Equivalent verification method of single-platform non-equal-arm interferometer for space gravitational wave detection

Abstract

The invention provides an equivalent verification method of a single-platform non-equal-arm interferometer for space gravitational wave detection. The single-platform non-equal-arm interferometer comprises a laser, an optical fiber splitter, an acoustic optical modulator, an optical fiber collimator, a beam expander, a diaphragm, a fast reflecting mirror, a beam splitter, a four-quadrant detector, a phase meter and an upper computer. The fast reflecting mirror is mounted in front of the beam splitter and is used for generating directional jitter of a far-end light beam and pressing the directional jitter respectively; and the beam expander is mounted in front of the fast reflecting mirror and is used for simulating a far-field Gaussian flat-topped beam. According to the invention, the beam expanding mirror and the fast reflecting mirror are used for simulating a Gaussian flat-topped beam light field and pointing jitter of a far-field beam, and the upper computer and the fast reflecting mirror are used for closed-loop control, heterodyne interference signals are processed and pointing jitter is suppressed, so that equivalent verification of the single-platform non-equal-arm interferometer for space gravitational wave detection is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of space gravitational wave detection interferometers, and in particular relates to an equivalent verification method for a single-platform non-equal-arm interferometer for space gravitational wave detection. Background Art

[0002] The non-equal-arm interferometer measures the tiny length changes caused by gravitational waves by means of laser interference. It usually consists of multiple spacecraft that form an equilateral triangle or other geometric shape, and the distance between the spacecraft can reach millions of kilometers. When a gravitational wave passes, it causes a tiny change in the distance between the spacecraft, which can be accurately measured by a laser interferometer. The core of the device lies in its high-precision measurement capability, which can sense extremely small distance changes caused by gravitational waves. Each spacecraft is equipped with components such as a laser transmitter, an optical platform, a telescope, a detector, and a phase meter, which work together to form a laser interference pattern. When a gravitational wave passes, the changes in the interference pattern are accurately recorded, thereby inferring the existence of the gravitational wave and its characteristics.

[0003] In space gravitational wave detection, it is necessary to detect gravitational wave signals through the unequal-arm Michelson interferometer. In order to reduce the risk of space missions and ensure the successful implementation of space gravitational wave detection missions, it is necessary to conduct equivalent ground verification of the unequal-arm interferometer based on the Michelson interferometer.

[0004] The main problems in the current ground verification include: 1. Equivalence verification of the ground optical system of the ultra-long unequal arm interferometer, that is, simulating the interference problem of the arm length of three million kilometers and the sub-meter arm length of the local satellite. Specifically, due to the unequal interferometer arms of the intersatellite laser, the laser frequency noise cannot be eliminated in common mode, so that the weak gravitational wave signal is submerged by the laser frequency noise. The time delay interferometry (TDI) technology delays the laser phase data in time to form a virtual equal-arm interferometer, thereby reducing the impact of laser frequency noise on the detection of gravitational wave signals. In order to verify on the ground that TDI technology can reduce the impact of laser frequency noise on gravitational wave detection to 3×10^(-7)Hz / Hz at the Fourier frequency of 1mHz, it is necessary to analyze the main sources of the background noise of the TDI ground verification system and propose important parameter design requirements for the laser interferometer for ground verification of TDI technology; 2. The problem of equivalent verification of heterodyne interference between a local Gaussian beam in space and a Gaussian flat-top beam received from a remote satellite. Specifically: when a Gaussian beam propagates in free space, its amplitude and phase will change with the propagation distance. In order to accurately simulate this process, the beam propagation algorithm BPM is usually used, including the fast Fourier-beam propagation algorithm FFT-BPM, the finite difference-beam propagation algorithm (FD-BPM) and the finite element-beam propagation algorithm FE-BPM. In practical applications, it is necessary to consider the impact of the change in the refractive index of the ionosphere on the beam quality and the impact of the initial wavefront distortion on the receiving surface; 3. The equivalent verification problem of laser pointing jitter by the precision pointing system based on DWS technology. In laser pointing control, the measurement beam will inevitably have pointing jitter and other problems. When coupled to the detector, the reference beam position will remain unchanged, and the measurement beam will produce a beam offset on the image plane of the detector. The two beams will have a reduced degree of convergence on the detector detection surface and uneven distribution. The error caused by this nonlinear measurement will affect the stability of the pointing control.

[0005] How to solve the problems of ultra-long unequal-arm interference, stray light interference, laser frequency noise influence and equivalent verification of laser pointing jitter by precision pointing system, and provide an equivalent verification method of single-platform non-equal-arm interferometer for space gravitational wave detection are technical problems that technicians in this field need to solve urgently. Summary of the invention

[0006] The purpose of the present invention is to provide an equivalent verification method for a single-platform non-equal-arm interferometer for space gravitational wave detection in response to the problems in the prior art.

[0007] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] The equivalent verification method of a single-platform non-equal-arm interferometer for space gravitational wave detection is characterized by comprising the following steps:

[0009] S1, Construction of simulation laboratories or test sites: Simulate microgravity, high vacuum, extreme temperature changes, and cosmic ray conditions to approximate the space environment, and build simulation laboratories or test sites to accurately test the actual performance of spacecraft and its components in space;

[0010] S2, build an equivalent verification system, in which the laser emits laser light, and the laser beam is divided into two by the optical fiber splitter; the acousto-optic modulator modulates the two laser beams; the two laser beams are collected and emitted by the first optical fiber collimator and the second optical fiber collimator respectively; the laser emitted by the first optical fiber collimator in the beam expander; the laser passing through the beam expander in the aperture; the first fast mirror reflects the laser passing through the aperture; the second fast mirror reflects the laser emitted by the second optical fiber collimator; the first beam splitter combines the two laser beams reflected by the first fast mirror and the second fast mirror; the second beam splitter emits the combined laser beam to the first four-quadrant detector and the second four-quadrant detector respectively; the phase meter reads the signals generated by the first four-quadrant detector and the second four-quadrant detector; the host computer uses the differential wavefront sensing technology DWS to process the signal read by the phase meter, and controls the deflection of the second fast mirror to achieve closed-loop control;

[0011] S3, perform system cascade adjustment test: in the simulation laboratory or test site constructed in step S1, start the equivalent verification system constructed in step S2, simulate the Gaussian flat-top beam light field and the generated pointing jitter of the far-field beam emitted by the remote satellite in space through the beam expander and the fast reflection mirror, and use the fast reflection mirror, the beam splitter, the four-quadrant detector phase meter and the upper-level simulation local satellite to receive the laser emitted by the remote satellite and the local laser to form heterodyne interference, so as to suppress the pointing jitter through closed-loop control;

[0012] S4, data analysis and evaluation: During the test, collect and record data on the stability of the laser beam, the response speed of the detector, and the reading accuracy of the phase meter. Use the closed-loop control of the host computer and DWS technology to suppress the pointing jitter. Finally, use the power spectrum density to analyze the pointing jitter suppression data and evaluate whether the system performance meets the requirements.

[0013] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0014] As a preferred technical solution of the present invention: in step S2, a beam expander is used to expand the Gaussian beam emitted from the first optical fiber collimator, and the expanded laser is intercepted by an aperture to simulate a Gaussian flat-top beam in the far field;

[0015] The Gaussian flat-top beam passing through the aperture is reflected by a first fast reflection mirror, and the first fast reflection mirror is controlled to be rapidly deflected to simulate the pointing jitter of the far-field beam;

[0016] The Gaussian beam emitted from the second optical fiber collimator is reflected by the second fast reflection mirror, and the second fast reflection mirror is controlled based on the signal obtained by the host computer, so as to realize the controllability of the deflection of the Gaussian beam;

[0017] The Gaussian flat-top beam reflected by the first fast reflector and the Gaussian beam reflected by the second fast reflector are combined by the first beam splitter to realize heterodyne interference of unequal arms;

[0018] The combined beam of the first beam splitter is directed to the first four-quadrant detector and the second four-quadrant detector by the second beam splitter to collect heterodyne interference signals, so that the signals generated by the Gaussian beam and the Gaussian flat-top beam can be analyzed in both heading and pitch postures.

[0019] As a preferred technical solution of the present invention: a phase meter is used to read the phase signals of the first four-quadrant detector and the second four-quadrant detector, so that the host computer uses differential wavefront sensing technology to process the signals, controls the deflection of the second fast reflection mirror to suppress the pointing jitter generated by the first fast reflection mirror, performs closed-loop control, and realizes precise ranging and inversion of gravitational wave signals, which can realize the equivalent verification of a single-platform non-equal-arm interferometer for space gravitational wave detection.

[0020] As a preferred technical solution of the present invention: a first fast-reflection mirror, a beam expander and an aperture are used to simulate the remote satellite in space transmitting a laser signal to generate pointing jitter; a second fast-reflection mirror, a first beam splitter, a second beam splitter, a four-quadrant detector, a phase meter and a host computer are used to simulate the local satellite receiving the laser transmitted by the remote satellite and the local laser to form heterodyne interference, thereby suppressing the pointing jitter through closed-loop control.

[0021] As a preferred technical solution of the present invention: in step S3, the differential wavefront sensing technology DWS signal is the phase difference of the left and right or upper and lower quadrants of the four-quadrant detector QPD read by the phase meter PM:

[0022]

[0023] Where DWS is the differential wavefront sensing technology signal, φ A is the phase of the signal in quadrant A, φ B is the phase of the signal in quadrant B, φ C is the phase of the signal in quadrant C, φ D is the phase of the signal in quadrant D.

[0024] The host computer PC inverts the differential wavefront sensing technology DWS signal into the pointing jitter α through a calibrated coefficient k:

[0025] α=DWS / k,

[0026] Where k is the linear fitting coefficient of the differential wavefront sensing technology signal, and α is the laser angle measured by the differential wavefront sensing technology.

[0027] As a preferred technical solution of the present invention: in step S4, the power spectrum density needs to collect N pointing jitters α in the time domain to obtain x[n], and perform discrete Fourier transform on them to obtain X N (f):

[0028]

[0029] Then, the data X obtained by discrete Fourier transform N (f) Processing to obtain power spectrum density:

[0030]

[0031] As a preferred technical solution of the present invention: the power spectrum density value obtained in step S4 is suppressed to 10nrad / HZ at 1HZ and lower frequencies according to the pointing jitter 1 / 2 The order of magnitude is used to determine whether the single-platform non-equal-arm interferometer used for space gravitational wave detection can meet aerospace needs.

[0032] Compared with the prior art, the equivalent verification method of the single-platform unequal-arm interferometer for space gravitational wave detection of the present invention has the following beneficial effects: in the ground verification, by using the first fast reflection mirror, the beam expander and the aperture to simulate the Gaussian flat-top beam light field of the far-field light beam emitted by a remote satellite in space and the pointing jitter generated by it, the problem of equivalent verification of the ground optical system of the ultra-long unequal-arm interferometer is solved.

[0033] The present invention simulates the heterodyne interference formed by the laser emitted by the remote satellite and the local laser received by the local satellite through the second fast-reflecting mirror, the first beam splitter, the second beam splitter, the four-quadrant detector, the phase meter and the host computer, so as to realize closed-loop control to suppress the pointing jitter, and solve the problem of equivalent verification of the heterodyne interference between the local Gaussian beam in space and the Gaussian flat-top beam received from the remote satellite. By performing power spectral density analysis on the suppressed pointing jitter data, it is ensured that it is suppressed to the order of 10nrad / Hz^(1 / 2) at a frequency of 1Hz and below, and the problem of equivalent verification of the laser pointing jitter by the precision pointing system based on the DWS technology is solved, and the equivalent verification of the non-equal-arm interferometer for space gravitational wave detection is realized on a single platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of an equivalent verification system constructed in step S2 in the equivalent method of the single-platform non-equal-arm interferometer for space gravitational wave detection of the present invention;

[0035] In the accompanying drawings, there are laser 1; fiber splitter 2; acousto-optic modulator 3; first fiber collimator 4; second fiber collimator 5; beam expander 6; aperture 7; first fast mirror 8; second fast mirror 9; first beam splitter 10; second beam splitter 11; first four-quadrant detector 12; second four-quadrant detector 13; phase meter 14; host computer 15; differential wavefront sensing technology 16. DETAILED DESCRIPTION

[0036] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0037] The invention discloses an equivalent verification method for a single-platform non-equal-arm interferometer for space gravitational wave detection, comprising a laser 1, an optical fiber splitter 2, an acousto-optic modulator 3, an optical fiber collimator, a beam expander BE, an aperture ID, a fast reflection mirror FSM, a beam splitter BS, a four-quadrant detector QPD, a phase meter PM and a host computer PC; the method is characterized in that: the laser 1 emits a laser, and the laser beam is split into two by the optical fiber splitter 2; the acousto-optic modulator 3 modulates two laser beams, and the two laser beams are collected by a first optical fiber collimator 4 and a second optical fiber collimator 5, and are emitted by the first optical fiber collimator 4 and the second optical fiber collimator 5; the beam expander 6 emits a laser beam by the first optical fiber collimator 4 and the second optical fiber collimator 5; the laser beam is transmitted to the optical fiber collimator 6 by the first optical fiber collimator 6; the optical fiber collimator 6 emits a laser beam ... The laser light emitted by the optical fiber collimator 4; the laser light passing through the beam expander 6 in the aperture 7; the first quick-reflection mirror 8 reflects the laser light passing through the aperture 7; the second quick-reflection mirror 9 reflects the laser light emitted by the second optical fiber collimator 5; the first beam splitter 10 combines the two laser light beams reflected by the first quick-reflection mirror 8 and the second quick-reflection mirror 9; the first beam splitter 11 respectively directs the combined laser light beam to the first four-quadrant detector 12 and the second four-quadrant detector 13; the phase meter 14 reads the signals generated by the first four-quadrant detector 12 and the second four-quadrant detector 13; the host computer 15 analyzes the signals read by the phase meter 14 and controls the deflection of the second quick-reflection mirror 9.

[0038] Furthermore, the laser 1 generates a stable Gaussian beam, and the laser beam is split into two by a 50:50 optical fiber splitter 2 to generate two Gaussian beams with the same power and frequency.

[0039] Furthermore, the two laser beams with the same frequency are modulated into two laser beams with a stable frequency difference by using the acousto-optic modulator 3. The two laser beams are injected into the optical path at different positions and directions through the first optical fiber collimator 4 and the second optical fiber collimator 5 to facilitate interference in the subsequent optical path.

[0040] Furthermore, the Gaussian beam emitted from the first optical fiber collimator 4 is expanded by a beam expander 6, and the expanded laser is intercepted by an aperture 7 to simulate a Gaussian flat-top beam in the far field.

[0041] Furthermore, the Gaussian flat-top beam passing through the aperture 7 is reflected by the first fast reflection mirror 8, and the first fast reflection mirror 8 is controlled to perform rapid deflection to simulate the pointing jitter of the far-field beam.

[0042] Furthermore, the second fast reflection mirror 9 is used to reflect the Gaussian beam emitted by the second optical fiber collimator 5 , and the second fast reflection mirror 9 is controlled based on the signal obtained by the host computer 15 , thereby achieving controllability of the deflection of the Gaussian beam.

[0043] Furthermore, the first beam splitter 10 is used to combine the Gaussian flat-top beam reflected by the first fast reflection mirror 8 and the Gaussian beam reflected by the second fast reflection mirror 9 to realize heterodyne interference of unequal arms.

[0044] Furthermore, the combined light beam of the first beam splitter 10 is directed to the first four-quadrant detector 12 and the second four-quadrant detector 13 by the first beam splitter 11 to collect heterodyne interference signals, so that the signals generated by the Gaussian beam and the Gaussian flat-top beam can be analyzed in both heading and pitch postures.

[0045] Furthermore, the phase meter 14 is used to read the phase signals of the first four-quadrant detector 12 and the second four-quadrant detector 13, so that the host computer 15 uses the differential wavefront sensing technology DWS to process the signals, control the deflection of the second fast mirror 9 to suppress the pointing jitter generated by the first fast mirror 8, perform closed-loop control, and realize precise ranging and inversion of gravitational wave signals, which can realize the equivalent verification of the single-platform non-equal-arm interferometer for space gravitational wave detection.

[0046] The beneficial effects of the present invention are as follows: the present invention utilizes a beam expander and a fast reflector to simulate the Gaussian flat-top beam field and pointing jitter of a far-field beam, utilizes a host computer and a fast reflector to perform closed-loop control, processes heterodyne interference signals and suppresses pointing jitter, thereby realizing equivalent verification of a single-platform non-equal-arm interferometer for space gravitational wave detection.

[0047] Example 1

[0048] like Figure 1As shown, an equivalent verification method of a single-platform non-equal-arm interferometer for space gravitational wave detection includes a laser 1, an optical fiber splitter 2, an acousto-optic modulator 3, a first optical fiber collimator 4, a second optical fiber collimator 5, a beam expander 6, an aperture 7, a first fast-reflecting mirror 8, a second fast-reflecting mirror 9, a first beam splitter 10, a second beam splitter 11, a first four-quadrant detector 12, a second four-quadrant detector 13, a phase meter 14, and a host computer 15; the laser 1 emits a laser, and the optical fiber splitter 2 splits the laser beam into two; the acousto-optic modulator 3 modulates two laser beams, and the two laser beams are collected by the first optical fiber collimator 4 and the second optical fiber collimator 5 ... The first fiber collimator 4 and the second fiber collimator 5 emit; the laser emitted by the first fiber collimator 4 passes through the beam expander 6, the aperture 7, and the first quick-reflection mirror 8 in succession; the laser emitted by the second fiber collimator 5 passes through the second quick-reflection mirror 9; the first beam splitter 10 combines the two laser beams reflected by the first quick-reflection mirror 8 and the second quick-reflection mirror 9; the first beam splitter 11 respectively directs the combined laser beam to the first four-quadrant detector 12 and the second four-quadrant detector 13; the phase meter 14 reads the signals generated by the first four-quadrant detector 12 and the second four-quadrant detector 13; the host computer 15 analyzes the signal read by the phase meter 14 and controls the deflection of the second quick-reflection mirror 9.

[0049] The laser 1 uses a wavelength of 1064 nm, and the first fiber collimator 4 and the second fiber collimator 5 are customized models to reduce the divergence angle of the laser. The beam expansion ratio of the beam expander 6 is 20 times, and the first fast mirror 8 and the second fast mirror 9 are PI's S-330. The first beam splitter 10 and the second beam splitter 11 use UV fused quartz broadband plate spectroscopes. The first four-quadrant detector 12 and the second four-quadrant detector 13 are a high-sensitivity large-photosensitive surface four-quadrant photoelectric detection module.

[0050] The acousto-optic modulator 3 makes the interference laser produce a stable frequency difference, and the Gaussian beam in one end of the optical path is converted into a Gaussian flat-top beam by using the beam expander 6. The first fast mirror 8 is used to control the deflection angle of the Gaussian flat-top beam to produce pointing jitter, and the second fast mirror 9 controls the deflection of the Gaussian beam to suppress the pointing jitter, which can realize the equivalent verification of the single-platform non-equal-arm interferometer for space gravitational wave detection.

[0051] The present invention provides an equivalent verification method for a single-platform non-equal-arm interferometer for space gravitational wave detection, comprising the following steps:

[0052] (1) A 1064 nm laser 1 generates a stable Gaussian beam, which is split into two by a 50:50 fiber splitter 2 to generate two Gaussian beams with the same power and frequency.

[0053] (2) Under the working condition of 24V voltage, the acousto-optic modulator 3 modulates two laser beams with the same frequency into two laser beams with a frequency difference of 1.6MHZ. The two laser beams are injected into the optical path at different positions and directions through a customized fiber collimator.

[0054] (3) The Gaussian beam emitted from the first optical fiber collimator 4 is expanded by a 20x beam expander 6, and the expanded laser is intercepted by an aperture 7 to simulate a Gaussian flat-top beam in the far field.

[0055] (4) The S-330 first fast reflection mirror 8 of PI is used to reflect the Gaussian flat-top beam passing through the aperture 7, and the first fast reflection mirror 8 is controlled to perform rapid deflection to simulate the pointing jitter of the far-field beam.

[0056] (5) The S-330 second fast reflection mirror 9 of PI is used to reflect the Gaussian beam emitted by the second optical fiber collimator 5, and the second fast reflection mirror 9 is controlled based on the signal obtained by the host computer 15, so as to achieve the controllability of the Gaussian beam deflection.

[0057] (6) The Gaussian flat-top beam reflected by the first fast mirror 8 and the Gaussian beam reflected by the second fast mirror 9 are combined by the first beam splitter 10 to realize heterodyne interference of unequal arms.

[0058] (7) The combined light beam of the first beam splitter 10 is directed by the first beam splitter 11 to the first four-quadrant detector 12 and the second four-quadrant detector 13 with an operating voltage of plus or minus 5V to collect heterodyne interference signals, so as to analyze the signals generated by the Gaussian beam and the Gaussian flat-top beam in both heading and pitch postures.

[0059] (8) The phase meter 14 is used to read the phase signals of the first four-quadrant detector 12 and the second four-quadrant detector 13, so that the host computer 15 can use the differential wavefront sensing technology DWS to process the signals, control the deflection of the second fast mirror 9 to suppress the pointing jitter generated by the first fast mirror 8, and perform closed-loop control to achieve precise ranging and inversion of gravitational wave signals, thereby realizing the equivalent verification of the single-platform non-equivalent arm interferometer for space gravitational wave detection.

[0060] The first fast-reflection mirror, the beam expander and the aperture are used to simulate the Gaussian flat-top beam light field and the generated pointing jitter of the far-field light beam emitted by the remote satellite in space, thereby solving the equivalent verification of the ground optical system of the ultra-long unequal-arm interferometer, that is, simulating the interference problem of the arm length of three million kilometers and the sub-meter arm length of the local satellite; the second fast-reflection mirror 9, the first beam splitter 10, the first beam splitter 11, the four-quadrant detector, the phase meter 14 and the host computer are used to simulate the local satellite receiving the laser emitted by the remote satellite and the local laser to form heterodyne interference, thereby suppressing the pointing jitter through closed-loop control, thereby solving the problem of equivalent verification of heterodyne interference between the local Gaussian beam in space and the Gaussian flat-top beam received from the remote satellite; by analyzing the power spectral density of the suppressed pointing jitter data, it is ensured that it is suppressed at the order of 10nrad / HZ1 / 2 at 1HZ and lower frequencies, thereby solving the problem of equivalent verification of laser pointing jitter by the precision pointing system based on DWS technology; finally, the equivalent verification of the non-equal-arm interferometer for space gravitational wave detection is realized on a single platform.

[0061] The present invention utilizes a beam expander and a fast reflection mirror to simulate the Gaussian flat-top beam field of a far-field beam emitted by a remote satellite in space and the resulting pointing jitter, and uses a fast reflection mirror, a beam splitter, a four-quadrant detector phase meter and an upper-level simulation local satellite to receive the laser emitted by the remote satellite and the local laser to form heterodyne interference, thereby suppressing the pointing jitter through closed-loop control; ultimately, equivalent verification of a non-equal-arm interferometer for space gravitational wave detection is achieved on a single platform.

[0062] The above-mentioned specific implementation methods are used to explain the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An equivalent verification method for a single-platform non-equal-arm interferometer for space gravitational wave detection, characterized in that: The following steps are involved: S1, Construction of simulation laboratories or test sites: Simulate microgravity, high vacuum, extreme temperature changes, and cosmic ray conditions to approximate the space environment, and build simulation laboratories or test sites to accurately test the actual performance of spacecraft and its components in space; S2, build an equivalent verification system, in which the laser emits laser light, and the laser beam is divided into two by the optical fiber splitter; the acousto-optic modulator modulates the two laser beams; the two laser beams are collected and emitted by the first optical fiber collimator and the second optical fiber collimator respectively; the laser emitted by the first optical fiber collimator in the beam expander; the laser passing through the beam expander in the aperture; the first fast mirror reflects the laser passing through the aperture; the second fast mirror reflects the laser emitted by the second optical fiber collimator; the first beam splitter combines the two laser beams reflected by the first fast mirror and the second fast mirror; the second beam splitter emits the combined laser beam to the first four-quadrant detector and the second four-quadrant detector respectively; the phase meter reads the signals generated by the first four-quadrant detector and the second four-quadrant detector; the host computer uses the differential wavefront sensing technology DWS to process the signal read by the phase meter, and controls the deflection of the second fast mirror to achieve closed-loop control; S3, perform system cascade adjustment test: in the simulation laboratory or test site constructed in step S1, start the equivalent verification system constructed in step S2, simulate the Gaussian flat-top beam light field and the generated pointing jitter of the far-field beam emitted by the remote satellite in space through the beam expander and the fast reflection mirror, and use the fast reflection mirror, the beam splitter, the four-quadrant detector phase meter and the upper-level simulation local satellite to receive the laser emitted by the remote satellite and the local laser to form heterodyne interference, so as to suppress the pointing jitter through closed-loop control; S4, data analysis and evaluation: During the test, collect and record data on the stability of the laser beam, the response speed of the detector, and the reading accuracy of the phase meter. Use the closed-loop control of the host computer and DWS technology to suppress the pointing jitter. Finally, use the power spectrum density to analyze the pointing jitter suppression data and evaluate whether the system performance meets the requirements.

2. The equivalent verification method of the single-platform non-equal-arm interferometer for space gravitational wave detection according to claim 1, characterized in that: In step S2, a beam expander is used to expand the Gaussian beam emitted from the first optical fiber collimator, and an aperture is used to intercept the expanded laser beam to simulate a Gaussian flat-top beam in the far field; The Gaussian flat-top beam passing through the aperture is reflected by a first fast reflection mirror, and the first fast reflection mirror is controlled to be rapidly deflected to simulate the pointing jitter of the far-field beam; The Gaussian beam emitted from the second optical fiber collimator is reflected by the second fast reflection mirror, and the second fast reflection mirror is controlled based on the signal obtained by the host computer, so as to realize the controllability of the deflection of the Gaussian beam; The Gaussian flat-top beam reflected by the first fast reflector and the Gaussian beam reflected by the second fast reflector are combined by the first beam splitter to realize heterodyne interference of unequal arms; The combined beam of the first beam splitter is directed to the first four-quadrant detector and the second four-quadrant detector by the second beam splitter to collect heterodyne interference signals, so that the signals generated by the Gaussian beam and the Gaussian flat-top beam can be analyzed in both heading and pitch postures.

3. The equivalent verification method of the single-platform non-equal-arm interferometer for space gravitational wave detection according to claim 1, characterized in that: A phase meter is used to read the phase signals of the first four-quadrant detector and the second four-quadrant detector, so that the host computer can use differential wavefront sensing technology to process the signals, control the deflection of the second fast mirror to suppress the pointing jitter generated by the first fast mirror, perform closed-loop control, and achieve precise ranging and inversion of gravitational wave signals. This can realize the equivalent verification of a single-platform non-equal-arm interferometer for space gravitational wave detection.

4. The equivalent verification method of the single-platform non-equal-arm interferometer for space gravitational wave detection according to claim 1, characterized in that: The first fast-return mirror, the beam expander and the aperture are used to simulate the remote satellite in space transmitting the laser signal to generate the pointing jitter. The second fast-return mirror, the first beam splitter, the second beam splitter, the four-quadrant detector, the phase meter and the host computer are used to simulate the local satellite receiving the laser transmitted by the remote satellite and the local laser to form heterodyne interference, thereby suppressing the pointing jitter through closed-loop control.

5. The equivalent verification method of the single-platform non-equal-arm interferometer for space gravitational wave detection according to claim 1, characterized in that: In step S3, the differential wavefront sensing technology DWS signal is the phase difference of the left and right or upper and lower quadrants of the four-quadrant detector QPD read by the phase meter PM: Where DWS is the differential wavefront sensing technology signal, φ A is the phase of the signal in quadrant A, φ B is the phase of the signal in quadrant B, φ C is the phase of the signal in quadrant C, φ D is the phase of the signal in quadrant D; The host computer PC inverts the differential wavefront sensing technology DWS signal into the pointing jitter α through a calibrated coefficient k: α=DWS / k, Where k is the linear fitting coefficient of the differential wavefront sensing technology signal, and α is the laser angle measured by the differential wavefront sensing technology.

6. The equivalent verification method of the single-platform non-equal-arm interferometer for space gravitational wave detection according to claim 1, characterized in that: In step S4, the power spectrum density needs to collect N pointing jitters α in the time domain to obtain x[n], and perform discrete Fourier transform on it to obtain X N (f): Then, the data X obtained by discrete Fourier transform N (f) Processing to obtain power spectrum density:

7. The equivalent verification method of the single-platform non-equal-arm interferometer for space gravitational wave detection according to claim 1, characterized in that: The power spectral density value obtained in step S4 is suppressed to 10nrad / HZ at 1HZ and the lower frequency according to the pointing jitter. 1 / 2 The order of magnitude is used to determine whether the single-platform non-equal-arm interferometer used for space gravitational wave detection can meet aerospace needs.

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