A sensitive optical path analysis method for inhibiting temperature variation zero bias mutation of an optical fiber gyroscope
Patent Information
- Application Number
- CN202510417277.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2026-10-16
AI Technical Summary
此种方法有一定概率能够修复变温零偏突变故障，但在根源上无法指导敏感光路装配方法，影响光纤陀螺的一次装配合格率
[0042]The beneficial effects of this invention are as follows: Through the above analysis method, this invention obtains the polarization crosstalk distribution law of double-ended pigtail coils, refines the sensitive optical path transfer function by using the rotation matrix and phase delay matrix to characterize the crosstalk point and the optical path between the crosstalk points, respectively, and can provide an explanation for the mechanism of the temperature-dependent zero bias change of the fiber optic gyroscope. Targeted measures can suppress the recurrence of the fault.
Smart Images
Figure CN122921131A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fiber optic gyroscope technology, specifically relating to a sensitive optical path analysis method for suppressing sudden changes in zero bias during temperature variations in fiber optic gyroscopes. Background Technology
[0002] Temperature-dependent zero-bias abrupt change in a fiber optic gyroscope refers to an abnormal change in the zero-bias value that can be repeatedly measured near a certain temperature point when the ambient temperature changes. This can degrade the zero-bias stability of the fiber optic gyroscope and is a typical fault commonly found in high-precision closed-loop fiber optic gyroscopes. The sensitive optical path of a fiber optic gyroscope is a closed optical path composed of a polarization-maintaining fiber ring and an integrated optical modulator. The two pigtails of the polarization-maintaining fiber ring and the integrated optical modulator are fused, coiled, and solidified on the optical path assembly, respectively.
[0003] It is generally believed that the temperature-dependent zero-bias sudden fault phenomenon in fiber optic gyroscopes occurs during the assembly of the sensitive optical path, which includes the splicing, coiling, and curing of the two pigtails. Due to the unclear mechanism, the commonly used engineering repair method is to re-splice and re-coil and cure the sensitive optical path pigtails. This method has a certain probability of repairing the temperature-dependent zero-bias sudden fault, but it cannot fundamentally guide the sensitive optical path assembly method, thus affecting the first-time assembly success rate of the fiber optic gyroscope. Summary of the Invention
[0004] The technical problem solved by this invention: In view of the problems of the prior art, the purpose of this invention is to provide a sensitive optical path analysis method to suppress sudden changes in zero bias of fiber optic gyroscopes due to temperature variations, locate the problem mechanism, establish and verify the fault model, guide the assembly process, and effectively suppress the recurrence of faults.
[0005] The technical solution of this invention:
[0006] A sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes, the method comprising:
[0007] Step 1: Use a white light interferometer to perform temperature cycling tests on the sensitive optical path of the fiber optic gyroscope to obtain the test results of temperature-dependent distributed crosstalk of the dual-end pigtails of the sensitive optical path.
[0008] Step 2: Based on the test results, establish an equivalent model of the crosstalk points in the assembly of the dual-end pigtail process of the sensitive optical path;
[0009] Step 3: Establish the transfer function of the sensitive optical path double-ended pigtail in the transfer function of the fiber optic gyroscope optical path system;
[0010] Step 4: Verify the transfer function of the dual-root pigtails in the sensitive optical path.
[0011] Furthermore,
[0012] In step one, the specific results of the variable temperature distributed crosstalk test are: the crosstalk values at different locations along the fiber length at different temperatures. The results of the variable temperature distributed crosstalk test show that at a certain location in the fiber, the cooling section increases and the heating section decreases.
[0013] Furthermore,
[0014] In step two, the dual-end pigtails of the fiber optic gyroscope sensitive optical path are located between the adhesive joint of the integrated optical modulator and the fiber outlet of the polarization-maintaining fiber ring magnetic shield. Each coil has one loop of dual-end pigtails, and the two pigtails pass through two melting point protection sleeves respectively. Each pigtail has four more crosstalk points within one loop.
[0015] Furthermore,
[0016] In step three, the optical path system of the fiber optic gyroscope is equivalent to a cascaded system of multiple short fiber micro-segments. The optical signal is transmitted from the beginning to the end of the optical path system along each fiber micro-segment in a certain order. The crosstalk points of the two end pigtails of the sensitive optical path are simplified to crosstalk matrices, and the optical fibers between the crosstalk points are simplified to phase delay matrices.
[0017] Furthermore,
[0018] Step three specifically involves:
[0019] Step 1: Establish the crosstalk matrix;
[0020] Step 2: Establish the phase delay matrix;
[0021] Step 3: Establish the Jones matrix for transmitting optical signals in the dual-end pigtail of the sensitive optical path.
[0022] Furthermore,
[0023] Step 1: Establish the crosstalk matrix, specifically:
[0024] At any two fiber segment connection points, the optical signal will crosstalk between the two polarization axes, which can be represented by the crosstalk matrix as follows:
[0025] Where t represents the crosstalk value of the optical signal intensity, and α represents the corresponding rotation angle.
[0026] Furthermore,
[0027] Step 2: Establish the phase delay matrix; specifically:
[0028] The phase delay of any fiber micro-segment can be represented by the phase delay matrix as follows:
[0029]
[0030] In the formula, d represents the phase delay of the optical signal transmitted along the fast and slow axes, Δβ represents the difference in transmission constants of the optical signal transmitted along the fast and slow axes, l represents the length of the fiber micro-segment, and i represents the imaginary unit.
[0031] Furthermore,
[0032] Step 3, establish the Jones matrix for transmitting optical signals in the dual-end pigtail of the sensitive optical path, specifically as follows:
[0033] Each loop of a single optical fiber has four crosstalk points, and each pair of crosstalk points creates a phase delay. The Jones matrix corresponding to one loop of the two-end pigtails in the sensitive optical path is:
[0034]
[0035] If the sensitive optical path has two pigtails wound n times, then the Jones matrix corresponding to each turn is:
[0036]
[0037] In the formula T 11 D represents the rotation matrix of the first crosstalk point in the first coil of the optical fiber. 11 T represents the fiber phase delay matrix between the first and second crosstalk points in the first coil of the fiber. n1 D represents the rotation matrix of the first crosstalk point in the nth coil of the optical fiber. n1 T represents the fiber phase delay matrix between the first and second crosstalk points in the first coil of the fiber. n2 D represents the rotation matrix of the second crosstalk point in the nth coil of the optical fiber. n2 This represents the fiber phase delay matrix between the second and third crosstalk points in the nth coiled fiber; and so on, with a total of n sets of multiplications in the formula.
[0038] Furthermore,
[0039] Step four is as follows:
[0040] Substitute the full-temperature distributed crosstalk test results of the double-ended pigtail region obtained in step one into the optical path system transfer function of the fiber optic gyroscope containing the transfer function of the sensitive optical path double-ended pigtail to calculate the full-temperature zero-bias curve of the fiber optic gyroscope.
[0041] The full-temperature zero-bias curve of the fiber optic gyroscope shows that the fiber optic gyroscope exhibits a zero-bias error of 0.1° / h to 0.15° / h in the low-temperature region of -20℃ to -30℃, which is consistent with the sudden zero-bias failure phenomenon of the fiber optic gyroscope under varying temperature.
[0042] The beneficial effects of this invention are as follows: Through the above analysis method, this invention obtains the polarization crosstalk distribution law of double-ended pigtail coils, refines the sensitive optical path transfer function by using the rotation matrix and phase delay matrix to characterize the crosstalk point and the optical path between the crosstalk points, respectively, and can provide an explanation for the mechanism of the temperature-dependent zero bias change of the fiber optic gyroscope. Targeted measures can suppress the recurrence of the fault. Attached Figure Description
[0043] Figure 1 The results of the temperature-dependent distributed crosstalk test for the dual-end pigtails of the sensitive optical path;
[0044] Figure 2 An equivalent model of crosstalk points in the assembly of dual-end pigtail process for sensitive optical paths;
[0045] Figure 3 The results show the full-temperature zero-bias error calculation for the sensitive optical path model of the fiber optic gyroscope. Detailed Implementation
[0046] This invention provides a sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias abrupt changes in fiber optic gyroscopes. It refines the transfer function model of the sensitive optical path portion of the fiber optic gyroscope by analyzing the accumulated angle of periodic polarization crosstalk generated at stress anomaly points under the action of pigtail winding. Based on this, a fault suppression scheme is proposed, which can clearly and effectively guide the assembly process of the sensitive optical path of the fiber optic gyroscope. Technical solution of this invention:
[0047] Temperature cycling tests were performed on the sensitive optical path of the fiber optic gyroscope using a white light interferometer to obtain the results of distributed crosstalk tests on the dual-end pigtails of the sensitive optical path under varying temperatures. Because the dual-end pigtails are coiled side by side and continuously coiled onto the upper layer of the previously coiled fiber, the thermal expansion and contraction of the melting point protection sleeve causes periodic changes in polarization crosstalk to occur in all the upper and lower layers of fiber in contact with the sleeve.
[0048] An equivalent model of crosstalk points in the assembly of dual-ended pigtails in the sensitive optical path is established. Each coil contains one loop of dual-ended optical fiber, with each fiber passing through two fusion point protection sleeves. Within one loop, each fiber has four additional crosstalk points.
[0049] The transfer function of the fiber optic gyroscope optical path system is refined. The optical path system of a fiber optic gyroscope can be equivalently represented as a cascaded system of multiple short fiber segments. The optical signal is transmitted sequentially along each fiber segment from the beginning to the end of the optical path system. The crosstalk points of the two-end pigtail in the sensitive optical path can be simplified to rotation matrices (crosstalk matrices), and the fiber between the crosstalk points can be simplified to phase delay matrices. The Jones matrix for transmitting the optical signal in the two-end pigtail in the sensitive optical path is obtained by cascading the phase delay matrix, rotation matrix, and crosstalk matrix.
[0050] The mathematical model of the fiber optic gyroscope with the transfer function of the dual-root pigtail in the supplementary sensitive optical path was verified, and it is consistent with the sudden change of zero bias fault phenomenon of the fiber optic gyroscope under varying temperature.
[0051] The above analysis method explains the temperature-dependent zero-bias sudden change fault in fiber optic gyroscopes. In the product design and process implementation, removing the sleeve at the melting point of the integrated optical modulator and polarization-maintaining fiber ring can suppress the temperature-dependent zero-bias sudden change problem caused by this mechanism.
[0052] The transfer function model of a fiber optic gyroscope optical path system can characterize the spectral and phase information of an optical signal from the input optical path system to the output point after passing through the entire optical path system. Through a polarization state correlation parameter testing platform, the typical periodic polarization crosstalk distribution law after splicing, coiling, and curing of the dual-end pigtails in the sensitive optical path is obtained. An equivalent model of the crosstalk points in the process assembly of the dual-end pigtails in the sensitive optical path is established. The Jones matrix of the transmitted optical signal in the dual-end pigtails in the sensitive optical path is obtained by cascading the phase delay matrix, rotation matrix, and crosstalk matrix, thus supplementing and refining the transfer function model of the dual ends of the sensitive optical path.
[0053] Step 1: Use a white light interferometer to perform temperature cycling tests on the sensitive optical path of the fiber optic gyroscope, and obtain the following results: Figure 1 The results of the temperature-dependent distributed crosstalk test on the dual-end pigtail of the sensitive optical path are shown. Specifically, the results are the crosstalk values at different locations along the fiber length at different temperatures. The temperature-dependent distributed crosstalk test results show that at a certain location in the fiber, there is a phenomenon that the cooling section increases and the heating section decreases.
[0054] At the fusion point sleeve of the dual ends of the integrated optical modulator, crosstalk increases during the cooling phase and decreases during the heating phase. This phenomenon occurs because the linear thermal expansion coefficient of the fusion point sleeve is 10 ppm / ℃, while the linear thermal expansion coefficient of the optical fiber at the melting point is 0.5 ppm / ℃. When the environment cools, the fusion point sleeve contracts rapidly, forcing the optical fibers at both ends of the protective sleeve to thin, leading to increased crosstalk. Conversely, when the environment heats up, the fusion point sleeve expands rapidly, forcing the optical fibers at both ends of the protective sleeve to thicken, leading to decreased crosstalk. Simultaneously, a periodic increase or decrease in polarization crosstalk value along the length of the dual ends of the sensitive optical path can be observed. This is because the dual-end pigtails are coiled together, with the coiling falling on top of the previously coiled fiber. Therefore, the thermal expansion and contraction of the fusion point sleeve causes all upper and lower layers of optical fibers in contact with the sleeve to experience increased crosstalk during the cooling phase and decreased crosstalk during the heating phase.
[0055] Step 2: Establish a system based on the test results, such as... Figure 2 The figure shows an equivalent model of the crosstalk point in the assembly of the dual-end pigtail process of the sensitive optical path.
[0056] The fiber optic gyroscope's sensitive optical path has two pigtails located between the integrated optical modulator's adhesive joint and the polarization-maintaining fiber's ring magnetic shield outlet. Each coil has one loop of two pigtails, and the two pigtails pass through two melting point protection sleeves respectively. Each pigtail has four more crosstalk points within one loop.
[0057] The sensitive optical path consists of two pigtails coiled approximately seven times. Two of the pigtails are fused together on the third and fourth turns, with a section of tubing protecting the fusion point. Both ends of the tubing serve as stress anomaly points. Each coil contains one turn of the two-ended fiber, with each fiber passing through two fusion point protection tubings. Each fiber has four additional crosstalk points per turn, resulting in eight more crosstalk points per turn. Seven turns of coiled two-ended fiber add a total of fifty-six crosstalk points, symmetrically distributed about the beam splitting and combining points of the integrated optical modulator (e.g., ...). Figure 2 (As shown).
[0058] Step 3: Based on the above analysis, establish the transfer function of the sensitive optical path's two-end pigtail in the fiber optic gyroscope optical path system transfer function. The optical path system of the fiber optic gyroscope can be equivalently represented as a cascaded system of multiple short fiber segments. The optical signal is transmitted in a certain order along each fiber segment from the beginning to the end of the optical path system. The crosstalk points of the sensitive optical path's two-end pigtail can be simplified as rotation matrices (crosstalk matrices), and the fiber between the crosstalk points can be simplified as phase delay matrices. The establishment process is as follows:
[0059] Step 1: Establish the rotation matrix (crosstalk matrix).
[0060] At any two fiber optic segments, the optical signals will crosstalk each other along the two polarization axes at the connection point, which can be represented by a rotation matrix (crosstalk matrix):
[0061]
[0062] Where t represents the crosstalk value of the optical signal intensity, and α represents the corresponding rotation angle.
[0063] Step 2: Establish the phase delay matrix.
[0064] The phase delay of any fiber micro-segment can be represented by a phase delay matrix as follows:
[0065]
[0066] In the formula, d represents the phase delay of the optical signal transmitted along the fast and slow axes, Δβ represents the difference in transmission constants of the optical signal transmitted along the fast and slow axes, l represents the length of the fiber micro-segment, and i represents the imaginary unit.
[0067] Step 3: Establish the Jones matrix for transmitting optical signals in the dual-end pigtail of the sensitive optical path.
[0068] Each loop of a single optical fiber has four crosstalk points, and each pair of crosstalk points creates a phase delay. The Jones matrix corresponding to one loop of the two-end pigtails in the sensitive optical path is:
[0069]
[0070] Assuming the sensitive optical path has two pigtails wound n times, the Jones matrix corresponding to each turn is:
[0071]
[0072] In the formula T 11 D represents the rotation matrix of the first crosstalk point in the first coil of the optical fiber. 11 T represents the fiber phase delay matrix between the first and second crosstalk points in the first coil of the fiber. n1 D represents the rotation matrix of the first crosstalk point in the nth coil of the optical fiber. n1 T represents the fiber phase delay matrix between the first and second crosstalk points in the first coil of the fiber. n2 D represents the rotation matrix of the second crosstalk point in the nth coil of the optical fiber. n2 This represents the fiber phase delay matrix between the second and third crosstalk points in the nth coil of the fiber. And so on, with a total of n sets of multiplications in the formula.
[0073] Step 4: Verify the transfer function of the dual-root pigtails in the sensitive optical path.
[0074] Substituting the full-temperature distributed crosstalk test results of the dual-end pigtail region obtained in Step 1 into the fiber optic gyroscope optical path system transfer function containing the transfer function of the sensitive optical path dual-end pigtail, the full-temperature zero-bias curve of the fiber optic gyroscope is calculated as follows: Figure 3 As shown in the figure, the fiber optic gyroscope exhibits a zero bias error of 0.1° / h to 0.15° / h in the low-temperature region of -20℃ to -30℃, which is consistent with the sudden zero bias failure phenomenon of the fiber optic gyroscope under varying temperature.
[0075] The above analysis method explains that the zero-bias sudden change fault in the fiber optic gyroscope due to temperature variation lies in the two melting point sleeves of the two pigtails of the integrated optical modulator and the two ends of the polarization-maintaining fiber ring. Due to the mismatch of the linear thermal expansion coefficients of the sleeves and the optical fibers, during the temperature change process, dozens of crosstalk points in the fiber related to the sleeves change simultaneously, forming a quasi-symmetrical point between the beam splitting and combining point of the integrated optical modulator. This results in the problem of zero-bias sudden change at certain temperature points.
[0076] In the product design and manufacturing process, removing the sleeve at the melting point of the integrated optical modulator and polarization-maintaining fiber ring can solve the problem of sudden temperature-induced zero-bias abrupt change caused by this mechanism. To avoid the reliability issues caused by moisture seeping into the melting point region after removing the protective sleeve, even without removing the sleeve, applying a second coat of adhesive to the sleeve area will significantly reduce the crosstalk value during temperature changes, thereby suppressing the amplitude of the sudden temperature-induced zero-bias abrupt change and solving the problem.
Claims
1. A sensitive optical path analysis method for suppressing sudden changes in zero bias during temperature variations in fiber optic gyroscopes, characterized in that, The method includes: Step 1: Use a white light interferometer to perform temperature cycling tests on the sensitive optical path of the fiber optic gyroscope to obtain the test results of temperature-dependent distributed crosstalk of the dual-end pigtails of the sensitive optical path. Step 2: Based on the test results, establish an equivalent model of the crosstalk points in the assembly of the dual-end pigtail process of the sensitive optical path; Step 3: Establish the transfer function of the sensitive optical path double-ended pigtail in the transfer function of the fiber optic gyroscope optical path system; Step 4: Verify the transfer function of the dual-root pigtails in the sensitive optical path.
2. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 1, characterized in that, In step one, the specific results of the variable temperature distributed crosstalk test are: the crosstalk values at different locations along the fiber length at different temperatures. The results of the variable temperature distributed crosstalk test show that at a certain location in the fiber, the cooling section increases and the heating section decreases.
3. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 2, characterized in that, In step two, the dual-end pigtails of the fiber optic gyroscope sensitive optical path are located between the adhesive joint of the integrated optical modulator and the fiber outlet of the polarization-maintaining fiber ring magnetic shield. Each coil has one loop of dual-end pigtails, and the two pigtails pass through two melting point protection sleeves respectively. Each pigtail has four more crosstalk points within one loop.
4. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 3, characterized in that, In step three, the optical path system of the fiber optic gyroscope is equivalent to a cascaded system of multiple short fiber micro-segments. The optical signal is transmitted from the beginning to the end of the optical path system along each fiber micro-segment in a certain order. The crosstalk points of the two end pigtails of the sensitive optical path are simplified to crosstalk matrices, and the optical fibers between the crosstalk points are simplified to phase delay matrices.
5. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 4, characterized in that, Step three specifically involves: Step 1: Establish the crosstalk matrix; Step 2: Establish the phase delay matrix; Step 3: Establish the Jones matrix for transmitting optical signals in the dual-end pigtail of the sensitive optical path.
6. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 5, characterized in that, Step 1: Establish the crosstalk matrix, specifically: At any two fiber segment connection points, the optical signal will crosstalk between the two polarization axes, which can be represented by the crosstalk matrix as follows: Where t represents the crosstalk value of the optical signal intensity, and α represents the corresponding rotation angle.
7. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 5, characterized in that, Step 2: Establish the phase delay matrix; specifically: The phase delay of any fiber micro-segment can be represented by the phase delay matrix as follows: In the formula, d represents the phase delay of the optical signal transmitted along the fast and slow axes, Δβ represents the difference in transmission constants of the optical signal transmitted along the fast and slow axes, l represents the length of the fiber micro-segment, and i represents the imaginary unit.
8. The sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 5, characterized in that, Step 3, establish the Jones matrix for transmitting optical signals in the dual-end pigtail of the sensitive optical path, specifically as follows: Each loop of a single optical fiber has four crosstalk points, and each pair of crosstalk points creates a phase delay. The Jones matrix corresponding to one loop of the two-end pigtails in the sensitive optical path is: If the sensitive optical path has two pigtails wound n times, then the Jones matrix corresponding to each turn is: In the formula T 11 D represents the rotation matrix of the first crosstalk point in the first coil of the optical fiber. 11 T represents the fiber phase delay matrix between the first and second crosstalk points in the first coil of the fiber. n1 D represents the rotation matrix of the first crosstalk point in the nth coil of the optical fiber. n1 T represents the fiber phase delay matrix between the first and second crosstalk points in the first coil of the fiber. n2 D represents the rotation matrix of the second crosstalk point in the nth coil of the optical fiber. n2 This represents the fiber phase delay matrix between the second and third crosstalk points in the nth coiled fiber; and so on, with a total of n sets of multiplications in the formula.
9. A sensitive optical path analysis method for suppressing sudden temperature-induced zero-bias changes in fiber optic gyroscopes according to claim 5, characterized in that, Step four is as follows: Substitute the full-temperature distributed crosstalk test results of the double-ended pigtail region obtained in step one into the optical path system transfer function of the fiber optic gyroscope containing the transfer function of the sensitive optical path double-ended pigtail to calculate the full-temperature zero-bias curve of the fiber optic gyroscope. The full-temperature zero-bias curve of the fiber optic gyroscope shows that the fiber optic gyroscope exhibits a zero-bias error of 0.1° / h to 0.15° / h in the low-temperature region of -20℃ to -30℃, which is consistent with the sudden zero-bias failure phenomenon of the fiber optic gyroscope under varying temperature.