A dynamic angle measurement device

Abstract

This invention belongs to the field of dynamic angle measurement technology and relates to a dynamic angle measuring device, which includes an integrated base, a turntable, a ring laser gyroscope angle measuring unit, an adjustment fixture, a dynamic angle zeroing unit, and a control processing unit. The integrated base is set on a vibration isolation platform, and the rotating part of the turntable is connected to the ring laser gyroscope angle measuring unit set above it. The dynamic angle zeroing unit includes a sensitive module, and the target mirror of the sensitive module is set on the ring laser gyroscope angle measuring unit. The dynamic angle zeroing unit also includes a dual-frequency laser-fiber coupling module and a measurement module. The laser beam emitted by the dual-frequency laser-fiber coupling module is directed towards the target mirror after passing through the measurement module. When the direction of the light emitted by the measurement module coincides with the direction of the reflected light after passing through the target mirror, the dynamic angle zeroing unit sends a zeroing pulse to the control processing unit, and the control processing unit begins to record the dynamic angle measured by the ring laser gyroscope angle measuring unit.

Description

Technical Field

[0001] This invention belongs to the field of dynamic angle measurement technology and relates to a dynamic angle measuring device. Background Technology

[0002] Dynamic angle measurement represents a significant technological advancement in angle measurement, moving beyond static constraints and towards universal measurement capabilities. It involves measuring angular motion parameters and dynamic angular characteristics. This technology organically links the angular unit of radians (rad) with the time unit of seconds (s), ensuring accurate and reliable measurement of a series of key parameters such as angular rate, angular acceleration, angular position measurement frequency response, and harmonic distortion in typical applications like aircraft control, multi-axis machine tool linkage, and CT scanning. This technology plays a crucial foundational role in the development of aerospace, high-end manufacturing, and precision medicine.

[0003] Currently, the industry employs various methods for measuring different dynamic angles, such as circular grating angle measurement, autocollimation angle measurement, optical internal reflection small angle measurement, photoelectric shaft angle encoder angle measurement, and laser interferometry. However, they all share common problems.

[0004] 1. The circular grating angle measurement method and the photoelectric shaft angle encoder angle measurement method are prone to the problem of misalignment between the measuring axis and the rotating axis, which leads to a decrease in measurement accuracy. The laser interferometry method, although it has very high measurement accuracy, cannot achieve 360° full circumference measurement.

[0005] 2. Traditional dynamic nulling devices are susceptible to various factors such as ambient light interference, tilting motion errors of the target mirror during rotation, and trigger thresholds in the Schmitt triggering system. These factors can cause errors in the nulling pulse emission time or even false triggering, thus affecting the stability of the time reference during dynamic angle measurement and consequently the accuracy of dynamic angle calibration with the target.

[0006] Finally, regarding the measurement of circular grating lines, there are now specialized devices on the market for dynamically measuring circular grating lines, such as high-speed spectral imaging systems, high-speed camera systems, and dynamic grating scanning systems. These devices utilize high-speed imaging technology and data processing algorithms to capture and analyze the motion trajectory, changes, and related parameter variations of the circular grating lines in real time. However, the biggest problem with these devices is that they cannot dynamically measure the line spacing of the circular grating; they can only take pictures of the circular grating under the camera, which is a static measurement rather than a dynamic one. The accuracy of high-speed camera methods for measuring grating lines is limited by the pixel density of the CCD in the camera, therefore, they cannot dynamically measure the line spacing of the highest-level metrology-grade circular gratings. Summary of the Invention

[0007] In view of this, the present invention provides a dynamic angle measuring device with a wide measurement range and high measurement accuracy. The measuring device also has the feature of dynamically acquiring the grating spacing.

[0008] The dynamic angle measuring device includes: an integrated base, a turntable, a ring laser gyroscope angle measuring unit, an adjustment fixture, a dynamic angle zeroing unit, and a control and processing unit;

[0009] The integrated base is mounted on the vibration isolation platform.

[0010] The integrated base is equipped with a turntable and a control processing unit;

[0011] The rotating component of the turntable is connected to the annular laser gyroscope angle measuring unit mounted above it.

[0012] The dynamic angle zeroing unit includes a sensitive module, and the target mirror of the sensitive module is mounted on the ring laser gyroscope angle measuring unit;

[0013] The mounting fixture fixes the target to be measured above the target mirror and rotates with the ring laser gyroscope angle measuring unit.

[0014] The dynamic angle zeroing unit also includes a dual-frequency laser-fiber coupling module and a measurement module;

[0015] The laser beam emitted by the dual-frequency laser-fiber coupling module passes through the measurement module and is then directed toward the target mirror.

[0016] When the direction of the light emitted by the measurement module coincides with the direction of the reflected light after passing through the target mirror, the dynamic angle zeroing unit sends a zeroing pulse to the control processing unit, and the control processing unit begins to record the dynamic angle measured by the ring laser gyroscope angle measuring unit.

[0017] Preferably, the dual-frequency laser-fiber coupling module includes a dual-frequency laser, a coupling mirror, and a polarization-maintaining fiber;

[0018] The laser beam emitted by the dual-frequency laser enters the polarization-maintaining fiber through the coupling mirror, and the polarization-maintaining fiber delivers the laser beam to the measurement module.

[0019] Preferably, the measurement module adopts a single-beam Michelson interferometer optical path structure, which includes a collimator, an unpolarized beam splitter, a polarized beam splitter prism, a mirror, a polarizer, a quarter-wave plate, a half-wave plate, a PIN photodetector, and a four-quadrant detector.

[0020] The laser beam emitted from the dual-frequency laser-fiber coupling module passes through the collimator, and then sequentially passes through the unpolarized beam splitter, the half-wave plate, the polarized beam splitter prism, and the quarter-wave plate before being directed toward the target mirror of the sensitive module.

[0021] A polarizer and a PIN photodetector are provided on the unpolarized beam splitter;

[0022] The reflected light incident on the unpolarized beam splitter is received by the PIN photodetector after passing through the polarizer;

[0023] The polarizing beam splitter is equipped with a quarter-wave plate, a mirror, and a four-quadrant detector.

[0024] The laser beam passes through the polarizing beam splitter and the quarter-wave plate before being directed toward the target mirror.

[0025] The reflected light from the target mirror is directed to the four-quadrant detector through the reflector on the polarizing beam splitter.

[0026] The PIN photodetector and the four-quadrant detector are used to realize photoelectric signal conversion;

[0027] The dynamic angle nulling unit controls the output time of the nulling pulse based on the phase change between the interference signals in each quadrant of the four-quadrant detector in the measurement module.

[0028] Preferably, it also includes a grating line dynamic aiming unit;

[0029] The grating line dynamic aiming unit is also mounted on the integrated base and located on one side of the turntable. When the target to be measured is a circular grating, the grating line dynamic aiming unit can dynamically identify the spacing of the grating lines.

[0030] The control processing unit can receive the grating line dynamic aiming unit and the grating pulse information emitted by it.

[0031] Preferably, the laser gyroscope in the ring laser gyroscope angle measuring unit is square;

[0032] The laser gyroscope is an external cavity ring laser gyroscope, an internal cavity ring laser gyroscope, or a fiber optic gyroscope.

[0033] Preferably, the bearings of the turntable are air-bearing bearings.

[0034] A dynamic angle calibration method, employing the dynamic angle measuring device according to any one of claims 1-6, comprises the following steps:

[0035] S1: The mounting fixture fixes the target to be tested onto the target scope;

[0036] S2: Under the control of the control processing unit, the turntable drives the external cavity ring laser gyroscope and the target to be measured above to rotate together at a set angular velocity, or to perform variable angular velocity and variable angular acceleration motion according to the dynamic angle measurement requirements set by the target to be measured.

[0037] S3: The dynamic angle zero unit emits a laser beam toward the target mirror, and the target mirror reflects the laser beam back to the dynamic angle zero unit;

[0038] S4: Control the output of the zero-point pulse based on the weighted phase average value between photodiodes in adjacent quadrants in the measurement module. When the direction of the emitted light and the reflected light coincide, the dynamic angle zero-point unit sends the zero-point pulse signal to the control processing unit.

[0039] S5: The control processing unit begins to receive the gyroscope pulse signal emitted by the laser gyroscope and performs dynamic angle calculation to obtain the actual dynamic angle parameters;

[0040] S5: Compare the dynamic angle output by the target itself with the dynamic angle calculated by the control processing unit.

[0041] A method for measuring the spacing between circular grating lines, comprising the following steps:

[0042] S1: The mounting fixture fixes the circular grating to be tested onto the target mirror of the external cavity ring laser gyroscope;

[0043] S2: Under the control of the control processing unit, the turntable drives the external cavity ring laser gyroscope and the circular grating under test to rotate together at a set fixed angular velocity, or to move with variable angular velocity and variable angular acceleration according to the dynamic angle measurement requirements of the circular grating under test.

[0044] S3: When the dynamic angle zero-pointing unit emits a laser towards the target mirror, the target mirror reflects the laser back to the dynamic angle zero-pointing unit. The zero-pointing pulse is controlled to be output according to the weighted phase average value between the photodiodes in adjacent quadrants in the measurement module. When the direction of the emitted light and the reflected light coincide, the dynamic angle zero-pointing unit sends a zero-pointing pulse signal to the control processing unit.

[0045] S4: The control processing unit begins to receive the grating line dynamic aiming unit's grating pulse information;

[0046] S5: The control processing unit collects the grating scribe pulse information and completes the measurement of the grating scribe spacing.

[0047] Beneficial effects:

[0048] (I) The integrated base is equipped with a turntable, a laser gyroscope angle measuring unit, a dynamic angle zeroing unit, a mounting and adjusting fixture, and a control and processing unit, which solves the problem of operators changing and adjusting between different measuring devices to achieve different angle measuring ranges and accuracies. It achieves a full-circle angle measuring range of 0°-360°, with an angle measuring accuracy of 0.05″ (very high accuracy, reaching 1 / 20 of an angle in seconds), and a measurement speed range of 1° / s-360° / s.

[0049] (II) The dynamic angle nulling unit in this invention is based on the differential wavefront interferometry principle. This unit uses a four-quadrant detector to determine the pose of the target mirror (reflector) during rotation by measuring the phase difference between the light and the reference light. Based on the pose, it determines whether to output a nulling pulse: a nulling pulse is output only when the phases of the four quadrants in the four-quadrant detector are consistent. The dynamic angle nulling unit does not depend on the intensity of the returned light or the threshold value of the Schmitt trigger. Instead, it generates the nulling pulse by judging the phase difference between the four interference signals in the four-quadrant detector. This solves the problem of errors or even false triggering in the transmission time of the nulling pulse in existing dynamic angle nulling devices; it can output the nulling pulse more accurately, ensuring the stability of the time reference during the operation of the entire dynamic angle measurement device and improving the calibration accuracy of the dynamic angle parameters.

[0050] (III) The measuring device is also equipped with a dynamic aiming unit for grating lines. On the one hand, it solves the technical problem that existing dynamic angle measuring devices cannot dynamically measure the spacing between the grating lines. On the other hand, the dynamic angle measuring device of the present invention requires the circular grating to rotate on the laser gyroscope, and traces the angle between the grating lines to the laser wavelength in the ring laser gyroscope, with a clear tracing chain. Attached Figure Description

[0051] Figure 1 This is a diagram of a dynamic angle measuring device assembly according to the present invention;

[0052] Figure 2 This is a structural and signal logic diagram of a dynamic angle measuring device according to the present invention;

[0053] Among them, 1-vibration isolation platform, 2-integrated base, 3-turntable, 4-ring laser gyroscope angle measuring unit, 5-assembly and adjustment fixture, 6-dynamic angle zeroing unit, 7-control and processing unit, 8-grating line dynamic aiming unit, 61-dual-frequency laser-fiber coupling module, 62-measurement module, 63-sensitive module, 611-dual-frequency laser, 612-coupler mirror, 613-polarization-maintaining fiber, 621-collimator, 622-unpolarized beam splitter, 623-polarized beam splitter prism, 624-reflector, 625-polarizer, 626-1 / 4 wave plate, 627-1 / 2 wave plate, 628-PIN photodetector, 629-four-quadrant detector, 631-target mirror. Detailed Implementation

[0054] The present invention will be further described below with reference to the accompanying drawings. It should be emphasized that the embodiments described in the present invention are illustrative and not limiting. Therefore, the present invention is not limited to the embodiments described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

[0055] Example 1:

[0056] like Figure 1-2 The aforementioned dynamic angle measuring device, mounted on a vibration isolation platform 1, includes an integrated base 2, a turntable 3, a ring laser gyroscope angle measuring unit 4, an adjustment fixture 5, and a dynamic angle zeroing unit 6. The integrated base 2 is mounted on the vibration isolation platform 1; the turntable 3 and a control processing unit 7 are mounted on the integrated base 2. The turntable 3 includes a base and a rotating component. The base is fixedly connected to the vibration isolation platform 1, and the rotating component is connected to the ring laser gyroscope angle measuring unit 4 above it. The ring laser gyroscope angle measuring unit 4 can rotate around the axis of the turntable 3 under the drive of the turntable 3, and calculates the dynamic angle by outputting laser gyroscope pulse signals to the control processing unit 7 (this is prior art). In addition to calculating the dynamic angle of the target, the control processing unit 7 can also control the turntable 3 and the ring laser gyroscope angle measuring unit 4. The target is fixed to the ring laser gyroscope angle measuring unit 4 by the adjustment fixture 5 and rotates with the ring laser gyroscope angle measuring unit 4. The dynamic angle zeroing unit 6 is used to determine the measurement start position of the target to be measured, so as to improve the calibration accuracy of the dynamic angle measuring device.

[0057] The dynamic angle zeroing unit 6 includes a dual-frequency laser-fiber coupling module 61, a measurement module 62, and a sensing module 63; wherein, the dual-frequency laser-fiber coupling module 61 includes a dual-frequency laser 611, a coupling mirror 612, and a polarization-maintaining fiber 613; the laser beam emitted by the dual-frequency laser 611 enters the polarization-maintaining fiber 613 through the coupling mirror 612.

[0058] The sensing module 63 is disposed on the ring laser gyroscope angle measuring unit 4, and includes a target mirror 631 (e.g., a polyhedron) for receiving and reflecting the laser beam emitted from the measuring module 62.

[0059] The measurement module 62 compares and analyzes the laser beam emitted by the dual-frequency laser-fiber coupling module 61 and the laser beam received from the sensitive module 63 based on the differential wavefront interferometry principle (which has high-precision phase measurement capability, reduces pulse output error caused by changes in the external environment and pulse output error caused by tilting motion error of the target mirror 631 during rotation) to determine the time to send the zero pulse to the control processing unit 7. The measurement module 62 adopts a single-beam Michelson interferometer optical path structure, specifically including a collimator 621, an unpolarized beam splitter 622, a polarizing beam splitter prism 623, a mirror 624, a polarizer 625, a quarter-wave plate 626, a half-wave plate 627, a PIN photodetector 628, and a four-quadrant detector 629. The laser beam emitted from the dual-frequency laser-fiber coupling module 61 passes through the collimator 621, and then sequentially passes through the unpolarized beam splitter 622, the half-wave plate 627, the polarizing beam splitter prism 623, and the quarter-wave plate 626 before being directed towards the target of the sensing module 63. The target mirror 631 has a polarizer 625 and a PIN photodetector 628 on the non-polarizing beam splitter 622, and a quarter-wave plate 626, a reflector 624 and a quadrant detector 629 on the polarizing beam splitter 623. The laser light entering the non-polarizing beam splitter 622 is split into two beams. One beam is reflected light, which is received by the PIN photodetector 629 after passing through the polarizer 625. The other beam is transmitted light, which enters the polarizing beam splitter 623 after passing through the half-wave plate 627, and then illuminates the target mirror 631 after passing through the quarter-wave plate 626 on the polarizing beam splitter 623.

[0060] The PIN photodetector 628 and the four-quadrant detector 629 are used to realize photoelectric signal conversion and send zero pulse signals to the control processing unit 7.

[0061] The single-beam Michelson interferometer optical path structure consists of a single beam of light emitted from a source, which is split into two beams by the unpolarized beam splitter 622. One beam is reflected back after striking the target mirror 631 and interferes with the other beam. This structure changes the optical path difference of the target mirror 631 as the position of the target changes, and determines the timing of sending the null pulse to the control processing unit 7 based on the phase change between the interference signals in each quadrant of the four-quadrant detector 629.

[0062] Dynamic angle refers to the working principle of zero unit:

[0063] Coupler 612 couples two laser beams of different wavelengths emitted by dual-frequency laser 611 to polarization-maintaining fiber 613, which then transmits the beams to measurement module 62. Within measurement module 62, the beams are collimated by collimator 621 and then enter unpolarized beam splitter 622. In unpolarized beam splitter 622, a portion of the laser beam is reflected to PIN photodetector 628, while the other portion, the transmitted light, passes through half-wave plate 627 and enters polarized beam splitter 623. In polarized beam splitter 623, a portion of the transmitted light passes through quarter-wave plate 626 and is reflected back to polarized beam splitter 623 by mirror 624. The other portion of the transmitted light passes through quarter-wave plate 626 and illuminates target mirror 631, then is reflected by target mirror 631 and returns to polarized beam splitter 623 via quarter-wave plate 626. Both transmitted beams returning to polarized beam splitter 623 then pass through polarizer 625 and illuminate quadrant detector 629. The zero-point pulse is controlled by the weighted phase average value between adjacent quadrant photodiodes in the quadrant detector 629. When the direction of the emitted light and the reflected light coincide, that is, when there is no angle between the light illuminating the target mirror 631 and the light reflected by the target mirror 631, the PIN photodetector 628 and the quadrant detector 629 output the zero-point pulse through photoelectric signal conversion.

[0064] The dynamic angle zeroing unit 6 is located on one side of the ring laser gyroscope angle measuring unit 4 and is responsible for sending zeroing pulse signals to the control processing unit 7. A target mirror 631 is mounted on the laser gyroscope of the ring laser gyroscope angle measuring unit 4. The target mirror 631 receives and reflects the laser beam emitted by the dynamic angle zeroing unit 6. After receiving the reflected laser beam, the dynamic angle zeroing unit 6 controls the output of a zeroing pulse based on the weighted phase average value between the photodiodes in adjacent quadrants of the four-quadrant detector 629. A zeroing pulse is output when the directions of the emitted and reflected light coincide, i.e., when there is no angle between the light illuminating the target mirror 631 and the light reflected by the target mirror 631. The dynamic angle zeroing unit 6 sends the zeroing pulse to the control processing unit 7. After receiving the zeroing pulse signal, the control processing unit 7 begins to receive the dynamic angle of the target output by the ring laser gyroscope angle measuring unit 4.

[0065] When the target under test can output a dynamic angle, the purpose of using the dynamic angle zeroing unit 6 is to compare the dynamic angle of the target under test with that of the ring laser gyroscope angle measuring unit 4 at the same time, and to calibrate the dynamic angle output by the target under test.

[0066] When the target under test cannot output a dynamic angle, the dynamic angle zeroing unit 6 also needs to send a zeroing signal. The function of the zeroing signal is to determine the measurement start position, that is, to set a measurement reference for the dynamic angle measured by the ring laser gyroscope angle measuring unit 4.

[0067] As an example, the laser gyroscope is an external cavity ring laser gyroscope.

[0068] As an example, the laser gyroscope is an internal cavity ring laser gyroscope or a fiber optic gyroscope.

[0069] The mounting fixture 5, also known as a two-dimensional displacement stage, has an in-plane displacement adjustment function. The mounting fixture 5 can make the axis of the target under test coaxial with the axis of the turntable 3.

[0070] As an example, the rotating component of the turntable 3 is an air-bearing bearing, and the turntable 3 is an air-bearing turntable. This air-bearing turntable provides the hardware foundation for the dynamic angle measurement device and will not introduce interfering torque to the target being measured.

[0071] Working principle:

[0072] The rotating components on the turntable 3 drive the ring laser gyroscope angle measuring unit 4 and the target to be measured above it to rotate; at the same time, the control processing unit 7 drives the dynamic angle zeroing unit 6 to emit laser to the target mirror 631 and receives the zeroing pulse signal from the dynamic angle zeroing unit 6 to complete the dynamic angle zeroing operation (the purpose of this is to ensure that the measuring device can accurately and stably identify the position of the angle zero point during operation).

[0073] The steps for calibrating a target that can output dynamic angles using this device are as follows:

[0074] S1: Fixture 5 secures the target to be tested onto the target scope 631;

[0075] S2: Under the control of the control processing unit 7, the turntable 3 drives the external cavity ring laser gyroscope and the target to be measured above to rotate together at a set fixed angular velocity, or to perform variable angular velocity and variable angular acceleration motion according to the dynamic angle measurement set by the target to be measured.

[0076] S3: The dynamic angle zero unit 6 emits a laser towards the target mirror 631, and the target mirror 631 reflects the laser back to the dynamic angle zero unit 6.

[0077] S4: The zero-pointing pulse is controlled and output according to the weighted phase average value between the photodiodes in adjacent quadrants of the four-quadrant detector 629. When the direction of the emitted light and the reflected light coincide, that is, when there is no angle between the light illuminating the target mirror 631 and the light reflected by the target mirror 631, the dynamic angle zero-pointing unit 6 sends a zero-pointing pulse signal to the control processing unit 7.

[0078] S5: The control processing unit 7 starts receiving the gyroscope pulse signal emitted by the laser gyroscope and performs dynamic angle calculation to obtain the actual dynamic angle parameters.

[0079] S5: Compare the dynamic angle output by the target itself with the dynamic angle calculated by the control processing unit 7.

[0080] Example 2:

[0081] Based on the above embodiment 1, the measuring device further includes a grating dynamic aiming unit 8; the grating dynamic aiming unit 8 is also disposed on the integrated base 2 and located on one side of the turntable 3; when the target to be measured is a circular grating, the grating dynamic aiming unit 8 can dynamically identify the spacing of the grating lines. The control processing unit 7 on the integrated base 2 processes the grating pulse information emitted by the grating dynamic aiming unit 8.

[0082] The steps for dynamically acquiring the spacing between circular grating lines are as follows:

[0083] S1: Fixture 5 fixes the circular grating to be tested onto the target mirror 631 of the external cavity ring laser gyroscope;

[0084] S2: Under the control of the control processing unit 7, the turntable 3 drives the external cavity ring laser gyroscope and the circular grating to be measured to rotate together at a set fixed angular velocity, or to move with variable angular velocity and variable angular acceleration according to the dynamic angle measurement requirements of the circular grating to be measured.

[0085] S3: When the dynamic angle zeroing unit 6 emits a laser to the target mirror 631, the target mirror 631 reflects the laser back to the dynamic angle zeroing unit 6. The zeroing pulse is controlled to be output according to the weighted phase average value between the photodiodes in adjacent quadrants of the four-quadrant detector 629. When the direction of the emitted light and the reflected light coincide, that is, when there is no angle between the light illuminating the target mirror 631 and the light reflected by the target mirror 631, the dynamic angle zeroing unit 6 sends a zeroing pulse signal to the control processing unit 7.

[0086] S4: Control processing unit 7 begins to receive grating line pulse information from grating line dynamic aiming unit 8;

[0087] S5: Control processing unit 7 collects the grating scribe pulse information and completes the measurement of the grating scribe spacing.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A dynamic angle measuring device, mounted on a vibration isolation platform, characterized in that, Includes an integrated base, turntable, ring laser gyroscope angle measuring unit, assembly and adjustment fixture, dynamic angle zeroing unit, and control and processing unit; The integrated base is mounted on the vibration isolation platform. The integrated base is equipped with a turntable and a control processing unit; The rotating component of the turntable is connected to the annular laser gyroscope angle measuring unit mounted above it. The dynamic angle zeroing unit includes a sensitive module, and the target mirror of the sensitive module is mounted on the ring laser gyroscope angle measuring unit; The mounting fixture fixes the target to be measured above the target mirror and rotates with the ring laser gyroscope angle measuring unit. The dynamic angle zeroing unit also includes a dual-frequency laser-fiber coupling module and a measurement module; the measurement module adopts a single-beam Michelson interferometer optical path structure, which includes a collimator, a non-polarizing beam splitter, a polarizing beam splitter prism, a reflector, a polarizer, a quarter-wave plate, a half-wave plate, a PIN photodetector, and a four-quadrant detector. The laser beam emitted from the dual-frequency laser-fiber coupling module passes through the collimator, and then sequentially passes through the unpolarized beam splitter, the half-wave plate, the polarized beam splitter prism, and the quarter-wave plate before being directed toward the target mirror of the sensitive module. A polarizer and a PIN photodetector are provided on the unpolarized beam splitter; The reflected light incident on the unpolarized beam splitter is received by the PIN photodetector after passing through the polarizer; The polarizing beam splitter is equipped with a quarter-wave plate, a mirror, and a four-quadrant detector. The laser beam passes through the polarizing beam splitter and the quarter-wave plate and then is directed toward the target mirror. The reflected light from the target mirror is directed to the four-quadrant detector through the reflector on the polarizing beam splitter. The PIN photodetector and the four-quadrant detector are used to realize photoelectric signal conversion; The dynamic angle nulling unit controls the output time of the nulling pulse based on the phase change between the interference signals in each quadrant of the four-quadrant detector in the measurement module. When the direction of the light emitted by the measurement module coincides with the direction of the reflected light after passing through the target mirror, the dynamic angle zeroing unit sends a zeroing pulse to the control processing unit, and the control processing unit begins to record the dynamic angle measured by the ring laser gyroscope angle measuring unit.

2. The dynamic angle measuring device according to claim 1, characterized in that, The dual-frequency laser-fiber coupling module includes a dual-frequency laser, a coupling mirror, and a polarization-maintaining fiber; The laser beam emitted by the dual-frequency laser enters the polarization-maintaining fiber through the coupling mirror, and the polarization-maintaining fiber delivers the laser beam to the measurement module.

3. The dynamic angle measuring device according to claim 1, characterized in that, It also includes a dynamic aiming unit for grating lines; The grating line dynamic aiming unit is also mounted on the integrated base and located on one side of the turntable. When the target to be measured is a circular grating, the grating line dynamic aiming unit can dynamically identify the spacing of the grating lines. The control processing unit can receive the grating line dynamic aiming unit and the grating pulse information emitted by it.

4. A dynamic angle measuring device according to any one of claims 1-3, characterized in that, The laser gyroscope in the ring laser gyroscope angle measuring unit is square; The laser gyroscope is either an external cavity ring laser gyroscope or an internal cavity ring laser gyroscope.

5. A dynamic angle measuring device according to any one of claims 1-3, characterized in that, The turntable uses air-bearing bearings.

6. A dynamic angle calibration method, based on the ability of the target to output a dynamic angle, characterized in that, The dynamic angle measuring device according to any one of claims 1, 2, 3, and 5 comprises the following steps: S1: The mounting fixture fixes the target to be tested onto the target scope; S2: Under the control of the control processing unit, the turntable drives the external cavity ring laser gyroscope and the target to be measured above to rotate together at a set angular velocity, or to perform variable angular velocity and variable angular acceleration motion according to the dynamic angle measurement requirements set by the target to be measured. S3: The dynamic angle zero unit emits a laser beam toward the target mirror, and the target mirror reflects the laser beam back to the dynamic angle zero unit; S4: Control the output of the zero-point pulse based on the weighted phase average value between photodiodes in adjacent quadrants in the measurement module. When the direction of the emitted light and the reflected light coincide, the dynamic angle zero-point unit sends the zero-point pulse signal to the control processing unit. S5: The control processing unit begins to receive the gyroscope pulse signal emitted by the laser gyroscope and performs dynamic angle calculation to obtain the actual dynamic angle parameters; S5: Compare the dynamic angle output by the target itself with the dynamic angle calculated by the control processing unit.

7. A method for measuring the spacing of circular grating lines, characterized in that, The dynamic angle measuring device according to any one of claims 3 and 5 comprises the following steps: S1: The mounting fixture fixes the circular grating to be tested onto the target mirror of the external cavity ring laser gyroscope; S2: Under the control of the control processing unit, the turntable drives the external cavity ring laser gyroscope and the circular grating under test to rotate together at a set fixed angular velocity, or to move with variable angular velocity and variable angular acceleration according to the dynamic angle measurement requirements of the circular grating under test. S3: When the dynamic angle zero-pointing unit emits a laser towards the target mirror, the target mirror reflects the laser back to the dynamic angle zero-pointing unit. The zero-pointing pulse is controlled to be output according to the weighted phase average value between the photodiodes in adjacent quadrants in the measurement module. When the direction of the emitted light and the reflected light coincide, the dynamic angle zero-pointing unit sends a zero-pointing pulse signal to the control processing unit. S4: The control processing unit begins to receive the grating line dynamic aiming unit's grating pulse information; S5: The control processing unit collects the grating scribe pulse information and completes the measurement of the grating scribe spacing.

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