A temperature test and evaluation system for a polarization-maintaining optical path assembly of an optical fiber gyroscope

Abstract

The application discloses a temperature test and evaluation system for a polarization-maintaining optical path assembly of an optical fiber gyroscope. The polarization-maintaining optical path assembly and a test tool thereof are placed in a temperature box with a vibration isolation foundation. Other optical devices and gyroscope circuits are placed outside the temperature box. Through a test cable, a power supply box, the optical fiber gyroscope and a collection device are electrically connected. Before temperature test, the output of the optical fiber gyroscope at normal temperature is monitored, the collection time is set, the mean value and the standard deviation of the output data at normal temperature are calculated, and after the requirements are met, the temperature test can be started. According to the full-temperature output data, the extreme values and the standard deviations before and after temperature compensation are calculated, which together constitute the evaluation indexes of the polarization-maintaining optical path assembly. The system realizes the improvement of the qualified rate of the full-temperature zero-bias stability of the optical fiber gyroscope product after compensation.

Description

TECHNICAL FIELD

[0001] The application relates to a temperature test and evaluation system for a polarization-maintaining optical path assembly of an optical fiber gyroscope. BACKGROUND

[0002] The polarization-maintaining optical path assembly is composed of a fiber coil and a Y waveguide integrated optical device, fiber coil double-end tail fibers, Y waveguide double-end tail fibers and two polarization-maintaining fusion points, and forms a Sagnac interferometer in the optical fiber gyroscope. In the polarization-maintaining optical path assembly, an optical wave signal is split at the Y waveguide, propagates in opposite directions through the fiber coil, and then is combined at the Y waveguide to become an interference signal. The optical fiber gyroscope realizes the sensitivity to angular velocity by taking the interference signal as a carrier.

[0003] The polarization-maintaining optical path assembly is a core sensitive assembly of the optical fiber gyroscope, and its performance directly affects the precision of the optical fiber gyroscope. The temperature characteristics of the polarization-maintaining optical path assembly are affected by the coiling process of the fiber coil, the Y waveguide, the fiber coil double-end tail fibers, the Y waveguide double-end tail fibers and the fusion quality of the two polarization-maintaining fusion points. In particular, the temperature characteristics of the fiber coil restrict the full-temperature zero-bias stability of the optical fiber gyroscope. The Y waveguide integrated optical device has the functions of polarization, bias and modulation of light waves, and is also easily affected by temperature. Compared with the test of only one optical device, such as the fiber coil and the Y waveguide, the test of the polarization-maintaining fusion points, the polarization-maintaining tail fibers (including the fiber coil tail fibers and the Y waveguide tail fibers) and the coiling process cannot be ignored. For high-precision optical fiber gyroscopes, under the full-temperature condition of a temperature range of-40℃ to +60℃ and a temperature change rate of 1℃ / min, the compensated precision requirement is not more than 0.01° / h (100s, 1σ), and the influence of the polarization-maintaining fusion points and the coiling process cannot be ignored. The previous temperature performance screening of only a single optical device cannot meet the temperature requirements of high-precision and very high-precision optical fiber gyroscopes.

[0004] The fiber coil double-end tail fibers and the Y waveguide double-end tail fibers are polarization-maintaining optical fibers. The polarization-maintaining tail fibers are coiled and fused, and the stresses at the two ends are different, so they are also easily affected by temperature. The temperature performance screening of the fiber coil and the Y waveguide alone ignores the coiling process of the fiber coil double-end tail fibers and the Y waveguide double-end tail fibers and the fusion quality of the two polarization-maintaining fusion points, and is not sufficient to represent the temperature characteristics of the entire polarization-maintaining optical path assembly. Therefore, in order to ensure the full-temperature precision of the optical fiber gyroscope and improve the qualification rate of the optical fiber gyroscope, it is more practical to screen the temperature characteristics of the entire polarization-maintaining optical path assembly.

[0005] At present, many scholars judge the temperature performance of the fiber ring by establishing a fiber ring temperature test and evaluation system. A high-precision optical waveguide full-temperature screening test method is established to test the temperature performance of Y waveguide integrated optical devices. These detection methods are only for temperature screening of single devices, and it is difficult to evaluate the temperature index of polarization maintaining optical path components from a single aspect, and it cannot accurately represent the temperature performance of the fiber optic gyroscope. Therefore, it is particularly important to build a polarization maintaining optical path component temperature test and evaluation system. SUMMARY

[0006] The technical solution of the present application is to overcome the shortcomings of the prior art and provide a polarization maintaining optical path component temperature test and index evaluation system for a fiber optic gyroscope. The system can improve the full-temperature zero-bias stability qualification rate of the fiber optic gyroscope product after compensation.

[0007] The technical solution of the present application is a polarization maintaining optical path component temperature test and evaluation system for a fiber optic gyroscope, which comprises an erbium-doped fiber light source, a fiber coupler, a polarization maintaining optical path component, a detector, a temperature sensor, a light source driving circuit and a digital circuit, a test tool, a test cable, an evaluation unit and a temperature box. The polarization maintaining optical path component comprises a Y waveguide and a fiber ring. The Y waveguide has two sections of polarization maintaining tail fibers on one side, and the fiber ring has two sections of polarization maintaining tail fibers. A closed loop is formed by fusion between the two sections of polarization maintaining tail fibers. The fusion point between the polarization maintaining tail fibers is called a polarization maintaining fusion point. The fiber ring is placed in the test tool, and the temperature sensor is placed in the center of the fiber ring coil. The test tool is placed in the temperature box with a vibration isolation foundation. The light source driving circuit, the digital circuit, the power supply box and the evaluation unit are electrically connected through a three-port test cable.

[0008] The erbium-doped fiber light source generates light signal i1 by providing driving current through the light source driving circuit, the light signal i1 forms light signal i2 after being split by the optical fiber coupler, the light signal i2 reaches the Y waveguide, generates two linearly polarized lights after being polarized and split, the two linearly polarized lights enter the fiber ring after passing through the polarization-maintaining tail fiber and the polarization-maintaining fusion joint between the Y waveguide and the fiber ring in turn, the two linearly polarized lights reach the Y waveguide after passing through the polarization-maintaining tail fiber and the polarization-maintaining fusion joint between the Y waveguide and the fiber ring in turn again after propagating through the fiber ring in reverse, and form light signal i3 after being combined, the light signal i3 forms light signal i4 after being split by the optical fiber coupler again, and the light signal i4 reaches the detector, the detector converts the received light signal i4 into an electrical signal, the electrical signal forms three signals after being calculated by the digital circuit: angular velocity signal y1, modulation signal y2 and gain error signal y3, the digital circuit is composed of a front-end signal processing circuit, a digital signal processing logic chip and a back-end signal processing circuit, the front-end signal processing circuit includes a filter circuit, a first amplification circuit and an analog-to-digital converter, the back-end signal processing circuit includes a first digital-to-analog converter, a second amplification circuit, a switching switch, a second digital-to-analog converter and a third amplification circuit, the angular velocity signal y1 represents the signal of the gyro sensitive to the angular velocity of the external environment and is outputted externally, the modulation signal y2 is used as a feedback signal to compensate the Y waveguide to form a first closed-loop feedback loop, and the gain error signal y3 is used as a feedback signal to compensate the first digital-to-analog converter to form a second closed-loop feedback loop to compensate the gain error caused by the change of the half-wave voltage of the Y waveguide, and the temperature sensor packs the measured fiber ring temperature information and the output angular velocity signal y1 of the gyro to form gyro data and uploads the gyro data to the evaluation unit, and the evaluation unit obtains the evaluation index according to the angular velocity signal y1 and the temperature information of the gyro.

[0009] The polarization-maintaining fusion joint has a loss of not more than 0.1 dB and a crosstalk value of not less than 35 dB, and the polarization-maintaining tail fibers of the fiber ring and the Y waveguide are wound in a preset path, and the fiber is ensured to be free of twisting, extrusion and suspension during the winding process.

[0010] The evaluation index includes the range and the compensated standard deviation of the polarization-maintaining optical path assembly under temperature test, the range is used to judge the temperature sensitivity of the polarization-maintaining optical path assembly, and the compensated standard deviation is used to judge the precision level of the polarization-maintaining optical path assembly after compensation.

[0011] The calculation method of the range of the polarization-maintaining optical path assembly is that: the original data is first smoothed for 100 seconds, then the smoothed data is smoothed for 10 seconds, and finally the maximum value and the minimum value of the sliding smoothed data are found to obtain the range by subtraction.

[0012] The specific calculation process of the range of the polarization-maintaining optical path assembly is as follows:

[0013] The original output angular velocity data of the polarization maintaining optical path assembly is B, and the sampling time is t, and the 100s smoothed data is:

[0014]

[0015] Wherein, i represents the number of data, represents the total number of data collected within 100s; mean() represents the average value of all data in the parentheses;

[0016] The 100s smoothed data is 10s sliding smoothed to obtain a smoother curve, and the 10s smoothed data is

[0017]

[0018] Wherein, represents the total number of data collected within 10s;

[0019] The maximum value in the smoother curve is subtracted from the minimum value, that is, the temperature range is obtained.

[0020] Before collecting the angular velocity data of the polarization maintaining optical path assembly, the polarization maintaining optical path assembly is placed in a temperature box, the temperature of the temperature box is set to-40℃ for 3 hours, then the temperature is increased to 60℃ at a temperature change rate of 1℃ / min, and then maintained for 3 hours.

[0021] The calculation method of the standard deviation of the polarization maintaining optical path assembly after compensation is:

[0022] Let the original output angular velocity data be B, the sampling time be t, and the temperature information be T;

[0023] The ratio of the temperature difference before and after the change to the time is used as the temperature change rate; wherein T is the temperature information, t is the sampling time, and Δt is the time interval;

[0024] Let the derivative signal based on the temperature information be T , T 2 , T 3 , …, in turn x1, x2, …, x m ;

[0025] Let there be x1, x2, …, x m variables, then the multiple linear regression model is formula

[0026] B=β0+β1x1+β2x2+ … +β m x m +ε

[0027] wherein β0, β1, … β m are m+1 unknown numbers; if n sets of observation data are obtained, the linear regression model is

[0028]

[0029] Written in matrix form is

[0030]

[0031] wherein

[0032]

[0033] The unknown numbers of the multiple linear regression equation are usually estimated by least squares, and the least squares estimate is

[0034]

[0035] The sample regression model formula under the ordinary least squares method is

[0036]

[0037] The compensated output angular velocity data are The standard deviation of is calculated. The standard deviation after compensation of the polarization maintaining optical path assembly.

[0038] Before collecting the angular velocity and temperature data of the polarization maintaining optical path assembly, the polarization maintaining optical path assembly is placed in a temperature chamber, the temperature of the temperature chamber is set to-40℃ for 3 hours, then the temperature is increased to 60℃ at a temperature change rate of 1℃ / min, and then maintained for 3 hours.

[0039] Before starting the test, the pre-test detection of the system is also included, including:

[0040] After being powered on for 3 hours at room temperature, the compensated standard deviation of the polarization maintaining optical path assembly and the temperature change curve with time are obtained, and the data of the last 2 hours are used, if the compensated standard deviation is not greater than 0.05° / h, the system is considered normal, and the test data is available.

[0041] The temperature chamber is set to constant temperatures of-40℃ and +60℃ respectively, and is powered on for 3 hours at the two temperatures, the compensated standard deviation of the polarization maintaining optical path assembly and the temperature change curve with time are obtained, and the data of the last 2 hours are used, if the compensated standard deviation is not greater than 0.05° / h, the system is considered normal, and the test data is available.

[0042] Compared with the prior art, the advantages of the present application are:

[0043] The present invention provides a temperature testing and evaluation system for polarization-maintaining optical path components of fiber optic gyroscopes. Its testing section performs temperature screening on the polarization-maintaining optical path components, covering the entire path of light wave from splitting to combining, thus providing more information than testing a single device. Its evaluation section provides temperature performance indicators for the polarization-maintaining optical path components, including temperature range and compensated standard deviation, offering criteria for screening polarization-maintaining optical path components. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the polarization-maintaining optical path component testing system of the present invention.

[0045] Figure 2 The test curves for the polarization-maintaining optical path components at room temperature are shown in this invention.

[0046] Figure 3 The test curve of the polarization-maintaining optical path component at a constant temperature point (-40℃) of the present invention is shown.

[0047] Figure 4 The test curve of the polarization-maintaining optical path component at a constant temperature point (+60℃) of the present invention is shown.

[0048] Figure 5 The test curve for adding polarization-maintaining fusion splice 1 to the fiber coiling process 1 of the polarization-maintaining optical path component of the present invention.

[0049] Figure 6 The test curve for the polarization-maintaining optical path component fiber coiling process 2 and the polarization-maintaining fusion splice 2 of the present invention.

[0050] Figure 7 This is a flowchart for evaluating the performance of polarization-maintaining optical path components according to the present invention. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] like Figure 1 As shown, a temperature testing and evaluation system for a fiber optic gyroscope polarization-maintaining optical path assembly includes an optical path section, a circuit section, and testing equipment. The optical path section includes an erbium-doped fiber light source 1, a fiber coupler 2, and a polarization-maintaining optical path assembly 3, comprising a fiber ring, a Y-waveguide integrated optical device, a polarization-maintaining fiber pigtail, a polarization-maintaining fusion splice, and a detector 4. The circuit section includes a temperature sensor 5, a light source driving circuit 6, and a digital circuit 7. The testing equipment includes a test fixture 8, test cables 9, a power supply box 10, a testing unit 11, and a temperature chamber 12. Before improvement: the fiber ring was placed separately in the temperature chamber; after improvement, the entire polarization-maintaining optical path assembly, consisting of the fiber ring, the Y-waveguide integrated optical device, the polarization-maintaining fiber pigtail, and the polarization-maintaining fusion splice, is placed in the temperature chamber. From an optical path perspective, the fiber ring is a component for the propagation of two phase-directed light waves, while the polarization-maintaining optical path assembly is a component that splits light into two beams, allows the two beams to propagate in opposite directions, and then combines the two beams. It is the entire interference optical path, encompassing light polarization, polarization maintenance, and light interference, thus possessing greater completeness.

[0053] The parts of the optical path are spliced by optical fibers, and the optical path and the circuit part are connected by a detector and an electric wire. The test cable connects the circuit part, the power supply box and the computer to complete the electrical connection of the test system.

[0054] The flow direction of the photoelectric signal of the test system is as follows: the erbium-doped fiber light source 1 provides a driving current to generate a light signal i1 through the light source driving circuit 6, the light signal i1 forms a light signal i2 after being split by the optical fiber coupler 2, the light signal i2 reaches the Y waveguide, and two linearly polarized lights are generated after being polarized and split, the two linearly polarized lights enter the optical fiber ring after passing through the polarization-maintaining tail fiber and the polarization-maintaining splicing point between the Y waveguide and the optical fiber ring in turn, and after propagating through the optical fiber ring, the two linearly polarized lights pass through the polarization-maintaining tail fiber and the polarization-maintaining splicing point between the Y waveguide and the optical fiber ring in reverse in turn again, and then reach the Y waveguide to form a light signal i3 carrying the rotation speed information after being combined; the interference signal i3 is split by the optical fiber coupler 2 again to form a light signal i4 and reaches the detector 4, the detector 4 converts the received light signal i4 into an electric signal; the electric signal forms three signals after being solved by the digital circuit 7: an angular velocity signal y1, a modulation signal y2 and a gain error signal y3; the digital circuit 7 is composed of a front-end signal processing circuit, a digital signal processing logic chip and a back-end signal processing circuit; wherein the front-end signal processing circuit includes a filter circuit, a first amplification circuit and an analog-to-digital converter; the back-end signal processing circuit includes a first digital-to-analog converter, a second amplification circuit, a switching switch, a second digital-to-analog converter and a third amplification circuit; the angular velocity signal y1 represents a signal of the gyro sensitive to the angular velocity of the external environment and is outputted externally; the modulation signal y2 is used as a feedback signal to compensate the Y waveguide to form a first closed-loop feedback circuit; the gain error signal y3 is used as a feedback signal to compensate the first digital-to-analog converter to form a second closed-loop feedback circuit to compensate the gain error caused by the change of the half-wave voltage of the Y waveguide; the temperature sensor 5 packs the measured temperature information of the optical fiber ring and the output angular velocity signal y1 of the gyro to form gyro data and uploads the gyro data to the evaluation unit 11; the evaluation unit 11 obtains evaluation indexes according to the angular velocity signal y1 and the temperature information of the gyro.

[0055] In order to avoid the influence of other optical, circuit components, temperature boxes on the test of the polarization-maintaining optical path assembly, certain requirements are put forward for the test accuracy at room temperature and constant temperature points.

[0056] The test curve of the polarization-maintaining optical path assembly at room temperature is as shown in Figure 2 The zero-bias stability is 0.0017° / h (100s, 1σ) calculated by using the data of the last two hours, which reflects the room temperature noise level of the gyro circuit and the optical path.

[0057] Constant temperature point test, the oven is set to constant temperature -40℃, +60℃, power on for 3 hours, the test curve of polarization maintaining optical path assembly is as follows Figure 3 , Figure 4 Using the data of the last 2 hours, the zero bias stability is calculated as 0.0038° / h (100s, 1σ), 0.0025° / h (100s, 1σ), which reflects the low high temperature noise level of the gyro circuit, optical path, and the anti-vibration performance of the oven.

[0058] After the above two tests meet the accuracy index, no further measurement is required.

[0059] Full temperature test, set the temperature range: -40℃~+60℃, temperature change rate: 1℃ / min, high and low temperature holding time 3 hours. The test curve of polarization maintaining optical path assembly is as follows Figure 5 , Figure 6 Among them, the fiber ring and Y waveguide integrated optical device remain unchanged, and the change is the tail fiber disc fiber process and fusion point. Figure 5 The test curve of polarization maintaining optical path assembly disc fiber process 1 plus polarization maintaining fusion point 1, the temperature difference is calculated as 0.3° / h, and the compensated zero bias stability is 0.018° / h (100s, 1σ), Figure 6 The test curve of polarization maintaining optical path assembly disc fiber process 2 plus polarization maintaining fusion point 2, the temperature difference is calculated as 0.18° / h, and the compensated zero bias stability is 0.007° / h (100s, 1σ). Figure 5 and Figure 6 It can be seen that by changing the disc fiber process and polarization maintaining fusion point, the full temperature difference of the polarization maintaining optical path assembly is reduced from 0.3° / h to 0.18° / h, a reduction of 60%, and the compensated zero bias stability is reduced from 0.018° / h (100s, 1σ) to 0.007° / h (100s, 1σ), an increase of 2.6 times. Only by testing the entire polarization maintaining optical path assembly can the influence of the disc fiber process and the polarization maintaining fusion point be measured.

[0060] The evaluation index in the evaluation system includes the temperature difference of the polarization maintaining optical path assembly under temperature test and the compensated standard deviation. The temperature difference represents the temperature sensitivity of the polarization maintaining optical path assembly, and the larger the value, the worse the temperature difference symmetry. The compensated standard deviation represents the accuracy level of the polarization maintaining optical path assembly after compensation. The larger the value, the worse the accuracy of the fiber optic gyroscope after compensation, and the smaller the two indexes, the better. Through the two indexes, the quality of the polarization maintaining optical path assembly can be judged.

[0061] The test temperature condition of the polarization maintaining optical path assembly is consistent with the test condition of the gyro after the whole table.

[0062] The temperature range reflects the symmetry of the polarization maintaining optical path assembly, and the greater the value, the greater the temperature sensitivity of the polarization maintaining optical path assembly. The size of the standard deviation after compensation reflects the precision level of the polarization maintaining optical path assembly after compensation, and the greater the value, the poorer the precision of the fiber optic gyroscope after compensation. The specific calculation process is as follows Figure 7 .

[0063] The evaluation system includes a data loading module, a parameter selection and setting module, a data processing module, a result display module, and a graphical display module.

[0064] The data loading module loads and displays the number of data rows and columns of the gyroscope data, and the content of the gyroscope data includes the output angular velocity and temperature of the gyroscope.

[0065] The parameter selection and setting module displays the start row and end row of the gyroscope data, and the column number of the gyroscope data in the data file. In the parameter selection and setting module, the data sampling frequency, smoothing time, and scale factor are set. The default data start row is 1, the end row is the total length of the data, and the gyroscope data is located in the 2nd column. The sampling frequency is 1 Hz, the smoothing time is 100 s, and the scale factor is the ratio of the data average value to the ground speed. The user can change any one of the parameters according to the actual situation.

[0066] The data processing module calculates the evaluation index according to the output angular velocity and temperature of the gyroscope, and transmits it to the result display module or the graphical display module.

[0067] The result display module displays the temperature range of the polarization maintaining optical path assembly and the standard deviation after compensation. It also displays the bias value, bias stability before and after compensation.

[0068] The graphical display module displays the curve of the bias value of the polarization maintaining optical path assembly before compensation with respect to time, or the comparative curve of the bias value of the polarization maintaining optical path assembly before and after compensation with respect to time. At the same time, the graphical display module outputs the Figure graphics of matlab.

[0069] The method for evaluating the polarization maintaining optical path assembly of the fiber optic gyroscope using the fiber optic gyroscope polarization maintaining optical path assembly temperature test and evaluation system includes the following steps:

[0070] Test the normal temperature and constant temperature point precision of the test and evaluation system to ensure that the precision index is met.

[0071] Set the temperature range, temperature change rate, and high-low temperature holding time of the temperature chamber, collect and save the gyroscope data of the polarization maintaining optical path assembly.

[0072] Load the gyroscope data using the evaluation system, and set the data sampling frequency, smoothing time, and scale factor in the evaluation system.

[0073] In the evaluation system, the temperature range of the polarization maintaining optical path assembly, the standard deviation after compensation, the zero offset value, the zero offset stability before and after compensation, and the curve of the zero offset value of the polarization maintaining optical path assembly changing with time are displayed, and the contrast curve of the zero offset value of the polarization maintaining optical path assembly changing with time before and after compensation is obtained, and the Figure graph of the zero offset curve of the polarization maintaining optical path assembly changing with time is obtained.

[0074] The contents not described in detail in the specification of the present application are the known technology of the person skilled in the art.

Claims

1. A temperature test and evaluation system for a polarization maintaining optical path assembly of a fiber-optic gyroscope, characterized in that, The application relates to a temperature compensation type fiber-optic gyroscope, which comprises an erbium-doped fiber light source (1), a fiber coupler (2), a polarization-maintaining light path assembly (3), a detector (4), a temperature sensor (5), a light source driving circuit (6), a digital circuit (7), a test tool (8), a test cable (9), a test and evaluation unit (11) and a temperature box (12); the polarization-maintaining light path assembly (3) comprises a Y waveguide and a fiber ring; the Y waveguide is provided with two sections of polarization-maintaining tail fibers on one side, and the fiber ring is provided with two sections of polarization-maintaining tail fibers; a closed loop is formed through fusion between the two sections of polarization-maintaining tail fibers; the fusion points between the polarization-maintaining tail fibers are called polarization-maintaining fusion points; the fiber ring is placed in the test tool (8), the temperature sensor (5) is placed in the center of the fiber ring coil, and the test tool (8) is placed in the temperature box (12) with a vibration-isolating foundation; the light source driving circuit (6), the digital circuit (7), a power supply box (10) and the test and evaluation unit (11) are electrically connected through the three-port test cable (9); The erbium-doped fiber light source (1) generates an optical signal i1 through the light source driving circuit (6) to provide a driving current, the optical signal i1 is split by the fiber coupler (2) to form an optical signal i2, the optical signal i2 reaches the Y waveguide, generates two linearly polarized lights after polarization and light splitting, and then enters the fiber ring after passing through the polarization-maintaining tail fibers and the polarization-maintaining fusion points between the Y waveguide and the fiber ring; after propagating through the fiber ring, the two linearly polarized lights pass through the polarization-maintaining tail fibers and the polarization-maintaining fusion points between the Y waveguide and the fiber ring again in reverse order, reach the Y waveguide, are combined to form an optical signal i3 carrying rotation speed information; the interference signal i3 is split by the fiber coupler (2) again to form an optical signal i4 and reaches the detector (4), the detector (4) converts the received optical signal i4 into an electrical signal; the electrical signal is solved by the digital circuit (7) to form three signals: an angular velocity signal y1, a modulation signal y2 and a gain error signal y3; the digital circuit (7) is composed of a front-end signal processing circuit, a digital signal processing logic chip and a rear-end signal processing circuit; the front-end signal processing circuit comprises a filter circuit, a first amplification circuit and an analog-to-digital converter; the rear-end signal processing circuit comprises a first digital-to-analog converter, a second amplification circuit, a switching switch, a second digital-to-analog converter and a third amplification circuit; the angular velocity signal y1 represents a signal of a gyro sensitive to external angular velocity and is outputted externally; the modulation signal y2 is used as a feedback signal to compensate the Y waveguide to form a first closed-loop feedback circuit; the gain error signal y3 is used as a feedback signal to compensate the first digital-to-analog converter to form a second closed-loop feedback circuit, which compensates the gain error caused by the half-wave voltage change of the Y waveguide; the temperature sensor (5) packs the measured fiber ring temperature information and the output angular velocity signal y1 of the gyro to form gyro data and uploads the gyro data to the test and evaluation unit (11); the test and evaluation unit (11) obtains evaluation indexes according to the angular velocity signal y1 and the temperature information of the gyro. The evaluation index includes the range of the polarization maintaining optical path assembly (3) under temperature test and the standard deviation after compensation; the range is used to judge the temperature sensitivity of the polarization maintaining optical path assembly (3), and the standard deviation after compensation is used to judge the precision level of the polarization maintaining optical path assembly (3) after compensation. The calculation method of the range of the polarization maintaining optical path assembly is that: first, the original data is smoothed for 100s, then the smoothed data is smoothed for 10s, and finally the maximum value and the minimum value of the smoothed data are found to obtain the range. The specific calculation process of the range of the polarization maintaining optical path assembly is that: The original output angular velocity data of the polarization maintaining optical path assembly (3) is B, and the sampling time is t, so the 100s smoothed data is where i represents the number of data, represents the total number of data collected within 100s; mean() represents the average of all data in the parentheses; The 10s smoothed data is obtained by smoothing the 100s smoothed data for 10s to obtain a smoother curve. wherein, represents the total number of data collected within 10 s; The maximum value and the minimum value in the smoother curve are subtracted to obtain the temperature range.

2. The temperature test and evaluation system for a polarization maintaining optical path assembly of a fiber-optic gyroscope according to claim 1, characterized in that, The polarization maintaining fusion point loss is not greater than 0.1dB, and the crosstalk value is not less than 35dB; the polarization maintaining tail fiber of the optical fiber ring and the Y waveguide is wound in the preset path, and the optical fiber is ensured to be free of twisting, extrusion and suspension during the winding process.

3. The temperature test and evaluation system for a polarization maintaining optical path assembly of a fiber-optic gyroscope according to claim 2, characterized in that, Before collecting the angular velocity data of the polarization maintaining optical path assembly (3), the polarization maintaining optical path assembly (3) is placed in the oven (12), the temperature of the oven (12) is set to-40℃ and kept for 3 hours, then the temperature is increased to 60℃ at a temperature change rate of 1℃ / min, and then kept for 3 hours.

4. The temperature test and evaluation system for a polarization maintaining optical path assembly of a fiber-optic gyroscope according to claim 3, characterized in that, The calculation method of the standard deviation after compensation of the polarization maintaining optical path assembly is that: The original output angular velocity data is B, the sampling time is t, and the temperature information is T. Utilizing a ratio of a temperature difference before and after a change to time as a rate of temperature change; where T is temperature information, t is a sampling time, and Δt is a time interval; Let a derivative signal T based on temperature information be defined as T 2 , T 3 , x1, x2,..., x m ; Let x1, x2, …, x m be variables, then the multiple linear regression model is written as B = β0+ β1x1+ β2x2+... + β m x m + ε where β0, β1,... βm are unknown parameters; if n sets of observation data are obtained, the linear regression model is m where β0, β1,... βm are unknown parameters; if n sets of observation data are obtained, the linear regression model is The matrix form is Wherein The unknown number of the multiple linear regression equation is usually estimated by the least square method, and the least square value is The sample regression model formula under the ordinary least square method is The compensated output angular velocity data is The standard deviation of is calculated as the standard deviation of the compensated polarization maintaining optical path assembly.

5. The temperature test and evaluation system for a polarization maintaining optical path assembly of a fiber-optic gyroscope according to claim 4, characterized in that Before collecting the angular velocity and temperature data of the polarization maintaining optical path assembly (3), the polarization maintaining optical path assembly (3) is placed in the oven (12), the temperature of the oven (12) is set to-40℃ and kept for 3 hours, then the temperature is increased to 60℃ at a temperature change rate of 1℃ / min, and then kept for 3 hours.

6. The temperature test and evaluation system for a polarization maintaining optical path assembly of an optical fiber gyroscope according to claim 1, characterized in that, Before starting the test, it also includes pre-test detection of the system, including: The oven (12) is set to constant temperature of-40℃ and +60℃ respectively, and powered on for 3 hours to obtain the standard deviation after compensation of the polarization maintaining optical path assembly (3) and the temperature change curve with time, and the last 2 hours of data is used, if the standard deviation after compensation is not greater than 0.05° / h, the system is considered normal, and the test data is available; The oven (12) is set to constant temperature of-40℃ and +60℃ respectively, and powered on for 3 hours to obtain the standard deviation after compensation of the polarization maintaining optical path assembly (3) and the temperature change curve with time, and the last 2 hours of data is used, if the standard deviation after compensation is not greater than 0.05° / h, the system is considered normal, and the test data is available.

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