Optical spectrum error analysis method for fiber optic gyroscope based on fusion of OSA and OCDP

Abstract

The present application relates to the field of optical sensing fiber gyroscope, and particularly relates to a fiber-optic gyroscope light path spectrum error analysis method based on OSA and OCDP fusion, comprising: measuring the power spectral density function of a fiber-optic gyroscope light source, the spectral transmission function of a coupler and a Y waveguide; obtaining a polarization coupling intensity distribution curve; obtaining the optical path difference and amplitude intensity ratio of a plurality of characteristic coupling points of the polarization coupling intensity distribution curve; sequentially multiplying the power spectral density function of the fiber-optic gyroscope light source, the spectral transmission function of the coupler and the Y waveguide to obtain an ideal normalized main spectrum; obtaining the full light path spectrum of the fiber-optic gyroscope based on the ideal normalized main spectrum and the optical path difference and amplitude intensity ratio of the plurality of characteristic coupling points; and based on the full light path spectrum, analyzing to obtain a physical defect position and error intensity; the present application can improve the error analysis accuracy of the fiber-optic gyroscope.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology for optical sensing, and specifically to a method for analyzing optical path spectral errors of fiber optic gyroscopes based on the fusion of OSA and OCDP. Background Technology

[0002] Fiber optic gyroscopes (FOGs), as high-precision inertial navigation devices based on the Sagnac effect, are widely used in aerospace and navigation positioning fields. The stability of their scaling factor directly depends on the stability of the average wavelength of the light source and the spectral characteristics of the optical path. In the research and production of FOGs, accurate detection and control of optical path errors are crucial for improving gyroscope accuracy. Currently, the evaluation of optical path performance mainly relies on independent, discrete testing methods: on the one hand, technicians typically use an optically spectral analyzer (OSA) to monitor the output spectral shape, center wavelength, and spectral width of a broadband light source (such as an ASE light source) to assess the quality of the light source itself; on the other hand, they use an optically coherent polarimeter (OCDP) or optical frequency domain reflectometer (OBR) to perform distributed scanning of the fiber optic sensitive loop to locate polarization coupling points or scattering points within the fiber optic loop. These traditional testing methods are relatively mature in their respective single dimensions, providing some data support for the process selection of fiber optic gyroscopes.

[0003] However, existing optical path error analysis methods have significant limitations. Traditional testing methods often consider the spectral transmission characteristics of the light source and passive devices separately from the distribution defects of the fiber optic loop, lacking a comprehensive, system-level error propagation analysis method. For example, OSA alone cannot determine which specific location in the optical path causes subtle spectral distortions, while OCDP, although capable of locating physical defects, struggles to directly quantify the specific impact of these defects on the final optical path spectrum and scaling factor. This hinders the precise location and quantitative analysis of spectral error sources in the fiber optic gyroscope's optical path, which to some extent limits further optimization and improvement of fiber optic gyroscope performance. Summary of the Invention

[0004] In view of the above problems, the present invention provides a fiber optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion, which solves the technical problem that the error analysis of fiber optic gyroscopes is not accurate enough in the prior art.

[0005] This invention provides a method for analyzing the optical path spectral error of a fiber optic gyroscope based on the fusion of OSA and OCDP, comprising the following steps:

[0006] Step S1: Measure the power spectral density function of the fiber optic gyroscope source using a spectrometer, and measure the spectral transmission function of the coupler and the Y-waveguide respectively.

[0007] Step S2: Scan the fiber loop of the fiber optic gyroscope using an optical coherence polarimeter to obtain the polarization coupling intensity distribution curve; determine the optical path difference and amplitude intensity ratio of multiple characteristic coupling points of the polarization coupling intensity distribution curve;

[0008] Step S3: Multiply the power spectral density function of the fiber optic gyroscope source, the spectral transmission function of the coupler and the Y-waveguide sequentially to obtain the ideal normalized main spectrum. ;

[0009] The full optical path spectrum of the fiber optic gyroscope is obtained based on the ideal normalized main spectrum and the optical path difference and amplitude intensity ratio of multiple characteristic coupling points.

[0010] A full-path spectral error model for the fiber optic gyroscope is established. This model derives the full-path spectrum based on the ideal normalized main spectrum and the optical path difference and amplitude intensity ratio at multiple characteristic coupling points. The expression is as follows:

[0011]

[0012] in, Indicates the entire optical path spectrum. Indicates spectral frequency, This represents the amplitude intensity ratio corresponding to the i-th characteristic coupling point. This represents the optical path difference corresponding to the i-th feature coupling point. This represents the phase constant corresponding to the i-th characteristic coupling point. Indicates the total number of characteristic coupling points;

[0013] Step S4: Analyze the full optical path spectrum to obtain the location and error intensity of physical defects in the full optical path of the fiber optic gyroscope.

[0014] Preferably, in step S2, the method for determining the optical path difference and amplitude intensity ratio of multiple characteristic coupling points of the polarization coupling intensity distribution curve specifically includes:

[0015] A preset threshold is used to filter out multiple polarization coupling peaks whose amplitude intensity ratio exceeds the preset threshold from the obtained polarization coupling intensity distribution curve;

[0016] For each polarization coupling peak, the optical path difference and amplitude intensity ratio are extracted from the polarization coupling intensity distribution curve.

[0017] Preferably, the preset threshold value ranges from -50dB to -80dB.

[0018] Preferably, in step S3, the expression for the step of sequentially multiplying the power spectral density function of the fiber optic gyroscope source, the spectral transmission function of the coupler, and the Y-waveguide to obtain the ideal normalized main spectrum is as follows:

[0019]

[0020] in, This represents the ideal normalized main spectrum. This indicates normalized calculation. , , , , These represent the power spectral density function of the fiber optic gyroscope source, the spectral transmission functions of the forward and reverse couplers, and the spectral transmission functions of the forward and reverse Y-waveguides, respectively.

[0021] Preferably, step S4 specifically includes:

[0022] Step S4-1: Obtain the autocorrelation function-optical path difference curve of the full optical path spectrum based on the Fourier transform of the full optical path spectrum. Locate the polarization cross-coupling point, fusion splice point, and pigtail connection point based on the positions of multiple secondary peaks other than the zero-delay main peak in the autocorrelation function-optical path difference curve. This includes:

[0023] The location of the physical defect is determined based on the optical path difference corresponding to the secondary peak, including: determining whether the optical path difference interval between multiple secondary peaks is equally spaced; if not equally spaced, then determining whether the secondary peak is the fusion splice point of the fiber optic ring, the coupling point of the fiber optic ring, or the coupling point of the Y-waveguide.

[0024] If the distribution is evenly spaced, then the secondary peak is determined to be the crossover point between fiber ring layers or the fiber ring layer replacement location.

[0025] Step S4-2: Determine the phase error, zero bias error, and relative error of the scaling factor based on the intensity of the parasitic wave at the physical defect location, the intensity of the main signal wave, and the optical path difference.

[0026] Preferably, in step S4-2, the calculation expressions for phase error, zero bias error, and relative scaling factor error are as follows:

[0027]

[0028]

[0029]

[0030]

[0031] in, For parasitic wave intensity, Main signal wave intensity, The optical path difference corresponding to the j-th defect position The autocorrelation function value at that location, For phase error, At the speed of light, This refers to the operating wavelength of the fiber optic gyroscope's optical path. This is the total length of the fiber optic ring. The diameter of the fiber optic ring. Zero bias error This represents the power-weighted average wavelength. Indicates the operating wavelength of the fiber optic gyroscope optical path. The power distribution is the independent variable. Indicates the relative error of the scaling factor. This represents the change in wavelength of the power-weighted average.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] (1) This invention achieves a precise correspondence between “OCDP polarization crosstalk location information” and “OSA spectral ripple characteristics” by acquiring the polarization coupling intensity distribution curve in the fiber optic gyroscope loop and combining it with the power spectral density function and spectral transmission function measured in step S1. The “position-spectrum” mapping method can accurately locate the physical defect location that causes specific spectral distortion, such as the fusion splice or device coupling point, thus improving the accuracy and reliability of defect location.

[0034] (2) By measuring the optical characteristics of different devices such as the light source, coupler, Y-waveguide, and fiber ring step by step, and multiplying and comprehensively modeling the parameters according to the optical path transmission sequence, this invention establishes a segmented full-process error model. This model can comprehensively reflect the impact of the performance of each device on the overall optical path of the fiber optic gyroscope, providing a theoretical basis for quantitative analysis and optimization of optical path design, and helping to scientifically manage and control system errors.

[0035] (3) This invention is not limited to traditional time-domain or spatial-domain error analysis, but is based on comprehensive analysis of the entire optical path spectrum, integrating frequency-domain and spatial-domain information, which significantly improves the dimensionality of error analysis. This method can sensitively identify subtle errors that only appear in specific spectral frequency bands, enhance the sensitivity and accuracy of fiber optic gyroscope error detection, and effectively support the precision measurement needs in complex environments. Attached Figure Description

[0036] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0037] Figure 1 The flowchart shows the fiber optic gyroscope optical path spectral error analysis method based on the fusion of OSA and OCDP provided by this invention.

[0038] Figure 2 A schematic diagram of the power spectrum of the light source provided by the present invention.

[0039] Figure 3A schematic diagram of the polarization coupling intensity distribution curve provided by the present invention.

[0040] Figure 4 This is a schematic diagram of the full optical path spectrum provided by the present invention. Detailed Implementation

[0041] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0042] This method aims to measure the optical path error of a fiber optic gyroscope using a segmented, full-process optical path error analysis approach based on spectral analysis. Utilizing the OSA and OCDP spectrometers, the method measures the spectral shape changes from the light source to the detector, as well as the position and amplitude information of the mid-polarization crosstalk in the fiber optic loop, thereby achieving precise location of the fiber optic gyroscope error. Furthermore, it analyzes the spectral error of the entire optical path of the optical device based on the spectral curves.

[0043] To illustrate the effectiveness of the method proposed in this invention, the following detailed description of the above technical solution is provided through a specific embodiment, such as... Figure 1 As shown, this invention discloses a method for analyzing the optical path spectral error of a fiber optic gyroscope based on the fusion of OSA and OCDP. The specific implementation steps are as follows:

[0044] Step S1: Measure the power spectral density function of the fiber optic gyroscope source using a spectrometer and measure the spectral transmission function of the coupler and the Y-waveguide respectively.

[0045] In this step, the present invention uses an optical spectrum analyzer (OSA) to measure the spectral characteristics of each key component in the optical path of the fiber optic gyroscope, which is used to establish the full optical path spectrum in subsequent steps.

[0046] In some embodiments, a preset resolution can be set to preferably be 0.01 nm to 0.1 nm, and the light source, coupler and Y waveguide of the fiber optic gyroscope can be measured independently.

[0047] First, spectral measurements are performed on the output of the fiber optic gyroscope light source to obtain its power spectral density function. This function fully describes the energy distribution characteristics of the light source in the frequency domain. This invention can extract key shape parameters of this power spectral density function, including the center wavelength and spectral width. The center wavelength directly affects the scaling factor of the fiber optic gyroscope, and the spectral width affects the coherence length of the light, thus influencing the fiber optic gyroscope's sensitivity to parasitic interference. Figure 2As shown, the ideal light source spectrum should present a broadband Gaussian smooth envelope. Any distortion that deviates from the ideal shape, such as spectral asymmetry, spectral depression, or the presence of modulation ripple, will affect the gyroscope performance.

[0048] The optical path transmission sequence of the fiber optic gyroscope of the present invention is as follows: broadband light source → coupler → Y-waveguide input end → Y-waveguide beam splitter → fiber optic ring → Y-waveguide beam combiner → coupler → detector.

[0049] Multiport spectral measurements are performed on the coupler. Specifically, a light source is connected to the input of the coupler, and the spectrum is measured at each output port. By normalizing and comparing the output spectrum with the input spectrum, the spectral transmittance function of the coupler is calculated. The spectral transmittance function of the coupler characterizes its dispersive ratio characteristics at different wavelengths and its wavelength dependence. A high-quality coupler should have a flat spectral transmittance characteristic. If the transmittance function exhibits obvious wavelength selectivity or periodic fluctuations, it indicates that the coupler itself has spectral distortion, which will change the shape of the spectrum after passing through the device.

[0050] In some embodiments, during the optical path transmission process, since the coupler transmits light in both forward and reverse directions, the process of measuring the spectral transmission function of the coupler in this invention includes measuring the spectral transmission functions of the forward and reverse couplers.

[0051] Multiport spectral measurements were performed on a Y-waveguide. The Y-waveguide has one input port and two output ports. Light is split and phase-modulated within the Y-waveguide before being output. A light source was coupled to the input port of the Y-waveguide, and the spectra at the two output ports were measured. The spectral transmission function of the Y-waveguide was then calculated using normalization. As a core component of a fiber optic gyroscope, the spectral transmission function of the Y-waveguide reflects information such as the device's beam-splitting characteristics.

[0052] Through the above measurements, this step yields three sets of key data: the power spectral density function of the light source, the spectral transmission function of the coupler, and the spectral transmission function of the Y-waveguide. These functions characterize the spectral variations of the optical signal during transmission through each device and are used to construct the full optical path spectrum in subsequent steps.

[0053] In some embodiments, during the optical path transmission process, since the Y-waveguide transmits light in both forward and reverse directions, the process of measuring the Y-waveguide spectral transmission function of the present invention includes measuring the forward and reverse Y-waveguide spectral transmission functions.

[0054] Step S2: Scan the fiber loop of the fiber optic gyroscope using an optical coherence polarimeter to obtain the polarization coupling intensity distribution curve; determine the optical path difference and amplitude intensity ratio of multiple characteristic coupling points of the polarization coupling intensity distribution curve;

[0055] This step utilizes an optical coherence domain polarimeter (OCDP) to perform a high-resolution distributed scan of the fiber optic sensitive ring of the fiber optic gyroscope to obtain information on the location and intensity of polarization coupling defects inside the fiber optic ring, thereby extracting the microscopic perturbation parameters that cause spectral errors.

[0056] Specifically, the test light from the OCDP is coupled into the fiber optic loop. The OCDP uses coherent detection technology to scan the polarization coupling points distributed along the fiber length. The working principle of the OCDP is based on the coherent superposition of polarization states. When polarization coupling points exist in the fiber, polarization crosstalk is generated, causing some optical power to couple from the dominant polarization state to the orthogonal polarization state, forming a polarization coupling peak.

[0057] By scanning the polarization coupling points, a complete polarization coupling intensity distribution curve is obtained. The horizontal axis of this curve represents the optical path difference, and the vertical axis represents the amplitude-to-intensity ratio. Figure 3 As shown.

[0058] In the obtained polarization coupling intensity distribution curve, a preset threshold is set to filter out multiple polarization coupling peaks that exceed the threshold.

[0059] In some embodiments, the preset threshold can be determined according to the accuracy requirements of the fiber optic gyroscope, preferably -50dB to -80dB.

[0060] These polarization coupling peaks correspond to the physical defect locations in the fiber optic ring, including: fusion splices, interlayer crossovers, layer-switching points, and coupling points between the fiber optic ring and the Y-waveguide, among other characteristic coupling points.

[0061] For each polarization coupling peak identified, two key parameters, optical path difference and amplitude intensity ratio, are extracted from the polarization coupling intensity distribution curve.

[0062] Step S3: Multiply the power spectral density function of the fiber optic gyroscope source, the spectral transmission function of the coupler and the Y waveguide in sequence to obtain the ideal normalized main spectrum.

[0063] The full optical path spectrum of the fiber optic gyroscope is obtained based on the ideal normalized main spectrum and the optical path difference and amplitude intensity ratio of multiple characteristic coupling points.

[0064] In this step, a spectral error transmission model based on broadband light source coherence is established to fuse the device-level spectral characteristics with the micro-polarization coupling parameters, thereby achieving a quantitative mapping from micro-physical defects to macro-spectral distortion.

[0065] First, an ideal main spectrum is constructed according to the actual optical path configuration and light transmission sequence of the fiber optic gyroscope. The optical path transmission sequence of the fiber optic gyroscope of this invention is: broadband light source → coupler → Y-waveguide input → Y-waveguide beam splitter → fiber loop → Y-waveguide beam combiner → coupler → detector. Based on the above light transmission sequence, the spectral functions of each device measured in step S1 are multiplied sequentially to calculate the ideal normalized main spectrum reaching the detector.

[0066] The formula for calculating the ideal normalized main spectrum is:

[0067]

[0068] in, This represents the ideal normalized main spectrum. This indicates normalized calculation. , , , , These represent the power spectral density function of the fiber optic gyroscope source, the spectral transmission functions of the forward and reverse couplers, and the spectral transmission functions of the forward and reverse Y-waveguides, respectively.

[0069] The normalization operation divides the power spectrum by its integral over the entire frequency range, resulting in a normalized spectrum with an integral value of 1. The square term of the Y-waveguide transmission function in the formula reflects the process of light undergoing two propagations (forward beam splitting and reverse beam combining) within the Y-waveguide. The resulting ideal normalized main spectrum... This represents the spectral shape of the optical path output of a fiber optic gyroscope under ideal conditions of no polarization crosstalk and no parasitic interference.

[0070] Based on this, this invention establishes a spectral error transmission model for the superposition of multiple amplitude-type error beams to obtain the full optical path spectrum of a fiber optic gyroscope. In practical fiber optic gyroscopes, due to the existence of multiple characteristic coupling points in the fiber optic loop, amplitude-type parasitic beams are generated at each coupling point during the transmission of the main beam. These parasitic beams have time delays and amplitude differences with the main beam, and when they reach the detector, they coherently superimpose with the main beam, producing parasitic interference. According to the theory of optical wave superposition and the Fourier optics principle, when the main beam is superimposed with n amplitude-type error beams, the normalized power spectral density of the output can be expressed as a superposition form containing multiple cosine modulation terms.

[0071] Based on the low coherence characteristics of broadband light sources, and under the approximate condition that the amplitude intensity ratio between each parasitic light is much smaller than the given value, the second-order cross-interference term between parasitic lights can be ignored, simplifying the fiber optic gyroscope's full-path spectral error model to the following expression:

[0072]

[0073] in, Indicates the entire optical path spectrum. Indicates spectral frequency, This represents the amplitude intensity ratio corresponding to the i-th coupling point. This represents the optical path difference corresponding to the i-th coupling point. This represents the phase constant corresponding to the i-th coupling point. This represents the total number of characteristic coupling points.

[0074] The above expression indicates that each characteristic coupling point will superimpose a periodic modulation in the form of a raised cosine on the ideal main spectrum, i.e., a spectral ripple. The frequency characteristics of the ripple are determined by the optical path difference at the coupling points. The amplitude characteristics of the ripple are determined by the amplitude-to-intensity ratio. The decision is made. Specifically, the free spectral range (FSR) of the spectral ripple generated at the i-th coupling point is... That is, it exhibits a period of on the spectral curve. Oscillations. Large optical path difference. A smaller FSR corresponds to a denser fine ripple wave; a larger amplitude ratio A larger ripple amplitude corresponds to more significant spectral fluctuations.

[0075] The presence of ripples can guide the actual coupling design. If significant ripple interference occurs during actual testing, it can be determined that there are coupling problems such as misalignment of the angular coupling part of the polarization-maintaining optical path.

[0076] The full-path spectrum of the fiber optic gyroscope can be obtained by calculating the ideal normalized main spectrum obtained in the preceding steps, as well as the optical path difference and amplitude intensity ratio at multiple characteristic coupling points, using the above expressions. The full-path spectrum curve can represent the spectral evolution process and error accumulation effect along the entire optical path from the light source to the detector.

[0077] Figure 4 The full optical path spectrum obtained by this invention is shown.

[0078] Step S4: Analyze the full optical path spectrum to obtain the location and error intensity of physical defects in the full optical path of the fiber optic gyroscope.

[0079] In this step, the physical defects of the fiber optic gyroscope are accurately located and the error intensity is quantitatively assessed based on the full optical path spectrum, ultimately providing specific guidance for the optical path optimization of the fiber optic gyroscope.

[0080] Specifically, autocorrelation analysis is performed on the entire optical path spectrum, for example, by using Fourier transform to obtain the corresponding autocorrelation function.

[0081] The independent variable of the autocorrelation function is mapped to the actual optical path difference in the fiber optic gyroscope path, thus obtaining the autocorrelation function-optical path difference curve. Based on the positions of multiple secondary peaks other than the zero-delay main peak in the autocorrelation function-optical path difference curve, the polarization cross-coupling point, fusion splice point, and pigtail connection point are located, including:

[0082] The location of the physical defect is determined based on the optical path difference corresponding to the secondary peak, including: determining whether the optical path difference interval between multiple secondary peaks is equally spaced; if not equally spaced, then determining whether the secondary peak is the fusion splice point of the fiber optic ring, the coupling point of the fiber optic ring, or the coupling point of the Y-waveguide.

[0083] If the distribution is evenly spaced, the secondary peaks are determined to be the crossover points between fiber ring layers or the locations where fiber ring layers are replaced.

[0084] After determining the defect location, the phase error caused by the defect is calculated based on the coherence relationship between the parasitic wave and the main signal wave, and the corresponding zero-bias error is further obtained, expressed as:

[0085]

[0086]

[0087] in, For parasitic wave intensity, Main signal wave intensity, The optical path difference corresponding to the j-th defect position The autocorrelation function value at that location, For phase error, At the speed of light, This refers to the operating wavelength of the fiber optic gyroscope's optical path. This is the total length of the fiber optic ring. The diameter of the fiber optic ring. It has zero bias error.

[0088] Furthermore, to assess the impact of spectral drift on the gyroscope scaling factor, the power-weighted average wavelength of the spectrum is calculated, and the relative error of the scaling factor is determined based on the change in this average wavelength, expressed as:

[0089]

[0090]

[0091] in, This represents the power-weighted average wavelength. Indicates the operating wavelength of the fiber optic gyroscope optical path. The power distribution is the independent variable. Indicates the relative error of the scaling factor. This represents the change in wavelength of the power-weighted average.

[0092] Through the above processing, the location of physical defects inside the fiber optic gyroscope can be identified, and the coherence error, zero bias error, and scaling factor error caused by the defects can be quantitatively evaluated.

[0093] As described above, by analyzing and processing each characteristic coupling point, the physical defect location and error intensity of the entire optical path can be obtained.

[0094] The following is a detailed description of the fiber optic gyroscope optical path spectral error analysis method based on the fusion of OSA and OCDP according to a specific embodiment of the present invention.

[0095] Taking a certain type of fiber optic gyroscope as an example, the specific application of the method of the present invention is illustrated. This fiber optic gyroscope uses an ASE broadband light source with a center wavelength of 1310nm and a 3dB spectral width of 45nm. The fiber loop length is 500 meters, and it is wound with polarization-maintaining fiber.

[0096] S1: The power spectral density function of the light source was measured using a spectrometer. The center wavelength was found to be 1310.5 nm, the spectral width to be 45.2 nm, and the spectral shape to be close to a Gaussian distribution. The spectral transmission functions of the coupler and the Y-waveguide were measured separately.

[0097] S2: Using OCDP to scan the fiber optic loop, with a threshold of -70dB, 12 significant characteristic coupling points were identified, including 2 Y-waveguide coupling interfaces, 2 fiber fusion splices, and 8 interlayer crossover points. The strongest coupling point was found to have an optical path difference of 800mm and an amplitude intensity ratio of -65dB.

[0098] S3: Construct a model according to the light transmission sequence, and multiply the power spectrum of the light source, the transmission function of the coupler, and the Y-waveguide to obtain the ideal main spectrum. Substitute the parameters of the 12 characteristic coupling points into the spectral error transmission model to calculate the full optical path spectrum.

[0099] S4: Analysis of the entire optical path spectrum confirmed the detection of a frequency of 1.9595*. Dense ripples at Hz. Through mapping, the origin of these ripples was identified as strong coupling points at a distance from the Y-wave inlet, and the corresponding physical defect locations and error intensities were obtained.

[0100] While the specific embodiments of the present invention depict actions or steps in a particular order, this should be understood as requiring such actions or steps to be performed in the specific order shown or in sequential order, or requiring all illustrated actions or steps to be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0101] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for analyzing the optical path spectral error of a fiber optic gyroscope based on the fusion of OSA and OCDP, characterized in that, Includes the following steps: Step S1: Measure the power spectral density function of the fiber optic gyroscope source using a spectrometer, and measure the spectral transmission function of the coupler and the Y-waveguide respectively. Step S2: Scan the fiber loop of the fiber optic gyroscope using an optical coherence polarimeter to obtain the polarization coupling intensity distribution curve; determine the optical path difference and amplitude intensity ratio of multiple characteristic coupling points of the polarization coupling intensity distribution curve; Step S3: Multiply the power spectral density function of the fiber optic gyroscope source, the spectral transmission function of the coupler and the Y-waveguide sequentially to obtain the ideal normalized main spectrum. ; The full optical path spectrum of the fiber optic gyroscope is obtained based on the ideal normalized main spectrum and the optical path difference and amplitude intensity ratio of multiple characteristic coupling points. A full-path spectral error model for the fiber optic gyroscope is established. This model derives the full-path spectrum based on the ideal normalized main spectrum and the optical path difference and amplitude intensity ratio at multiple characteristic coupling points. The expression is as follows: in, Indicates the entire optical path spectrum. Indicates spectral frequency, This represents the amplitude intensity ratio corresponding to the i-th characteristic coupling point. This represents the optical path difference corresponding to the i-th feature coupling point. This represents the phase constant corresponding to the i-th characteristic coupling point. Indicates the total number of characteristic coupling points; Step S4: Analyze the full optical path spectrum to obtain the location and error intensity of physical defects in the full optical path of the fiber optic gyroscope.

2. The fiber optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion according to claim 1, characterized in that, In step S2, the method for determining the optical path difference and amplitude intensity ratio of multiple characteristic coupling points of the polarization coupling intensity distribution curve specifically includes: A preset threshold is used to filter out multiple polarization coupling peaks whose amplitude intensity ratio exceeds the preset threshold from the obtained polarization coupling intensity distribution curve; For each polarization coupling peak, the optical path difference and amplitude intensity ratio are extracted from the polarization coupling intensity distribution curve.

3. The fiber optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion according to claim 2, characterized in that, The preset threshold value ranges from -50dB to -80dB.

4. The fiber optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion according to claim 3, characterized in that, In step S3, the expression for the ideal normalized main spectrum is: in, This represents the ideal normalized main spectrum. This indicates normalized calculation. , , , , These represent the power spectral density function of the fiber optic gyroscope source, the spectral transmission functions of the forward and reverse couplers, and the spectral transmission functions of the forward and reverse Y-waveguides, respectively.

5. The fiber optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion according to claim 4, characterized in that, Step S4 specifically includes: Step S4-1: Obtain the autocorrelation function-optical path difference curve of the full optical path spectrum based on the Fourier transform of the full optical path spectrum. Locate the polarization cross-coupling point, fusion splice point, and pigtail connection point based on the positions of multiple secondary peaks other than the zero-delay main peak in the autocorrelation function-optical path difference curve. This includes: The location of the physical defect is determined based on the optical path difference corresponding to the secondary peak, including: determining whether the optical path difference interval between multiple secondary peaks is equally spaced; if not equally spaced, then determining whether the secondary peak is the fusion splice point of the fiber optic ring, the coupling point of the fiber optic ring, or the coupling point of the Y-waveguide. If the distribution is evenly spaced, then the secondary peak is determined to be the crossover point between fiber ring layers or the fiber ring layer replacement location. Step S4-2: Determine the phase error, zero bias error, and relative error of the scaling factor based on the intensity of the parasitic wave at the physical defect location, the intensity of the main signal wave, and the optical path difference.

6. The fiber optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion according to claim 5, characterized in that, In step S4-2, the expressions for phase error, zero bias error, and relative scaling factor error are: in, For parasitic wave intensity, Main signal wave intensity, The optical path difference corresponding to the j-th defect position The autocorrelation function value at that location, For phase error, At the speed of light, This refers to the operating wavelength of the fiber optic gyroscope's optical path. This is the total length of the fiber optic ring. The diameter of the fiber optic ring. Zero bias error This represents the power-weighted average wavelength. Indicates the operating wavelength of the fiber optic gyroscope optical path. The power distribution is the independent variable. Indicates the relative error of the scaling factor. This represents the change in wavelength of the power-weighted average.

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