), the first measuring mirror (3), and the second measuring mirror (4) are plane mirrors coated with a reflective film.

9. A biaxial zero-difference interferometer for synchronously measuring positioning accuracy and motion deflection according to claim 8, characterized in that, A single-frequency laser source (1) is incident perpendicularly onto a polarizing beam splitter (6) to obtain transmitted light and reflected light respectively. The reflected light is set as the first axis input beam, and the polarization state of the first axis input beam is vertically polarized. The transmitted light is set as the second axis input beam, and the polarization state of the second axis input beam is horizontally polarized.

Images