A temperature compensation method for disc type optical fiber accelerometer based on thermal induced strain matching

Abstract

The application provides a disc type optical fiber accelerometer temperature compensation method based on thermal strain matching, and belongs to the field of optical fiber sensing. The method is composed of a glue effectiveness test module, a single-mode adhesive ring strain test module, a polarization maintaining adhesive ring strain test module, a glue strain change amount quantification module and a light path noise comparison module before and after adding glue, and is characterized in that: in view of the problem that the adhesive fiber rings of the two arms of the optical fiber interferometer cannot be completely matched, the method of adding glue with high thermal expansion coefficient and large Young's modulus is adopted to increase the temperature response coefficient of the arm with small strain integral amount, so that the phase change amounts of the two arms of the interferometer are the same. According to the test route of free optical fiber first and then optical fiber ring, single-mode optical fiber ring first and then polarization maintaining optical fiber ring, and the phase noise test comparison of the light paths before and after adding glue, the application can effectively reduce the temperature and strain cross-sensitivity problems in optical fiber sensing, reduce low-frequency temperature noise, effectively suppress the problem of light source frequency noise lifting, and reduce the phase noise of the optical fiber interferometer.

Description

Technical fields:

[0001] This invention designs a temperature compensation method for a disk-type fiber optic accelerometer based on thermal strain matching, which belongs to the field of fiber optic interferometer sensing and measurement. Background technology:

[0002] Optical fibers possess advantages such as small size and light weight, resistance to electromagnetic interference, corrosion resistance, electrical insulation, ability to operate in harsh environments, and flexibility. Fiber optic sensing technology is primarily used in fields such as earthquake precursor detection, long-range marine target detection, and resource exploration. For seismic signal acquisition, electromechanical seismometers are limited by their inability to improve sensitivity, expand dynamic range, and overcome harsh environmental conditions such as high temperature, high pressure, and strong electromagnetic fields. Compared to electromechanical seismometers, fiber optic seismometers offer advantages such as high sensitivity, wide measurement range, and superior environmental adaptability.

[0003] The principle behind the disk-type vibration pickup structure in a fiber optic accelerometer is that the system converts vibration information into strain information of the sensing fiber. When external vibration occurs, the elastic disk, caused by the mass block, bends, inducing a corresponding change in the fiber optic loop, i.e., a change in the length of the sensing fiber. In other words, when subjected to environmental vibration, the disk-type pickup structure converts the vibration signal into a strain signal in the sensing fiber, thereby causing a change in the output signal of the fiber optic interferometer. By detecting the interference signal and using a phase carrier generation demodulation method to demodulate the phase information, high-precision measurement of external vibrations with a linear phase response is achieved. The disk-type pickup structure consists of an elastic disk and a fiber optic loop. After the fiber optic loop is bonded, its thermally induced strain curve changes significantly, resulting in a nonlinear component when the fiber optic interferometer is placed in the probe. The elastic disk and adhesive have a significant impact on the thermally induced strain of the fiber optic loop, causing the two loops of the bonded loop to not be perfectly matched, which introduces additional noise into the fiber optic accelerometer.

[0004] In 2021, researchers Ignazio Floris, Valentino Sangiorgio, and others, in their article "Effects of bonding on the performance of optical fiber strain sensors," conducted an in-depth study of the geometric and mechanical parameters affecting the surface bonding efficiency of fiber optic point sensors using a combination of computational simulation, experimental testing, sensor fabrication, and data analysis. Through extensive finite element analysis, they investigated the strain transfer mechanism of surface-bonded fiber optic sensors.

[0005] In 2017, Yang Jun et al. from Harbin Engineering University disclosed a polarization-maintaining fiber interferometer for simultaneous strain and temperature measurement in Chinese invention patent CN201711309566.2. This invention uses polarization-maintaining fiber devices to build a fully polarization-maintaining interferometer. Since the optical signal is transmitted simultaneously in the fast and slow axes of the polarization-maintaining fiber, two sensing systems are formed. The two sensing systems have different responses to temperature and strain, respectively, thus enabling simultaneous measurement of both. In 2020, Yang Jun et al. from Harbin Engineering University improved the polarization-maintaining fiber interferometer and proposed a device and method for simultaneous strain and temperature measurement based on a polarization-maintaining fiber dual-arm off-axis interferometer in Chinese patent CN202011246818.3. This method achieves off-axis interference of the two arms (fast and slow axes) by welding one sensing arm of the interferometer off-axis. At the same time, the lengths of the sensing fibers of the two arms are changed to adjust the temperature response coefficients of the two interference systems, thereby constructing an ideal response matrix and achieving complete separation of temperature and strain responses. In 2022, researchers at Guangdong University of Technology disclosed a distributed high-precision strain measurement method for fiber optic sensing rings under temperature conditions in Chinese invention patent CN202211009570.8. At a fixed temperature, the method uses a DTS system to measure the temperature distribution data of the fiber optic sensing ring at different lengths, and a BOTDA system to measure the distributed Brillouin frequency shift data of the fiber optic sensing ring. Based on the temperature distribution data measured by DTS, temperature compensation is performed on the distributed Brillouin frequency shift data within the fiber optic ring measured by BOTDA, thus calculating the high-precision internal stress distribution of the fiber optic sensing ring. The linear part of the sensor can achieve good response by changing materials and designing special structures, while the nonlinear part requires the introduction of additional materials to modify parameters and improve the response of the linear part.

[0006] In 2024, Yunhao Ren et al. from Wuhan University of Technology proposed a modeling analysis and experimental study method for epoxy-encapsulated fiber Bragg grating sensors for cryogenic temperature measurement in their paper "Modeling analysis and experimental study on epoxy-packaged FBG sensor for cryogenic temperature measurement". The aim was to improve the sensor's sensitivity and linearity and predict its response time at low temperatures. A mathematical model was established to describe the temperature sensitivity and temperature response time of the recoated FBG sensor. The model considered parameters such as the coefficient of thermal expansion, elastic modulus, and thermo-optic coefficient between the fiber and the coating. The relationship between the geometric parameters of the polymer coating structure and the sensor's temperature response characteristics was verified. Experimental results show that the thicker the coating, the greater the role of polymer material parameters in sensor performance.

[0007] In 2024, Jiangquan Sun et al. from Guangdong University of Technology, in their article "Phase noise suppression of optical flexural disk accelerometer by studying the thermal stability of optical fiber ring," first used the finite element method to analyze the thermal strain distribution characteristics of an optical fiber ring. Their results were consistent with strain measurements obtained using the Rayleigh optical frequency domain reflection method. By constructing a fully symmetrical polarization-maintaining Mach-Zehnder interferometer with an arm length exceeding 100 meters, they further investigated the interferometer's phase noise caused by the distributed strain difference. The article shows that the distributed thermal strain difference between the two fiber rings causes additional phase fluctuations, leading to higher low-frequency noise.

[0008] Therefore, existing technologies have certain shortcomings. Literature and patents only study the strain transfer mechanism of surface-bonded fiber optic sensors, without analyzing the problems encountered. Regarding the temperature cross-sensitivity problem, a decoupling calculation to solve for temperature was proposed, improving the software algorithm but only focusing on the linear part, without hardware improvements or discussion of the nonlinear part. Adding a polymer coating to change the polymer's geometric parameters is only applicable to short-distance fibers, not long-distance fibers. The distributed thermal strain difference causes additional phase fluctuations, leading to higher low-frequency noise, which has been theoretically analyzed, but specific solutions are still under investigation. Therefore, a temperature compensation method for disk-type fiber optic accelerometers based on thermally induced strain matching is proposed. By matching the bonded fiber ring to achieve identical phase outputs on both arms of the interferometer, low-frequency noise is reduced and accelerometer performance is improved. This method focuses on the nonlinear response and is studied from a hardware perspective. Summary of the Invention:

[0009] This invention aims to solve the problem of additional phase fluctuations in fiber optic interferometers caused by mismatch between the bonded fiber rings in the disc-type vibration pickup structure and the temperature-induced strain differences in the bonded fiber rings.

[0010] To achieve the above-mentioned objectives, the technical solution adopted is as follows:

[0011] A temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching is characterized by addressing the issue of incomplete matching of the bonded fiber optic rings in the two arms of the fiber optic interferometer. This method involves adding an adhesive with a high coefficient of thermal expansion and a large Young's modulus to increase the temperature response coefficient of the arm with the smaller strain integral, thus ensuring equal phase changes. The method follows a test route of first freeing the fiber, then the fiber ring, and first the single-mode fiber ring, then the polarization-maintaining fiber ring. Noise tests are then conducted to compare the optical paths before and after adding the adhesive.

[0012] 1) This method includes the following modules: adhesive effectiveness testing module (401), single-mode bonded ring strain testing module (402), polarization-maintaining bonded ring strain testing module (403), adhesive strain change quantification module (404), and optical path noise comparison module before and after adhesive addition (405). It also includes: frequency-stabilized light source, tunable light source, polarization-maintaining fiber, polarization-maintaining jumper, epoxy resin adhesive, silicone rubber, single-mode bonded fiber ring, polarization-maintaining fiber ring, Y-waveguide, fiber polarization-maintaining coupler, temperature chamber device, data acquisition and demodulation device, photoelectric conversion board, and strain determination program.

[0013] 2) The device is characterized by a light source, a free, unwound optical fiber, epoxy resin adhesive, silicone rubber, a data acquisition and demodulation device, a strain relief program, and a temperature chamber. The tunable light source (201) is connected to the OFDR test optical path (206), which is connected to a polarization-maintaining jumper. The jumper connects to the free, unwound bare fiber (204), which is fixed to an acrylic plate (202). Adhesive (205) is applied to the free optical fiber portion. The adhesive consists of epoxy resin adhesive and silicone rubber. The performance of the two adhesives is compared through testing. The entire experimental setup is placed in a temperature chamber (203) and heated and maintained at a fixed temperature gradient.

[0014] 3) The single-mode bonded ring strain testing module includes: a tunable light source, a single-mode bonded fiber ring, a single-mode jumper, an OFDR test optical path, a data acquisition and demodulation device, a strain demodulation program, and a temperature chamber. The single-mode bonded fiber ring (307) is welded to the single-mode jumper at 0° (308). The fiber inlet (306) of the bonded ring on the upper surface of the single-mode bonded fiber ring (307) is welded to the polarization-maintaining jumper at 0° (308). The fiber outlet (305) of the bonded ring on the upper surface of the single-mode bonded fiber ring (307) is connected to the fiber inlet bonded to the lower surface of the disk. The jumper is connected to the tunable light source (301). The frequency-stabilized light source (301) is connected to the OFDR test optical path (309). The OFDR test optical path (309) is connected to the data acquisition and demodulation device (310). The single-mode bonded fiber optic ring was placed in a foam box (302) for heat preservation and vibration isolation. The entire optical path was tested in a temperature chamber (303) with a fixed temperature gradient for heating and insulation. The collected data was then processed by a strain solution program (311) to obtain the strain distribution results.

[0015] 4) The polarization-maintaining bonded fiber optic ring strain test module includes: a tunable light source, a polarization-maintaining bonded fiber optic ring, a polarization-maintaining jumper, an OFDR test optical path, a data acquisition and demodulation device, a strain demodulation program, and a temperature chamber. The polarization-maintaining bonded fiber optic ring and the single-mode bonded fiber optic ring are constructed with the same test optical path. The fiber inlet (306) of the bonded ring on the upper surface of the polarization-maintaining bonded fiber optic ring (307) is welded to the polarization-maintaining jumper at 0° (308). The fiber outlet (305) of the bonded ring on the upper surface of the polarization-maintaining bonded fiber optic ring (307) is connected to the fiber inlet bonded to the lower surface of the disk. The jumper is connected to the tunable light source (301). The tunable light source (301) is connected to the OFDR test optical path (309). The OFDR test optical path (309) is connected to the data acquisition and demodulation device (310). The entire optical path was placed in a temperature chamber (303) for testing, and the collected data was used to solve the strain distribution results through a strain solution program (311).

[0016] 5) The polarization-maintaining bonded fiber ring (307) includes a copper disk (304) and upper and lower surface fiber rings. The details of the bonding disk are the layers (103), turns (102) of the bonded fiber ring (104), as well as the winding central axis (101), elastic disk (106) and mass block (105) of the bonding fiber ring (104).

[0017] 6) The glue strain change quantification module consists of two parts: a strain difference quantification analysis using a free, unwound optical fiber (203) as the object, and a strain difference quantification analysis using a bonded optical fiber ring as the object. The free, unwound optical fiber design is performed directly on an acrylic plate, with the glued portion (204) being 30cm. The bonded optical fiber ring is first wound inwards three times and glue is added. Based on the amount of glue added and the strain change test results, the strain change corresponding to the amount of glue added when winding back one loop of the pigtail is calculated. The theoretical relationship between the change in the thermal expansion coefficient of the optical fiber after adding the glue coating is: the strain change Δε of the optical fiber and the coating. f and Δε c The value is relative to the initial strain and minus ε. pre1 and ε pre2 The initial preload is independent of the strain change following the fiber grating response. α f and α c These are the coefficients of thermal expansion of the optical fiber and the coating, respectively. ΔT is the input temperature difference. and These represent the strains of the optical fiber and the coating under thermal stress, respectively. During cooling, the optical fiber is compressed by the coating, which has a high coefficient of thermal expansion, resulting in… Coating reaction generation The equilibrium equation is expressed as:

[0018]

[0019] Among them, A f Let A be the cross-sectional area of ​​the optical fiber. cE represents the cross-sectional area of ​​the coating. f and E c Elastic modulus of optical fiber and coating. Strain of fiber and polymer can be solved:

[0020]

[0021] Therefore, the coupled thermal expansion coefficient of the structure can be expressed as:

[0022]

[0023] According to this formula, adding a coating can change the strain of the optical fiber, thereby changing the coupling thermal expansion coefficient of the structure.

[0024] 7) Optical path noise comparison module before and after adding adhesive: Optical path phase noise is tested by building an MZ interferometer with the amount of adhesive added before and after adding adhesive. The module includes a frequency-stabilized light source (401), a reference arm for bonding fiber ring (403), a measuring arm for bonding fiber ring (404), a Y waveguide (402), a polarization-maintaining coupler (405), a photoelectric signal conversion board (408), and a data acquisition and demodulation device (409).

[0025] 8) A module for comparing optical path noise before and after adding adhesive is used. The light source is a frequency-stabilized light source (401). The frequency-stabilized light source (401) is welded to the Y-waveguide (402) at 90°. The fiber ring (404) of the interferometer reference arm is welded at 0° to the Y-waveguide (402) and 0° to the Y-waveguide (402) and 0° to the polarization-maintaining coupler (405). The polarization-maintaining coupler (405) is welded at 0° to the polarization-maintaining jumper. The polarization-maintaining jumper is connected to the photoelectric conversion board (408). The photoelectric conversion board (408) transmits the signal to the acquisition card and demodulation device (409) for phase noise observation in the time and frequency domains. Theoretical derivation is performed using a polarization-maintaining fiber MZ interferometer. In the MZ interferometer, the phase change of the transmitted light caused by the sensing fiber of length L is:

[0026]

[0027] Where L is the fiber length, n is the fiber refractive index, and λ is the wavelength of light in a vacuum.

[0028] Theoretically, there is a certain length difference between the sensing fibers of the two arms of the MZ interferometer, therefore the output phase difference of the MZ interferometer is:

[0029]

[0030] Where L M and L R These are the fiber lengths of the sensing arm and reference arm of the MZ interferometer, respectively.

[0031] When an optical fiber is in a free and loose state, and the sensing fiber is affected by a temperature change ΔT, the resulting phase change of the transmitted light can be expressed as:

[0032]

[0033] The changes in the refractive index n and length L of the optical fiber depend on the temperature change ΔT. The changes in refractive index Δn caused by the thermo-optic effect and the changes in length ΔL caused by the thermal expansion effect are respectively:

[0034] Δn=nCΔT

[0035] ΔL=αLΔT

[0036] Where α is the thermal expansion coefficient of quartz material; C is the thermo-optic coefficient of the refractive index of optical fiber; ΔT is the change in ambient temperature, which can be expressed by the formula:

[0037]

[0038] Therefore, when the optical fiber is in a free and loose state, and the MZ interferometer is affected by a temperature change ΔT, its output phase change can be expressed as:

[0039]

[0040] When the fiber loop is affected by temperature changes, the refractive index n of the fiber depends on the strain ε. ij and temperature T, in addition to strain ε ij Depending on temperature T, the phase change of the transmitted light caused by a fiber loop of length L can be expressed as:

[0041]

[0042] According to geometric terms Where the direction θ represents the orthogonal radial direction in the cylindrical frame formed by the fiber ring, the phase change can also be expressed as:

[0043]

[0044] According to the elastic effect The formula can be expressed as:

[0045]

[0046] Where ν is the Poisson's ratio of the optical fiber; p 11 p 12 The optical elasticity of the optical fiber; the optical thermo-optical coefficient of the optical fiber.

[0047] Due to axial strain ε zz and radial strain ε rrMuch smaller than the orthogonal radial strain ε θθ Therefore, for orthogonal radial strain, axial and radial strains can be neglected, and thus formula (3.10) can be expressed as:

[0048]

[0049] For a fiber loop with a total sensing fiber length of L', the strain of the sensing fiber with length dl located at position l is: Formula (3.11) can be expressed as:

[0050]

[0051] Therefore, the output phase change of the fiber MZ interferometer can be expressed as:

[0052]

[0053] Among them L' M L is the fiber length of the fiber loop in the interferometer's sensing arm. M L' is the fiber length of the interferometer's sensing arm. R L is the fiber length of the fiber loop in the interferometer reference arm. R Let L be the fiber length of the interferometer reference arm. Here, the strain integral difference is defined as L. ε :

[0054]

[0055] 9) The main purpose of the single-mode bonding ring module is to reduce costs. Since the amount of adhesive added is almost a one-way irreversible operation, but the polarization-maintaining fiber ring is relatively expensive, the single-mode fiber ring is used for preliminary testing first.

[0056] Compared with the prior art, the advantages of the present invention are as follows:

[0057] 1. A noise compensation method for MZ fiber optic interferometers was proposed, and a glue effectiveness testing device, a glue strain quantification testing device, and an MZ fiber optic interferometer noise testing device were built to achieve the function of matching the strain integral of the bonded fiber optic ring, thereby further reducing the phase noise and improving the sensitivity of the entire fiber optic sensing device.

[0058] 2. For the entire fiber optic interferometer, this scheme compensates for the symmetry of the fiber optic rings in both arms of the interferometer to achieve matching of the bonded fiber optic rings, thereby reducing low-frequency temperature noise and improving the low-frequency measurement resolution of the unit, while effectively suppressing the rise of the light source frequency.

[0059] 3. The glue addition operation improves the optical path itself. By adding glue, the strain of the fiber optic loop is altered. The change in refractive index is related to strain, and this change in refractive index leads to a change in optical path length, which in turn determines the change in the measured phase. Improving the optical path itself can enhance the measurement accuracy of the fiber optic accelerometer. Hardware improvements can provide more accurate test data for subsequent software algorithm improvements. Attached image description:

[0060] Figure 1 This is a schematic diagram of a disk-type vibration pickup structure for a fiber optic accelerometer.

[0061] Figure 2 Schematic diagram of a free, unwound optical fiber testing device;

[0062] Figure 3 This is a schematic diagram of the optical path for strain testing of a bonding ring in a temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching.

[0063] Figure 4 This is a schematic diagram of the optical path for a temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching.

[0064] Figure 5 This is a flowchart illustrating the implementation steps of a temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching. Specific implementation plan:

[0065] To clearly illustrate the features and advantages of the temperature compensation method for a disk-type fiber optic accelerometer based on thermal strain matching, the present invention will be further described in conjunction with examples and accompanying drawings, but this should not be construed as limiting the scope of protection of the present invention.

[0066] A temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching, and a multi-parameter measurement sensor for a polarization-maintaining fiber optic interferometer are shown in the attached figure. Figure 4 As shown.

[0067] A temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching comprises an adhesive effectiveness testing module (401), a single-mode bonding ring strain testing module (402), a polarization-maintaining bonding ring strain testing module (403), an adhesive strain change quantification module (404), and an optical path noise comparison module before and after adhesive addition (405). Wherein:

[0068] A schematic diagram of the disk-type vibration pickup structure of the fiber optic accelerometer is shown below. Figure 1 As shown, the number of turns (102) of the wound optical fiber ring is 15, the number of layers (103) is 120, and it contains a mass block (105) and an elastic disk (103) made of copper for strain information transmission.

[0069] A schematic diagram of a free, unwound optical fiber testing device is shown below. Figure 2 As shown, the adhesive material (205) added to the surface of the free optical fiber is a polymer material, which is required to have high Young's modulus and high coefficient of expansion. Specifically, epoxy resin adhesive and silicone rubber are compared. The temperature response coefficient of the sensor is improved by changing the geometric parameters of the polymer coating structure. The length of the adhesive part is 30cm.

[0070] The optical path diagram for the adhesive ring strain test of the thermally induced strain of the disc-type fiber optic accelerometer is shown below. Figure 3 As shown. The light source (301) is a tunable light source with a sweep frequency range of 1530nm~1570nm and a center wavelength parameter of 1550nm. The sweep frequency rate is selected as 20nm / s, the data sampling rate is 62.5HZ, and the spatial resolution is 0.5cm.

[0071] A schematic diagram of the optical path for a temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching is shown below. Figure 4 As shown, the light source (401) adopts a DFM frequency-stabilized light source. The length difference between the control reference arm (404) and the measuring arm of the fiber interferometer is less than 5 cm, and the optical path difference is almost zero. The polarization-maintaining coupler (405) has a working wavelength of 1310 / 1550 nm and a splitting ratio of 50:50. The jumper connecting the light source (401) is welded to the Y waveguide (402) at a 90° angle. When the MZ polarization-maintaining fiber interferometer performs optical path noise testing, a thermometer is added to collect temperature data while using a foam box for heat insulation and vibration isolation, thereby suppressing low-frequency temperature drift. Finally, the phase noise result is obtained through the demodulation device (DAQ).

Claims

1. A temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching, characterized in that, To address the issue of incomplete matching of the bonded fiber optic rings on the two arms of the fiber optic interferometer, a method was adopted to add adhesive with a high coefficient of thermal expansion and a large Young's modulus to increase the temperature response coefficient of the arm with a smaller strain integral, thereby making the phase change equal. In addition, a light source, free and unwound optical fiber, data acquisition and demodulation device, strain destraining program, and temperature chamber were also used. The tunable light source is connected to the OFDR test optical path, the OFDR test optical path is connected to the polarization-maintaining jumper, the polarization-maintaining jumper is connected to the free unwound bare fiber, the free unwound bare fiber is fixed on the acrylic plate, the free fiber part is attached with glue, the glue composition is epoxy resin glue and silicone rubber, the two glues are tested to compare performance, the whole experimental device is placed in the temperature chamber and heated and kept warm with a fixed temperature gradient, including the following steps: (1) glue effectiveness test: the single-mode bonded fiber ring is placed in the foam box for heat preservation and vibration isolation, the whole optical path is placed in the temperature chamber for testing, heated and kept warm with a fixed temperature gradient, the collected data is solved by the strain distribution program to obtain the strain distribution result; (2) Quantification of adhesive strain change: The strain difference was quantitatively analyzed using free, unwound optical fiber as the object and the strain difference was quantitatively analyzed using bonded optical fiber ring as the object. The free, unwound optical fiber was designed to be operated directly on an acrylic plate with an adhesive coating of 30cm. The bonded optical fiber ring was first wound inward three times and adhesive was added. The strain change corresponding to the amount of adhesive added when the pigtail was wound back one turn was calculated based on the amount of adhesive added and the strain change test results.

2. The temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching according to claim 1, characterized in that, The strain testing procedure for the polarization-maintaining bonding ring is as follows: the input fiber of the bonding ring on the upper surface of the polarization-maintaining bonding fiber ring is welded to the polarization-maintaining jumper at 0°; the output fiber of the bonding ring on the upper surface of the polarization-maintaining bonding fiber ring is connected to the input fiber of the bonding ring on the lower surface of the disk; the jumper is connected to the tunable light source; the tunable light source is connected to the OFDR test optical path; the OFDR test optical path is connected to the data acquisition and demodulation device; the entire optical path is placed in a temperature chamber for testing; the acquired data is processed by a strain determination program to obtain the strain distribution result.

3. The temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching according to claim 2, characterized in that, The polarization-maintaining bonded fiber optic ring includes a copper disk and upper and lower surface fiber optic rings. The details of the bonding disk include the layers and turns of the fiber optic ring, as well as the winding central axis, elastic disk, and mass block.

4. The temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching according to claim 1, characterized in that, The steps for comparing optical path noise before and after adding adhesive are as follows: Optical path phase noise is tested by building an MZ interferometer that includes both the amount of adhesive added and the amount of adhesive added. The test device includes a frequency-stabilized light source, a reference arm for the bonded fiber optic ring, a measurement arm for the bonded fiber optic ring, a Y-waveguide, a polarization-maintaining coupler, a photoelectric signal conversion board, a data acquisition and demodulation device.

5. The temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching according to claim 4, characterized in that, The light source uses a frequency-stabilized light source, which is welded to the Y-waveguide at 90°. The fiber optic ring of the interferometer reference arm is welded at 0° to the Y-waveguide output fiber and at 0° to the polarization-maintaining coupler input fiber. The polarization-maintaining coupler output fiber is welded at 0° to the polarization-maintaining jumper wire. The polarization-maintaining jumper wire is connected to the photoelectric conversion board. The photoelectric conversion board transmits the signal to the acquisition card and demodulation device for phase noise observation in the time and frequency domains.

6. The temperature compensation method for a disk-type fiber optic accelerometer based on thermally induced strain matching according to claim 1, characterized in that, The strain test procedure for single-mode adhesive rings is as follows: Since the amount of adhesive added is almost a unidirectional and irreversible operation, and the price of polarization-maintaining fiber rings is relatively expensive, in order to reduce costs, a single-mode fiber ring is used for preliminary testing.

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