阅读说明：本技术 电光调制激光干涉线位移及角位移测量装置和方法 (Electro-optical modulation laser interference linear displacement and angular displacement measuring device and method ) 是由 黄腾超 王先帆 车双良 舒晓武 于 2020-11-25 设计创作，主要内容包括：本发明公开了一种电光调制激光干涉线位移及角位移测量装置和方法,属于精密测量领域。该装置包括一个单频He-Ne激光器、一个电光相位调制器、三个光电探测器、两个测量角锥反射镜以及若干光学元件,单频He-Ne激光器用于产生及发射线偏振光,电光相位调制器给参考激光信号相位调制,一个光电探测器探测参考激光干涉信号,另外两个光电探测器分别探测由两个测量角锥反射镜得到的两个测量干涉信号,若干光学元件用于控制激光传输方向和偏振态,通过解调技术得到参考干涉信号和测量干涉信号的相位,继而分别得到两个测量干涉信号与参考干涉信号的相位差,即可得到对应的线位移和角位移。(The invention discloses an electro-optic modulation laser interference linear displacement and angular displacement measuring device and method, and belongs to the field of precision measurement. The device comprises a single-frequency He-Ne laser, an electro-optic phase modulator, three photoelectric detectors, two measuring pyramid reflectors and a plurality of optical elements, wherein the single-frequency He-Ne laser is used for generating and emitting linearly polarized light, the electro-optic phase modulator is used for modulating the phase of a reference laser signal, one photoelectric detector is used for detecting the reference laser interference signal, the other two photoelectric detectors are used for respectively detecting two measuring interference signals obtained by the two measuring pyramid reflectors, the plurality of optical elements are used for controlling the laser transmission direction and the polarization state, the phase of the reference interference signal and the phase of the measuring interference signal are obtained through a demodulation technology, then the phase difference of the two measuring interference signals and the phase difference of the reference interference signal are respectively obtained, and the corresponding linear displacement and angular displacement can be obtained.)

1. The measuring device is characterized by comprising a single-frequency He-Ne laser (1), a half wave plate (2), a first beam splitting cube (3), an electro-optic phase modulator (4), a second beam splitting cube (5), a reference pyramid reflector (6), a third beam splitting cube (7), a fourth beam splitting cube (8), a first photoelectric detector (9), a first polarization beam splitting cube (10), a reflector (11), a first measurement pyramid reflector (12), a second measurement pyramid reflector (13), a second polarization beam splitting cube (14), a second photoelectric detector (15) and a third photoelectric detector (16); the light beam emitted by the single-frequency He-Ne laser (1) is linearly polarized in the vertical direction, passes through a half wave plate (2) with a rotation angle of 22.5 degrees, the linearly polarized light is changed into 45 degrees with the vertical direction from the vertical direction, under the light splitting action of a first beam splitting cube (3), 50% of laser light is reflected to enter an electro-optic phase modulator (4), the modulated laser light is transmitted through a second beam splitting cube (5) and is reflected by a reference pyramid reflecting mirror (6), the reflected laser light is transmitted from the first beam splitting cube (3) to a second polarization beam splitting cube (14), the laser light of a horizontal component is reflected to irradiate onto a second photoelectric detector (15), and the laser light of a vertical component is transmitted to irradiate onto a third photoelectric detector (16); the modulated laser light reflected by the second beam splitting cube (5) is reflected by the fourth beam splitting cube (8) and irradiates a first photoelectric detector (9); 50% of the laser light transmitted by the first beam splitter cube (3) is acted on by the third beam splitter cube (7), wherein 50% of the laser light is reflected and transmitted to the fourth beam splitter cube (8) and then irradiates the first photodetector (9); the linearly polarized light of 45 degrees transmitted by the third beam splitting cube (7) is irradiated on the first polarization beam splitting cube (10), the linearly polarized light component in the horizontal direction is transmitted and then irradiated on the first measuring pyramid reflecting mirror (12), the reflected light is transmitted by the first polarization beam splitting cube (10), reflected by the first beam splitting cube (3), transmitted by the second polarization beam splitting cube (14) and finally irradiated on the third photoelectric detector (16) in sequence; under the action of the first polarization beam splitting cube (10), linearly polarized light components in the vertical direction are reflected by the first polarization beam splitting cube (10) and the reflecting mirror (11) and irradiate on the second measuring pyramid reflecting mirror (13), the reflected light is reflected by the reflecting mirror (11) in sequence, reflected by the first polarization beam splitting cube (10), reflected by the first beam splitting cube (3) and reflected by the second polarization beam splitting cube (14) finally irradiate on the second photoelectric detector (15).

2. The device according to claim 1, wherein the signal measured by the first photodetector (9) is a reference laser interference signal, and the two laser beams participating in interference are reflected by the second beam splitting cube (5) and the third beam splitting cube (7), and then merged and interfered in the fourth beam splitting cube (8); the signal measured by the second photoelectric detector (15) is a measuring laser interference signal, two beams of laser participating in interference are respectively reflected by the reference pyramid reflector (6) and the first measuring pyramid reflector (12), and then are converged and interfered on the reflecting surface of the second polarization beam splitting cube (14); the signal measured by the third photoelectric detector (16) is a measuring laser interference signal, two beams of laser participating in interference are respectively reflected by the reference pyramid reflector (6) and the first measuring pyramid reflector (12), and then are transmitted through the second polarization beam splitting cube (14) to be converged and interfered.

3. The device according to claim 1, characterized in that the electro-optical phase modulator (4) is rotated 45 degrees around its pass-light axis such that the crystal principal axis of the electro-optical phase modulator coincides with the laser polarization direction.

4. A method for electro-optically modulated laser interferometric linear and angular displacement measurement using the apparatus of claim 1, comprising the steps of:

step 1: the device is installed and adjusted according to a laser transmission path, a first measuring pyramid reflector (12) and a second measuring pyramid reflector (13) are fixed together and are installed on a multi-dimensional motion platform capable of supporting linear motion and angular motion, and a single-frequency He-Ne laser (1), an electro-optical phase modulator (4), a first photoelectric detector (9), a second photoelectric detector (15), a third photoelectric detector (16) and other optical elements are fixed after being adjusted;

step 2: applying a modulation voltage to the electro-optical phase modulator (4), and respectively acquiring laser interference signals from a first photoelectric detector (9), a second photoelectric detector (15) and a third photoelectric detector (16), wherein at the moment, after low-pass filtering, a reference interference signal acquired by the first photoelectric detector (9) is represented as:

wherein the content of the first and second substances,λrepresents the wavelength of a single-frequency He-Ne laser (1),L ₃₇ is the distance between the first beam splitter cube (3) and the third beam splitter cube (7),L ₇₈ is the distance between the third beam splitter cube (7) and the fourth beam splitter cube (8),L ₃₅ is the distance between the first beam-splitting cube (3) and the second beam-splitting cube (5),L ₅₈ is the distance between the second beam-splitting cube (5) and the fourth beam-splitting cube (8),j _EOM representing the phase of an electro-optical phase modulator (4),j _EOM is recorded asw _c ；

After low-pass filtering, the measurement laser interference signal acquired by the second photoelectric detector (15) is expressed as:

wherein the content of the first and second substances,L ₃₁₀ is the distance between the first beam splitting cube (3) and the first polarizing beam splitting cube (10),L ₁₀₁₂ is the distance between the first polarizing beam splitting cube (10) and the first measurement cube corner mirror (12),d ₁ for the displacement of the first measurement cube-corner mirror (12),L ₃₆ is the distance between the first beam splitter cube (3) and the reference pyramid reflector (6),j _EOM representing the phase of an electro-optical phase modulator (4);

after low-pass filtering, the measurement laser interference signal acquired by the third photoelectric detector (16) is expressed as:

wherein the content of the first and second substances,L ₃₁₀ is the distance between the first beam splitting cube (3) and the first polarizing beam splitting cube (10),L ₁₀₁₂ is the distance between the first polarizing beam splitting cube (10) and the first measurement cube corner mirror (12),d ₂ for the displacement of the second measurement cube-corner mirror (13),L ₃₆ is the distance between the first beam splitter cube (3) and the reference pyramid reflector (6),j _EOM representing the phase of an electro-optical phase modulator (4);

and step 3: by modulating the fundamental frequency of the frequencyw _c And frequency doubling 2 of the modulation frequencyw _c The phase changes generated by the movement of the first measuring pyramid reflector (12) and the second measuring pyramid reflector (13) can be obtained by multiplying two measuring laser interference signals and filtering the signals, and are respectively marked as∆j _m1 And∆j _m2 and calculating to obtain the displacement of the pyramid reflector, which is respectively as follows:

in addition, the reference laser interference signal acquired by the first photoelectric detector (9) is subjected to Fourier transform, and the modulation frequency can be obtainedw _c 。

Technical Field

The invention relates to the field of linear displacement and angular displacement measurement, in particular to a device and a method for measuring linear displacement and angular displacement by using electro-optic modulation laser interference.

Background

The continuous development and perfection of the precision machining and manufacturing industry require the continuous improvement of the precision of the measurement technology and the device, and the laser interference technology applies the main technical implementation means to the field of high-precision measurement. The laser interferometer is an important means for performing high-precision measurement by taking laser wavelength as a length reference, and has the advantages of high measurement precision, traceability and the like. According to the working principle of laser interferometers, the laser interferometers are mainly divided into two categories, namely homodyne laser interferometers and heterodyne laser interferometers.

For a zero-difference laser interferometer, a typical laser optical path structure is a michelson interferometer, a beam splitter is adopted to divide a laser beam emitted by a single-frequency He-Ne laser into a reference laser beam and a measurement laser beam, the reference laser beam and the measurement laser beam are respectively emitted to a reference reflector and a measurement reflector, the reflected reference laser beam and the reflected measurement laser beam are interfered on the beam splitter, interference signals are detected by a photoelectric detector, and the displacement of the measurement reflector can be obtained by demodulating light intensity information of the detector. The optical path of the homodyne laser interferometer is simple, the signal processing is convenient, however, because the bandwidth of the photoelectric detector is limited, the interference signal detected by the photoelectric detector is a direct current signal, the anti-interference capability of the interference signal is weak, and the interference signal is easily interfered by the environment.

The heterodyne laser interferometer has two forms, one is a double-frequency He-Ne laser based on the Zeeman effect, under the action of an external magnetic field, the laser can emit two laser beams with different frequencies and orthogonal polarization directions, a reference laser interference signal and a measurement laser interference signal are respectively obtained by utilizing devices such as a beam splitter, a polarization beam splitter, a pyramid reflector and the like, and information such as displacement of an object to be measured is obtained by a phase meter; the other method is to adopt an acousto-optic frequency shifter, divide a laser beam emitted by a common single-frequency He-Ne laser into two beams by a spectroscope, wherein the laser frequency of one beam of laser changes after passing through the acousto-optic frequency shifter, a reference laser interference signal and a measurement laser interference signal are obtained through heterodyne detection, and information such as the displacement of an object to be measured can be obtained by comparing the frequency difference of the two interference signals. Compared with a homodyne interferometer, an interference signal obtained by the heterodyne interferometer is an alternating-current signal, and the homodyne interferometer has the advantages of high precision, strong anti-interference capability and the like, however, the heterodyne interferometer can introduce a periodic nonlinear error into a measurement result due to the adoption of a polarization component, in addition, the price of the double-frequency He-Ne laser and the acousto-optic frequency shifter is higher, and the development and production cost of the heterodyne laser interferometer is higher.

In order to make up for the defects of homodyne interferometers and heterodyne interferometers, researchers have subsequently proposed a phase modulation laser interferometer, which superimposes a reference signal and a measurement signal of the laser interferometer on a carrier wave of modulation frequency by adjusting an optical path difference or a phase difference of a reference arm of the laser interferometer by adopting a piezoelectric ceramic (PZT) or an electro-optical phase modulator (EOM), so that an interference signal detected by the laser interferometer is an alternating current signal, and the anti-interference capability of the interference interferometer is improved. However, the current phase modulation laser interferometer is only used for displacement measurement and cannot meet the requirements of angular displacement measurement and simultaneous measurement of linear displacement and angular displacement.

Disclosure of Invention

The invention aims to provide an electro-optical modulation laser interference linear displacement and angular displacement measuring device and method aiming at the defects of the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the utility model provides an electro-optical modulation laser interference linear displacement and angle displacement measuring device:

the measuring device comprises a single-frequency He-Ne laser, a half wave plate, a first beam splitting cube, an electro-optic phase modulator, a second beam splitting cube, a reference pyramid reflector, a third beam splitting cube, a fourth beam splitting cube, a first photoelectric detector, a first polarization beam splitting cube, a reflector, a first measuring pyramid reflector, a second polarization beam splitting cube, a second photoelectric detector and a third photoelectric detector. The light beam emitted by the single-frequency He-Ne laser is linearly polarized in the vertical direction, the linearly polarized light passes through a half wave plate with a rotation angle of 22.5 degrees, the angle of 45 degrees is changed from the vertical direction to the vertical direction, under the light splitting action of the first beam splitting cube, 50% of laser light is reflected to enter the electro-optic phase modulator, the modulated laser light is transmitted through the second beam splitting cube and is reflected by the reference pyramid reflector, the reflected laser light is transmitted through the first beam splitting cube, under the action of the second polarization beam splitting cube, the laser light with the component in the horizontal direction is reflected to irradiate the second photoelectric detector, and the laser light with the component in the vertical direction is transmitted to irradiate the third photoelectric detector; the modulated laser reflected by the second beam splitting cube is reflected by the fourth beam splitting cube and then irradiates the first photoelectric detector; 50% of laser light transmitted by the first beam splitting cube is under the action of the third beam splitting cube, wherein 50% of laser light is reflected and transmitted to the fourth beam splitting cube and then irradiates the first photodetector; the 45-degree linearly polarized light transmitted by the third beam splitting cube irradiates on the first polarization beam splitting cube, the linearly polarized light component in the horizontal direction transmits and then irradiates on the first measuring pyramid reflector, and the reflected light sequentially passes through the transmission of the first polarization beam splitting cube, the reflection of the first beam splitting cube, the transmission of the second polarization beam splitting cube and finally irradiates on the third photoelectric detector; under the action of the first polarization beam splitting cube, linearly polarized light components in the vertical direction are reflected by the first polarization beam splitting cube and the reflecting mirror and irradiate onto the second measuring pyramid reflecting mirror, and the reflected light sequentially passes through the reflection of the reflecting mirror, the reflection of the first polarization beam splitting cube, the reflection of the first beam splitting cube and the second polarization beam splitting cube and finally irradiates onto the second photoelectric detector.

The signal detected by the first photoelectric detector is a reference laser interference signal, two beams of laser participating in interference are respectively reflected by the second beam splitting cube and the third beam splitting cube, and then are converged and interfered in the fourth beam splitting cube; the signal measured by the second photoelectric detector is a measuring laser interference signal, two beams of laser participating in interference are reflected by the reference pyramid reflector and the first measuring pyramid reflector respectively, and then are converged and interfered on the reflecting surface of the second polarization beam splitting cube; the signal measured by the third photoelectric detector is a measuring laser interference signal, and two beams of laser participating in interference are reflected by the reference pyramid reflector and the first measuring pyramid reflector respectively and then transmitted through the second polarization beam splitting cube to converge and interfere.

The electro-optical phase modulator rotates 45 degrees around the light passing axis of the electro-optical phase modulator, so that the crystal main axis of the electro-optical phase modulator is consistent with the polarization direction of laser.

Secondly, an electro-optic modulation laser interference linear displacement and angular displacement measuring method comprises the following steps:

step 1: the electro-optic modulation laser interference linear displacement and angular displacement measuring device is installed and adjusted according to a laser transmission path, a first measuring pyramid reflector and a second measuring pyramid reflector are fixed together and are installed on a multi-dimensional moving platform capable of supporting linear movement and angular movement, and a single-frequency He-Ne laser, an electro-optic phase modulator, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector and other optical elements are fixed after being adjusted.

Step 2: applying modulation voltage to the electro-optic phase modulator, respectively obtaining laser interference signals from the first photoelectric detector, the second photoelectric detector and the third photoelectric detector, wherein at the moment, after low-pass filtering, reference interference signals obtained by the first photoelectric detector are represented as:

wherein λ represents the wavelength of a single-frequency He-Ne laser, L₃₇Is the distance between the first and third beam-splitting cubes, L₇₈Is the distance between the third and fourth beam-splitting cubes, L₃₅Is the distance, L, between the first and second beam-splitting cubes₅₈Between the second and fourth beam-splitting cubesThe distance between the first and second electrodes,representing the phase of the electro-optic phase modulator.

After low-pass filtering, the measurement interference signal obtained by the second photodetector is expressed as:

wherein L is₃₁₀Is the distance, L, between the first beam-splitting cube and the first polarizing beam-splitting cube₁₀₁₂Is the distance between the first polarizing beam splitting cube and the first measurement cube corner mirror, d₁For the first measurement of the displacement of the cube-corner mirror, L₃₆The distance between the first beam splitter cube and the reference cube corner,representing the phase of the electro-optic phase modulator.

After low-pass filtering, the measurement interference signal obtained by the third photodetector is expressed as:

wherein L is₃₁₀Is the distance, L, between the first beam-splitting cube and the first polarizing beam-splitting cube₁₀₁₂Is the distance between the first polarizing beam splitting cube and the first measurement cube corner mirror, d₂For the second measurement of the displacement of the cube-corner mirror, L₃₆The distance between the first beam splitter cube and the reference cube corner,representing the phase of the electro-optic phase modulator.

And step 3: the motion of the first and second measurement cube-corner mirrors can be derived by phase demodulation techniquesPhase change, respectivelyAndtherefore, the displacement of the pyramid reflector can be calculated and obtained, which respectively comprises the following steps:

in addition, in order to ensure the accuracy of the phase demodulation result, the modulation frequency ω of the precise feedback electro-optical phase modulator is required_c The reference interference signal acquired by the first photoelectric detector is subjected to Fourier transform, and the modulation frequency omega can be extracted_c。

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention adopts the electro-optic phase modulation laser interference technology to modulate the phase of the reference laser light path, and loads the reference laser interference signal and the measurement laser interference signal on the carrier wave of the electro-optic phase modulation, so that the reference laser interference signal and the measurement laser interference signal are changed into alternating current signals, thereby improving the anti-interference capability of the laser interferometer and ensuring the measurement precision of the laser interferometer.

(2) The device adopts three photoelectric detectors and two measuring pyramid reflectors, wherein one photoelectric detector receives a reference laser interference signal and accurately obtains the modulation frequency of the electro-optic phase modulator loaded in a light path of a laser interferometer, and further, the two photoelectric detectors respectively obtain measuring laser interference signals obtained by the two measuring pyramid reflectors and obtain displacement information of the measuring laser interference signals through a signal demodulation technology, and the device can realize the simultaneous measurement of linear displacement and angular displacement by comparing the displacements of the two measuring pyramid reflectors.

(3) The laser optical path structure adopted by the invention is designed as a quasi-common optical path, namely, the measurement laser interference signal detected by the second photoelectric detector and the measurement laser interference signal detected by the third photoelectric detector are respectively obtained by converging and interfering the laser returned by the reference pyramid reflector and the laser returned by the measurement pyramid reflector, and the optical paths of the measurement laser interference signal and the reference pyramid reflector are only different from the optical path between the first polarization beam splitting cube and the reflector, so that the influence of the temperature and humidity change in the environment on the interference signal can be reduced, and the accuracy of the measurement signal is improved.

(4) The invention adopts the single-frequency He-Ne laser and the electro-optic phase modulator, and has lower cost compared with a heterodyne double-frequency laser interferometer.

Drawings

FIG. 1 is a schematic diagram of an electro-optically modulated laser interferometric linear and angular displacement measuring device according to the present invention.

FIG. 2 is a schematic diagram of an experimental device for calibrating the transverse displacement of a rotary table by using the electro-optically modulated laser interference linear displacement and angular displacement measuring device of the invention.

FIG. 3 is a schematic diagram of an experimental device for calibrating the angular displacement of a turntable by using the electro-optically modulated laser interference linear displacement and angular displacement measuring device of the present invention.

In the figure: He-Ne laser 1, a half wave plate 2, a first beam splitting cube 3, an electro-optic phase modulator 4, a second beam splitting cube 5, a reference pyramid reflector 6, a third beam splitting cube 7, a fourth beam splitting cube 8, a first photodetector 9, a first polarization beam splitting cube 10, a reflector 11, a first measurement pyramid reflector 12, a second measurement pyramid reflector 13, a second polarization beam splitting cube 14, a second photodetector 15, a third photodetector 16, an electro-optic modulation laser interference part 17, an upper computer 18, a pyramid reflector part 19 and a turntable 20 to be measured.

Detailed Description

The invention is further illustrated below with reference to the figures and examples.

As shown in fig. 1, an electro-optically modulated laser interference linear displacement and angular displacement measuring device includes a He-Ne laser 1, a half wave plate 2, a first beam splitting cube 3, an electro-optically phase modulator 4, a second beam splitting cube 5, a reference pyramid reflector 6, a third beam splitting cube 7, a fourth beam splitting cube 8, a first photodetector 9, a first polarization beam splitting cube 10, a reflector 11, a first measurement pyramid reflector 12, a second measurement pyramid reflector 13, a second polarization beam splitting cube 14, a second photodetector 15, and a third photodetector 16. The light beam emitted by the single-frequency He-Ne laser 1 is linearly polarized in the vertical direction, the linearly polarized light passes through the half wave plate 2 with the rotation angle of 22.5 degrees, the angle between the linearly polarized light and the vertical direction is changed to 45 degrees, 50% of laser light is reflected to enter the electro-optic phase modulator 4 under the light splitting action of the first beam splitting cube 3, the modulated laser light is transmitted through the second beam splitting cube 5 and reflected by the reference pyramid reflecting mirror 6, the reflected laser light is transmitted through the first beam splitting cube 3, the laser light of the horizontal direction component is reflected to irradiate onto the second photoelectric detector 15 under the action of the second polarization beam splitting cube 14, and the laser light of the vertical direction component is transmitted to irradiate onto the third photoelectric detector 16; the modulated laser light reflected by the second beam splitting cube 5 is reflected by the fourth beam splitting cube 8 and then irradiates on the first photoelectric detector 9; 50% of the laser light transmitted by the first beam splitter cube 3 is acted by the third beam splitter cube 7, wherein 50% of the laser light is reflected and transmitted to the fourth beam splitter cube 8 and then irradiates the first photodetector 9; the 45-degree linearly polarized light transmitted through the third beam splitting cube 7 is irradiated on the first polarization beam splitting cube 10, the linearly polarized light component in the horizontal direction is transmitted and then irradiated on the first measuring pyramid reflecting mirror 12, and the reflected light is sequentially transmitted through the first polarization beam splitting cube 10, reflected by the first beam splitting cube 3, transmitted by the second polarization beam splitting cube 14 and finally irradiated on the third photodetector 16; under the action of the first polarizing beam splitting cube 10, the linearly polarized light component in the vertical direction is reflected by the first polarizing beam splitting cube 10 and the reflecting mirror 11 and is irradiated onto the second measuring pyramid reflecting mirror 13, and the reflected light is reflected by the reflecting mirror 11, the first polarizing beam splitting cube 10, the first beam splitting cube 3 and the second polarizing beam splitting cube 14 in sequence and is finally irradiated onto the second photodetector 15.

The signal measured by the first photoelectric detector 9 is a reference interference signal, two beams of laser participating in interference are respectively reflected by the second beam splitting cube 5 and the third beam splitting cube 7, and then are converged and interfered in the fourth beam splitting cube 8; the signal measured by the second photodetector 15 is a measurement interference signal, and two beams of laser beams participating in interference are reflected by the reference pyramid reflector 6 and the first measurement pyramid reflector 12 respectively and then are converged and interfered on the reflecting surface of the second polarization beam splitter cube 14; the signal measured by the third photodetector 16 is a measurement interference signal, and two beams of laser participating in interference are respectively reflected by the reference pyramid reflector 6 and the first measurement pyramid reflector 13, and then transmitted through the second polarization beam splitter cube 14 to be converged and interfered;

the electro-optical phase modulator 4 rotates 45 degrees around the light passing axis thereof, so that the crystal main axis of the electro-optical phase modulator is consistent with the polarization direction of the laser.

As shown in fig. 2, the apparatus used comprises: the single-frequency He-Ne laser device comprises a single-frequency He-Ne laser device 1, a first photoelectric detector 9, a second photoelectric detector 15, a third photoelectric detector 16, an electro-optical modulation laser interference part 17, an upper computer 18, a pyramid reflector part 19 and a turntable 20 to be tested, wherein the electro-optical modulation laser interference part 17 comprises a half wave plate 2, a first beam splitter cube 3, an electro-optical phase modulator 4, a second beam splitter cube 5, a reference pyramid reflector 6, a third beam splitter cube 7, a fourth beam splitter cube 8, a first polarization beam splitter cube 10 and a reflector 11, the pyramid reflector part comprises a first measurement pyramid reflector 12 and a second measurement pyramid reflector 13, during the actual rotation of the turntable, the rotating shaft cannot be guaranteed to rotate around the rotating shaft of the rotating shaft at any moment, and under the action of inertia moment, the rotating shaft has a swinging movement tendency to cause the rotation of the turntable to rotate, the table top can move transversely, the transverse displacement can reflect the quality of the turntable development to a certain extent and can also influence the measurement precision of the turntable, therefore, during the working process of the rotary table, the simultaneous measurement of the angular displacement and the transverse displacement of the rotary table is absolutely necessary, in this embodiment, the pyramid reflector part 19 is fixed on the top of the turntable 20 to be measured, and aligned with the electro-optically modulated laser interference part 17, the single-frequency He-Ne laser 1 is turned on and waits for a period of time to stabilize the laser frequency and power, the first photodetector 9, the second photodetector 15, and the third photodetector 16 are connected to the upper computer 18 via a data acquisition card, and laser interference signals are respectively acquired from the first photodetector 9, the second photodetector 15, and the third photodetector 16, at this time, after low-pass filtering, the reference interference signal obtained by the first photodetector 9 is represented as:

wherein λ represents the wavelength of the single-frequency He-Ne laser 1, L₃₇Is the distance, L, between the first and third beam-splitting cubes 3, 7₇₈Is the distance between the third and fourth beam-splitting cubes 7, 8, L₃₅Is the distance, L, between the first beam-splitting cube 3 and the second beam-splitting cube 5₅₈The distance between the second and fourth beam-splitting cubes 5, 8,the phase of the electro-optical phase modulator 4 is shown.

After low-pass filtering, the measured interference signal obtained by the second photodetector 15 is represented as:

wherein L is₃₁₀Is the distance, L, between the first beam-splitting cube 3 and the first polarizing beam-splitting cube 10₁₀₁₂Is the distance, d, between the first polarizing beam splitting cube 10 and the first measurement cube corner 12₁Is the displacement, L, of the first measurement cube-corner mirror 12₃₆The distance between the first beam splitter cube 3 and the reference corner cube 6,the phase of the electro-optical phase modulator 4 is shown.

After low-pass filtering, the measurement interference signal obtained by the third photodetector 16 is represented as:

wherein L is₃₁₀Is the distance, L, between the first beam-splitting cube 3 and the first polarizing beam-splitting cube 10₁₀₁₂Is the distance, d, between the first polarizing beam splitting cube 10 and the first measurement cube corner 12₂Is the displacement, L, of the second measurement cube-corner mirror 13₃₆The distance between the first beam splitter cube 3 and the reference corner cube 6,the phase of the electro-optical phase modulator 4 is shown.

Fourier transform is carried out on the reference laser interference signal obtained by the first photoelectric detector 9 to obtain the modulation frequency omega of the electro-optic phase modulator 4_cThen modulating the fundamental frequency omega of the frequency_cAnd frequency doubling 2 omega_cMixing the signals with the interference signals of the measuring laser received by the second photodetector 15 and the third photodetector 16, and obtaining the phase changes generated by the movement of the first measuring pyramid reflector 12 and the second measuring pyramid reflector 13 through a low-pass filter and a signal demodulation technology, which are respectively recorded asAndfrom this the displacements of the first measurement cube-corner mirror 12 and the second measurement cube-corner mirror 13 can be calculated, respectively:

a linear displacement of the cube-corner mirror segments 19 of (d) is obtained₁+d₂) (ii)/2, the transverse displacement of the turntable 20 to be measured is obtained as (d)₁+d₂)/2。

Meanwhile, the rotation angle of the turntable 20 to be measured can be measured according to the measurement laser interference signals received by the second photodetector 15 and the third photodetector 16, as shown in fig. 3, when the pyramid reflector part 19 rotates along with the turntable 20 to be measured, the displacements of the first measurement pyramid reflector 12 and the second measurement pyramid reflector 13 are calculated according to the reference laser interference signal received by the first photodetector 9 and the measurement laser interference signals received by the second photodetector 15 and the third photodetector 16, which are respectively:

so that the angular displacement of the pyramid mirror part 19 is obtained as (| d)₁|+|d₂L)/(2 l), namely the angle theta of the turntable 20 to be measured is (| d)₁|+|d₂|)/(2l)。

The foregoing lists merely illustrate specific embodiments of the invention. It will be apparent that the present invention is not limited to the above embodiments, but is susceptible to numerous modifications and variations. All modifications and variations that may be apparent to a person skilled in the art from the present disclosure or may be inferred are intended to be within the scope of the present invention. The protection scope of the invention is subject to the claims.