Tail fiber length quantitative control's optical fiber gyroscope thermal zero drift range optimization method

Abstract

The application discloses a tail fiber length quantitative control optical fiber gyroscope thermal induced zero drift range optimization method, belongs to the optical fiber gyroscope and optical measurement field. Its characterized in that: under a certain temperature change rate, the polarization maintaining OFDR is combined with the multi-parameter decoupling technology to obtain the temperature and thermal strain distribution in the ring; the refractive index change amount is calculated to predict the zero drift of each temperature point; the relationship between the zero drift and the tail fiber length change of the fiber ring under all temperature points is further predicted to determine the tail fiber optimization direction and the optimization length L min ; the tail fiber length is quantitatively controlled, the geometric symmetry of the fiber ring is corrected, and the zero drift performance of the ring is optimized. The method belongs to the quantitative tail fiber length optimization method of the optical fiber gyroscope thermal induced zero drift, is based on theoretical prediction, and can realize the zero drift range optimization of all temperature points through one correction. The traditional qualitative tail fiber adjustment is improved to the quantitative control of the tail fiber length, the optimization process is simple, and the method plays an important role in the performance improvement of the optical fiber gyroscope system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of optical fiber gyroscope and optical measurement, and relates to a tail fiber length quantitative control optical fiber gyroscope thermal-induced zero drift range optimization method. BACKGROUND

[0002] The optical fiber gyroscope is an angular velocity sensor based on the Sagnac effect principle, has no moving parts and wear parts, has high precision, simple production and manufacturing process, and rapidly replaces the previously applied and developed mechanical gyroscope and laser gyroscope, and has wide application prospects in many fields.

[0003] The optical fiber ring is a core device of the optical fiber gyroscope, and is sensitive to temperature and strain changes as the "brain" of the optical fiber gyroscope inertial navigation technology to sense the attitude change of the outside world. In the actual working process of the optical fiber gyroscope, when the internal heat and the change of the environmental temperature are applied to a section of the optical fiber in the optical fiber ring, a temperature disturbance is caused, and unless the section of the optical fiber is located in the middle of the optical fiber ring, a non-reciprocal phase shift is inevitably caused. Since the non-reciprocal phase shift cannot be distinguished from the phase difference caused by rotation, a large drift error of the optical fiber gyroscope is caused, and the output precision of the optical fiber gyroscope is affected.

[0004] At present, the optical fiber ring generally adopts improved winding process to improve the symmetry, such as adopting quadrupole, octupole and hexadecapole, but the winding technology of the optical fiber ring is complex, and it is difficult to guarantee the perfect symmetry of the optical fiber ring in the winding process. The geometric symmetry of the optical fiber sensitive ring describes the symmetry property of the structure, and is affected by the winding mode, winding defects and length midpoint position. Among them, the length midpoint deviation is the main factor causing the geometric symmetry error. Therefore, the geometric symmetry of the optical fiber sensitive ring can be adjusted by controlling the length of the tail fiber to optimize the zero drift, but the length of the tail fiber on both sides needs to be accurately controlled. The traditional method is to repeatedly cut the tail fiber, and the zero drift result of the gyroscope is obtained through continuous testing, which has certain blindness and irreversibility. When the cutting length is greater than the length required for the optimization of the zero drift performance, waste is caused and the optimization target cannot be achieved. Even if good results are obtained, the law cannot be summarized and generalized to optimize the zero drift of other optical fiber sensitive rings.

[0005] In 2011, Yao Xiaotian of Suzhou Guanghuang Technology Co., Ltd. proposed to detect the dynamic characteristics of the fiber sensitive ring to be tested, so that the equivalent asymmetric length of the fiber ring can be calculated, and then the asymmetric length of the two-arm tail fiber can be compensated according to the difference in the equivalent asymmetric length between the two arms, so as to achieve the goal of optimizing the performance of the fiber ring. (A method for improving the quality of a fiber ring by using compensation technology, CN 201110040569.7) In 2013, Yao Xiaotian et al. proposed to assemble a fiber optic gyroscope system integrated with the fiber ring to be tested, and to apply a radial temperature excitation to the fiber ring while measuring its rotation speed to obtain the pointing thermal error angle of the gyroscope system. According to the rotation speed and the pointing thermal error angle, the pointing error temperature sensitivity coefficient of the fiber ring to be tested can be calculated to determine its equivalent asymmetric length. Finally, by compensating for the asymmetric length caused by the length reduction of the tail fiber, the quality of the fiber ring is improved. (A method for detecting the quality of a fiber ring for a gyroscope and a device thereof, CN 201210523580.3)

[0006] The above methods all require a complete set of fiber optic gyroscope test system, and require repeated cutting or lengthening of the tail fiber on one side of the fiber ring to obtain the output of the fiber ring detection device under different compensation fiber lengths to determine whether the optimal performance of the tail fiber control length is achieved. The entire calculation process and operation are complex and difficult to apply in practice.

[0007] Zhao Wei et al. of the 41st Research Institute of China Electronics Technology Group measured the stress distribution of the fiber ring at different temperatures using BOTDA technology, and then calculated the asymmetric length by calculating the stress integral difference, so as to cut the tail fiber on one side to achieve the purpose of optimizing the zero drift performance of the fiber optic gyroscope. (Method for compensating asymmetric length of fiber ring for fiber optic gyroscope, CN 201510282059.9) However, measuring the stress distribution of the fiber ring by BOTDA technology has low measurement accuracy and spatial resolution, making it difficult to accurately calculate the length of the tail fiber to be cut from the fiber ring, and unable to meet the requirements of zero drift optimization of the fiber ring.

[0008] Compared with the above methods, the distributed strain measurement technology based on optical frequency domain Rayleigh scattering detection has higher spatial resolution and measurement accuracy, and can provide accurate measurement data for zero drift prediction and optimization of the fiber sensitive ring.

[0009] In view of the problems in the prior art that the length of the fiber tail cannot be accurately corrected once to achieve the optimal optimization of the zero drift of the fiber sensitive ring, and the operation is complicated and the process is complex, the present application discloses a tail fiber length quantitative control fiber gyro thermal zero drift range optimization method. The relationship between the zero drift and the length change of the tail fiber in different directions of the fiber ring is determined to determine the optimal tail fiber length and direction, and then the corresponding side tail fiber is cut or lengthened to the optimal tail fiber length to adjust the geometric symmetry of the ring, thereby optimizing the zero drift of the fiber sensitive ring. Only one correction of the tail fiber is required to optimize the zero drift of the fiber ring, and the correction length of the tail fiber is accurate, which significantly improves the quality of the fiber ring in practical application. SUMMARY

[0010] The present application aims to provide a tail fiber length quantitative control fiber gyro thermal zero drift range optimization method, which solves the problem of accurately correcting the tail fiber once to achieve zero drift optimization in the background art.

[0011] 1. A tail fiber length quantitative control fiber gyro thermal zero drift range optimization method, characterized in that: based on the principle of adjusting the tail fiber in different directions of the fiber ring and the corresponding length to optimize the zero drift, the relationship between the zero drift and the length change of the tail fiber in different directions of the fiber ring is determined to determine the optimal tail fiber length, and then the corresponding side tail fiber is cut or lengthened to the optimal tail fiber length to adjust the geometric symmetry of the ring, thereby optimizing the zero drift of the fiber sensitive ring. The specific steps are as follows:

[0012] Step one (S01): Place the fiber sensitive ring (501) in a temperature box (502), and test the fiber sensitive ring (501) under continuous temperature change field by using a polarization maintaining OFDR multi-parameter testing device to obtain the left and right tail fiber lengths L1 and L2 of the ring, the corresponding standard refractive index distribution n0 of the tail fiber, and the corresponding temperature and thermal strain change data during the test;

[0013] Step two (S02): decouple the measured temperature and thermal strain change data to calculate the refractive index change α T ;

[0014] Step three (S03): the refractive index change α T obtained by decoupling calculation in step two (S02) can obtain the zero drift prediction result Z0 of the fiber sensitive ring (501) under full temperature test with temperature change, and set the corresponding zero drift optimization target Z1;

[0015] Step four (S04): determine a temperature point, adjust the right tail fiber length L2 of the fiber sensitive ring (501), and fit the relationship between the refractive index change α T and the right tail fiber length change.

[0016] Step five (S05): observing whether the fitting curve between the zero drift of the fiber sensitive ring (501) and the length change of the right tail fiber passes through the zero point;

[0017] Step six (S06): if the answer is yes in step five (S05), the optimal optimization direction and the length L of the tail fiber required for the zero drift optimization of the fiber sensitive ring (501) at this temperature point can be determined min ;

[0018] Step seven (S07): if the answer is no in step five (S05), the length L1 of the left tail fiber of the fiber sensitive ring is adjusted, and the relationship between the refractive index change α T , the zero drift and the length change of the left tail fiber is fitted, and then step five (S05) is returned;

[0019] Step eight (S08): repeating steps four (S04) to seven (S07), the optimal optimization direction and the length L of the tail fiber of the fiber sensitive ring (501) at the remaining temperature points in the test are calculated min ;

[0020] Step nine (S09): the optimal optimization direction of the tail fiber at all temperature points is counted, and the final optimization direction is determined according to the same direction of the most temperature points;

[0021] Step ten (S10): the average value L m of the optimization tail fiber length at each temperature point is calculated as the final adjustment length;

[0022] Step eleven (S11): comparing the optimal optimization length L m / n0 of the tail fiber and the tail fiber length corresponding to the optimization direction to determine the final optimization method of the tail fiber of the fiber sensitive ring (501);

[0023] 2. The method of claim 1, wherein the polarization maintaining OFDR multi-parameter measurement device in step one (S01) comprises 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), a fiber sensing ring (501), and a temperature box (502); the continuous swept 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 degrees, and then passes through the first polarization maintaining coupler (102) to divide the light into two beams; 1% of the light signal is injected into the auxiliary interferometer module (20) to generate an auxiliary interference signal for eliminating 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), and then passes through a second polarization maintaining coupler (301) to divide the light into two beams; 1% of the light signal is injected into a reference arm, and 99% of the light signal is injected into a measurement arm in which a polarization maintaining ring (302) is located; the reflected signal light passes through the polarization maintaining ring (302) again and then converges; the main interference signal passes through a first polarization beam splitter (304) and a second polarization beam splitter (306) and then enters a first photoelectric balance detector (305) and a second photoelectric balance detector (307), respectively, to convert the light signal into an electrical signal; finally, the auxiliary interference signal and the main interference signal are collected by a collection card (401) in the data acquisition and processing module (40), and the data is transmitted to a computer (402).

[0024] 3. The method of claim 1, wherein the zero drift prediction result Z0(i) of the fiber sensing ring (501) with temperature change under full-temperature test and the set corresponding zero drift optimization value Z2(i) in step three (S03) are obtained, i is the i th temperature point, i = 1, 2, 3…N, and N is the total number of temperature points.

[0025] 4. The method of claim 1, wherein in step five (S05), it is determined whether the fitting curve passes through the zero point, where the zero point refers to the right tail fiber length corresponding to the zero drift of 0 at the temperature point.

[0026] 5. The method of claim 1, wherein in step eleven (S11), the optimal tail fiber length L mThe size between n0 and the tail fiber length corresponding to the optimization direction determines the final method for optimizing the tail fiber of the fiber sensing ring (501), when the tail fiber is optimized to the length L m If n0 is greater than the tail fiber length corresponding to the optimization direction, the tail fiber is lengthened to the length L m If n0 is less than the tail fiber length corresponding to the optimization direction, the tail fiber is shortened to the length L m If n0 is less than the tail fiber length corresponding to the optimization direction, the tail fiber is shortened to the length L

[0027] The change amount of the refractive index under the action of thermal strain is α T The expression is as follows:

[0028]

[0029] In the formula, n0 is a standard refractive index, p 11 , and p 12 is a photoelastic coefficient, ε θ is an axial thermal strain, n T is a thermal-optical coefficient of the fiber.

[0030] The CW light of the fiber sensing ring is disturbed by external temperature at the point s, and the refractive index change is generated, which causes a positive phase difference. Similarly, the CCW light also has a refractive index change at L-s, but a negative phase difference is generated. Therefore, the two lights generate different refractive index changes on the symmetric length, which is called the asymmetric distribution of the refractive index α Ts . The expression of the asymmetric distribution of the refractive index α Ts is as follows:

[0031] α Ts = α T (s, T) - α T (L-s, T) (2)

[0032] The relationship expression between the asymmetric distribution of the refractive index α Ts and the thermal-induced drift is as follows:

[0033]

[0034] Compared with the existing optimization method, the present application has the following advantages:

[0035] The present application proposes a method for optimizing the zero drift of the fiber optic gyroscope based on quantitative tail fiber length control. Compared with the traditional qualitative tail fiber length adjustment method, the present application realizes the promotion from qualitative to quantitative, and significantly improves the optimization accuracy.

[0036] The optimization method proposed by the present application only needs to perform a correction operation on the tail fiber to realize the optimal optimization of the zero drift performance of the fiber sensing ring.

[0037] The optimization method can correct the length of the tail fiber accurately, is suitable for all temperature points, and can realize optimization of the full-temperature zero drift extreme difference of the fiber sensitive ring.

[0038] The optimization method has simple process, can effectively correct the geometric symmetry of the fiber ring, and improves the zero drift performance, and can be popularized and applied to the development of high-precision gyro systems. BRIEF DESCRIPTION OF DRAWINGS

[0039] To more clearly illustrate the device design of the embodiments of the present application, the drawings of the embodiments of the present application will be briefly introduced hereinafter. The drawings are only used to show some embodiments of the present application, and the present application is not limited to the drawings.

[0040] Figure 1 It is a tail fiber length quantitative control fiber optic gyroscope thermal induced zero drift extreme difference optimization method flow chart;

[0041] Figure 2 It is a polarization maintaining OFDR multi-parameter testing device diagram;

[0042] Figure 3 It is a temperature rate change curve with time change in full-temperature test;

[0043] Figure 4 It is a refractive index change amount alpha T with fiber length change curve;

[0044] Figure 5 It is a refractive index change amount alpha T with fiber sensitive ring right tail fiber cutting length change curve;

[0045] Figure 6 It is a zero drift curve with fiber sensitive ring right tail fiber cutting length change. DETAILED DESCRIPTION

[0046] To more clearly illustrate the device design of the embodiments of the present application, the drawings of the embodiments of the present application will be briefly introduced hereinafter. The drawings are only used to show some embodiments of the present application, and the present application is not limited to the drawings. Specific embodiment 1

[0048] A tail fiber length quantitative control fiber optic gyroscope thermal induced zero drift extreme difference optimization method, the specific operation steps are:

[0049] Firstly, the fiber sensitive ring 501 is placed in the temperature box 502, and the fiber sensitive ring is tested by the polarization maintaining OFDR multi-parameter testing device under the continuous temperature change field, and the left and right tail fiber lengths L1 and L2 of the ring and the standard refractive index distribution n0 corresponding to the tail fiber are obtained, and the corresponding temperature and thermal strain change data in the test are obtained.

[0050] As shown in Figure 2 The polarization maintaining OFDR multi-parameter testing device used in the first step is shown in the figure, and the selection and parameters of the main optoelectronic devices in the device are as follows:

[0051] The light source 10 is a narrow line width tunable laser source, the light source line width is 70 kHz, the set wavelength tuning range is 1545 nm-1555 nm, the sweep frequency rate is 10 nm / s, and the sweep frequency time is 1 s.

[0052] The maximum detection bandwidth of the first balanced photodetector 305 and the second balanced photodetector 307 is 80 MHz, the time domain peak-peak value VP-P of the electric noise is less than 30 mV, and the conversion gain is 4×104 V / W.

[0053] The sampling rate of the acquisition card 401 is set to 180 MHz / s, the effective number of bits after compensation is 8.6 bits, the spurious-free dynamic range is 67.4 dB, and the idle load electric noise is VP-P=2.8 mV.

[0054] The first coupler 102, the second coupler 301 and the third coupler 303 are all polarization maintaining couplers. The light splitting ratio of the first polarization maintaining coupler 101 and the second polarization maintaining coupler 301 is 99:1, and the light splitting ratio of the third polarization maintaining coupler 303 is 50:50.

[0055] The auxiliary interferometer module 20 adopts a Michelson interferometer, and the refractive index of the single-mode optical fiber used is 1.456.

[0056] The fiber sensitive ring 501 to be optimized is wound by a panda type polarization maintaining optical fiber.

[0057] The temperature change rate of the temperature box 502 in the full temperature test of the fiber sensitive ring is shown in Figure 3 The specific process is as follows: first, keep the temperature at 25℃ for 20 minutes; then, reduce the temperature to-45℃ at a temperature change rate of 1℃ / min, which takes 70 minutes; then, keep the temperature at-45℃ for 60 minutes, and then increase the temperature to 70℃ at a temperature change rate of 1℃ / min, which takes 115 minutes; finally, keep the temperature at 70℃ for 60 minutes, and the full temperature test is completed. From the beginning of the full temperature test, every 5℃ is a temperature point.

[0058] The specific embodiment of the fiber sensitive ring tested by the polarization maintaining OFDR multi-parameter testing device in the first step is as follows: the fiber sensitive ring 501 is placed in the temperature box 502, and a complete temperature change curve is set. The continuous swept frequency light emitted by the light source 10 first passes through the 45° polarizer 101 to adjust the polarization state of the injected light to 45°, and then is divided into two beams by the first polarization maintaining coupler 101, 1% of the light signal is injected into the auxiliary interferometer module 20 to generate an auxiliary interference signal for eliminating the phase noise of the beat frequency signal output by the main interferometer module 30; and 99% of the light signal is injected into the main interferometer module 30; then the polarized light is divided into two beams by the second polarization maintaining coupler 301, 1% of the light signal is injected into the reference arm; 99% of the light signal is injected into the measurement arm where the polarization maintaining ring 302 is located, and then enters the fiber sensitive ring 501 to be optimized through the polarization maintaining ring 302, and the reflected signal light is again converged after passing through the polarization maintaining ring 302; the main interference signal passes through the polarization beam splitter 304 and 306 respectively, the beat frequency signal is separated and enters the first photoelectric balance detector 305 and the second photoelectric balance detector 307 respectively to convert the light signal into an electrical signal. The auxiliary interference signal and the main interference signal generated by the main interferometer module 30 are collected by the collection card 401 in the data acquisition and processing module 40, and the data is transmitted to the computer end 402 for storage.

[0059] In the second step, the measured temperature and thermal strain change data are decoupled to calculate the refractive index change α T The calculation formula of the refractive index change α T is as follows:

[0060]

[0061] The refractive index change α T changes with the length of the fiber as shown in Figure 4 .

[0062] In the third step, the refractive index change α T calculated by decoupling in the second step can obtain the asymmetric distribution of the refractive index α Ts , and the expression is as follows:

[0063] α Ts = α T (s,T)- α T (L-s,T)

[0064] Through the relationship between the non-uniform distribution of the refractive index α Ts and the thermal induced drift, the expression is as follows:

[0065]

[0066] Thus, the zero drift prediction result Z0 of the fiber sensitive ring with temperature change under full temperature test can be obtained, and the corresponding zero drift optimization target Z1 is set.

[0067] Fourth step, determine the initial temperature point, adjust the right tail fiber length of the fiber sensitive ring, and fit the refractive index change α T , the relationship between the zero drift and the right tail fiber length change, as shown in Figure 5 and 6 .

[0068] Fifth step, observe the fitting curve between the zero drift of the fiber ring and the right tail fiber length change, and the optimal optimization point corresponding to the cutting right tail fiber length is about 7.6m.

[0069] Sixth step, calculate the optimal optimization direction of the tail fiber of the fiber sensitive ring at the remaining temperature points in the full temperature test and the tail fiber length L min ;

[0070] Seventh step, count the optimal optimization direction of the tail fiber at all temperature points, and determine the final optimization direction according to the same direction of the most temperature points.

[0071] Eighth step, calculate the average value L m of the optimization tail fiber length at each temperature point as the final adjustment length.

[0072] Ninth step, calculate the optimal optimization length of the tail fiber, which is less than the tail fiber length corresponding to the optimization direction, so that the right tail fiber can be cut to reach the optimal optimization point to adjust the geometric symmetry, thereby completing the zero drift optimization of the fiber optic gyroscope.

[0073] The above embodiments detail some of the embodiments of the tail fiber length quantitative control method for optimizing the thermal-induced zero drift range of the fiber optic gyroscope. However, for those skilled in the art, various modifications and variations can be made to the above specific embodiments without departing from the principles of the present application, and various technical features and structures proposed by the present application can be combined differently, but not beyond the protection scope of the present application, which should be considered as the protection scope of the present application.

Claims

1. A tail fiber length quantitative control optical fiber gyroscope thermal induced zero drift range optimization method, characterized in that; Based on the principle of adjusting the tail fiber on different sides of the fiber loop and the corresponding length to optimize the zero drift, the optimal tail fiber length is determined through the relationship between the zero drift and the length change of the tail fiber on different sides of the fiber loop, and then the corresponding side tail fiber is cut or lengthened to the optimal tail fiber length to adjust the geometric symmetry of the loop, thereby realizing the optimization of the zero drift of the fiber sensitive loop. The specific steps are as follows: Step one (S01): Place the fiber sensitive loop (501) in the temperature box (502), and test the fiber sensitive loop (501) under continuous temperature change field by the polarization maintaining OFDR multi-parameter testing device to obtain the left and right tail fiber lengths L1 and L2 and the corresponding standard refractive index distribution n0 of the tail fiber, as well as the corresponding temperature and thermal strain change data in the test; Step two (S02): Decoupling the measured temperature and thermal strain change data to calculate the refractive index change a T ; Step three (S03): the refractive index change α calculated by decoupling in step two (S02) T The zero drift prediction result Z0 of the fiber sensing ring (501) changing with temperature can be obtained under full temperature test, and the corresponding zero drift optimization target Z1 is set. Step four (S04): Determine a temperature point, adjust the right tail fiber length L2 of the fiber sensitive ring (501), and respectively fit the change of the refractive index α T , the relationship between zero drift and the change of the right tail fiber length Step five (S05): Observe whether the fitting curve between the zero drift of the fiber sensitive loop (501) and the length change of the right tail fiber passes through the zero point; Step six (S06): If step five (S05) judges yes, the optimal optimization direction and the length L of the tail fiber needed to adjust the fiber sensitive ring (501) zero drift optimization at this temperature point can be determined min ; Step seven (S07): If the step five (S05) is judged as no, the left tail fiber length L1 of the fiber sensitive ring is adjusted, and the refractive index change α is fitted respectively T , the relationship between the zero drift and the left tail fiber length change, and then returns to step five (S05); Step eight (S08): repeat step four (S04) to step seven (S07) to calculate the optimal optimization direction of the fiber sensitive ring (501) adjusting the pigtail and the length L of the pigtail at the remaining temperature points in the test min ; Step nine (S09): Statistically determine the optimal optimization direction of the adjusted tail fiber at all temperature points, and determine the final optimization direction according to the same direction of the most temperature points; Step ten (S10): Calculate the average value L of the optimized tail fiber length at each temperature point m as the final adjustment length; Step eleven (S11): comparing the optimal length L of the pigtail m / n0 and the pigtail length corresponding to the optimal direction, to determine the final fiber sensing loop (501) pigtail optimization method.

2. The method according to claim 1, wherein the tail fiber length is quantitatively controlled. The polarization maintaining OFDR multi-parameter measurement device in the 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), a fiber sensitive loop (501) and a temperature box (502). The continuous swept light emitted by the light source (10) first passes through the 45° polarizer (101) to adjust the polarization state of the injected light to 45°, and then passes through the first polarization maintaining coupler (102) to divide into two beams. 1% of the light signal is injected into the auxiliary interferometer module (20) to generate an auxiliary interference signal for eliminating the phase noise of the beat frequency signal output by the main interferometer module (30). Another 99% of the light signal is injected into the main interferometer module (30), and then passes through the second polarization maintaining coupler (301) to divide into two beams. 1% of the light signal is injected into the reference arm, and 99% of the light signal is injected into the measurement arm of the polarization maintaining loop (302). Then the signal light reflected back passes through the polarization maintaining loop (302) again and is merged. The main interference signal passes through the first polarization beam splitter (304) and the second polarization beam splitter (306) respectively, and enters the first photoelectric balance detector (305) and the second photoelectric balance detector (307) respectively to convert the light signal into an electrical signal. Finally, the auxiliary interference signal and the main interference signal are collected by the acquisition card (401) in the data acquisition and processing module (40), and the data is transmitted to the computer end (402).

3. The method of claim 1, wherein the tail fiber length is quantitatively controlled. The zero drift prediction result Z0(i) of the fiber sensitive loop (501) under the full temperature test and the corresponding zero drift optimization value Z2(i) set under the full temperature test in the step three (S03), i is the i th temperature point, i=1, 2, 3…N, N is the total number of temperature points.

4. The method of claim 1, wherein the tail fiber length is quantitatively controlled. In the step five (S05), it is judged whether the fitting curve passes through zero point, where the zero point refers to the right tail fiber length corresponding to the temperature point at which the zero drift is 0.

5. The method of claim 1, wherein the method is characterized in that, In step eleven (S11), the optimal tail fiber length L m / n0 is greater than the tail fiber length corresponding to the optimization direction, the tail fiber is lengthened by L m / n0 in the opposite direction to make the fiber length L m / n0 in the opposite direction to make the fiber length L m / n0 in the opposite direction to make the fiber length L

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