A six-degree-of-freedom optical measurement system
Patent Information
- Application Number
- CN202610818995.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-08
- Publication Date
- 2026-09-25
AI Technical Summary
[0004]本发明旨在克服现有技术中六自由度光学测量系统无法兼顾大范围覆盖与高精度检测的同步需求、集成化程度低的问题，提供了一种六自由度光学测量系统
[0014]综上所述，本发明提供了一种六自由度光学测量系统，采用单束激光分光形成参考光路与测量光路，参考光经第一角锥反射靶标分生成多路，测量光经第二角锥反射靶标分生成多路，多束测量光与参考光用于干涉解算X轴位移、俯仰角、偏航角，一路测量光用于探测解算Y轴位移、Z轴位移与滚转角，实现被测物体六自由度的同步、高精度测量。
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Figure CN122813653A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optical measurement technology, and in particular to a six-degree-of-freedom optical measurement system. Background Technology
[0002] Six-degree-of-freedom optical measurement systems are widely used in CNC machine tools, semiconductor processing, precision assembly and other fields to achieve synchronous high-precision detection of the three-dimensional displacement (X / Y / Z axis displacement) and three-dimensional attitude (pitch angle / yaw angle / roll angle) of the object under test.
[0003] Existing six-degree-of-freedom laser interferometry instruments generally suffer from core pain points such as poor integration performance and difficulty in balancing measurement range and accuracy. These devices rely on mature laser interferometry principles and can achieve high measurement accuracy at the nanometer level. However, due to the discrete layout of the optical structure, the overall optical path design is scattered, the core components are arranged in a fragmented manner, and the system integration is low, which is not conducive to compact application scenarios. At the same time, due to the inherent constraints of the interferometric ranging principle, the effective working range is significantly limited while maintaining a high level of measurement accuracy, resulting in a small measurement range that cannot simultaneously meet the requirements of large-area coverage and high-precision detection. Summary of the Invention
[0004] The present invention aims to overcome the problems of existing six-degree-of-freedom optical measurement systems, such as the inability to simultaneously meet the requirements of large-area coverage and high-precision detection, and the low degree of integration, and provides a six-degree-of-freedom optical measurement system.
[0005] To achieve the above objectives, the technical solution of the present invention is: to provide a six-degree-of-freedom optical measurement system, comprising, A light source that emits laser light; The first polarizing beam splitter reflects the laser light to form a first reference light and transmits it to form a first measurement light. The first pyramidal reflective target reflects the first reference light to form multiple second reference lights, which are then incident on the first polarizing beam splitter. The second pyramidal reflective target reflects the first measurement light to form multiple second and third measurement lights. The second measurement light passes through the first waveplate and enters the first polarizing beam splitter. The second reference light and the second measurement light are combined to form interference light. The first detection module, wherein the interference light enters the first detection module, is used to obtain the X-axis displacement, pitch angle and yaw angle of the second pyramidal reflective target; A first right-angle prism reflects the third measuring light; The second detection module receives the third measuring light, which is used to obtain the Y-axis displacement, Z-axis displacement, and roll angle of the second pyramidal reflective target.
[0006] In one embodiment, the first cornerstone reflective target includes a first beam splitter and a first cornerstone prism. The first reference light enters the first beam splitter to form multiple second reference lights. The multiple second reference lights are reflected by the first cornerstone prism and pass through the first beam splitter.
[0007] In one embodiment, the second cornerstone reflective target includes a second beam splitter and a second cornerstone prism. The first measurement light enters the second beam splitter to form multiple beams of the second measurement light and the third measurement light, which are reflected by the second cornerstone prism and pass through the second beam splitter.
[0008] In one embodiment, the first beam splitter and the second beam splitter are selected as a one-to-four beam splitter.
[0009] In one embodiment, the first detection module includes a second right-angle prism, a first beam splitter, a first detector, a third right-angle prism, a second beam splitter, a second detector, a fourth right-angle prism, a third beam splitter, and a third detector. A pair of interfering beams are reflected by the second right-angle prism, pass through the first beam splitter, and enter the first detector; a pair of interfering beams are reflected by the third right-angle prism, pass through the second beam splitter, and enter the second detector; a pair of interfering beams are reflected by the fourth right-angle prism, pass through the third beam splitter, and enter the third detector. The first detector, the second detector, and the third detector all acquire interference signals and calculate the X-axis displacement. The pitch angle and yaw angle are calculated based on the X-axis displacement and the tangent of the distance between the beams of the interfering beams.
[0010] In one embodiment, the second detection module includes a third waveplate, a second polarizing beam splitter, a first position-sensitive detector, and a second position-sensitive detector. The third measurement light is sequentially incident on the third waveplate and the second polarizing beam splitter. A portion of the third measurement light passes through the second polarizing beam splitter and enters the first position-sensitive detector, while another portion of the third measurement light is reflected by the second polarizing beam splitter and enters the second position-sensitive detector. Both the first and second position-sensitive detectors collect position signals and light intensity signals to calculate the Y-axis displacement, Z-axis displacement, and roll angle.
[0011] In one embodiment, a first wave plate is also included, through which the first reference light passes after exiting the first polarizing beam splitter, passes through the first wave plate, and enters the first pyramidal reflective target.
[0012] In one embodiment, a second waveplate is also included, through which the first measuring light passes after exiting the first polarizing beam splitter, passes through the second waveplate, and enters the second pyramidal reflective target.
[0013] In one embodiment, the light source is equipped with a collimator, and the laser is emitted after being collimated by the collimator.
[0014] In summary, this invention provides a six-degree-of-freedom optical measurement system. It uses a single-beam laser to split the reference beam and the measurement beam. The reference beam is split into multiple paths by a first pyramidal reflective target, and the measurement beam is split into multiple paths by a second pyramidal reflective target. The multiple measurement beams and the reference beam are used to interferometrically calculate the X-axis displacement, pitch angle, and yaw angle. One measurement beam is used to detect and calculate the Y-axis displacement, Z-axis displacement, and roll angle, thereby achieving synchronous and high-precision measurement of the six degrees of freedom of the measured object.
[0015] To make the above-mentioned features and advantages of the invention more apparent and understandable, specific embodiments are described below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the six-degree-of-freedom optical measurement system in this invention.
[0017] Figure 2 This is the optical path diagram of the six-degree-of-freedom optical measurement system in this invention. Figure label: Light source-1; Collimator-11; First polarizing beam splitter-2; First wave of film -3; First pyramidal reflective target-4; First beam splitter-41; First pyramidal prism-42; Second wave of film -5; Second pyramidal reflector target-6; Second beam splitter-61; Second pyramidal prism-62; First right-angle prism-7; First detection module-8; Second right-angle prism-81; First beam splitter-82; First detector-83; Third right-angle prism-84; Second beam splitter-85; Second detector-86; Fourth right-angle prism-87; Third beam splitter-88; Third detector-89; Second detection module-9; Third waveplate-91; Second polarization beam splitter-92; First position sensitive detector-93; Second position sensitive detector-94. Detailed Implementation
[0018] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0020] It should be understood that although the terms "first," "second," etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.
[0021] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the actual number, shape and size of the components, the form, quantity and proportion of each component can be arbitrarily changed in actual implementation, and the layout of the components may also be more complex.
[0022] like Figure 1 The six-degree-of-freedom optical measurement system shown includes a light source 1, which emits a laser X. The laser X is reflected by the first polarizing beam splitter 2 to form a first reference light A1 (see...). Figure 2 ), and transmits to form the first measurement light B1 (see Figure 2 The first reference beam A1 passes through the first waveplate 3 and is reflected by the first pyramidal reflective target 4 to form multiple beams of second reference beam A2 (see...). Figure 2 The second reference light A2 passes through the first waveplate 3 and enters the first polarizing beam splitter 2; the first measurement light B1 passes through the second waveplate 5 and is reflected by the second pyramidal reflective target 6 to form multiple beams of second measurement light B2 and third measurement light B3 (see...). Figure 2 The second measuring light B2 passes through the first waveplate 3 and enters the first polarizing beam splitter 2; the second reference light A2 and the second measuring light B2 are combined to form interference light C (see...). Figure 2The interference light C enters the first detection module 8 to obtain the X-axis displacement, pitch angle, and yaw angle of the second pyramidal reflective target 6; the third measurement light B3 is reflected by the first right-angle prism 7 into the second detection module 9 to obtain the Y-axis displacement, Z-axis displacement, and roll angle of the second pyramidal reflective target 6.
[0023] It is worth noting that the second pyramidal reflective target 6 is mounted on the object under test. The system obtains the six degrees of freedom data of the object under test by measuring the displacement and attitude of the second pyramidal reflective target 6. All other components are fixedly mounted on the six-degree-of-freedom optical measurement system.
[0024] The light source 1 generates a monochromatic laser X with a stable frequency and is equipped with a collimator 11 so that the laser X is focused and collimated by the collimator 11 before being emitted.
[0025] The first waveplate 3 and the second waveplate 5 are quarter-wave plates used to change the polarization state of light.
[0026] The first pyramidal reflective target 4 includes a first beam splitter 41 and a first pyramidal prism 42. After the first reference light A1 passes through the first waveplate 3, it first enters the first beam splitter 41 to form multiple second reference lights A2. The multiple second reference lights A2 are reflected by the first pyramidal prism 42 and then pass through the first beam splitter 41.
[0027] Similarly, the second pyramidal reflective target 6 includes a second beam splitter 61 and a second pyramidal prism 62. After the first measuring light B1 passes through the second waveplate 5, it first enters the second beam splitter 61 to form multiple beams of the second measuring light B2 and the third measuring light B3, which are then reflected by the second pyramidal prism 62 and pass through the second beam splitter 61.
[0028] Preferably, both the first beam splitter 41 and the second beam splitter 61 are four-beam splitters, used to split the single beam of the first reference beam A1 into four beams of second reference beam A2, and to split the first measurement beam B1 into three beams of second measurement beam B2 and one beam of third measurement beam B3. The second reference beams A2 are parallel and have equal intensity, and the second measurement beams B2 and the third measurement beam B3 are parallel and have equal intensity.
[0029] The second reference light A2 and the second measurement light B2 are combined at the first polarizing beam splitter 2 to form interference light C. One pair of interference lights C is reflected by the second right-angle prism 81, passes through the first beam splitter 82, and enters the first detector 83. Another pair of interference lights C is reflected by the third right-angle prism 84, passes through the second beam splitter 85, and enters the second detector 86. A third pair of interference lights C is reflected by the fourth right-angle prism 87, passes through the third beam splitter 88, and enters the third detector 89. The first detector 83, the second detector 86, and the third detector 89 are all illuminated to form measurement light spots. The interference signals of the interference lights C are collected, and the X-axis displacement is calculated. The pitch angle and yaw angle can be calculated based on the X-axis displacement and the tangent of the distance between the light spots of each pair of interference lights C.
[0030] The third measuring light B3, after being reflected by the first right-angle prism 7, sequentially enters the third waveplate 91 and the second polarizing beam splitter 92. A portion of the third measuring light B3 passes through the second polarizing beam splitter 92 and enters the first position-sensitive detector 93, while another portion is reflected by the second polarizing beam splitter 92 and enters the second position-sensitive detector 94. Both the first and second position-sensitive detectors 93 and 94 receive the third measuring light B3 to form light spots, collecting the position and intensity signals of these spots to read the Y-axis and Z-axis displacements and calculate the roll angle. Specifically, the intensity of the light spots on the first and second position-sensitive detectors 93 and 94 is read. I 1 and I 2 ,according to I 1 =I 0 cos 2 θ , I 2 =I 0 sin 2 θ Calculate the roll angle θ ,in I 0 The initial light intensity.
[0031] Preferably, the third measuring light B3 is divided into two beams of light with mutually perpendicular polarization states by the second polarizing beam splitter 92.
[0032] The third waveplate 91 is a quarter-wave plate.
[0033] In summary, this invention provides a six-degree-of-freedom optical measurement system. It uses a single-beam laser to split the reference beam and the measurement beam. The reference beam is split into multiple paths by a first pyramidal reflective target, and the measurement beam is split into multiple paths by a second pyramidal reflective target. The multiple measurement beams and the reference beam are used to interferometrically calculate the X-axis displacement, pitch angle, and yaw angle. One measurement beam is used to detect and calculate the Y-axis displacement, Z-axis displacement, and roll angle, thereby achieving synchronous and high-precision measurement of the six degrees of freedom of the measured object.
[0034] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
Claims
1. A six-degree-of-freedom optical measurement system, characterized in that, include, A light source that emits laser light; The first polarizing beam splitter reflects the laser light to form a first reference light and transmits it to form a first measurement light. The first pyramidal reflective target reflects the first reference light to form multiple second reference lights, which are then incident on the first polarizing beam splitter. The second pyramidal reflective target reflects the first measurement light to form multiple second and third measurement lights. The second measurement light passes through the first waveplate and enters the first polarizing beam splitter. The second reference light and the second measurement light are combined to form interference light. The first detection module, wherein the interference light enters the first detection module, is used to obtain the X-axis displacement, pitch angle and yaw angle of the second pyramidal reflective target; A first right-angle prism reflects the third measuring light; The second detection module receives the third measuring light, which is used to obtain the Y-axis displacement, Z-axis displacement, and roll angle of the second pyramidal reflective target.
2. The six-degree-of-freedom optical measurement system as described in claim 1, characterized in that, The first cornerstone reflective target includes a first beam splitter and a first cornerstone prism. The first reference light enters the first beam splitter to form multiple second reference lights. The multiple second reference lights are reflected by the first cornerstone prism and pass through the first beam splitter.
3. The six-degree-of-freedom optical measurement system as described in claim 2, characterized in that, The second cornerstone reflective target includes a second beam splitter and a second cornerstone prism. The first measurement light enters the second beam splitter to form multiple beams of the second measurement light and the third measurement light, which are reflected by the second cornerstone prism and pass through the second beam splitter.
4. The six-degree-of-freedom optical measurement system as described in claim 3, characterized in that, The first beam splitter and the second beam splitter are selected as one-to-four beam splitters.
5. The six-degree-of-freedom optical measurement system as described in claim 1, characterized in that, The first detection module includes a second right-angle prism, a first beam splitter, a first detector, a third right-angle prism, a second beam splitter, a second detector, a fourth right-angle prism, a third beam splitter, and a third detector. A pair of interfering beams are reflected by the second right-angle prism, pass through the first beam splitter, and enter the first detector. A pair of interfering beams are reflected by the third right-angle prism, pass through the second beam splitter, and enter the second detector; A pair of interfering beams are reflected by the fourth right-angle prism, pass through the third beam splitter, and enter the third detector. The first detector, the second detector, and the third detector all collect the interference signal and calculate the X-axis displacement. The pitch angle and yaw angle are calculated based on the X-axis displacement and the tangent of the distance between the beams of the two interfering beams.
6. The six-degree-of-freedom optical measurement system as described in claim 1, characterized in that, The second detection module includes a third waveplate, a second polarizing beam splitter, a first position-sensitive detector, and a second position-sensitive detector. The third measurement light is sequentially incident on the third waveplate and the second polarizing beam splitter. A portion of the third measurement light passes through the second polarizing beam splitter and enters the first position-sensitive detector, while another portion of the third measurement light is reflected by the second polarizing beam splitter and enters the second position-sensitive detector. Both the first position-sensitive detector and the second position-sensitive detector collect position signals and light intensity signals to calculate the Y-axis displacement, Z-axis displacement, and roll angle.
7. The six-degree-of-freedom optical measurement system as described in claim 1, characterized in that, It also includes a first wave plate, through which the first reference light passes after exiting the first polarizing beam splitter, passes through the first wave plate, and enters the first pyramidal reflective target.
8. The six-degree-of-freedom optical measurement system as described in claim 1, characterized in that, It also includes a second wave plate, through which the first measuring light passes from the first polarizing beam splitter, passes through the second wave plate, and enters the second pyramidal reflective target.
9. A six-degree-of-freedom optical measurement system as described in claim 1, characterized in that, The light source is equipped with a collimator, and the laser is emitted after being collimated by the collimator.