Dynamic performance calibration device and method for signal processing link of heterodyne laser interferometer based on acousto-optic frequency shifter

Abstract

The application relates to a dynamic performance calibration device and method of a heterodyne laser interferometer signal processing link based on an acousto-optic frequency shifter, and belongs to the technical field of dynamic measurement performance calibration of a heterodyne laser interferometer. The calibration method of the existing heterodyne laser interferometer couples Abbe error, cosine error and data period error caused by non-synchronous measurement due to mechanical installation, and brings the problem that the dynamic measurement performance of the signal processing link of the interferometer is difficult to evaluate. The calibration device comprises a laser assembly, a first measurement light path, a second measurement light path, an AOFS drive and motor controller light path and a phase meter; the laser assembly emits laser into a beam splitter prism assembly, the beam splitter prism assembly divides the incident light into two beams of laser which are respectively injected into the first measurement light path and the second measurement light path, and finally sent to the phase meter to calculate the phase difference. The application is suitable for the equivalent calibration device of the dynamic measurement performance of the signal processing link of the heterodyne laser interferometer under target high-speed motion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dynamic measurement performance calibration of heterodyne laser interferometer, in particular to the technical field of equivalent calibration device of dynamic measurement performance of signal processing link of heterodyne laser interferometer under target high-speed motion. BACKGROUND

[0002] Heterodyne laser interferometer has a very wide application in the fields of ultra-precision numerical control machining, microelectronic equipment manufacturing, precision sensor calibration, etc. With the rapid development of these fields, the demand for high speed and high precision of dynamic measurement performance of heterodyne laser interferometer is put forward. As the signal processing link determines the limit measurement performance of heterodyne laser interferometer, the calibration of its dynamic measurement performance is also a new challenge.

[0003] In the dynamic measurement process of heterodyne laser interferometer, mechanical installation and vibration of the target to be measured will introduce Abbe error and cosine error; temperature change, humidity fluctuation and air pressure disturbance caused by high-speed motion of m / s level will introduce air refractive index error; and the measurement time delay of the interferometer will introduce data cycle error. Similarly, these errors still exist in the mainstream calibration method of laser interferometer, and will be coupled into the calibration result, resulting in the inability to calibrate the measurement performance of the signal processing link of the laser interferometer, and further making it difficult to evaluate the limit dynamic measurement performance of the laser interferometer.

[0004] Currently, there are mainly two calibration methods for heterodyne laser interferometer. The first method is to calibrate each part of the heterodyne interferometer, including temperature, humidity, air pressure sensors, optical lens group, stripe counter, light source, etc., respectively, and calculate the calibration result of the overall performance of the interferometer. For example, Calibration of Displacement Laser Interferometer Systems for Industrial Metrology published on Sensor on September 22, 2019, uses a PZT micro displacement stage or a heated aluminum tube to test the limit precision of the counting link of the interferometer. However, this method cannot realize high-speed dynamic calibration, and does not introduce air refractive index error, etc. In 2009, the paper Ultra-precision dynamic laser interferometer signal processing unit standard test platform design was published on June 1. An electrical signal is used to simulate the dynamic motion trajectory of the heterodyne laser interferometer to realize the calibration test of the signal processing unit. However, this method does not support the optical-electric conversion part which is a key part of the signal processing link.

[0005] The second method is to make the interferometer to be calibrated and a high-precision reference interferometer measure the same target on a comparison platform, and determine the performance of the interferometer to be calibrated according to the difference between the measurement results.

[0006] Performance Evaluation of Displacement-Measuring Laser Interferometers describes and analyzes the method in detail. Although this kind of calibration method can evaluate the performance of the interferometer as a whole, the calibration result is coupled with the Abbe error, cosine error caused by mechanical installation, and the data period error caused by non-synchronous measurement, and it is difficult to evaluate the dynamic measurement performance of the signal processing link of the interferometer. SUMMARY

[0007] The present application solves the problem of the calibration method of the existing heterodyne laser interferometer, which is coupled with the Abbe error, cosine error caused by mechanical installation, and the data period error caused by non-synchronous measurement, and it is difficult to evaluate the dynamic measurement performance of the signal processing link of the interferometer.

[0008] To achieve the above-mentioned purpose, the present application provides the following scheme:

[0009] The present application provides a heterodyne laser interferometer signal processing link dynamic performance calibration device based on an acousto-optic frequency shifter, which comprises a laser assembly, a first measurement light path, a second measurement light path, an AOFS drive and motor controller light path, and a phase meter.

[0010] The first measurement light path comprises a first mirror, a first AOFS, a first diaphragm, a first 1 / 2 wave plate, a polarization beam splitter PBS, a polarizer, and a photodetector PD.

[0011] The second measurement light path comprises a beam splitter assembly, a second AOFS, a second diaphragm, a second 1 / 2 wave plate, a second mirror, and a motor.

[0012] The laser assembly is used to emit laser light into the beam splitter assembly, and the beam splitter assembly divides the incident light into two beams of laser light with perpendicular polarization directions and respectively enters the first mirror and the second AOFS.

[0013] The first reflector reflects the incident light into the first AOFS, the first AOFS diffracts the incident light into multi-order diffracted light and emits the multi-order diffracted light into the first diaphragm, the first diaphragm selects the +1 order diffracted light of the multi-order diffracted light and emits the +1 order diffracted light into the first 1 / 2 wave plate, the first 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and emits the +1 order diffracted light into the polarization beam splitter PBS, the polarization beam splitter PBS emits the +1 order diffracted light into the polarizer, the polarizer converts the +1 order diffracted light into beat frequency optical signal and sends the beat frequency optical signal to the photodetector PD, and the photodetector PD converts the beat frequency optical signal into electrical signal and sends the electrical signal to the phase meter;

[0014] The second AOFS diffracts the light beam into multi-order diffracted light and emits the multi-order diffracted light into the second diaphragm, the second diaphragm selects the +1 order diffracted light of the multi-order diffracted light and emits the +1 order diffracted light into the second 1 / 2 wave plate, the second 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and emits the +1 order diffracted light into the second reflector, and the second reflector reflects the +1 order diffracted light into the polarization beam splitter PBS;

[0015] The laser assembly is further configured to provide a reference light signal to the AOFS drive and motor controller optical path;

[0016] The AOFS drive and motor controller optical path is configured to control the driving frequency of the first AOFS and the second AOFS respectively, to control the angle of the second reflector through the motor, and to convert the laser emitted by the laser assembly into a reference electrical signal and send the reference electrical signal to the phase meter;

[0017] The phase meter is configured to calculate the phase difference according to the received electrical signal.

[0018] Further, there is a preferred embodiment, and the laser assembly is implemented by using a dual-frequency laser with a reference light signal;

[0019] The beam splitter assembly is implemented by using a first polarization beam splitter PBS;

[0020] The AOFS drive and motor controller optical path comprises a depolarization beam splitter NPBS, a second photodetector PD, a third photodetector PD, and an AOFS drive and motor controller;

[0021] The dual-frequency laser with a reference light signal emits two laser beams, one of which is emitted into the first polarization beam splitter PBS, and the other of which is emitted into the depolarization beam splitter NPBS, the depolarization beam splitter NPBS divides the incident light into two linearly polarized beams, which are respectively emitted into the second photodetector PD and the third photodetector PD, the second photodetector PD converts the incident light signal into electrical signal and sends the electrical signal to the AOFS drive and motor controller, and the third photodetector PD converts the incident light signal into electrical signal and sends the electrical signal to the phase meter.

[0022] The AOFS driver and motor controller is configured to adjust the driving frequencies of the first and second AOFSs respectively according to the received electrical signals as driving clock, and is configured to control the motor.

[0023] Further, there is another preferred embodiment, the dual-frequency laser with reference light signal emits two coaxial transmission lasers with perpendicular polarization directions and different frequencies.

[0024] Further, there is another preferred embodiment, the laser assembly can also be implemented by a dual-frequency laser without reference light signal;

[0025] The light splitting prism assembly can also be implemented by a first polarization splitting prism PBS;

[0026] The AOFS driver and motor controller optical path comprises a first non-polarization splitting prism NPBS, a second polarizer, a second non-polarization splitting prism NPBS, a second photodetector PD, a third photodetector PD, and an AOFS driver and motor controller;

[0027] The dual-frequency laser without reference light signal emits a laser, which is incident into the first non-polarization splitting prism NPBS, the first non-polarization splitting prism NPBS splits the incident light into two polarized lasers, which are incident into the first polarization splitting prism PBS and the second polarizer respectively, the second polarizer converts the incident light into beat frequency light signal, which is incident into the second non-polarization splitting prism NPBS, the second non-polarization splitting prism NPBS splits the incident light into two linearly polarized lights, which are incident into the second photodetector PD and the third photodetector PD respectively, the second photodetector PD converts the incident light signal into an electrical signal and sends it to the AOFS driver and motor controller, and the third photodetector PD converts the incident light signal into an electrical signal and sends it to the phase meter;

[0028] The AOFS driver and motor controller is configured to adjust the driving frequencies of the first and second AOFSs respectively according to the received electrical signals as driving clock, and is configured to control the motor.

[0029] Further, there is another preferred embodiment, the dual-frequency laser without reference light signal emits two coaxial transmission lasers with perpendicular polarization directions and different frequencies.

[0030] Further, there is another preferred embodiment, the laser assembly can also be implemented by a single-frequency laser;

[0031] The light splitting prism assembly can also be implemented by a second non-polarization splitting prism NPBS;

[0032] The AOFS driving and motor controller circuit comprises a first depolarization beam splitter prism NPBS, a third mirror, a third depolarization beam splitter prism NPBS, a fourth AOFS, a fourth diaphragm, a fourth 1 / 2 wave plate, a fifth mirror, a fourth mirror, a third AOFS, a third diaphragm, a third 1 / 2 wave plate, a second polarization beam splitter PBS, a second polarizer, a second photodetector PD and an AOFS driving and motor controller.

[0033] The single-frequency laser emits a beam of laser light into the first depolarization beam splitter prism NPBS, which divides the incident light into two beams of laser light, which are respectively incident into the second depolarization beam splitter prism NPBS and the third mirror.

[0034] The third mirror reflects the incident light into the third depolarization beam splitter prism NPBS, which divides the incident light into two beams of laser light, which are respectively incident into the fourth mirror and the fourth AOFS. The fourth mirror reflects the incident light into the third AOFS, which diffracts the incident light into a plurality of levels of diffracted light and emits it into the third diaphragm. The third diaphragm selects the +1 level of diffracted light from the plurality of levels of diffracted light and emits it into the third 1 / 2 wave plate. The third 1 / 2 wave plate adjusts the polarization direction of the +1 level of diffracted light and emits it into the second polarization beam splitter PBS. The second polarization beam splitter PBS emits the incident light into the second polarizer, which converts the incident light into a beat frequency optical signal and sends it to the second photodetector PD. The second photodetector PD converts the beat frequency optical signal into an electrical signal and sends it to the phase meter.

[0035] The fourth AOFS diffracts the incident light into a plurality of levels of diffracted light and emits it into the fourth diaphragm. The fourth diaphragm selects the +1 level of diffracted light from the plurality of levels of diffracted light and emits it into the fourth 1 / 2 wave plate. The fourth 1 / 2 wave plate adjusts the polarization direction of the +1 level of diffracted light and emits it into the fifth mirror, which reflects the incident light into the second polarization beam splitter PBS.

[0036] The AOFS driving and motor controller is used to adjust the driving frequencies of the first AOFS, the second AOFS, the third AOFS and the fourth AOFS respectively, and is also used to control the motor.

[0037] Further, there is a preferred embodiment in which the single-frequency laser emits a beam of linearly polarized single-frequency light.

[0038] Further, there is a preferred embodiment in which the depolarization beam splitter prism NPBS divides the incident light into two beams of laser light with the same polarization direction.

[0039] Further, there is a preferred embodiment that the AOFS driver and motor controller are used to set the driving signal frequency of the third AOFS and the fourth AOFS to a fixed value.

[0040] The application also provides a dynamic performance calibration method for a heterodyne laser interferometer signal processing link based on an acousto-optic frequency shifter, and the calibration method is realized by using the dynamic performance calibration device for the heterodyne laser interferometer signal processing link based on the acousto-optic frequency shifter, and the calibration method is as follows:

[0041] S1, pre-measurement: adjust the rotation angles of the first 1 / 2 wave plate and the first 1 / 2 wave plate respectively, so that the rotation direction is perpendicular to the light path direction, adjust the polarization beam splitter PBS, change the optical power of the two laser beams that finally interfere, adjust the rotation angle of the polarizer, so that the rotation direction is perpendicular to the light path direction, adjust the driving frequencies of the first AOFS and the second AOFS respectively, and measure the optical power and AC / DC ratio of the beat frequency optical signal under different beat frequencies, and the optical power and AC / DC ratio of the AOFS driver and motor controller circuit clock;

[0042] S2, measurement initialization: adjust the driving frequencies of the two acousto-optic frequency shifters AOFS in the first measurement light path and the second measurement light path to adjust the beat frequency of the measurement path beat frequency optical signal to a preset value, and adjust the rotation angles of the two 1 / 2 wave plates and the polarizer in the first measurement light path and the second measurement light path to adjust the optical power and AC / DC ratio of the measurement path beat frequency optical signal to a preset value;

[0043] S3, select test points;

[0044] S4, start measurement: simultaneously adjust the driving frequencies of the two AOFS in the first measurement light path and the second measurement light path and the angle of the mirror by using the AOFS driver and motor controller to make the beat frequency of the measurement path beat frequency optical signal reach the test point, adjust the rotation angles of the two 1 / 2 wave plates and the polarizer in the first measurement light path and the second measurement light path to adjust the optical power and AC / DC ratio of the measurement path beat frequency optical signal, use the phase meter to be measured to measure the phase difference between the interference light and the actual simulated phase of the target motion to be measured in real time, and perform dynamic test performance test and calibration of the heterodyne laser interferometer signal processing link.

[0045] The application has the following beneficial effects:

[0046] 1. The application provides a kind of based on acousto-optic frequency shifter heterodyne laser interferometer signal processing link dynamic performance calibration device, by AOFS drive and motor controller simultaneously adjust the frequency of two AOFS drives of first measurement light path and second measurement light path and mirror angle to make the beat frequency of measurement path beat frequency light signal reach test point, adjust the rotation angle of two 1 / 2 wave plate and polarizer of first measurement light path and second measurement light path to adjust the light power and ac / dc ratio of measurement path beat frequency light signal, utilize the phase difference of real-time measurement interference light and actual analog target motion phase of the phase meter to be measured, carry out heterodyne laser interferometer signal processing link dynamic test performance test and calibration.

[0047] 2, the application provides a kind of based on acousto-optic frequency shifter heterodyne laser interferometer signal processing link dynamic performance calibration device, based on the basic heterodyne laser interference structure is designed, adopt AOFS drive and motor controller simultaneously change the frequency of two acousto-optic frequency shifter AOFS drives or keep the frequency of one acousto-optic frequency shifter AOFS drive unchanged and adjust the frequency of another acousto-optic frequency shifter AOFS drive to continuously modulate the frequency of the final synthesized beat frequency light signal, to simulate different target motion modes to be measured.AOFS drive and motor controller simultaneously drive motor to adjust the angle of second mirror, so that the two laser beams of first measurement light path and second measurement light path have good coincidence degree when finally synthesized, to ensure the quality of interference light signal in the modulation process.

[0048] 3, existing heterodyne laser interferometer often couples environmental error, Abbe error, cosine error, data cycle error and other errors in displacement measurement, which can bring the problem that the dynamic measurement performance of interferometer signal processing link is difficult to evaluate.The application provides a kind of based on acousto-optic frequency shifter heterodyne laser interferometer signal processing link dynamic performance calibration device, by generating interference beat frequency light signal and adjusting its frequency to simulate high-speed motion of target to be measured, while realizing the adjustment of beat frequency light signal light power and ac / dc ratio, which can effectively avoid the influence of environmental error, Abbe error, cosine error, data cycle error and other factors, and can realize dynamic performance test and calibration of heterodyne laser interferometer signal processing link under high-speed motion of target.

[0049] 4, the application provides a kind of based on acousto-optic frequency shifter heterodyne laser interferometer signal processing link dynamic performance calibration device, based on the basic heterodyne laser interference structure is designed, can flexibly adjust the light power, ac / dc ratio and frequency of measurement path interference beat frequency light signal, and ensures that the interference signals of measurement path and reference path are homologous, not only can be used for dynamic measurement performance measurement and calibration of heterodyne laser interferometer signal processing link, but also can be used for simulation of beat frequency light signal in dynamic measurement of heterodyne laser interferometer and adjustment of light power, ac / dc ratio and frequency.

[0050] The application is suitable for the equivalent calibration device of the signal processing link of the heterodyne laser interferometer under the dynamic measurement performance of the target high-speed motion. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 is the system diagram of the dynamic performance calibration device of the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter according to the first embodiment;

[0052] Figure 2 is the system diagram of the dynamic performance calibration device of the signal processing link of the heterodyne laser interferometer according to the second embodiment, wherein the laser assembly is realized by using the dual-frequency laser with the reference light signal, and the beam splitting prism assembly is realized by using the first polarization beam splitting prism PBS;

[0053] Figure 3 is the system diagram of the dynamic performance calibration device of the signal processing link of the heterodyne laser interferometer according to the fourth embodiment, wherein the laser assembly is realized by using the dual-frequency laser without the reference light signal, and the beam splitting prism assembly is realized by using the first polarization beam splitting prism PBS;

[0054] Figure 4 is the system diagram of the dynamic performance calibration device of the signal processing link of the heterodyne laser interferometer according to the sixth embodiment, wherein the laser assembly is realized by using the single-frequency laser, and the beam splitting prism assembly is realized by using the second non-polarization beam splitting prism NPBS. DETAILED DESCRIPTION

[0055] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present application, and these changes and improvements are within the scope of protection of the present application.

[0056] Embodiment one. Referring to Figure 1 In this embodiment, the dynamic performance calibration device of the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter is provided, and the calibration device comprises a laser assembly, a first measurement light path, a second measurement light path, an AOFS drive and motor controller light path, and a phase meter;

[0057] The first measurement light path comprises a first mirror, a first AOFS, a first diaphragm, a first 1 / 2 wave plate, a polarization beam splitting prism PBS, a polarizer, and a photodetector PD;

[0058] The second measurement light path comprises a beam splitting prism assembly, a second AOFS, a second diaphragm, a second 1 / 2 wave plate, a second mirror, and a motor;

[0059] The laser assembly is used for emitting laser light into the beam splitter prism assembly, and the beam splitter prism assembly splits the incident light into two beams of laser light with perpendicular polarization directions and respectively into the first mirror and the second AOFS;

[0060] The first mirror reflects the incident light into the first AOFS, the first AOFS diffracts the incident light into multi-order diffracted light and into the first diaphragm, the first diaphragm selects the +1 order diffracted light of the multi-order diffracted light and into the first 1 / 2 wave plate, the first 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and into the polarizing beam splitter PBS, the polarizing beam splitter PBS reflects the incident light into the polarizer, the polarizer converts the incident light into beat frequency optical signals and into the photodetector PD, the photodetector PD converts the beat frequency optical signals into electrical signals and into the phase meter;

[0061] The second AOFS diffracts the light beam into multi-order diffracted light and into the second diaphragm, the second diaphragm selects the +1 order diffracted light of the multi-order diffracted light and into the second 1 / 2 wave plate, the second 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and into the second mirror, and the second mirror reflects the incident light into the polarizing beam splitter PBS;

[0062] The laser assembly is also used for providing a reference optical signal to the AOFS drive and motor controller optical path;

[0063] The AOFS drive and motor controller optical path is used for controlling the driving frequency of the first AOFS and the second AOFS respectively, and is also used for controlling the angle of the second mirror through the motor, and is also used for converting the laser light emitted by the laser assembly into a reference electrical signal and sending the reference electrical signal to the phase meter;

[0064] The phase meter is used for calculating the phase difference according to the received electrical signal.

[0065] In actual application, the embodiment is as follows: Figure 1The laser assembly is used for emitting laser light, which is incident into the beam splitter prism assembly. The beam splitter prism assembly splits the incident light into two beams of laser light with perpendicular polarization directions, realizes the separation of the two beams of laser light with perpendicular polarization directions, and respectively enters the first reflector and the second AOFS. One of the two beams of laser light is reflected by the first reflector and then enters the first AOFS. The first AOFS diffracts the incident light to generate multiple orders of diffracted light, which enters the first diaphragm. The first diaphragm selects the +1 order of diffracted light and then enters the first 1 / 2 wave plate to adjust the polarization direction of the light beam and then enters the polarization beam splitter PBS. The other beam of laser light enters the second AOFS. The second AOFS diffracts the incident light to generate multiple orders of diffracted light, which enters the second diaphragm. The second diaphragm selects the +1 order of diffracted light and then enters the second 1 / 2 wave plate to adjust the polarization direction of the light beam and then enters the second reflector. The second reflector emits the light beam to the polarization beam splitter PBS. The polarization beam splitter PBS emits the received light beam to the polarizer to generate beat frequency light signals and then the beat frequency light signals are received by the photodetector PD to generate an electrical signal which enters the phase meter for further processing. The laser assembly is also used for providing a reference light signal to the AOFS drive and motor controller optical path. The AOFS drive and motor controller optical path is used for controlling the driving frequencies of the first AOFS and the second AOFS respectively, for controlling the angle of the second reflector through the motor, and for converting the laser light emitted by the laser assembly into a reference electrical signal which is sent to the phase meter. The phase meter is used for calculating the phase difference according to the received electrical signal. The calibration method of the existing heterodyne laser interferometer is solved. The calibration results are coupled with the Abbe error, the cosine error caused by the mechanical installation, and the data cycle error caused by the non-synchronous measurement, which makes it difficult to evaluate the dynamic measurement performance of the signal processing link of the interferometer.

[0066] The embodiment provides a heterodyne laser interferometer signal processing link dynamic performance calibration device based on an acousto-optic frequency shifter. The AOFS drive and motor controller are used for simultaneously adjusting the driving frequencies of the two AOFSs in the first measurement light path and the second measurement light path and the angle of the reflector so that the beat frequency of the beat frequency light signals in the measurement paths reaches a test point. The two 1 / 2 wave plates and the rotation angle of the polarizer in the first measurement light path and the second measurement light path are adjusted to adjust the optical power and the AC / DC ratio of the beat frequency light signals in the measurement paths. The phase difference between the interference light and the actual simulated target motion phase is measured in real time by the phase meter to be tested, and the dynamic test performance test and calibration of the signal processing link of the heterodyne laser interferometer are performed.

[0067] The embodiment provides a dynamic performance calibration device for a heterodyne laser interferometer signal processing link based on an acousto-optic frequency shifter, is designed based on a basic heterodyne laser interference structure, adopts an AOFS drive and a motor controller to simultaneously change two acousto-optic frequency shifter AOFS drive frequencies or keep one acousto-optic frequency shifter AOFS drive frequency unchanged and adjust the other acousto-optic frequency shifter AOFS drive frequency to continuously modulate the frequency of the finally synthesized beat frequency optical signal, and simulates different target motion modes to be measured. The AOFS drive and the motor controller simultaneously drive the motor to adjust the angle of the second mirror, so that the two laser beams of the first measurement light path and the second measurement light path have good coincidence when finally synthesized, so as to ensure the quality of the interference optical signal in the modulation process.

[0068] The existing heterodyne laser interferometer often couples various errors such as environmental errors, Abbe errors, cosine errors and data period errors in displacement measurement, which brings the problem that it is difficult to evaluate the dynamic measurement performance of the signal processing link of the interferometer. The embodiment provides a dynamic performance calibration device for a heterodyne laser interferometer signal processing link based on an acousto-optic frequency shifter, which can effectively avoid the influence of factors such as environmental errors, Abbe errors, cosine errors and data period errors, and can realize dynamic performance testing and calibration of the signal processing link of the heterodyne laser interferometer under high-speed target motion.

[0069] The embodiment provides a dynamic performance calibration device for a heterodyne laser interferometer signal processing link based on an acousto-optic frequency shifter, is designed based on a basic heterodyne laser interference structure, adopts an AOFS drive and a motor controller to simultaneously change two acousto-optic frequency shifter AOFS drive frequencies or keep one acousto-optic frequency shifter AOFS drive frequency unchanged and adjust the other acousto-optic frequency shifter AOFS drive frequency to continuously modulate the frequency of the finally synthesized beat frequency optical signal, and simulates different target motion modes to be measured. The AOFS drive and the motor controller simultaneously drive the motor to adjust the angle of the second mirror, so that the two laser beams of the first measurement light path and the second measurement light path have good coincidence when finally synthesized, so as to ensure the quality of the interference optical signal in the modulation process.

[0070] Embodiment two. Refer to Figure 2 The embodiment is used to illustrate the laser assembly, the beam splitting prism assembly and the AOFS drive and the motor controller light path in the dynamic performance calibration device for a heterodyne laser interferometer signal processing link based on an acousto-optic frequency shifter in the embodiment one, the laser assembly adopts a dual-frequency laser with a reference light signal; the beam splitting prism assembly adopts a first polarization beam splitting prism PBS;

[0071] The AOFS drive and the motor controller light path comprises a depolarization beam splitting prism NPBS, a second photodetector PD, a third photodetector PD and an AOFS drive and a motor controller;

[0072] The dual-frequency laser with reference light signal emits two beams of laser, one of which is incident into the first polarization beam splitter PBS, and the other is incident into the depolarization beam splitter NPBS, which separates the incident light into two linearly polarized beams, which are respectively incident into the second photodetector PD and the third photodetector PD. The second photodetector PD converts the incident light signal into an electrical signal and sends it to the AOFS drive and motor controller. The third photodetector PD converts the incident light signal into an electrical signal and sends it to the phase meter.

[0073] The AOFS drive and motor controller adjusts the driving frequency of the first AOFS and the second AOFS based on the received electrical signal, and controls the motor.

[0074] In actual application, as shown in Figure 2 The laser assembly is implemented by a dual-frequency laser with reference light signal, and the beam splitter assembly is implemented by a first polarization beam splitter PBS. The AOFS drive and motor controller optical path includes a depolarization beam splitter NPBS, a second photodetector PD, a third photodetector PD, and an AOFS drive and motor controller. The dual-frequency laser with reference light signal outputs two coaxially transmitted, vertically polarized, and different frequency lasers, which are incident into the first polarization beam splitter PBS to separate the two lasers with vertical polarization. One of the lasers is reflected by the first mirror and enters the first AOFS and the second AOFS to produce multiple-order diffracted light. The +1 order diffracted light of the two lasers is selected by the first and second diaphragms, and the polarization direction of the two diffracted lights is adjusted by the first and second 1 / 2 wave plates. The two diffracted lights are combined by the second mirror at the polarization beam splitter PBS, and the beat frequency light signal is generated by the polarizer interference and received by the photodetector PD to generate a measurement electrical signal entering the phase meter for further processing.

[0075] The reference light signal of the dual-frequency laser is a beat frequency light signal formed by the interference of two coaxially transmitted and different frequency lasers. After the reference light signal is processed by the depolarization beam splitter NPBS, it is divided into two paths. One of the paths is converted into a reference electrical signal by the third photodetector PD and enters the phase meter for further processing, and the other path is converted into an electrical signal by the second photodetector PD and used as the driving clock of the AOFS drive and motor controller to ensure that the measurement and reference interference signals are homologous. The AOFS drive and motor controller continuously modulates the frequency of the final synthesized beat frequency light signal by simultaneously changing the driving frequencies of the two AOFS or keeping one AOFS driving frequency unchanged and adjusting the driving frequency of the other AOFS to simulate different target motion modes.

[0076] The embodiment modulates the frequency of the final synthesized beat frequency optical signal by controlling the first acousto-optic frequency shifter AOFS driving frequency to be unchanged and adjusting the second acousto-optic frequency shifter AOFS driving frequency. Since changing the acousto-optic frequency shifter AOFS driving frequency will cause the angle of the +1 order diffraction light to change, the AOFS driving and motor controller simultaneously drives the motor to adjust the angle of the second mirror, so that the two lasers of the first measurement light path and the second measurement light path have good coincidence when finally synthesized, thereby ensuring the quality of the interference optical signal during modulation.

[0077] The embodiment provides a heterodyne laser interferometer signal processing link dynamic performance calibration device based on an acousto-optic frequency shifter. The device is designed based on a basic heterodyne laser interference structure. The AOFS driving and motor controller simultaneously changes the AOFS driving frequencies of the two acousto-optic frequency shifters or keeps the AOFS driving frequency of one acousto-optic frequency shifter unchanged and adjusts the AOFS driving frequency of the other acousto-optic frequency shifter to continuously modulate the frequency of the final synthesized beat frequency optical signal, thereby simulating different target motion modes. The AOFS driving and motor controller simultaneously drives the motor to adjust the angle of the second mirror, so that the two lasers of the first measurement light path and the second measurement light path have good coincidence when finally synthesized, thereby ensuring the quality of the interference optical signal during modulation.

[0078] The specific implementation steps of the embodiment in actual application are as follows:

[0079] Step one, preliminary measurement: Before measurement initialization, the application range of the calibration device needs to be measured. The rotation angles of the two 1 / 2 wave plates of the first measurement light path and the second measurement light path are adjusted so that the rotation direction is perpendicular to the light path direction, the polarization directions of the two laser beams of the first measurement light path and the second measurement light path can be changed, the power of the two laser beams that finally interfere can be changed through the polarizing beam splitter PBS, the rotation angle of the polarizer in the first measurement light path is adjusted so that the rotation direction is perpendicular to the light path direction, the interference degree of the two laser beams of the measurement path can be changed, that is, the AC / DC ratio can be changed, the beat frequency of the synthesized beat frequency optical signal of the measurement path can be adjusted by adjusting the AOFS driving frequencies of the two acousto-optic frequency shifters, and thus the power of the measurement beat frequency optical signal and the adjustable range of the AC / DC ratio under different beat frequencies can be measured by adjusting the AOFS driving frequencies of the two acousto-optic frequency shifters, the rotation angles of the 1 / 2 wave plates and the polarizer. The power of the reference optical signal and the optical signal providing the clock of the AOFS driving and motor controller is measured and recorded.

[0080] Step two, measurement initialization: The beat frequency of the measurement beat frequency optical signal is adjusted to a preset value by adjusting the AOFS driving frequencies of the two acousto-optic frequency shifters of the first measurement light path and the second measurement light path, and the power of the measurement beat frequency optical signal and the AC / DC ratio are adjusted to preset values by adjusting the rotation angles of the two 1 / 2 wave plates and the polarizer of the first measurement light path and the second measurement light path.

[0081] Step three, test point selection: using the mapping relationship between the target motion velocity to be measured in the heterodyne laser interferometer displacement measurement system and the measured beat frequency optical signal frequency of the equivalent measurement device, a test point is selected;

[0082] Step four, start measurement: by simultaneously adjusting the AOFS drive frequency and the mirror angle of the first measurement light path and the second measurement light path through the AOFS drive and the motor controller to make the measurement beat frequency optical signal beat frequency reach the test point, the first measurement light path and the second measurement light path two 1 / 2 wave plates and the polarization plate rotation angle can be adjusted to adjust the measurement beat frequency optical signal optical power and AC / DC ratio, the phase difference between the interference light and the actual simulated target motion phase is measured in real time by the phase meter to be measured, and the dynamic performance test and calibration of the heterodyne laser interferometer signal processing link are performed.

[0083] Embodiment three. This embodiment is an example of the double-frequency laser with reference light signal in the dynamic performance calibration device of the heterodyne laser interferometer signal processing link based on the acousto-optic frequency shifter described in embodiment two, which emits two coaxial transmission lasers with perpendicular polarization directions and different frequencies.

[0084] Embodiment four. Referring to Figure 3 This embodiment is an example of the laser assembly, the beam splitting prism assembly and the AOFS drive and motor controller light path in the dynamic performance calibration device of the heterodyne laser interferometer signal processing link based on the acousto-optic frequency shifter described in embodiment one, and the laser assembly can also be realized by using a double-frequency laser without reference light signal;

[0085] The beam splitting prism assembly is realized by using a first polarization beam splitting prism PBS;

[0086] The AOFS drive and motor controller light path includes a first non-polarization beam splitting prism NPBS, a second polarization plate, a second non-polarization beam splitting prism NPBS, a second photodetector PD, a third photodetector PD and an AOFS drive and motor controller;

[0087] The dual-frequency laser without the reference light signal emits a laser beam into the first non-polarizing beam splitter NPBS, which splits the incident light into two beams of polarized light, which are respectively incident into the first polarizing beam splitter PBS and the second polarizing plate. The second polarizing plate converts the incident light into a beat frequency light signal, which is incident into the second non-polarizing beam splitter NPBS. The second non-polarizing beam splitter NPBS splits the incident light into two beams of linearly polarized light, which are respectively incident into the second photodetector PD and the third photodetector PD. The second photodetector PD converts the incident light signal into an electrical signal, which is sent to the AOFS drive and motor controller. The third photodetector PD converts the incident light signal into an electrical signal, which is sent to the phase meter.

[0088] The AOFS drive and motor controller is configured to adjust the driving frequencies of the first AOFS and the second AOFS based on the received electrical signals as driving clocks, and to control the motor.

[0089] In actual application, as shown in FIG. 1, the laser assembly can also be implemented by a dual-frequency laser without a reference light signal. The beam splitter assembly is implemented by a first polarizing beam splitter PBS. The AOFS drive and motor controller optical path includes a first non-polarizing beam splitter NPBS, a second polarizing plate, a second non-polarizing beam splitter NPBS, a second photodetector PD, a third photodetector PD, and an AOFS drive and motor controller. Figure 3 The dual-frequency laser is a dual-frequency laser without a reference light signal. The measurement light signal, the reference light signal, and the light signal providing the clock of the AOFS drive and motor controller are all generated by two coaxial transmitted laser beams with perpendicular polarization directions and different frequencies output by the dual-frequency laser.

[0090] The laser beam output by the dual-frequency laser is split into two beams after being processed by the first non-polarizing beam splitter NPBS. One of the two beams is processed by the first polarizing beam splitter PBS to generate the measurement light signal. The other beam is processed by the second polarizing plate to generate a beat frequency light signal, which is then split into two beams by the second non-polarizing beam splitter NPBS to generate the reference light signal and the light signal providing the clock of the AOFS drive and motor controller. The light signal providing the clock of the AOFS drive and motor controller is generated by the reference light. The AOFS drive and motor controller generates the AOFS driving signal based on the clock provided by the beat frequency light signal of the laser, to ensure that the measurement light signal and the reference light signal have the same clock source.

[0091] The AOFS driving and motor controller is used to drive the acousto-optic frequency shifters AOFS and the motor of the first measurement light path and the second measurement light path. The two acousto-optic frequency shifters AOFS driving frequencies of the first measurement light path and the second measurement light path are simultaneously changed or one acousto-optic frequency shifter AOFS driving frequency is kept unchanged and the other acousto-optic frequency shifter AOFS driving frequency is adjusted to continuously modulate the beat frequency of the finally synthesized beat frequency optical signal to simulate different target motion modes to be measured. In the embodiment, the beat frequency of the finally synthesized beat frequency optical signal is modulated by keeping the first acousto-optic frequency shifter AOFS driving frequency unchanged and adjusting the second acousto-optic frequency shifter AOFS driving frequency. Since changing the acousto-optic frequency shifter AOFS driving frequency will change the +1 order diffraction light exit angle, the controller simultaneously drives the motor to adjust the angle of the second mirror to make the two laser beams of the first measurement light path and the second measurement light path have good coincidence when finally synthesized to ensure the quality of the interference optical signal in the modulation process.

[0092] The specific implementation steps of the embodiment in actual application are as follows:

[0093] Step one, pre-measurement: Before the measurement initialization, the application range of the calibration device needs to be measured. The rotation angles of the two 1 / 2 wave plates of the first measurement light path and the second measurement light path are adjusted to make the rotation direction perpendicular to the light path direction, the polarization directions of the two laser beams of the first measurement light path and the second measurement light path can be changed, and then the power of the two laser beams for finally interfering is changed by the polarizing beam splitter PBS. The rotation angle of the polarizer in the first measurement light path is adjusted to make the rotation direction perpendicular to the light path direction, the interference degree of the two laser beams of the measurement path can be changed, that is, the AC / DC ratio can be changed. The frequency of the synthesized beat frequency optical signal of the measurement path can be adjusted by adjusting the driving frequencies of the two acousto-optic frequency shifters AOFS of the first measurement light path and the second measurement light path. Thus, the power of the measurement beat frequency optical signal and the adjustable range of the AC / DC ratio under different beat frequencies can be measured by adjusting the driving frequencies of the two acousto-optic frequency shifters AOFS and the rotation angles of the 1 / 2 wave plates and the polarizer. The power of the reference optical signal and the optical signal providing the clock of the AOFS driving and motor controller are measured and recorded.

[0094] Step two, measurement initialization: the beat frequency of the beat frequency optical signal of the measurement path is adjusted to a preset value by adjusting the driving frequencies of the two acousto-optic frequency shifters AOFS of the first measurement light path and the second measurement light path, and the power of the beat frequency optical signal of the measurement path and the AC / DC ratio are adjusted to a preset value by adjusting the rotation angles of the two 1 / 2 wave plates and the polarizer of the first measurement light path and the second measurement light path.

[0095] Step three, test point selection: the test point is selected by using the mapping relationship between the target motion speed to be measured in the heterodyne laser interference displacement measurement system and the beat frequency optical signal frequency of the measurement path of the equivalent measurement device.

[0096] Step four, start measurement: by simultaneously adjusting the two AOFS drive frequencies and the mirror angle of the first measurement light path and the second measurement light path through the AOFS drive and motor controller to make the measurement path beat frequency light signal beat reach the test point, the first measurement light path and the second measurement light path two 1 / 2 wave plates and the polarization plate rotation angle can be adjusted as needed to adjust the measurement path beat frequency light signal light power and AC / DC ratio, the phase difference between the interference light and the actual simulated target motion phase is measured in real time by the phase meter to be tested, and the heterodyne laser interferometer signal processing link dynamic test performance test and calibration are carried out.

[0097] Embodiment five. This embodiment is an example of a double-frequency laser without a reference light signal in the heterodyne laser interferometer signal processing link dynamic performance calibration device based on the acousto-optic frequency shifter described in embodiment four. The double-frequency laser without a reference light signal emits two coaxial transmission lasers with perpendicular polarization directions and different frequencies.

[0098] Embodiment six. Referring to Figure 4 This embodiment is an example of the laser assembly, the beam splitting prism assembly, and the AOFS drive and motor controller optical path in the heterodyne laser interferometer signal processing link dynamic performance calibration device based on the acousto-optic frequency shifter described in embodiment one. The laser assembly can also be implemented using a single-frequency laser; the beam splitting prism assembly can also be implemented using a second non-polarizing beam splitter NPBS;

[0099] The AOFS drive and motor controller circuit includes a first non-polarizing beam splitter NPBS, a third mirror, a third non-polarizing beam splitter NPBS, a fourth AOFS, a fourth diaphragm, a fourth 1 / 2 wave plate, a fifth mirror, a fourth mirror, a third AOFS, a third diaphragm, a third 1 / 2 wave plate, a second polarizing beam splitter PBS, a second polarizer, a second photodetector PD, and an AOFS drive and motor controller;

[0100] The single-frequency laser emits a laser beam that enters the first non-polarizing beam splitter NPBS. The non-polarizing beam splitter NPBS divides the incident light into two beams, which enter the second non-polarizing beam splitter NPBS and the third mirror, respectively.

[0101] The third mirror reflects the incident light to the third depolarization beam splitter prism NPBS, the depolarization beam splitter prism NPBS divides the incident light into two beams of laser light, which are respectively incident into the fourth mirror and the fourth AOFS, the fourth mirror reflects the incident light to the third AOFS, the third AOFS diffracts the incident light into a plurality of levels of diffracted light and is incident into the third diaphragm, the third diaphragm selects the +1 order diffracted light of the plurality of levels of diffracted light and is incident into the third 1 / 2 wave plate, the third 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and is incident into the second polarization beam splitter prism PBS, the second polarization beam splitter prism PBS is incident into the second polarizer, the second polarizer converts the incident light into a beat frequency optical signal and sends it to the second photodetector PD, and the second photodetector PD converts the beat frequency optical signal into an electrical signal and sends it to the phase meter.

[0102] The fourth AOFS diffracts the incident light into a plurality of levels of diffracted light and is incident into the fourth diaphragm, the fourth diaphragm selects the +1 order diffracted light of the plurality of levels of diffracted light and is incident into the fourth 1 / 2 wave plate, the fourth 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and is incident into the fifth mirror, and the fifth mirror reflects the incident light to the second polarization beam splitter prism PBS.

[0103] The AOFS drive and motor controller is used to adjust the driving frequency of the first AOFS, the second AOFS, the third AOFS and the fourth AOFS respectively, and is also used to control the motor.

[0104] In actual application, as shown in Figure 4 The laser assembly is implemented by using a single-frequency laser, the beam splitter prism assembly is implemented by using a second depolarization beam splitter prism NPBS, and the AOFS drive and motor controller circuit includes a first depolarization beam splitter prism NPBS, a third mirror, a third depolarization beam splitter prism NPBS, a fourth AOFS, a fourth diaphragm, a fourth 1 / 2 wave plate, a fifth mirror, a fourth mirror, a third AOFS, a third diaphragm, a third 1 / 2 wave plate, a second polarization beam splitter prism PBS, a second polarizer, a second photodetector PD and an AOFS drive and motor controller.

[0105] The laser is a single-frequency laser, and the single-frequency laser outputs a linearly polarized single-frequency light, which is divided into two beams of laser light with the same polarization direction after passing through the first depolarization beam splitter prism NPBS. One of the two beams of laser light is divided into two beams of laser light to generate a measurement optical signal by passing through the second depolarization beam splitter prism NPBS, and the other beam is the same as the first beam and generates a reference optical signal after processing.

[0106] The AOFS driving and motor controller clock reference signal is generated by a self clock generating circuit. Since the measurement light signal and the reference light signal are both generated by the controller driving the acousto-optic frequency shifter AOFS, the measurement light signal and the reference light signal can be guaranteed to be homologous.

[0107] The AOFS driving and motor controller is used for driving the first acousto-optic frequency shifter AOFS, the second acousto-optic frequency shifter AOFS and the motor. By simultaneously changing the driving frequencies of the two acousto-optic frequency shifters AOFS or keeping the driving frequency of one acousto-optic frequency shifter AOFS unchanged and adjusting the driving frequency of the other acousto-optic frequency shifter AOFS, the beat frequency of the finally synthesized beat frequency light signal is continuously modulated to simulate different target motion modes to be measured. In this embodiment, the frequency of the finally synthesized beat frequency light signal of the measurement path is modulated by keeping the driving frequency of the first acousto-optic frequency shifter AOFS unchanged and adjusting the driving frequency of the second acousto-optic frequency shifter AOFS. Since changing the driving frequency of the acousto-optic frequency shifter AOFS will cause the angle of the +1 order diffracted light to change, the controller simultaneously drives the motor to adjust the angle of the second mirror to make the two laser beams of the measurement path have good coincidence when they are finally synthesized, so as to guarantee the quality of the interference light signal in the modulation process. The beat frequency light signal of the reference path works with a preset beat frequency. The AOFS driving and motor controller sets the driving signal frequencies of the third acousto-optic frequency shifter AOFS and the fourth acousto-optic frequency shifter AOFS of the reference path to fixed values. Since the AOFS driving frequency does not need to be continuously adjusted, the mirror angle of the reference path does not need to be continuously adjusted by the motor.

[0108] The specific implementation steps of the embodiment in actual application are as follows:

[0109] Step one, pre-measurement: Before the measurement initialization, the application range of the calibration device needs to be measured in advance. By adjusting the rotation angles of the two 1 / 2 wave plates of the first measurement light path and the second measurement light path, the rotation direction is perpendicular to the light path direction, the polarization directions of the two laser beams of the first measurement light path and the second measurement light path can be changed, and then the power of the two laser beams finally interfering can be changed by the polarizing beam splitter PBS. By adjusting the rotation angle of the polarizer in the first measurement light path, the rotation direction is perpendicular to the light path direction, the interference degree of the two laser beams of the measurement path can be changed, that is, the AC / DC ratio can be changed. By adjusting the driving frequencies of the two acousto-optic frequency shifters AOFS of the first measurement light path and the second measurement light path, the frequency of the synthesized beat frequency light signal of the measurement path can be adjusted. Thus, by adjusting the driving frequencies of the two acousto-optic frequency shifters AOFS, the rotation angles of the 1 / 2 wave plates and the polarizer, the power of the measurement beat frequency light signal under different beat frequencies and the adjustable range of the AC / DC ratio can be measured. The power of the reference light signal and the light signal providing the clock of the AOFS driving and motor controller and the AC / DC ratio are measured and recorded.

[0110] Step two, measurement initialization: adjust the driving frequency of the two acousto-optic frequency shifters (AOFS) in the first and second measurement light paths to adjust the beat frequency of the measurement beat frequency light signal to a preset value, and adjust the rotation angles of the two 1 / 2 wave plates and polarizers in the first and second measurement light paths to adjust the optical power and AC / DC ratio of the measurement beat frequency light signal to a preset value.

[0111] Step three, test point selection: select a test point based on the mapping relationship between the target motion speed and the measurement beat frequency light signal frequency in the heterodyne laser interferometer displacement measurement system.

[0112] Step four, start measurement: simultaneously adjust the driving frequencies of the two AOFS in the first and second measurement light paths and the angles of the mirrors by the AOFS driver and motor controller to make the beat frequency of the measurement beat frequency light signal reach the test point, and adjust the rotation angles of the two 1 / 2 wave plates and polarizers in the first and second measurement light paths to adjust the optical power and AC / DC ratio of the measurement beat frequency light signal as needed, and use the measured phase meter to measure the phase difference between the interference light and the actual simulated target motion phase in real time to test and calibrate the dynamic performance of the signal processing link of the heterodyne laser interferometer.

[0113] Embodiment seven. This embodiment is an example of a single-frequency laser in the dynamic performance calibration device for the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter as described in embodiment six, which emits a linearly polarized single-frequency light.

[0114] Embodiment eight. This embodiment is an example of a depolarization beam splitter prism NPBS in the dynamic performance calibration device for the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter as described in embodiment six, which splits the incident light into two beams with the same polarization direction.

[0115] Embodiment nine. This embodiment is an example of an AOFS driver and motor controller in the dynamic performance calibration device for the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter as described in embodiment six, which is used to set the driving signal frequency of the third and fourth AOFS to a fixed value.

[0116] Embodiment ten. This embodiment provides a dynamic performance calibration method for the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter, which is implemented based on the dynamic performance calibration device for the signal processing link of the heterodyne laser interferometer based on the acousto-optic frequency shifter as described in any one of embodiments one to nine, and the calibration method is as follows:

[0117] S1, pre-measurement: adjust the rotation angle of the first 1 / 2 wave plate and the first 1 / 2 wave plate respectively, so that the rotation direction is perpendicular to the light path direction, adjust the polarization beam splitter PBS, change the power of the two laser beams that finally interfere, adjust the rotation angle of the polarizer, so that the rotation direction is perpendicular to the light path direction, adjust the driving frequency of the first AOFS and the second AOFS respectively, measure the beat frequency optical signal power and the AC / DC ratio adjustable range under different beat frequencies, and the optical signal power and the AC / DC ratio of the AOFS drive and the motor controller clock;

[0118] S2, measurement initialization: adjust the AOFS driving frequency of the first measurement light path and the second measurement light path to adjust the measurement path beat frequency to the preset value, and adjust the rotation angle of the first measurement light path and the second measurement light path 1 / 2 wave plate and polarizer to adjust the measurement path beat frequency optical signal power and AC / DC ratio to the preset value.

[0119] S3, select test points;

[0120] S4, start measurement: adjust the AOFS driving frequency and the motor controller of the first measurement light path and the second measurement light path to make the measurement path beat frequency reach the test point, adjust the rotation angle of the first measurement light path and the second measurement light path 1 / 2 wave plate and polarizer to adjust the measurement path beat frequency optical signal power and AC / DC ratio, and use the measured phase meter to measure the phase difference between the interference light and the actual simulated target motion phase in real time, and perform heterodyne laser interferometer signal processing link dynamic test performance test and calibration.

[0121] In actual application, step one, pre-measurement: before measurement initialization, the application range of the calibration device needs to be measured in advance, the rotation angle of the first measurement light path and the second measurement light path 1 / 2 wave plate is adjusted, so that the rotation direction is perpendicular to the light path direction, the polarization direction of the two laser beams of the first measurement light path and the second measurement light path can be changed respectively, and the power of the two laser beams that finally interfere is changed through the polarization beam splitter PBS, the rotation angle of the polarizer in the first measurement light path is adjusted, the rotation direction is perpendicular to the light path direction, the interference degree of the two laser beams of the measurement path can be changed, that is, the AC / DC ratio, and the driving frequency of the two acousto-optic frequency shifters AOFS of the first measurement light path and the second measurement light path is adjusted, so that the frequency of the synthesized beat frequency optical signal of the measurement path is adjusted, and thus the driving frequency of the two acousto-optic frequency shifters AOFS, the rotation angle of the 1 / 2 wave plate and the polarizer can be adjusted, and the adjustable range of the beat frequency optical signal power and the AC / DC ratio under different beat frequencies can be measured; the reference light signal and the optical signal power and the AC / DC ratio of the AOFS drive and the motor controller clock are measured and recorded.

[0122] Step two, measurement initialization: the measurement path beat frequency light signal is adjusted to a preset value by adjusting the AOFS driving frequency of the first measurement light path and the second measurement light path two acousto-optic frequency shifters, and the measurement path beat frequency light signal light power and AC / DC ratio are adjusted to a preset value by adjusting the rotation angle of the first measurement light path and the second measurement light path two 1 / 2 wave plates and polarizers;

[0123] Step three, test point selection: the test point is selected by using the frequency mapping relationship between the target motion speed to be measured in the heterodyne laser interference displacement measurement system and the measurement path beat frequency light signal frequency of the equivalent measurement device;

[0124] Step four, start measurement: the measurement path beat frequency light signal beat frequency is reached by simultaneously adjusting the AOFS driving frequency and the mirror angle of the first measurement light path and the second measurement light path through the AOFS driving and motor controller, and the measurement path beat frequency light signal light power and AC / DC ratio can be adjusted according to the need by adjusting the rotation angle of the first measurement light path and the second measurement light path two 1 / 2 wave plates and polarizers, and the phase difference between the interference light and the actual simulated target motion phase is measured in real time by using the phase meter to be measured, and the dynamic test performance test and calibration of the heterodyne laser interferometer signal processing link are carried out.

[0125] In addition, the terms "first", "second", "third" and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily described with a sequential number. The terms so used are interchangeable under appropriate circumstances and embodiments. Certain embodiments are described herein as comprising, consisting of, consisting essentially of, or some similar transitional term. This term should be interpreted in the manner it is employed in the patent law and can be read to exclude any elements not specified. In addition, the terms "a", "an" and "the" are used interchangeably in this document to refer to one or more instances of the thing to which the terms describe. The terms "comprise", "comprising", "comprises", "include", "including", and "includes" are used interchangeably in this document to mean various forms including, in an embodiment of, during an embodiment of, while an embodiment of, while performing an embodiment of, one embodiment of, etc. as well as to permit some specified features of the embodiments to be present or involved and others to be not present or involved, unless the context clearly indicates otherwise.

[0126] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0127] The above only describes the embodiments of the present application and does not limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A dynamic performance calibration device for a signal processing section of a heterodyne laser interferometer based on an acousto-optic frequency shifter, characterized in that The calibration device comprises a laser assembly, a first measuring light path, a second measuring light path, an AOFS driving and motor controller light path and a phase meter; The first measuring light path comprises a first mirror, a first AOFS, a first diaphragm, a first 1 / 2 wave plate, a polarization beam splitter PBS, a polarizer and a photodetector PD; The second measuring light path comprises a beam splitter assembly, a second AOFS, a second diaphragm, a second 1 / 2 wave plate, a second mirror and a motor; The laser assembly is configured to emit laser light into the beam splitter assembly, which splits the incident light into two beams of laser light with perpendicular polarization directions and respectively into the first mirror and the second AOFS; The first mirror reflects the incident light into the first AOFS, which diffracts the incident light into multiple orders of diffracted light and into the first diaphragm, which selects the +1 order of diffracted light and into the first 1 / 2 wave plate, which adjusts the polarization direction of the +1 order of diffracted light and into the polarization beam splitter PBS, which reflects the incident light into the polarizer, which converts the incident light into a beat frequency optical signal and into the photodetector PD, which converts the beat frequency optical signal into an electrical signal and into the phase meter; The second AOFS diffracts the light beam into multiple orders of diffracted light and into the second diaphragm, which selects the +1 order of diffracted light and into the second 1 / 2 wave plate, which adjusts the polarization direction of the +1 order of diffracted light and into the second mirror, which reflects the incident light into the polarization beam splitter PBS; The laser assembly is further configured to provide a reference optical signal to the AOFS driving and motor controller light path; The AOFS driving and motor controller light path is configured to control the driving frequencies of the first and second AOFS respectively, to control the angle of the second mirror through the motor and to convert the laser light emitted by the laser assembly into a reference electrical signal and to send the reference electrical signal to the phase meter; The phase meter is configured to calculate the phase difference based on the received electrical signal.

2. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter according to claim 1, characterized in that, The laser assembly is implemented by a dual-frequency laser with a reference optical signal; The beam splitter assembly is implemented by a first polarization beam splitter PBS; The AOFS driving and motor controller light path comprises a depolarization beam splitter NPBS, a second photodetector PD, a third photodetector PD and an AOFS driving and motor controller; The dual-frequency laser with a reference optical signal emits two beams of laser light, one of which is incident into the first polarization beam splitter PBS and the other of which is incident into the depolarization beam splitter NPBS, which splits the incident light into two beams of linearly polarized light and respectively into the second photodetector PD and the third photodetector PD, which convert the incident optical signals into electrical signals and send the electrical signals to the AOFS driving and motor controller and to the phase meter respectively; The AOFS driver and motor controller is configured to adjust the driving frequencies of the first and second AOFSs respectively according to the received electrical signals, and to control the motor.

3. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter according to claim 2, characterized in that, The dual-frequency laser with reference light signal emits two coaxial laser beams with perpendicular polarization directions and different frequencies.

4. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter according to claim 1, characterized in that, The laser assembly is also implemented by a dual-frequency laser without reference light signal; The light splitting prism assembly is also implemented by a first polarization splitting prism PBS; The AOFS driver and motor controller optical path comprises a first non-polarization splitting prism NPBS, a second polarizer, a second non-polarization splitting prism NPBS, a second photodetector PD, a third photodetector PD, and an AOFS driver and motor controller; The dual-frequency laser without reference light signal emits one laser beam, which is incident into the first non-polarization splitting prism NPBS, and the first non-polarization splitting prism NPBS splits the incident light into two polarized laser beams, which are incident into the first polarization splitting prism PBS and the second polarizer respectively, and the second polarizer converts the incident light into beat frequency light signals, which are incident into the second non-polarization splitting prism NPBS, and the second non-polarization splitting prism NPBS splits the incident light into two linearly polarized light beams, which are incident into the second photodetector PD and the third photodetector PD respectively, and the second photodetector PD converts the incident light signals into electrical signals and sends them to the AOFS driver and motor controller, and the third photodetector PD converts the incident light signals into electrical signals and sends them to the phase meter; The AOFS driver and motor controller is configured to adjust the driving frequencies of the first and second AOFSs respectively according to the received electrical signals, and to control the motor.

5. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter as claimed in claim 4, characterized in that, The dual-frequency laser without reference light signal emits two coaxial laser beams with perpendicular polarization directions and different frequencies.

6. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter as claimed in claim 1, characterized in that, The laser assembly is also implemented by a single-frequency laser; The light splitting prism assembly is also implemented by a second non-polarization splitting prism NPBS; The AOFS driver and motor controller circuit comprises a first non-polarization splitting prism NPBS, a third mirror, a third non-polarization splitting prism NPBS, a fourth AOFS, a fourth diaphragm, a fourth 1 / 2 wave plate, a fifth mirror, a fourth mirror, a third AOFS, a third diaphragm, a third 1 / 2 wave plate, a second polarization splitting prism PBS, a second polarizer, a second photodetector PD, and an AOFS driver and motor controller; The single-frequency laser emits one laser beam, which is incident into the first non-polarization splitting prism NPBS, and the non-polarization splitting prism NPBS splits the incident light into two laser beams, which are incident into the second non-polarization splitting prism NPBS and the third mirror respectively; The third mirror reflects the incident light to the third depolarization prism NPBS, the depolarization prism NPBS divides the incident light into two beams of laser, which are respectively incident into the fourth mirror and the fourth AOFS, the fourth mirror reflects the incident light to the third AOFS, the third AOFS diffracts the incident light into multi-order diffracted light and makes the multi-order diffracted light incident into the third diaphragm, the third diaphragm selects the +1 order diffracted light of the multi-order diffracted light and makes the +1 order diffracted light incident into the third 1 / 2 wave plate, the third 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and makes the +1 order diffracted light incident into the second polarization beam splitter PBS, the second polarization beam splitter PBS makes the incident light incident into the second polarizer, the second polarizer converts the incident light into beat frequency optical signals and sends the beat frequency optical signals to the second photodetector PD, and the second photodetector PD converts the beat frequency optical signals into electrical signals and sends the electrical signals to the phase meter; The fourth AOFS diffracts the incident light into multi-order diffracted light and makes the multi-order diffracted light incident into the fourth diaphragm, the fourth diaphragm selects the +1 order diffracted light of the multi-order diffracted light and makes the +1 order diffracted light incident into the fourth 1 / 2 wave plate, the fourth 1 / 2 wave plate adjusts the polarization direction of the +1 order diffracted light and makes the +1 order diffracted light incident into the fifth mirror, and the fifth mirror reflects the incident light to the second polarization beam splitter PBS. The AOFS drive and motor controller is used for adjusting the driving frequencies of the first AOFS, the second AOFS, the third AOFS and the fourth AOFS respectively, and is also used for controlling the motor.

7. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter as claimed in claim 6, characterized in that, The single-frequency laser emits a beam of linearly polarized single-frequency light.

8. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter as claimed in claim 6, characterized in that, The depolarization prism NPBS divides the incident light into two beams of laser with the same polarization direction.

9. The dynamic performance calibration apparatus for a heterodyne laser interferometer signal processing section based on an acousto-optic frequency shifter as claimed in claim 6, characterized in that, The AOFS drive and motor controller is used for setting the driving signal frequencies of the third AOFS and the fourth AOFS as fixed values.

10. A method for calibrating the dynamic performance of a signal processing section of a heterodyne laser interferometer based on an acousto-optic frequency shifter, characterized in that The calibration method is realized by the heterodyne laser interferometer signal processing link dynamic performance calibration device based on the acousto-optic frequency shifter according to any one of claims 1-9, and the calibration method comprises the following steps: S1, pre-measurement: respectively adjust the rotation angles of the first 1 / 2 wave plate and the first 1 / 2 wave plate, so that the rotation direction is perpendicular to the light path direction, adjust the polarization beam splitter PBS to change the optical power of the two beams of laser which finally interfere with each other, adjust the rotation angle of the polarizer so that the rotation direction is perpendicular to the light path direction, respectively adjust the driving frequencies of the first AOFS and the second AOFS, and measure the optical power of the beat frequency optical signals, the adjustable range of AC / DC ratio, and the optical power of the clock of the AOFS drive and motor controller circuit and the AC / DC ratio under different beat frequencies; S2, measurement initialization: adjust the driving frequencies of the two acousto-optic frequency shifters AOFS in the first measurement light path and the second measurement light path to adjust the beat frequency of the measurement path beat frequency optical signals to a preset value, and adjust the rotation angles of the two 1 / 2 wave plates and the polarizer in the first measurement light path and the second measurement light path to adjust the optical power and AC / DC ratio of the measurement path beat frequency optical signals to a preset value; S3, select test points; S4, start measurement: by AOFS drive and motor controller to adjust the first measurement light path and the second measurement light path two AOFS drive frequency and mirror angle to make the measurement path beat frequency light signal beat frequency to test point, adjust the first measurement light path and the second measurement light path two 1 / 2 wave plate and the polarization plate rotation angle to adjust the measurement path beat frequency light signal light power and AC / DC ratio, using the real-time measurement of the phase difference between the measured phase meter and the actual analog measured target motion phase, heterodyne laser interferometer signal processing link dynamic test performance test and calibration.

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