Online monitoring device and method for multiple parameters of optical path of gyroscope

Abstract

The invention provides an online monitoring device and method for multiple parameters of a gyro light path. The online monitoring device comprises an implemented device structure and a measurement method flow. The method is characterized by comprising the following steps: respectively injecting wide-spectrum light and sweep-frequency light into orthogonal polarization directions P and S in a gyroscope light path to generate reflection signals carrying temperature, strain and angular velocity information, and respectively injecting the signals into a gyroscope system and an optical frequency domain reflectometer through a coupler for testing, by controlling the test time sequence of the incubator, the 1 * N optical switch, the light source, the optical frequency domain reflectometer and the gyroscope system, the temperature, strain and angular velocity performance of multiple gyroscope optical paths can be monitored at the same time. According to the device, a plurality of gyroscope light paths are tested by using the same light source, the test structure and the incubator at the same time, so that the test precision is ensured, and the test efficiency is greatly improved. The device has the advantages of high integration degree, complete test parameters, simple control mode, environmental interference resistance and the like, and can be widely applied to performance monitoring and error compensation of a gyroscope optical path.

Description

Technical Field

[0001] The present invention relates to the field of optical measurement technology and fiber optic gyroscope, and in particular to an online monitoring device and method for multiple parameters of a gyroscope optical path. Background Art

[0002] Fiber optic gyroscope is a non-mechanical angular velocity measuring instrument based on Sagnac effect invented in the 1970s. It plays an important role in the fields of aerospace, military, and sensing. As the core component of the fiber optic gyroscope system, the geometric symmetry and optical symmetry of the fiber optic sensitive ring have a decisive influence on the thermal drift performance of the fiber optic gyroscope. Therefore, it is imperative to measure and analyze the physical properties of the optical fiber itself.

[0003] The accurate measurement of the refractive index of optical fiber is closely related to the accuracy of distributed optical fiber sensing. In 2020, Yuan Libo and others from Guilin University of Electronic Technology (CN 110968048 A) invented an orthogonal tilted three-core fiber Bragg grating parallel integrated MachZehnder interferometer. By detecting the output intensity after the interference of three beams, the effective refractive index of the transmission mode in N fiber cores can be calculated. In 2022, Liang Huijuan and others from the 38th Institute of China Electronics Technology Group Corporation (CN 114665957 A) invented a system and method for measuring the refractive index of optical fiber. A vector network analyzer is used to provide a sweeping signal including signals of different frequencies to the optoelectronic modulator, which is modulated into an optical signal by the optoelectronic modulator and transmitted through the optical fiber to be tested. After that, it is demodulated by the detector and returned to the vector network analyzer to analyze the phase of signals of different frequencies. The length of the optical fiber to be tested is further changed and measured again, thereby achieving high-precision calculation of the refractive index of the optical fiber to be tested.

[0004] On the other hand, under the action of temperature field, thermal strain will aggravate the deterioration of optical symmetry, thereby inducing Mohr effect and Shupe effect, significantly aggravating the thermal drift in the fiber optic gyroscope system. Therefore, it is particularly important to accurately test and analyze the thermal strain of the fiber optic sensitive ring. In 2022, Liu Qingwen et al. (CN 117451203 A) from Shanghai Jiaotong University invented a large-scale quasi-distributed fiber optic sensing method and system. The frequency value of the difference frequency term is obtained based on the beat frequency signal to calculate the optical path between two points, and the temperature change and strain of the optical fiber are obtained by detecting the change in the optical path. In the same year, Wen Kunhua et al. (CN 115452213 A) from Guangdong University of Technology invented a distributed high-precision strain measurement method for fiber optic sensitive rings under temperature variation conditions. It combines DTS and BOTDA systems, realizes temperature compensation of distributed stress test of fiber optic sensitive rings by inference, determines the temperature stability of its internal stress distribution, and thus infers the high-precision internal stress distribution of fiber optic sensitive rings. In 2023, Rao Yunjiang et al. (CN 116576897 A) from Zhijiang Laboratory invented a multi-parameter fiber-optic distributed sensing system and method thereof, which obtains the temperature or strain changes felt by each fiber Bragg grating in the sensing fiber by sensing the wavelength changes corresponding to the wavelength defects in the reflection spectrum of each fiber Bragg grating. In 2024, Dong Yongkang et al. (CN118623781 A) from Harbin Institute of Technology invented a method and device for decoupling temperature and strain of OPGW optical cables based on zero strain reference point and ANN algorithm, and used the temperature-strain decoupling method based on zero strain reference point to demodulate multiple Brillouin gain spectra, obtain the corresponding temperature value of each optical fiber, and realize accurate data demodulation. Zhang Zhuo from Harbin Engineering University (Physical Field Analysis and Coupling Characteristics of Marine Fiber Optic Gyroscopes) analyzed the physical field error mechanism of fiber optic gyroscopes under the coupling of temperature field and stress field, proposed the concepts of fiber optic ring temperature matrix, stress matrix, and weight matrix, and derived the traditional integral accumulation error model into the form of inner products of multiple matrices, providing guidance for the design of fiber optic ring parameters and the selection of optical fiber and solid adhesive materials, thereby improving the accuracy of gyroscopes.

[0005] In terms of fiber optic ring testing technology, B-OTDA and optical frequency domain reflectometry (OFDR) are two commonly used methods. B-OTDA provides absolute measurements, but its resolution needs to be improved. On the contrary, OFDR has better resolution, but it is only a relative measurement relative to the reference state. Since internal stress has a significant impact on winding quality, some studies have used B-OTDA to monitor the symmetrical stress of fiber optic sensitive rings. Han Zhengying of China Electronics 41 Research Institute (Application of BOTDA fiber optic sensing technology in fiber optic ring quality assessment) used B-OTDA technology to measure the strain distribution of fiber optic sensitive rings under different temperature conditions, and improved the performance of the gyro optical path by screening winding bodies with relatively symmetrical strain changes at each temperature. Yang Jigang and others from Beijing Institute of Automation and Control Equipment published (Research on methods to improve the quality of winding bodies of fiber optic winding bodies). In response to the problem of asymmetric fiber tension during inertial navigation ring winding, the strain data measured by B-OTDA was fed back to the tension control system in real time, thereby improving the stability and symmetry of tension control and significantly improving the symmetry of sensitive rings. At the same time, OFDR technology based on Rayleigh scattering has developed rapidly in recent years. The OFDR system using the polarization-maintaining scheme can simultaneously test temperature and thermal strain. The University of Ottawa in Canada published a paper (Long-range high spatial resolution distributed temperature and strain sensing based on optical frequency-domain reflectometry) proposing a corresponding test and demodulation scheme. By using the characteristics of negative temperature sensing coefficient and positive strain sensing coefficient, it achieved a temperature resolution of ±0.8°C and a thermal strain resolution of ±7.0°C at a sensing distance of 170m. The strain resolution and spatial resolution of 1.3 cm

[74] . Yu Zhangjun et al. published a paper (Distributed Polarization Measurement for Fiber Sensing Coils: A Review) in which they proposed a high-performance method to obtain a dynamic range of >90 dB, a measurement length of >10 km, a full-range spatial resolution of <10 cm, and time domain, frequency domain, and time-frequency domain diagnosis in the distributed polarization measurement of fiber sensing coils based on OFDR, which provided important inspiration for our research.

[0006] However, based on a large number of studies, the parameters that affect the thermal drift of the fiber ring and the relationship between the changes of these parameters in the environment are unclear. At the same time, there is a lack of suitable long-distance, high-precision, and high-spatial resolution temperature and thermal strain test methods, which seriously affects its measurement accuracy. Therefore, establishing a new transfer function from temperature to thermal drift and studying multi-parameter test methods for temperature and thermal strain are extremely important for parameter detection of fiber optic gyroscopes and distributed fiber optic sensing applications. Summary of the invention

[0007] The purpose of the present invention is to provide an OFDR beat frequency interferometer test device with high precision, stability and reliability, multi-parameter measurable, and simultaneous measurement of multiple gyro optical paths. The purpose of the present invention is also to provide a test method for the OFDR beat frequency interferometer test device.

[0008] The invention discloses an online monitoring device for multiple parameters of a gyro optical path, which is characterized by comprising a TLS light source module 1, an auxiliary interferometer module 2, a main interferometer module 3, a module to be tested 4, a temperature control sensor module 5, a control and data processing module 6 and a fiber optic gyro angular velocity test module 7. The control and data processing module 6 controls the TLS light source 101, the data acquisition card 603, the temperature box 501, the temperature sensor 502, N Y waveguide positive electrodes, N Y waveguide negative electrodes, the optical switch 410 and the SLD light source 701. The TLS light source module 1 injects a light beam into the first coupler 202, a part of the light is injected into the auxiliary interferometer module 2, and the other part of the light is injected into the main interferometer module 3 from the s path via the 90° polarizer 204. The module to be tested 4 is connected to the main interferometer module 3 and the fiber optic gyro angular velocity test module 7 and is placed in the temperature control sensor module 5, and the auxiliary interference signal and the main interference signal are merged into the data acquisition card 603 and uploaded to the processor for demodulation. Broad-spectrum light is injected from the SLD light source 701, and then injected into the gyro optical path from the P path through the sixth coupler 707 and the optical switch 410 via the 0° polarizer 703. The return light is returned to the gyro system 708 via the fifth coupler 308 for detection and demodulation. By respectively injecting broad-spectrum light and swept-frequency light into the orthogonal polarization directions P and S in the gyro optical path, space division multiplexing is achieved in the gyro optical path, and optical, force, and thermal multi-parameter tests are performed simultaneously.

[0009] 1. The gyro optical path multi-parameter online monitoring device according to claim 1, characterized in that the auxiliary interferometer module 2 comprises: a first coupler 202, a 90° polarizer 204, a first circulator 207, a second coupler 209, a first Faraday rotator 212, a second Faraday rotator 213, and a first balanced photodetector 214. Light undergoes beat frequency interference in the second coupler 209.

[0010] (1) The first coupler left arm 215 is connected to the TLS light source 101 through the first flange 201.

[0011] (2) The 90° polarizer upper arm 217 is connected to the first coupler right upper arm 216 through the second flange 203.

[0012] (3) The first circulator A port 220 is connected to the first coupler right lower arm 219 through the fourth flange 206.

[0013] (4) The second coupler right upper arm 223 is connected to the first circulator B port 221 through the fifth flange 208.

[0014] (5) The second coupler right lower arm 226 and the first circulator C port 222 are respectively connected to the first balanced photodetector 214.

[0015] (6) The first Faraday rotation mirror 212 is connected to the second coupler left upper arm 224 via the sixth flange 210 .

[0016] (7) The second Faraday rotation mirror 213 is connected to the second coupler left lower arm 225 via the seventh flange 211 .

[0017] (8) The first optical fiber 215 , the second optical fiber 216 , the third optical fiber 217 , the fourth optical fiber 218 , and the fifth optical fiber 219 are all polarization-maintaining optical fibers.

[0018] (9) The sixth optical fiber 220 , the seventh optical fiber 221 , the eighth optical fiber 222 , the ninth optical fiber 223 , the tenth optical fiber 224 , the delay optical fiber 225 , and the twelfth optical fiber 226 are all single-mode optical fibers.

[0019] 2. The online monitoring device for multiple parameters of a gyro optical path according to claim 1 is characterized in that the main interferometer module 3 comprises: a third coupler 302, a fourth coupler 306, a first polarization-maintaining beam splitter 315, a second polarization-maintaining beam splitter 319, a second balanced photodetector 321, a third balanced photodetector 325, and a fifth coupler 308. Light undergoes beat frequency interference in the fourth coupler 306.

[0020] 1) The third coupler right arm 301 is connected to the 90° polarizer lower arm 218 via the third flange 205 .

[0021] (2) The fourth coupler right upper arm 305 is connected to the third coupler left upper arm 303 through the eighth flange 304 .

[0022] (3) The fourth coupler right lower arm 311 is connected to the fifth coupler right upper arm 309 through the ninth flange 310 .

[0023] (4) The right arm 314 of the first polarization-maintaining beam splitter is connected to the upper left arm 312 of the fourth coupler through the tenth flange 313 .

[0024] (5) The right arm 318 of the second polarization-maintaining beam splitter is connected to the left lower arm 316 of the fourth coupler through the eleventh flange 317.

[0025] (6) The second balanced photodetector 321 is connected to the first polarization-maintaining beam splitter left upper arm 320 and the second polarization-maintaining beam splitter left upper arm 323 respectively.

[0026] (7) The third balanced photodetector 325 is connected to the first polarization-maintaining beam splitter left lower arm 322 and the second polarization-maintaining beam splitter left lower arm 324 respectively.

[0027] (8) The twelfth optical fiber 301, the thirteenth optical fiber 303, the fourteenth optical fiber 307, the fifteenth optical fiber 305, the sixteenth optical fiber 311, the seventeenth optical fiber 312, the eighteenth optical fiber 316, the nineteenth optical fiber 314, the twentieth optical fiber 318, the twenty-first optical fiber 320, the twenty-second optical fiber 322, the twenty-third optical fiber 323, the twenty-fourth optical fiber 324, the twenty-fifth optical fiber 326, the twenty-sixth optical fiber 327, the twenty-seventh optical fiber 328, the twenty-eighth optical fiber 329, and the twenty-ninth optical fiber 309 are all polarization-maintaining optical fibers.

[0028] 3. The online monitoring device for multiple parameters of a gyro optical path according to claim 1 is characterized in that the module to be tested 4 comprises: an optical switch 410, a second circulator 416, a third circulator 418 ... an N+1th circulator 424, a first gyro optical path 430, a first input pigtail 429, a second gyro optical path 432, a second input pigtail 431 ... an Nth gyro optical path 434, and an Nth input pigtail 433. The light is controlled by the optical switch 410 to flow through a certain gyro optical path to obtain its scattering spectrum.

[0029] (1) The optical switch 410 is a 1×N switch, including an optical switch input arm 402, an optical switch first output port 404, an optical switch second output port 411, an optical switch Nth output port 421 and an optical path converter 403. The use of an optical switch in one arm of the interferometer effectively reduces the influence of optical switch reflection.

[0030] (2) The optical switch input arm 402 is connected to the sixth coupler lower arm 714 through the twelfth flange 401 .

[0031] (3) The second circulator A port 406 is connected to the optical switch output first port 404 through the thirteenth flange 405 .

[0032] (4) The second circulator B port 408 is connected to the first input pigtail 429 through the fourteenth flange 409.

[0033] (5) The second circulator C port 415 is connected to the first lower arm 328 of the fifth coupler through the fifteenth flange 407 .

[0034] (6) The third circulator A port 413 is connected to the optical switch output second port 411 through the sixteenth flange 412 .

[0035] (7) The third circulator B port 419 is connected to the second input pigtail 431 through the seventeenth flange 420 .

[0036] (8) The third circulator C port 417 is connected to the fifth coupler second lower arm 327 via the eighteenth flange 416 .

[0037] (9) The Nth circulator A port 423 is connected to the optical switch output Nth port 421 through the nineteenth flange 422 .

[0038] (10) The Nth circulator B port 427 is connected to the Nth input pigtail 433 through the twentieth flange 428.

[0039] (11) The Nth circulator C port 426 is connected to the Nth lower arm 326 of the fifth coupler through the twenty-first flange 425.

[0040] (12) The 30th optical fiber 402, the 31st optical fiber 404, the 32nd optical fiber 411, the 33rd optical fiber 421, the 34th optical fiber 406, the 35th optical fiber 413, the 36th optical fiber 423, the 37th optical fiber 408, the 38th optical fiber 419, the 39th optical fiber 427, the 40th optical fiber 415, the 41st optical fiber 417, the 42nd optical fiber 426, the 43rd optical fiber 429, the 44th optical fiber 431, and the 45th optical fiber 433 are all polarization-maintaining optical fibers.

[0041] 4. The online monitoring device for multiple parameters of a gyro optical path according to claim 1, characterized in that the temperature control sensor module 5 comprises: a temperature box 501 and a temperature sensor 502. The temperature sensor 502 is placed in the temperature box 501. The first gyro optical path 430, the second gyro optical path 432, ... the Nth gyro optical path 434 are all placed in the temperature box 501.

[0042] 5 . The online monitoring device for multiple parameters of a gyro optical path according to claim 1 , wherein the control and data processing module 6 comprises: a control machine 601 , a data processing machine 602 , and a data acquisition card 603 .

[0043] (1) The first balanced photodetector 214 is connected to the data acquisition card 603 via the first electrical conductor 604 .

[0044] (2) The second balanced photodetector 321 is connected to the data acquisition card 603 via the second electrical conductor 605 .

[0045] (3) The third balanced photodetector 325 is connected to the data acquisition card 603 via the third electrical conductor 606 .

[0046] (4) The data acquisition card 603 is connected to the data processing machine 602 via a fourth electrical conductor 607 .

[0047] (5) The control machine 601 is connected to the data acquisition card 603 via the fifth electrical conductor 608 .

[0048] (6) The control machine 601 is connected to the temperature sensor 502 via the sixth electrical conductor 609 .

[0049] (7) The control machine 601 is connected to the temperature box 501 via the seventh electrical conductor 610 .

[0050] (8) The control machine 601 is connected to the optical switch 410 via the eighth electrical conductor 611 .

[0051] (9) The control machine 601 is connected to the TLS light source 101 via the ninth electrical conductor 612 .

[0052] (10) The control machine 601 is connected to the N Y waveguide positive electrodes and the N Y waveguide negative electrodes through the tenth electrical conductor 613.

[0053] (11) The control machine 601 is connected to the SLD light source 701 via the eleventh electrical conductor 614 .

[0054] 6. The online monitoring device for multiple parameters of a gyro optical path according to claim 1 is characterized in that the fiber optic gyro angular velocity test module 7 comprises: an SLD light source 701, a 0° polarizer 703, an optical isolator 705, a sixth coupler 707, and a gyro system 708.

[0055] (1) The left arm 709 of the 0° polarizer is connected to the SLD light source 701 through the twenty-second flange 702.

[0056] (2) The left arm 711 of the optical isolator is connected to the right arm 710 of the 0° polarizer through the twenty-third flange 704 .

[0057] (3) The optical isolator right arm 712 is connected to the sixth coupler left upper arm 713 through the twenty-fourth flange 706 .

[0058] (4) The sixth coupler right upper arm 717 is connected to the third coupler left lower arm 307 via the twenty-fifth flange 716 .

[0059] (5) The gyro system 708 is connected to the fifth coupler left upper arm 329 via the twenty-sixth flange 715 .

[0060] (6) The forty-seventh optical fiber 709, the forty-eighth optical fiber 710, the forty-ninth optical fiber 711, the fiftieth optical fiber 712, the fifty-first optical fiber 713, the fifty-second optical fiber 714, and the fifty-third optical fiber 717 are all polarization-maintaining optical fibers.

[0061] 7. The testing method of a gyro optical path multi-parameter online monitoring device according to claim 1 is characterized by:

[0062] (1) In order to ensure the stability of the gyro optical path, a full-temperature environmental test of the gyro optical path is performed.

[0063] (2) Connect the first gyro optical path 430, the second gyro optical path 432, ..., the Nth gyro optical path 434 to the test system to complete the optical path connection.

[0064] (3) The control machine 601 controls the TLS light source 101, the data acquisition card 603, the temperature box 501, the temperature sensor 502, the Y waveguide positive electrode, the Y waveguide negative electrode, the optical switch 410 and the SLD light source 701 to start synchronously to perform a system self-check.

[0065] (4) The gyro optical path is placed in the temperature box 501, and the control machine 601 sets the temperature box working curve, sets the temperature range to T1~T2, and maintains the temperature change rate at T3 / min.

[0066] (5) The SLD light source 701 is turned on and the gyro system 708 is tested in real time.

[0067] (6) The temperature chamber 501 is started, and the timing is set to 0. The control machine 601 starts to record the time, and the recording timing is increased by 1 every 1 minute.

[0068] (7) Define the initial timings of the first gyro optical path 430, the second gyro optical path 432, ..., the Nth gyro optical path 434 as 2, 3, ..., N+1, respectively, and then determine the current timing.

[0069] (8) When the sequence is 2, the optical switch 410 switches to the first output port, and the control machine 601 triggers the TLS light source 101 and the data acquisition card 603 to test the first gyro optical path 430.

[0070] (9) When the sequence is 3, the optical switch 410 switches to the second output port, and the control machine 601 triggers the TLS light source 101 and the data acquisition card 603 to test the second gyro optical path 432.

[0071] (10) When the sequence is N+1, the optical switch 410 switches to the Nth output port, and the control machine 601 triggers the TLS light source 101 and the data acquisition card 603 to test the Nth gyro optical path 434.

[0072] (11) Collect test data and upload it to the data processor 602.

[0073] (12) Compensate for phase noise and determine whether the intensity of the end reflection peak after compensation is consistent with that at normal temperature.

[0074] (13) If the intensities are consistent, the test of the first gyro optical path 430, the second gyro optical path 432, ..., the Nth gyro optical path 434 is completed, and the temperature sensor data of the corresponding time sequence is recorded.

[0075] (14) If the intensity is inconsistent, perform phase noise compensation again to ensure that the intensity of the end reflection peak after compensation is consistent with that at normal temperature.

[0076] (15) The initial timing of each gyro optical path is tested every time N is increased.

[0077] (16) Record the P and S test data and obtain the scattering spectrum signal after Fourier transformation.

[0078] (17) OFDR system strain demodulation.

[0079] (18) The gyro optical path strain data and gyro system angular velocity data are obtained by correcting the influence of the thermo-optical coefficient based on the temperature sensor data.

[0080] The purpose of the present invention is to provide a device and method for improving test efficiency, measuring multiple parameters in multiple gyroscope optical paths in one rapid temperature cycle, and constructing an optical frequency domain test system to be used for multi-parameter testing and performance monitoring of gyroscope optical paths and measuring the influence of rapid temperature changes on relative thermal strain in distributed optical fiber sensing systems.

[0081] The present invention proposes an online monitoring device for multiple parameters of a gyro optical path as shown in the attached figure. Figure 1 As shown, its characteristics are:

[0082] 1. It is composed of a TLS light source 101, a first coupler 202, a 90° polarizer 204, a first circulator 207, a second coupler 209, a first Faraday rotator 212, a second Faraday rotator 213, a first balanced photodetector 214, a third coupler 302, a fifth circulator 901, a fourth coupler 306, a first polarization-maintaining beam splitter 315, a second polarization-maintaining beam splitter 319, a second balanced photodetector 321, a third balanced photodetector 325, and a device under test 902.

[0083] 2. The TLS light source 101 provides input light through the first coupler 202. 1% of the output light enters the first circulator 207 through the first connecting optical fiber 903, and enters the second coupler 209 through the B port of the first circulator and the second connecting optical fiber 904. The remaining 99% of the output light enters the third coupler 302 through the 90° polarizer 204 and the third connecting optical fiber 905.

[0084] 3. 50% of the light entering the second coupler 209 is reflected by the first Faraday rotator 212 through the fourth connecting optical fiber 906 to form the first reflected light 907, and the other 50% is reflected by the second Faraday rotator 213 through the delay optical fiber 908 to form the second reflected light 909. The first reflected light 907 and the second reflected light 909 are subjected to beat frequency interference at the second coupler 209. A part of the beat frequency interference signal is sequentially input into the first balanced photodetector 214 through the second connecting optical fiber 904, the first circulator B port, the first circulator C port, and the fifth connecting optical fiber 910, and another part of the beat frequency interference signal is also input into the first balanced photodetector 214 through the sixth connecting optical fiber 911, and the two parts of the beat frequency interference signal are differentially detected.

[0085] 4. 1% of the light entering the third coupler 302 enters the fourth coupler 306 through the seventh connecting optical fiber 912, and the other 99% passes through the eighth connecting optical fiber 913 and the fifth circulator 901, and enters the device under test 902 from the fifth circulator A port, the fifth circulator B port and the ninth connecting optical fiber 914 in sequence. The third reflected signal 915 formed by reflection is also input into the fourth coupler 306 through the ninth connecting optical fiber 914, the fifth circulator B port, the fifth circulator C port and the tenth connecting optical fiber 916 to generate a beat frequency interference signal.

[0086] 5. 50% of the beat frequency interference signal generated at the fourth coupler 306 enters the first polarization-maintaining beam splitter 315 through the eleventh connecting optical fiber 917 , and the other 50% enters the second polarization-maintaining beam splitter 319 through the twelfth connecting optical fiber 918 .

[0087] 6. A portion of the light entering the first polarization-maintaining beam splitter 315 is input to the second balanced photodetector 321 via the thirteenth connecting optical fiber 919 , and another portion is input to the third balanced photodetector 325 via the fourteenth connecting optical fiber 920 .

[0088] 7. A portion of the light entering the second polarization-maintaining beam splitter 319 is input into the second balanced photodetector 321 via the fifteenth connecting optical fiber 921 , and another portion is input into the third balanced photodetector 325 via the sixteenth connecting optical fiber 922 .

[0089] The flowchart of the gyro optical path temperature and strain testing method proposed by the present invention is shown in the attached figure. Figure 2 As shown, its characteristics are:

[0090] Step 801 is a full-temperature environment test of the gyro optical path. The temperature environment commonly used by the gyro optical path system is set to test the full-temperature performance of the gyro optical path.

[0091] Step 802 is to connect the first gyro optical path, the second gyro optical path, ... the Nth gyro optical path to the test system to complete the optical path connection.

[0092] Step 803 is to use the control machine to control the TLS light source, data acquisition card, temperature box, temperature sensor, optical switch and SLD light source to start synchronously to perform system self-test.

[0093] Step 804 is to place the gyro optical path in a temperature box, and the control machine sets the temperature box working curve, the temperature range is T1~T2, and the temperature rate is maintained at T3 / min.

[0094] Step 805 is to start the SLD light source and implement the gyro system test.

[0095] Step 806 is to start the incubator, set the timing to 0, and the controller starts timing, recording the timing by 1 every 1 minute.

[0096] Step 807 is to define the initial timings of the first gyro optical path, the second gyro optical path, ... the Nth gyro optical path as 2, 3, ... N+1, respectively, and start judging the timing.

[0097] From step 808, if the timing reaches 2, step 816 is executed: the optical switch is switched to the first port, and the control machine triggers the light source and the acquisition card, thereby testing the first gyroscope optical path.

[0098] From step 809, if the timing reaches 3, step 816 is executed: the optical switch is switched to the second port, and the control machine triggers the light source and the acquisition card, thereby testing the second gyroscope optical path.

[0099] From step 810, if the timing reaches N+1, step 816 is executed: the optical switch is switched to the Nth port, and the control machine triggers the light source and the acquisition card, thereby testing the optical path of the Nth gyroscope.

[0100] Step 811 is to upload the test data collected by the data acquisition card to the data processing machine.

[0101] Step 812 is to compensate for phase noise and determine whether the intensity of the terminal reflection peak after compensation is consistent with that at normal temperature.

[0102] From step 812, if the intensity of the terminal reflection peak after compensation is consistent with the normal temperature, step 813 is executed: completing the test of the first gyro optical path, the second gyro optical path, ... the Nth gyro optical path, and recording the temperature sensor data of the corresponding time sequence.

[0103] From step 812, if the terminal reflection peak intensity after compensation is not consistent with the normal temperature, step 814 is executed: phase noise compensation is performed again until the terminal reflection peak intensity after compensation is consistent with the normal temperature.

[0104] Step 815 is to perform a test every time the initial timing of each gyro optical path increases by N.

[0105] Step 816 is to record the test results of P and S at different temperatures, and obtain the scattering spectrum signal after Fourier transformation.

[0106] Step 817 is OFDR system strain demodulation. The reference signal and the test signal are cross-correlated by a demodulation algorithm to obtain the Rayleigh dispersion frequency shift of the optical fiber ring under temperature variation.

[0107] Step 818 is to correct the influence of the thermo-optical coefficient according to the temperature sensor data, thereby obtaining the gyro optical path strain data.

[0108] The present invention proposes an OFDR-based online monitoring device and method for a gyro optical path. The basic principle of the device and method is the working principle of an optical frequency domain reflectometer. The OFDR system formed by an interferometer is used to demodulate the internal reflection signal of the gyro optical path to obtain the influence of temperature and strain on the frequency shift of the gyro optical path.

[0109] Device test principle:

[0110] The OFDR system built can realize independent strain and temperature testing. Based on the P and S signals, the relationship between the frequency shift and temperature and strain obtained by the test is as follows:

[0111]

[0112] Where: is the gauge factor of the cross-correlation frequency shift, is the temperature coefficient of the cross-correlation frequency shift.

[0113] It can be seen that the OFDR test results include both strain and temperature. The frequency shift obtained by OFDR testing includes the influence of both temperature and strain. The obtained spectral offset is converted by temperature and gauge coefficient to obtain the corresponding temperature and strain values.

[0114] Compared with the prior art, the advantages of the present invention are:

[0115] 1. The present invention realizes space division multiplexing in the gyroscope optical path by respectively injecting broadband light and swept frequency light into the orthogonal polarization directions P and S in the gyroscope optical path, and simultaneously performs optical, force and thermal multi-parameter tests.

[0116] 2. The test device proposed in the present invention can realize high-precision online monitoring of the temperature, strain and angular velocity of the gyroscope optical path.

[0117] 3. The present invention can monitor the performance of multiple gyro optical paths under temperature changes at the same time by designing a system timing control method.

[0118] 4. The present invention has a simple structure, high test accuracy, and is resistant to environmental interference, which effectively improves test efficiency and can be widely used in performance monitoring and error compensation of gyroscope optical paths. BRIEF DESCRIPTION OF THE DRAWINGS

[0119] Figure 1 This is the test principle diagram of Optical Frequency Domain Reflectometry (OFDR);

[0120] Figure 2 It is a flow chart of the gyro optical path temperature and strain test method;

[0121] Figure 3 is the optical path structure diagram of the gyroscope to be tested;

[0122] Figure 4 It is a flow chart of the full temperature test method;

[0123] Figure 5 It is a diagram of an online monitoring device for multiple parameters of a gyro optical path;

[0124] Figure 6 It is a schematic diagram of the gyroscope optical path strain test results. DETAILED DESCRIPTION

[0125] In order to clearly illustrate the device and method for online monitoring of gyro optical path based on OFDR of the present invention, the present invention is further described in conjunction with embodiments and drawings, but this should not limit the protection scope of the present invention.

[0126] Figure 3 This is the structure of the optical path of the gyroscope to be tested of the present invention. Its characteristics are:

[0127] The optical path structure of the gyro to be tested is composed of the first gyro optical path 430, the first Y waveguide 851, the first optical fiber ring 854, the second gyro optical path 432, the second Y waveguide 857, the second optical fiber ring 860 ... the Nth gyro optical path 434, the NYth waveguide 863, and the Nth optical fiber ring 866. The first Y waveguide 851 includes the first Y waveguide positive electrode 852 and the first Y waveguide negative electrode 853; the second Y waveguide 857 includes the second Y waveguide positive electrode 858 and the second Y waveguide negative electrode 859; the NYth waveguide 857 includes the NYth waveguide positive electrode 864 and the NYth waveguide negative electrode 865;

[0128] When any of the gyro optical paths is connected to the OFDR test system optical path, the light is divided into two paths after passing through the input pigtail and the Y waveguide. Therefore, the fiber optic gyroscope has clockwise forward transmission light and counterclockwise reverse transmission light. The controller 601 applies a square wave with an amplitude of half-wave voltage of the Y waveguide and a frequency of the eigenfrequency to the two electrodes, which can cancel out the interference of the forward and reverse transmission light of the fiber optic gyroscope and improve the test sensitivity. The forward and reverse transmission lights undergo beat frequency interference at the Y waveguide and return to the OFDR test system optical path with the scattering information of the gyroscope optical path.

[0129] At the same time, the broadband light is injected by the SLD light source 701, through the 0° polarizer 703, and then injected into the same gyro optical path from the P path through the sixth coupler 707 and the optical switch 410. The return light passes through the fifth coupler 308 and returns to the gyro system 708 for detection and demodulation.

[0130] Combination Figure 4 , the full temperature test method is as follows:

[0131] Step 819 is to set the temperature range of the high and low temperature box to T1~T2, and the temperature change rate to 1℃ / min.

[0132] Step 820 is to place the gyro optical path inside a temperature box to keep the gyro optical path heated on all four sides.

[0133] Step 821 is to keep the gyro optical path at temperature T3 for 30 minutes.

[0134] Step 822 is to cool the temperature of the oven from T3 to T1 at a rate of 1°C / min.

[0135] Step 823 is to keep the gyro optical path at temperature T1 for 60 minutes.

[0136] Step 824 is to increase the temperature of the oven from T1 to T2 at a rate of 1°C / min.

[0137] Step 825 is to keep the gyro optical path at temperature T2 for 60 minutes.

[0138] Step 826 is that the OFDR system performs a test every 5 minutes.

[0139] Figure 5 The invention is an online monitoring device for multi-parameters of a gyroscope optical path, comprising a TLS light source module 1, an auxiliary interferometer module 2, a main interferometer module 3, a module to be tested 4, a temperature control sensor module 5, a control and data processing module 6 and a fiber optic gyroscope angular velocity test module 7. The structure of the module to be tested 4 is similar to that of the TLS light source module 1. Figure 3 The optical path structures of the N gyroscopes to be tested are the same.

[0140] Combination Figure 5One implementation of the present invention is: setting the sweep range of the TLS light source 101 to 10nm~160nm and the sweep speed to 10nm / s, and 1% of the swept light emitted by the first coupler 202 enters the auxiliary interferometer module 2 and 99% enters the main interferometer module 3.

[0141] 1% of the light entering the main interferometer module 3 passes through the third coupler left upper arm 303 and the fourth coupler right upper arm 305 and enters the fourth coupler 306 , and the other 99% passes through the third coupler left lower arm 307 and the sixth coupler lower arm 714 and enters the optical switch 410 .

[0142] The 1% light passing through the third coupler left upper arm 303 and the fourth coupler right upper arm 305 is used as a reference signal, and the 99% light passing through the third coupler left lower arm 307 and the sixth coupler lower arm 714 is input into the optical switch 410 and a gyroscope optical path as a test signal. The two signals are received by the data acquisition card 603 with a sampling frequency of 180MHz after the beat frequency interference occurs at the fourth coupler 306.

[0143] The controller 601 performs opening and closing operations on the 1×N output ports of the optical switch 410.

[0144] If the current time sequence is a value in an arithmetic progression with a first term of 2 and a tolerance of N, the optical switch switches to the first port 404, and the control machine 601 triggers the TLS light source 101 and the data acquisition card 603 to test the first gyro optical path 430;

[0145] If the current time sequence is a value in an arithmetic progression with a first term of 3 and a tolerance of N, the optical switch switches to the second port 411, and the control machine 601 triggers the TLS light source 101 and the data acquisition card 603 to test the second gyro optical path 432;

[0146] If the current time sequence is a value in an arithmetic progression with the first term being N+1 and the tolerance being N, the optical switch switches to the Nth port 421 , and the control machine 601 triggers the TLS light source 101 and the data acquisition card 603 to test the Nth gyro optical path 434 .

[0147] When any of the gyro optical paths is connected to the OFDR test system optical path, the light is divided into two paths after passing through the input pigtail and the Y waveguide. Therefore, the fiber optic gyroscope has clockwise forward transmission light and counterclockwise reverse transmission light. The controller 601 applies a square wave with an amplitude of half-wave voltage of the Y waveguide and a frequency of the eigenfrequency to the two electrodes, which can cancel out the interference of the forward and reverse transmission light of the fiber optic gyroscope and improve the test sensitivity. The forward and reverse transmission lights undergo beat frequency interference at the Y waveguide and return to the OFDR test system optical path with the scattering information of the gyroscope optical path.

[0148] At the same time, the SLD light source 101 selects a wide-spectrum light source with a central wavelength of 1550nm±20nm and a spectrum width ≥40nm, and is injected into the same gyro optical path from the P path through the sixth coupler 707 and the optical switch 410 via the 0° polarizer 703. The return light passes through the fifth coupler 308 with a splitting ratio of 50:50 and returns to the gyro system 708 for detection and demodulation to obtain the angular velocity of the fiber optic gyroscope.

[0149] Collect test data. Perform phase noise compensation on the data uploaded to the data processor to determine whether the terminal reflection peak intensity after compensation is consistent with normal temperature. If consistent, complete the test of the gyro optical path and record the temperature sensor data of the corresponding time sequence. If inconsistent, re-perform phase noise compensation until the terminal reflection peak intensity after compensation is consistent with normal temperature.

[0150] Record the P and S test data, and get the scattering spectrum signal after Fourier transformation.

[0151] OFDR system strain demodulation. The reference signal and the test signal are cross-correlated by the demodulation algorithm to obtain the Rayleigh scatter frequency shift of the gyro optical path under temperature variation.

[0152] The influence of the thermo-optical coefficient is corrected according to the temperature sensor data, thereby obtaining the gyro optical path strain data. The gyro optical path strain test results are as follows: Figure 6 As shown in Figure 2, the spatial resolution of this OFDR-based gyro optical path multi-parameter test device is 5 cm, and the strain resolution is ±1 .

Claims

1. An online monitoring device for multiple parameters of a gyro optical path, characterized by: The invention comprises a TLS light source module (1), an auxiliary interferometer module (2), a main interferometer module (3), a module to be tested (4), a temperature control sensor module (5), a control and data processing module (6), and a fiber optic gyroscope angular velocity test module (7). The control and data processing module (6) controls the TLS light source (101), a data acquisition card (603), a temperature box (501), a temperature sensor (502), N Y waveguide positive electrodes, N Y waveguide negative electrodes, an optical switch (410), and an SLD light source (701). The TLS light source module (1) injects a light beam into a first coupler (202), a part of the light is injected into the auxiliary interferometer module (2), and the other part of the light is injected into the main interferometer module (3) from the s path via a 90° polarizer (204). The module to be tested (4) is connected to the main interferometer module (3) and the optical fiber gyroscope angular velocity test module (7) respectively and placed in the temperature control sensor module (5). The auxiliary interference signal and the main interference signal are merged into the data acquisition card (603) and uploaded to the processor for demodulation. The broadband light is injected from the SLD light source (701), and is injected into the gyroscope optical path from the P path through the sixth coupler (707) and the optical switch (410) via the 0° polarizer (703). The return light is returned to the gyroscope system (708) via the fifth coupler (308) for detection and demodulation. By injecting broadband light and swept frequency light into the orthogonal polarization directions P and S in the gyroscope optical path respectively, space division multiplexing is realized in the gyroscope optical path, and optical, force, and thermal multi-parameter tests are performed simultaneously.

2. The on-line monitoring device for multiple parameters of a gyro optical path according to claim 1 is characterized in that The auxiliary interferometer module (2) comprises: a first coupler (202), a 90° polarizer (204), a first circulator (207), a second coupler (209), a first Faraday rotation mirror (212), a second Faraday rotation mirror (213), and a first balanced photodetector (214). Light undergoes beat frequency interference in the second coupler (209). (1) The left arm (215) of the first coupler is connected to the TLS light source (101) via the first flange (201). (2) The 90° polarizer upper arm (217) is connected to the first coupler right upper arm (216) via the second flange (203). (3) The first circulator A port (220) is connected to the first coupler right lower arm (219) via the fourth flange (206). (4) The right upper arm (223) of the second coupler is connected to the B port (221) of the first circulator via the fifth flange (208). (5) The second coupler right lower arm (226) and the first circulator C port (222) are respectively connected to the first balanced photodetector (214). (6) The first Faraday rotation mirror (212) is connected to the left upper arm (224) of the second coupler via the sixth flange (210). (7) The second Faraday rotation mirror (213) is connected to the left lower arm (225) of the second coupler via the seventh flange (211). (8) The first optical fiber (215), the second optical fiber (216), the third optical fiber (217), the fourth optical fiber (218), and the fifth optical fiber (219) are all polarization-maintaining optical fibers. (9) The sixth optical fiber (220), the seventh optical fiber (221), the eighth optical fiber (222), the ninth optical fiber (223), the tenth optical fiber (224), the delay optical fiber (225), and the eleventh optical fiber (226) are all single-mode optical fibers.

3. The on-line monitoring device for multiple parameters of gyro optical path according to claim 1 is characterized in that The main interferometer module (3) comprises: a third coupler (302), a fourth coupler (306), a first polarization-maintaining beam splitter (315), a second polarization-maintaining beam splitter (319), a second balanced photodetector (321), a third balanced photodetector (325), and a fifth coupler (308). Light undergoes beat frequency interference in the fourth coupler (306). (1) The third coupler right arm (301) is connected to the 90° polarizer lower arm (218) via the third flange (205). (2) The fourth coupler right upper arm (305) is connected to the third coupler left upper arm (303) via the eighth flange (304). (3) The right lower arm (311) of the fourth coupler is connected to the right upper arm (309) of the fifth coupler via the ninth flange (310). (4) The right arm (314) of the first polarization-maintaining beam splitter is connected to the left upper arm (312) of the fourth coupler via the tenth flange (313). (5) The right arm (318) of the second polarization-maintaining beam splitter is connected to the left lower arm (316) of the fourth coupler through the eleventh flange (317). (6) The second balanced photodetector (321) is respectively connected to the left upper arm (320) of the first polarization-maintaining beam splitter and the left upper arm (323) of the second polarization-maintaining beam splitter. (7) The third balanced photodetector (325) is respectively connected to the left lower arm (322) of the first polarization-maintaining beam splitter and the left lower arm (324) of the second polarization-maintaining beam splitter. (8) The twelfth optical fiber (301), the thirteenth optical fiber (303), the fourteenth optical fiber (307), the fifteenth optical fiber (305), the sixteenth optical fiber (311), the seventeenth optical fiber (312), the eighteenth optical fiber (316), the nineteenth optical fiber (314), the twentieth optical fiber (318), the twenty-first optical fiber (320), the twenty-second optical fiber (322), the twenty-third optical fiber (323), the twenty-fourth optical fiber (324), the twenty-fifth optical fiber (326), the twenty-sixth optical fiber (327), the twenty-seventh optical fiber (328), the twenty-eighth optical fiber (329), and the twenty-ninth optical fiber (309) are all polarization-maintaining optical fibers.

4. The on-line monitoring device for multiple parameters of a gyro optical path according to claim 1 is characterized in that The module to be tested (4) comprises: an optical switch (410), a second circulator (416), a third circulator (418) ... an N+1th circulator (424), a first gyro optical path (430), a first input pigtail (429), a second gyro optical path (432), a second input pigtail (431) ... an Nth gyro optical path (434), and an Nth input pigtail (433). Light is controlled by the optical switch (410) to flow through a certain gyro optical path to obtain its scattering spectrum. (1) The optical switch (410) is a 1×N switch, comprising an optical switch input arm (402), an optical switch first output port (404), an optical switch second output port (411), an optical switch Nth output port (421), and an optical path converter (403). The use of an optical switch in one arm of the interferometer effectively reduces the influence of optical switch reflection. (2) The optical switch input arm (402) is connected to the sixth coupler lower arm (714) via the twelfth flange (401). (3) The second circulator A port (406) is connected to the optical switch output first port (404) through the thirteenth flange (405). (4) The second circulator B port (408) is connected to the first input pigtail (429) via the fourteenth flange (409). (5) The second circulator C port (415) is connected to the first lower arm (328) of the fifth coupler via the fifteenth flange (407). (6) The third circulator A port (413) is connected to the optical switch output second port (411) through the sixteenth flange (412). (7) The third circulator B port (419) is connected to the second input pigtail (431) through the seventeenth flange (420). (8) The C port (417) of the third circulator is connected to the second lower arm (327) of the fifth coupler through the eighteenth flange (416). (9) The Nth circulator A port (423) is connected to the optical switch output Nth port (421) through the nineteenth flange (422). (10) The Nth circulator B port (427) is connected to the Nth input pigtail (433) via the twentieth flange (428). (11) The C port (426) of the Nth circulator is connected to the Nth lower arm (326) of the fifth coupler via the twenty-first flange (425). (12) The 30th optical fiber (402), the 31st optical fiber (404), the 32nd optical fiber (411), the 33rd optical fiber (421), the 34th optical fiber (406), the 35th optical fiber (413), the 36th optical fiber (423), the 37th optical fiber (408), the 38th optical fiber (419), the 39th optical fiber (427), the 40th optical fiber (415), the 41st optical fiber (417), the 42nd optical fiber (426), the 43rd optical fiber (429), the 44th optical fiber (431) and the 45th optical fiber (433) are all polarization-maintaining optical fibers.

5. The on-line monitoring device for multiple parameters of gyro optical path according to claim 1 is characterized in that The temperature control sensor module (5) comprises: a temperature box (501) and a temperature sensor (502). The temperature sensor (502) is placed in the temperature box (501). The first gyro optical path (430), the second gyro optical path (432) ... the Nth gyro optical path (434) are all placed in the temperature box (501).

6. The on-line monitoring device for multiple parameters of gyro optical path according to claim 1 is characterized in that The control and data processing module (6) comprises: a control machine (601), a data processing machine (602), and a data acquisition card (603). (1) The first balanced photodetector (214) is connected to the data acquisition card (603) via a first electrical conductor (604). (2) The second balanced photoelectric detector (321) is connected to the data acquisition card (603) via a second electrical conductor (605). (3) The third balanced photoelectric detector (325) is connected to the data acquisition card (603) via a third electrical conductor (606). (4) The data acquisition card (603) is connected to the data processing machine (602) via a fourth electrical conductor (607). (5) The control machine (601) is connected to the data acquisition card (603) via a fifth electrical conductor (608). (6) The control machine (601) is connected to the temperature sensor (502) via a sixth electrical conductor (609). (7) The control machine (601) is connected to the temperature box (501) via a seventh electrical conductor (610). (8) The control machine (601) is connected to the optical switch (410) via an eighth electrical conductor (611). (9) The control machine (601) is connected to the TLS light source (101) via a ninth electrical conductor (612). (10) The control machine (601) is connected to the N Y waveguide positive electrodes and the N Y waveguide negative electrodes through the tenth electrical conductor (613). (11) The control machine (601) is connected to the SLD light source (701) via an eleventh electrical conductor (614).

7. The on-line monitoring device for multiple parameters of gyro optical path according to claim 1 is characterized in that The optical fiber gyro angular velocity test module (7) comprises: an SLD light source (701), a 0° polarizer (703), an optical isolator (705), a sixth coupler (707), and a gyro system (708). (1) The left arm (709) of the 0° polarizer is connected to the SLD light source (701) via the twenty-second flange (702). (2) The left arm (711) of the optical isolator is connected to the right arm (710) of the 0° polarizer through the twenty-third flange (704). (3) The right arm (712) of the optical isolator is connected to the left upper arm (713) of the sixth coupler via the twenty-fourth flange (706). (4) The sixth coupler right upper arm (717) is connected to the third coupler left lower arm (307) via the twenty-fifth flange (716). (5) The gyro system (708) is connected to the left upper arm (329) of the fifth coupler via the twenty-sixth flange (715). (6) The forty-sixth optical fiber (709), the forty-seventh optical fiber (710), the forty-eighth optical fiber (711), the forty-ninth optical fiber (712), the fiftieth optical fiber (713), the fifty-first optical fiber (714), and the fifty-second optical fiber (717) are all polarization-maintaining optical fibers.

8. The testing method of a gyro optical path multi-parameter online monitoring device according to claim 1 is characterized by: (1) In order to ensure the stability of the gyro optical path, a full-temperature environmental test of the gyro optical path is performed. (2) Connecting the first gyro optical path (430), the second gyro optical path (432), ... the Nth gyro optical path (434) to the test system to complete the optical path connection. (3) The control machine (601) controls the TLS light source (101), the data acquisition card (603), the temperature box (501), the temperature sensor (502), the Y waveguide positive electrode, the Y waveguide negative electrode, the optical switch (410) and the SLD light source (701) to start synchronously and perform a system self-check. (4) The gyro optical path is placed in a temperature box (501), and the control machine (601) sets the temperature box working curve, sets the temperature range to T1~T2, and maintains the temperature change rate at T3 / min. (5) The SLD light source (701) is turned on and the gyro system (708) is tested in real time. (6) The temperature box (501) is started, and the timing is set to 0. The control machine (601) starts to record the time, and the recording time is increased by 1 every 1 minute. (7) Defining the initial timings of the first gyro optical path (430), the second gyro optical path (432), ... the Nth gyro optical path (434) as 2, 3, ... N+1 respectively, and then determining the current timing. (8) When the sequence is 2, the optical switch (410) switches to the first output port, and the control machine (601) triggers the TLS light source (101) and the data acquisition card (603) to test the first gyro optical path (430). (9) When the sequence is 3, the optical switch (410) switches to the second output port, and the control machine (601) triggers the TLS light source (101) and the data acquisition card (603) to test the second gyro optical path (432). (10) When the sequence is N+1, the optical switch (410) switches to the Nth output port, and the control machine (601) triggers the TLS light source (101) and the data acquisition card (603) to test the Nth gyro optical path (434). (11) Collect test data and upload it to the data processing machine (602). (12) Compensate for phase noise and determine whether the intensity of the end reflection peak after compensation is consistent with that at normal temperature. (13) If the intensities are consistent, the test of the first gyro optical path (430), the second gyro optical path (432), ... the Nth gyro optical path (434) is completed, and the temperature sensor data of the corresponding time sequence is recorded. (14) If the intensity is inconsistent, perform phase noise compensation again to ensure that the intensity of the end reflection peak after compensation is consistent with that at normal temperature. (15) The initial timing of each gyro optical path is tested every time N is increased. (16) Record the P and S test data and obtain the scattering spectrum signal after Fourier transformation. (17) OFDR system strain demodulation. (18) The gyro optical path strain data and gyro system angular velocity data are obtained by correcting the influence of the thermo-optical coefficient based on the temperature sensor data.

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