An ultra-high precision zero drift optimization method based on fiber loop tail fiber strain control

Abstract

The application discloses an ultra-high precision zero drift optimization method based on fiber loop tail fiber strain control, and belongs to the field of fiber optic gyroscope and optical measurement technology. Its characteristics are: under a certain temperature change rate, using polarization maintaining OFDR combined with multi-parameter decoupling technology to test the temperature and thermal strain in the loop; performing loop zero drift prediction to obtain the zero drift value of each temperature point; setting the length of strain control, adjusting the tail fiber value in the test data, calculating the strain control value and direction of each temperature point; under the same temperature condition, using the electric control tension platform to apply the corresponding temperature point strain in the corresponding direction to accurately correct the zero drift of each temperature point. The method realizes ultra-high precision full-temperature zero drift optimization through active tail fiber strain control, and can theoretically achieve quantitative ultra-high precision (10 ‑5 order of magnitude) zero drift optimization, and can be used for development of an ultra-high precision gyro system, online zero drift compensation, and plays an important role in performance improvement of the gyro system.

Description

Technical fields:

[0001] This invention belongs to the fields of fiber optic gyroscopes and optical measurement. The invention relates to an ultra-high precision zero-drift range optimization method based on fiber optic loop strain control. Background technology:

[0002] A fiber optic gyroscope is a high-precision angular rate sensor based on the Sagnac effect. Compared to traditional mechanical gyroscopes, fiber optic gyroscopes have no rotating parts or wear components, and offer advantages such as short response time, strong resistance to vibration and shock, low cost, long lifespan, large dynamic range, and simple manufacturing process. Compared to laser gyroscopes, fiber optic gyroscopes do not require ultra-high precision optical processing, resulting in low power consumption and high reliability. Therefore, fiber optic gyroscopes are widely used in navigation and guidance systems in military, aerospace, and maritime fields.

[0003] The fiber optic sensing loop is one of the core components of a fiber optic gyroscope, often referred to as its "brain." In actual operation, both internal heating and external environmental temperature disturbances affect the gyroscope. When a segment of fiber in the sensing loop experiences a time-varying temperature disturbance, unless that segment is located at the midpoint of the sensing loop's geometry, a non-reciprocal phase shift will inevitably occur. This non-reciprocal phase shift is indistinguishable from the phase shift caused by rotation, resulting in a significant drift error and directly impacting the gyroscope's output accuracy.

[0004] The physical symmetry of an optical fiber sensing ring describes its related physical and material properties, including the temperature coefficient, temperature distribution, and symmetry of thermal strain distribution. Under the influence of the temperature field, thermal strain leads to the deterioration of physical symmetry, resulting in both the Mohr and Shupe effects. These effects significantly promote thermally induced drift in optical fiber gyroscope systems. Currently, the manufacturing process of optical fiber sensing rings mainly employs four-pole, eight-pole, and sixteen-pole symmetrical winding to ensure the midpoint symmetry of the structural position, thereby maximizing the symmetry of the physical field distribution.

[0005] In 2017, Liu Bohan et al. from the 707 Research Institute of China Shipbuilding Industry Corporation proposed a method to compensate for the stress of the sensitive loops in optical fibers by changing the colloidal modulus, bending radius, or winding tension of the pigtails with a specific number of turns, effectively reducing their non-reciprocity error. (A method for compensating for stress in the pigtails of optical fiber gyroscopes, CN201711351950.9)

[0006] In 2020, Huang Zhongwei of Beijing Sizhuo Borui Technology Co., Ltd. proposed adding a temperature sensor and piezoelectric ceramic to a fiber optic gyroscope testing system. One side of the fiber optic sensing loop is wound around the piezoelectric ceramic. During gyroscope system operation, the piezoelectric ceramic is controlled in real time based on the sensitive angular rate and temperature information, thereby applying stress to the pigtail to compensate for the zero drift of the fiber optic gyroscope. (Fiber optic gyroscope with stress compensation, CN202010586507.5)

[0007] In 2022, Liu Bohan et al. proposed fixing the fiber length compensator to the pigtail of the fiber optic sensing ring. When drift in the fiber optic gyroscope output is detected, the length of the outer fiber loop is changed by adjusting the linear expansion coefficient of the expansion core in the fiber length compensator, thus realizing online adjustment of the fiber optic gyroscope's pigtail. (Fiber optic gyroscope pigtail compensation method and fiber length compensator, CN202210915632.5)

[0008] The methods described above for detecting thermally induced drift in fiber optic sensing loops all involve placing the sensing loop on a gyroscope system for system-level testing. However, this testing method suffers from significant noise and is susceptible to environmental interference. Furthermore, system-level testing only provides the final system performance and cannot reflect the impact of the sensing loop on system performance. On the other hand, while these methods optimize the zero-drift performance of the sensing loop at different temperature points through pigtail stress control, they cannot precisely and quantitatively control the magnitude of the output stress, thus failing to meet the increasingly stringent zero-drift optimization requirements of fiber optic sensing loops.

[0009] To address the problems of complex operations and the inability to achieve optimal zero-drift optimization through precise stress compensation at all temperature points in current fiber optic sensing loop zero-drift optimization methods, this invention discloses an ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control. Based on the principle of optimizing zero drift by controlling the stress of the fiber optic sensing loop pigtail to adjust its physical symmetry, different magnitudes of stress are continuously and precisely applied to one side of the fiber optic sensing loop pigtail at various temperature points under a continuously changing temperature field using an electrically controlled displacement stage. This achieves the goal of optimizing its zero-drift performance, offering significant advantages such as precise and quantitative optimization of zero drift at different temperature points and simple operation steps. Summary of the Invention:

[0010] The purpose of this invention is to propose an ultra-high precision zero-drift optimization method based on fiber optic loop strain control, which solves the problem in the prior art of quantitatively optimizing the zero drift of the fiber optic sensitive loop at different temperature points.

[0011] An ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control is characterized by optimizing zero drift by controlling the stress of the fiber optic sensitive loop pigtail to adjust its physical symmetry. Under a continuous temperature change field, different stresses are applied to the pigtails on both sides of the fiber optic sensitive loop at various temperature points using an electrically controlled displacement stage, thereby optimizing the zero-drift performance of the fiber optic sensitive loop. The specific process is as follows:

[0012] Step 1 (S01): Place the fiber sensing ring (501) to be optimized into a temperature chamber (504), and test the fiber sensing ring (501) under a continuous temperature change field using a polarization-maintaining OFDR multi-parameter testing device to obtain the corresponding temperature and thermal strain change data.

[0013] Step 2 (S02): Decouple the measured temperature and thermal strain change data to obtain the refractive index change α. T ;

[0014] Step 3 (S03): The refractive index change α calculated in Step 2 (S02) T It can obtain the zero drift prediction result Z0 of the fiber sensing ring (501) under full temperature test as the temperature changes, and set the corresponding zero drift optimization target Z2 at the same time.

[0015] Step 4 (S04): Splice a length L1 of polarization-maintaining fiber with the same process and specifications to the pigtails on both sides of the fiber sensing ring (501) and fix them to the first electrically controlled displacement stage (502) and the second electrically controlled displacement stage (503) respectively. At the same time, measure the shortest controllable length L2 of the displacement stage to ensure that L2>L1.

[0016] Step 5 (S05): Apply different stress magnitudes F to the pigtails on the left and right sides of the fiber optic sensitive ring (501). 左 min and F 右min Adjust the magnitude of thermal strain on the left and right sides of the fiber optic sensing ring (501);

[0017] Step 6 (S06): Recalculate the zero drift value Z1 of the fiber sensing loop (501) at each temperature point, and compare whether Z1 and Z0 are equal. If they are equal, proceed to step 7 (107); if they are not equal, return to step 5 (S05) to readjust the stress F applied to both sides of the pigtail. 左min and F 右min Size;

[0018] Step 7 (S07): Record the stress magnitude F corresponding to the thermal strain adjustment on both sides of the fiber optic sensing ring (501) at each temperature point. 左min and F 右min ;

[0019] Step 8 (S08): Place the temperature sensor probe in the temperature chamber (504) and start it to monitor its temperature changes in real time;

[0020] Step 9 (S09): Based on the reading of the placed temperature sensor probe, apply the corresponding stress F to the left and right pigtails of the fiber optic sensing ring (501) respectively using the electrically controlled displacement stage, as recorded in Step 7 (107). 左min and F右min ;

[0021] Step 10 (S10): After adjustment, read the thermal strain at this temperature point and calculate the required application of magnitude F to the corresponding side of the fiber optic sensitive loop (501) pigtail to optimize zero drift. min The stress;

[0022] Step 11 (S11): At this temperature point, apply stress F precisely to the pigtail on one side of the fiber optic sensing ring (501) using an electrically controlled displacement stage. min ;

[0023] Step 12 (S12): Perform a second zero drift prediction Z3 and compare it with the set zero drift optimization target Z2;

[0024] Step 13 (S13): Determine whether the temperature point for this zero-drift optimization is the zero-drift optimization of the fiber optic sensing ring (501) under full-temperature testing. If it is not the last temperature point in the full-temperature testing process, repeat steps 9 (S09) to 12 (S12) to apply different stress magnitudes F to the fiber optic sensing ring (501) at each temperature point under the temperature test curve. min This ensures that the zero drift result is optimal at the corresponding temperature point; if it is the last temperature point of the temperature test curve, then the full-temperature zero drift range optimization of the fiber optic ring is completed.

[0025] The polarization-maintaining OFDR multi-parameter measurement device in step one (S01) includes a light source (10), a 45-degree polarizer (101), a first polarization-maintaining coupler (102), an auxiliary interferometer module (20), a main interferometer module (30), a data acquisition and processing module (40), an optical fiber sensing ring (501), a first electrically controlled displacement stage (502), a second electrically controlled displacement stage (503), and a temperature chamber (504). The continuous sweep light emitted by the light source 10 first passes through the 45-degree polarizer (101) to adjust the polarization state of the injected light to 45°, and then is split into two beams by the first polarization-maintaining coupler (102). 1% of the light signal is injected into the auxiliary interferometer module (20) to generate an auxiliary interference signal to eliminate the phase noise of the beat frequency signal output by the main interferometer module (30); in addition, 99% of the light signal is... The light is injected into the main interferometer module (30), and then split into two beams by the second polarization-maintaining coupler (301). 1% of the light signal is injected into the reference arm, and 99% of the light signal is injected into the measurement arm where the polarization-maintaining circulator (302) is located. After passing through the polarization-maintaining circulator 302, the light enters the fiber sensing loop (501) to be optimized. The reflected signal light passes through the polarization-maintaining circulator (302) again and merges back into the main interferometer. The main interferometer signal passes through the first and second polarization beam splitters (304) and (305) respectively, and then enters the first balanced photodetector (306) and the second balanced photodetector (307) to convert the light signal into an electrical signal. Finally, the auxiliary interferometer signal and the main interferometer signal are acquired by the acquisition card (401) in the data acquisition and processing module (40), and the data is transmitted to the computer (402).

[0026] In step three (S03), the zero drift prediction result Z0(i) of the fiber optic sensing ring (501) under full-temperature test as the temperature changes, and the set corresponding zero drift optimization value Z2(i), where i is the i-th temperature point, i = 1, 2, 3...N, and N is the total number of temperature points.

[0027] The change in refractive index α under thermal strain T The expression:

[0028]

[0029] In the formula, n0 is the standard refractive index, p 11 p 12 ε is the photoelastic coefficient. θ For axial thermal strain, n T This represents the thermo-optic coefficient of the optical fiber.

[0030] The CW light in the fiber optic sensing loop experiences a refractive index change at point s due to an external temperature disturbance, resulting in a positive phase difference. Similarly, the CCW light also exhibits a refractive index change at Ls, but this time with a negative phase difference. Therefore, the two beams produce different refractive index changes along their symmetrical lengths, a phenomenon known as the asymmetric refractive index distribution α. Ts The asymmetric distribution of refractive index α Ts The expression is as follows:

[0031] α Ts =α T (s,T)-α T (Ls,T) (2)

[0032] Asymmetric distribution of refractive index α Ts The relationship between thermally induced drift and thermal drift is expressed as follows:

[0033]

[0034] The expression for the moving distance Δl of the electronically controlled displacement stage when applying stress control to the pigtail is as follows:

[0035] Δl=L1·ε (4)

[0036] Compared with existing optimization methods, the advantages of this invention are:

[0037] This invention proposes a method for achieving ultra-high precision full-temperature zero-drift optimization based on active fiber strain control, which theoretically can achieve quantitative ultra-high precision (10). -5 Zero drift optimization (on a scale of magnitude).

[0038] The optimization method proposed in this invention can accurately and quantitatively compensate for the different stress levels required by the fiber optic sensing ring at each temperature point in the full-temperature test using an electrically controlled displacement stage. Compared with the shortcomings of traditional methods such as using piezoelectric ceramics or changing the modulus of the pigtail colloid, which cannot finely control the output stress, this method can achieve quantitative optimization with zero drift.

[0039] The optimization method proposed in this invention is simple to operate and can be widely used to optimize the zero-drift performance of fiber sensing rings with different fiber types and winding processes. Attached image description:

[0040] To more clearly illustrate the device design of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. The drawings are merely illustrative of some embodiments of the present invention and are not intended to limit the scope of the invention to all embodiments.

[0041] Figure 1 This is a flowchart of an ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control;

[0042] Figure 2 This is a diagram of the apparatus for multi-parameter polarization maintaining OFDR testing;

[0043] Figure 3 It is a graph showing the temperature change over time during a full-temperature test;

[0044] Figure 4 It is the change in refractive index α T A graph showing how the optical fiber length changes.

[0045] Figure 5 These are graphs showing the zero-drift results of the fiber optic sensing loop at different temperature points;

[0046] Figure 6 This is a diagram showing the displacement distance of the electrically controlled displacement stage under different temperature points controlled by stress applied to the pigtail.

[0047] Figure 7 This is the optimal zero-drift curve based on the fiber loop theory optimized by the pigtail stress control. Detailed implementation method:

[0048] To more clearly illustrate the purpose, technical solution, and advantages of this invention, the following will further explain the invention in conjunction with embodiments and accompanying drawings, but this should not limit the scope of protection of the invention. Specific Implementation Example 1

[0050] An ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control is described in the following steps:

[0051] Step 1: Place the fiber optic sensing ring to be optimized into a temperature chamber and perform high spatial resolution polarization-maintaining OFDR multi-parameter tests on the fiber optic sensing ring under a continuous temperature changing field to obtain the corresponding temperature and thermal strain change data.

[0052] like Figure 2 The diagram shows the polarization-maintaining OFDR multi-parameter testing device used in step one of this embodiment. The selection and parameters of the main optoelectronic devices in this device are as follows:

[0053] Light source 10 is a narrow linewidth tunable laser source with a linewidth of 70kHz, a set wavelength tuning range of 1545nm~1555nm, a sweep rate of 10nm / s, and a sweep time of 1s.

[0054] The maximum detection bandwidth of both the first balanced photodetector 306 and the second balanced photodetector 307 is 80MHz, and the peak-to-peak value of the electrical noise in the time domain is V. P-P <30mV, with a conversion gain of 4×104V / W.

[0055] The sampling rate of the 401 data acquisition card is set to 180MHz / s, with a compensated effective bit depth of 8.6 bits, a spurious-free dynamic range of 67.4dB, and an idle electrical noise of V. P-P =2.8mV.

[0056] The first coupler 102, the second coupler 301, and the third coupler 303 are all polarization-maintaining couplers. The splitting ratio of the first polarization-maintaining coupler 102 and the second polarization-maintaining coupler 301 is 99:1, and the splitting ratio of the third polarization-maintaining coupler 303 is 50:50.

[0057] The auxiliary interferometer module 20 uses a Mach-Zehnder type interferometer, and the single-mode fiber used has a refractive index of 1.456.

[0058] The fiber optic sensing ring 501 is wound with panda-type polarization-maintaining fiber.

[0059] The temperature change set in the temperature chamber 504 during the full-temperature test of the fiber optic sensing ring 501 is as follows: Figure 3 As shown, the specific process is as follows: First, maintain the temperature at 25℃ for 20 minutes; then, cool down to -45℃ at a temperature change rate of 1℃ / min, which takes 70 minutes; then maintain the temperature at -45℃ for 60 minutes; next, increase the temperature to 70℃ at a temperature change rate of 1℃ / min, which takes 115 minutes; finally, maintain the temperature at 70℃ for 60 minutes, thus completing the full-temperature test. From the start of the full-temperature test, each 5℃ represents a temperature point.

[0060] The first electrically controlled displacement stage 502 and the second electrically controlled displacement stage 503 are set to a resolution of 0.1 μm / pulse for full step, which applies stress control to the pigtail.

[0061] The specific implementation method for testing the fiber optic sensitive ring using a polarization-maintaining OFDR multi-parameter testing device in step one is as follows: The fiber optic sensitive ring 501 is placed in a temperature chamber 504, and a temperature change curve is set. The continuous sweep light emitted by the light source 10 first passes through a 45° polarizer 101 to adjust the polarization state of the injected light to 45°, and then is split into two beams by the first polarization-maintaining coupler 102. 1% of the light signal is injected into the auxiliary interferometer module 20 to generate an auxiliary interference signal used to eliminate the phase noise of the beat frequency signal output by the main interferometer module 30; the other 99% of the light signal is injected into the main interferometer module 30. The polarized light is then split into two beams by the second polarization-maintaining coupler 301. 1% of the optical signal is injected into the reference arm, and 99% is injected into the measurement arm where the polarization-maintaining circulator 302 is located. The light then enters the fiber sensing loop 501 to be optimized via the polarization-maintaining circulator 302. The reflected signal light passes through the polarization-maintaining circulator 302 again before converging back into the reference arm. The main interference signal passes through polarization beam splitters 304 and 305, and then enters the first balanced photodetector 306 and the second balanced photodetector 307, respectively, to convert the optical signal into an electrical signal. The auxiliary interference signal and the main interference signal generated by the main interference module 30 are acquired by the acquisition card 401 in the data acquisition and processing module 40, and the data is transmitted to the computer terminal 402.

[0062] Step 2: By decoupling the measured temperature data and thermal strain data, the refractive index change α can be calculated. T The change in refractive index α T The calculation formula is:

[0063]

[0064] Refractive index change α T Variation with fiber length, such as Figure 4 As shown.

[0065] Step 3: Calculate the refractive index change α obtained in Step 2. T The asymmetric distribution α of the refractive index can be obtained. Ts The expression is:

[0066] α Ts =α T (s,T)-α T (Ls,T)

[0067] Through the non-uniform distribution of refractive index α Ts The relationship between thermally induced drift and thermal drift is expressed as:

[0068]

[0069] This allows us to obtain the zero-drift prediction result Z0 of the fiber optic sensing ring as a function of temperature under full-temperature testing, such as... Figure 5As shown, a corresponding zero-drift optimization target Z2 is set.

[0070] Step 4: Splice a section of polarization-maintaining fiber with the same process and specifications and a length of L1 to the pigtails on both sides of the fiber sensing ring and fix it to the first electrically controlled displacement stage 502 and the second electrically controlled displacement stage 503. At the same time, measure its shortest controllable length L2, which satisfies L2>L1.

[0071] Step 5: Apply different stress magnitudes F to the pigtails on the left and right sides of the fiber optic sensitive loop respectively. 左min and F 右min Adjust the magnitude of thermal strain on the left and right sides of the fiber optic sensitive ring.

[0072] Step Six: Recalculate the zero-drift value Z1 of the fiber optic sensing loop at each temperature point, and compare whether Z1 and Z0 are equal. If they are equal, proceed to Step Seven; if they are not equal, return to Step Five to readjust the stress F applied to both sides of the pigtail. 左 min and F 右min Size.

[0073] Step 7: Record the stress magnitude F corresponding to the thermal strain adjustment on both sides of the fiber optic sensing ring at each temperature point. 左min and F 右min .

[0074] Step 8: Place the temperature sensor probe in the incubator and start the incubator to monitor temperature changes in real time.

[0075] Step Nine: Based on the readings of the temperature sensor probe placed inside the incubator, apply the corresponding stress F to the left and right pigtails of the fiber optic sensing ring using the electrically controlled displacement stage, as recorded in Step Seven. 左min and F 右min .

[0076] Step 10: After adjustment, read the thermal strain at this temperature point and calculate the direction and magnitude F of the stress that needs to be applied to the fiber optic sensing ring to optimize zero drift. min Since the magnitude of the applied stress is controlled by the electrically controlled displacement stage, it can be converted into the magnitude of the displacement distance of the electrically controlled displacement stage, such as... Figure 6 As shown.

[0077] Step 11: At this temperature point, apply stress F precisely to the pigtail on one side of the fiber optic sensitive ring using an electrically controlled displacement stage. min .

[0078] Step 12: Perform a second zero drift prediction Z3 and compare it with the set zero drift optimization target Z2.

[0079] Step 13: Determine whether the temperature point for this zero-drift optimization is the same as the zero-drift optimization of the fiber optic ring under full-temperature testing. If it is not the last temperature point in the full-temperature testing process, repeat steps 9 to 12, applying different stress magnitudes F to the fiber optic sensitive ring at each temperature point under the temperature test curve. min This optimizes the zero-drift result at the corresponding temperature point; if it is the last temperature point of the temperature test curve, then the full-temperature zero-drift range optimization of the fiber optic ring is completed, such as... Figure 7 As shown.

[0080] The embodiments described above illustrate in detail some implementation methods of the ultra-high precision zero-drift optimization method based on fiber optic loop strain control proposed in this invention. However, those skilled in the art will recognize that various modifications and variations can be made to the above specific embodiments without departing from the principles of this invention, and different combinations can be made to the various technical features and structures proposed in this invention, without exceeding the protection scope of this invention. All of these should be considered within the protection scope of this invention.

Claims

1. An ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control, characterized in that, Based on the principle of optimizing zero drift by controlling the stress of the fiber optic sensing ring's pigtails to adjust its physical symmetry, different stresses of varying magnitudes are applied to the left and right pigtails of the fiber optic sensing ring at different temperature points under a continuous temperature change field using an electrically controlled displacement stage. This achieves optimization of the zero drift performance of the fiber optic sensing ring. The specific process is as follows: Step 1 (S01): Place the fiber sensing ring (501) to be optimized into a temperature chamber (504), and test the fiber sensing ring (501) under a continuous temperature change field using a polarization-maintaining OFDR multi-parameter testing device to obtain the corresponding temperature and thermal strain change data. Step 2 (S02): Decouple the measured temperature and thermal strain change data to obtain the refractive index change α. T ; Step 3 (S03): The refractive index change α calculated in Step 2 (S02) T It can obtain the zero drift prediction result Z0 of the fiber sensing ring (501) under full temperature test as the temperature changes, and set the corresponding zero drift optimization target Z2 at the same time. Step 4 (S04): Splice a length L1 of polarization-maintaining fiber with the same process and specifications to the pigtails on both sides of the fiber sensing ring (501) and fix them to the first electrically controlled displacement stage (502) and the second electrically controlled displacement stage (503) respectively. At the same time, measure the shortest controllable length L2 of the displacement stage to ensure that L2>L1. Step 5 (S05): Apply different stress magnitudes F to the pigtails on the left and right sides of the fiber optic sensitive ring (501). 左min and F 右min Adjust the magnitude of thermal strain on the left and right sides of the fiber optic sensing ring (501); Step 6 (S06): Recalculate the zero drift value Z1 of the fiber sensing loop (501) at each temperature point, and compare whether Z1 and Z0 are equal. If they are equal, proceed to step 7 (107); if they are not equal, return to step 5 (105) to readjust the stress F applied to both sides of the pigtail. 左min and F 右min Size; Step 7 (S07): Record the stress magnitude F corresponding to the thermal strain adjustment on both sides of the fiber optic sensing ring (501) at each temperature point. 左min and F 右min ; Step 8 (S08): Place the temperature sensor probe in the temperature chamber (504) and start it to monitor its temperature changes in real time; Step 9 (S09): Based on the reading of the placed temperature sensor probe, apply the corresponding stress F to the left and right pigtails of the fiber optic sensing ring (501) respectively using the electrically controlled displacement stage, as recorded in Step 7 (107). 左min and F 右min ; Step 10 (S10): After adjustment, read the thermal strain at this temperature point and calculate the required application of magnitude F to the corresponding side of the fiber optic sensitive loop (501) pigtail to optimize zero drift. min The stress; Step 11 (S11): At this temperature point, apply stress F precisely to the pigtail on one side of the fiber optic sensing ring (501) using an electrically controlled displacement stage. min ; Step 12 (S12): Perform a second zero drift prediction Z3 and compare it with the set zero drift optimization target Z2; Step 13 (S13): Determine whether the temperature point for this zero-drift optimization is the zero-drift optimization of the fiber optic sensing ring (501) under full-temperature testing. If it is not the last temperature point in the full-temperature testing process, repeat steps 9 (S09) to 12 (S12) to apply different stress magnitudes F to the fiber optic sensing ring (501) at each temperature point under the temperature test curve. min This ensures that the zero drift result is optimal at the corresponding temperature point; If it is the last temperature point on the temperature test curve, then the full-temperature zero-drift range optimization of the fiber optic ring is completed.

2. The ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control according to claim 1, characterized in that, The polarization-maintaining OFDR multi-parameter measurement device in step one (S01) includes a light source (10), a 45-degree polarizer (101), a first polarization-maintaining coupler (102), an auxiliary interferometer module (20), a main interferometer module (30), a data acquisition and processing module (40), an optical fiber sensing ring (501), a first electrically controlled displacement stage (502), a second electrically controlled displacement stage (503), and a temperature chamber (504). The continuous sweep light emitted by the light source 10 first passes through the 45-degree polarizer (101) to adjust the polarization state of the injected light to 45°, and then is split into two beams by the first polarization-maintaining coupler (102). 1% of the light signal is injected into the auxiliary interferometer module (20) to generate an auxiliary interference signal to eliminate the phase noise of the beat frequency signal output by the main interferometer module (30); in addition, 99% of the light signal is... The light is injected into the main interferometer module (30), and then split into two beams by the second polarization-maintaining coupler (301). 1% of the light signal is injected into the reference arm, and 99% of the light signal is injected into the measurement arm where the polarization-maintaining circulator (302) is located. After passing through the polarization-maintaining circulator 302, the light enters the fiber sensing loop (501) to be optimized. The reflected signal light passes through the polarization-maintaining circulator (302) again and merges back into the main interferometer. The main interferometer signal passes through the first and second polarization beam splitters (304) and (305) respectively, and then enters the first balanced photodetector (306) and the second balanced photodetector (307) respectively to convert the light signal into an electrical signal. Finally, the auxiliary interferometer signal and the main interferometer signal are acquired by the acquisition card (401) in the data acquisition and processing module (40), and the data is transmitted to the computer (402).

3. The ultra-high precision zero-drift optimization method based on fiber optic loop pigtail strain control according to claim 1, characterized in that, In step three (S03), the zero drift prediction result Z0(i) of the fiber optic sensing ring (501) under full-temperature test as the temperature changes, and the set corresponding zero drift optimization value Z2(i), where i is the i-th temperature point, i = 1, 2, 3...N, and N is the total number of temperature points.

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