A demodulation method for a resonant optical gyroscope based on a wide-spectrum light source

Abstract

The present invention belongs to the technical field of resonant optical gyroscopes and discloses a demodulation method for a resonant optical gyroscope based on a wide-spectrum light source. The method comprises: respectively eliciting resonant light in a CW direction and a CCW direction through an optical circulator; respectively performing optical demodulation through respective optical demodulation modules to form white light interference fringes; using a photoelectric conversion device in the optical demodulation module to convert the white light interference fringes in the CW direction and the CCW direction into electrical signals; performing algorithmic demodulation on the white light interference fringe signals in the CW direction and the CCW direction by a data processing unit to demodulate the relative changes in the positions of the respective white light interference peaks; and subtracting the changes in the positions of the respective white light interference peaks in the CW direction and the CCW direction to obtain information on the rotation speed and rotation direction of the gyroscope. The method can effectively eliminate the influence of light intensity fluctuation on demodulation, eliminate errors introduced by closed-loop control, and theoretically meet the requirements of high-precision and wide dynamic range gyroscope rotation speed detection.

Description

Technical Field

[0001] The present invention belongs to the field of resonant optical gyroscopes, and in particular relates to a demodulation method of a resonant optical gyroscope based on a wide-spectrum light source. Background Art

[0002] Resonant optical gyroscopes, such as those based on fiber rings and resonant micro-optical gyroscopes based on silicon optical cavities, are high-precision inertial angular velocity sensors based on the Sagnac effect. They combine the advantages of laser gyroscopes and interferometric fiber gyroscopes, improving detection sensitivity by employing the optical resonance principle and enhancing the Sagnac effect by increasing the number of loops. They offer advantages such as high precision, compact size, and all-solid-state performance, making them a key development direction in optical gyroscope technology. In recent years, resonant optical gyroscopes based on broadband light sources have become a hot topic of research in this field. To demodulate resonant optical gyroscopes based on broadband light sources, researchers currently generally use intensity demodulation, a method that is simple, direct, and fast to respond. However, intensity noise and optical power fluctuations in the intensity demodulation system can lead to inaccurate demodulation results. Furthermore, due to the spectral width of the interference fringes, the detection dynamic range is limited, resulting in low detection accuracy and a narrow dynamic range.

[0003] In order to improve the detection dynamic range of resonant optical gyroscopes based on wide-spectrum light sources, in March 2022, Shuangxiang Zhao et al. proposed a closed-loop detection scheme based on acousto-optic frequency shifters in the article "White-lignt-driven resonant fiber-optic gyro based on round trip filtering scheme" published in the journal Optics Letters. This scheme can improve the detection dynamic range of resonant optical gyroscopes based on wide-spectrum light sources, but the detection accuracy is low. Summary of the Invention

[0004] The purpose of the present invention is to address the problems in the background technology and propose a demodulation method for a resonant optical gyroscope based on a wide-spectrum light source. The method improves the speed detection accuracy and detection dynamic range of the resonant optical gyroscope based on a wide-spectrum light source, and solves the problems of low detection accuracy and small detection dynamic range of the existing resonant optical gyroscope based on a wide-spectrum light source.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions to achieve it.

[0006] A demodulation method for a resonant optical gyroscope based on a wide-spectrum light source, the method comprising:

[0007] Step 1: For a resonant optical gyroscope based on a wide-spectrum light source, resonant light in the CW direction and CCW direction is respectively induced through an optical circulator; the CW direction is a clockwise direction, and the CCW direction is a counterclockwise direction;

[0008] Step 2: The resonant light in the CW direction and CCW direction is optically demodulated by respective optical demodulation modules, and the optical demodulation forms white light interference fringes;

[0009] Step 3: Use the photoelectric conversion device in the optical demodulation module to convert the white light interference fringes in the CW direction and CCW direction into electrical signals, and collect them into the data processing unit through the signal acquisition system;

[0010] Step 4: The data processing unit performs algorithmic demodulation on the white light interference fringe signals in the CW and CCW directions to obtain the relative changes in the positions of the respective white light interference peaks; the difference between the changes in the positions of the respective white light interference peaks in the CW and CCW directions is calculated to obtain the speed and rotation direction information of the gyroscope.

[0011] The characteristics and further improvements of the technical solution of the present invention are:

[0012] (1) In step 1, a circulator is used on the optical path in the CW direction and the CCW direction to extract the resonant light in the CW direction and the CCW direction respectively.

[0013] (2) In step 2, the optical demodulation module includes: a point light source 6, a collimating lens 7, a polarizing plate 8, an optical wedge 9, an analyzing polarizing plate 10, and a linear array CCD 11 arranged in sequence.

[0014] (3) In step 2, the Sagnac effect is optically demodulated using an optical demodulation module;

[0015] The optical demodulation method includes: a resonant light signal emitted by a circulator is used as a point light source 6; the light signal is collimated by a collimating lens 7 to converge the incident light into a long linear shape to increase the illumination; the collimated light is polarized by a polarizer 8, with the polarization direction being 45 degrees to the optical axis direction of a rear-end birefringent wedge 9; the polarized light signal is incident on the wedge 9 and is divided into e-light and o-light; the e-light and o-light generate an optical path difference in the wedge 9, and then the vibration direction of the light signal is projected into the same direction by a polarizer 10; the polarization direction of the polarizer 10 is consistent with the polarization direction of the front-end polarizer 8; the light signal passing through the polarizer 10 generates self-coherent interference of the e-light and o-light on a CCD 11, generating white light interference fringes.

[0016] (4) In step 3: the white light interference fringes in the CW and CCW directions are converted into electrical signals through the linear array CCD.

[0017] (5) In step 4, the data processing unit performs an algorithmic demodulation method on the white light interference fringe signals in the CW direction and the CCW direction, demodulates the relative changes in the positions of the respective white light interference peaks, compares the changes in the positions of the respective white light interference peaks in the CW direction and the CCW direction, and obtains the speed and rotation direction information of the gyroscope.

[0018] (6) In step 4, the least squares fitting algorithm is used to demodulate the white light interference peak position x cw 、x ccw , the least squares fitting formula is as follows:

[0019] y=ba(xx cw ) 2 (1)

[0020] Among them, y is the light intensity signal, x is the pixel coordinate of the linear array CCD, and x cw is the coordinate of the peak point in the CW direction, b and a are coefficients related to light intensity and have no effect on the demodulation of the white light interference peak position.

[0021] (7) In step 4, the difference between the peak position changes of the white light interference in the CW direction and the CCW direction is calculated as shown in formula (2) to obtain the speed and rotation direction information of the gyroscope.

[0022] ΔΩ=k·(x cw -x ccw ) (2)

[0023] Among them, ΔΩ is the rotation speed information of the gyroscope, x cw 、x ccw is the demodulated white light interference peak position in the CW and CCW directions, and k is the scale factor.

[0024] This invention addresses the low demodulation accuracy and narrow dynamic range of existing resonant optical gyroscopes based on broad-spectrum light sources. By proposing a high-precision, large-dynamic-range demodulation method for resonant optical gyroscopes based on broad-spectrum light sources, the method employs spatial optical demodulation to separately demodulate the clockwise and counterclockwise resonant optical frequency variations. By comparing the optical frequency variations in these two directions, the gyroscope's rotational speed and direction of rotation are determined. This method significantly improves the demodulation accuracy and dynamic detection range of resonant optical gyroscopes based on broad-spectrum light sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a demodulation method for a resonant optical gyroscope based on a wide-spectrum light source;

[0026] Figure 2 A schematic diagram illustrating the optical demodulation method;

[0027] Figure 3Schematic diagram of demodulation algorithm;

[0028] Explanation of the accompanying symbols: 1 is a CW optical circulator; 2 is a CCW optical circulator; 3 is an optical demodulation system; 4 is a signal acquisition unit; 5 is a data processing unit; 6 is a point light source; 7 is a collimating lens; 8 is a polarizer; 9 is an optical wedge; 10 is an analyzer polarizer; 11 is a linear array CCD; 12 is a CW white light interference fringe; 13 is a CW fitting curve; 14 is a CCW white light interference fringe; 15 is a CCW fitting curve; 16 is a phase position difference. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] This embodiment provides a demodulation method for a resonant optical gyroscope based on a wide-spectrum light source. Resonant light in the clockwise (CW) and counterclockwise (CCW) directions is respectively extracted through an optical circulator. The extracted resonant light is optically demodulated by respective optical demodulation modules. The optical demodulation forms white light interference fringes. A linear array CCD is used to convert the white light interference fringes into electrical signals. The white light interference fringe electrical signals are collected and input into a data processing unit. The gyroscope's speed and rotation direction information is demodulated using an algorithm.

[0032] For ease of explanation, the attached Figure 1 As shown, the broadband light generated by the broadband light source is incident on the optical resonant cavity through the Y waveguide and the coupler, generating resonant light in the clockwise (CW) and counterclockwise (CCW) directions. The resonant light in the clockwise and counterclockwise directions is respectively extracted through the optical circulator 1 and the optical circulator 2, and optically demodulated by the optical demodulation system 3 involved in the present invention. After optical demodulation, white light interference fringes are formed, and the white light interference fringes are converted into electrical signals by a photoelectric conversion device. The white light interference fringes electrical signals are collected by the signal acquisition unit 4 and input into the data processing unit 5. The speed and rotation direction information of the gyroscope are demodulated by the algorithm.

[0033] For ease of explanation, the attached Figure 1 As shown, the light emitted by the optical circulator 1 and the optical circulator 2 is optically demodulated 3 respectively, and the speed and rotation direction information of the gyroscope are demodulated through the signal acquisition unit 4 and the data processing unit 5 through an algorithm.

[0034] Optical demodulation principle, as shown in the attached Figure 2As shown, the resonant light signal emitted by the circulator is a point light source 6. The light signal is collimated by a collimating lens 7, and the incident light is focused into a long line to improve the illumination. The collimated light passes through a polarizer 8 for polarization, and the polarization direction is 45 degrees to the optical axis direction of the rear end birefringent wedge 9. The polarized light signal is incident on the wedge 9 and is divided into e-light and o-light. After the e-light and o-light generate an optical path difference in the wedge 9, the vibration direction of the light signal is projected to the same direction by the polarizer 10. The polarization direction of the polarizer 10 is consistent with the polarization direction of the front end polarizer 8. The light signal passing through the polarizer 10 generates self-coherent interference fringes of the e-light and o-light. A photoelectric conversion device such as a linear array CCD 11 is used to convert the interference fringes into electrical signals. By detecting the relative movement of the peak point of the interference fringes on the linear array CCD, the change in the center frequency of the resonant light caused by the optical Sagnac effect during rotation can be detected.

[0035] Example 2

[0036] This embodiment further illustrates the present invention with respect to specific implementation methods:

[0037] This embodiment further illustrates the specific implementation process of the data processing unit. Figure 1 As shown in Figure 5, the linear array CCDs in the CW and CCW directions convert their respective white light interference fringes into electrical signals, which are then collected into the data processing unit through the acquisition unit. The data processing unit performs an algorithmic demodulation method on the white light interference fringe signals in the CW and CCW directions, demodulates the relative changes in the positions of the respective white light interference peaks, compares the changes in the positions of the respective white light interference peaks in the CW and CCW directions, and obtains the speed and rotation direction information of the gyroscope.

[0038] Specifically, the specific implementation of this embodiment has the following steps:

[0039] Step 1: As attached Figure 3 As shown, the white light interference fringes 12 collected by the CW direction linear array CCD and the white light interference fringes 14 collected by the CCW direction linear array CCD are fitted by least squares, and a CW direction fitting curve 13 and a CCW direction fitting curve 15 are obtained after fitting respectively;

[0040] Step 2: Detune the peak position x of the fitting curves by using CCW direction fitting curve 13 and CCW direction fitting curve 15. cw 、x ccw , the least squares fitting formula is as follows:

[0041] y=ba(xx cw ) 2 (1)

[0042] Among them, y is the light intensity signal P, x is the pixel coordinate of the linear array CCD, and xcw is the coordinate of the peak point in the CW direction, b and a are coefficients related to light intensity and have no effect on the demodulation of the white light interference peak position.

[0043] Step 3: Fit the peak position x of the CW direction fitting curve 13 and the CCW direction fitting curve 15 to cw 、x ccw The difference is calculated to obtain the phase position difference 16, thereby obtaining the speed and rotation direction information of the gyroscope as shown in formula (2).

[0044] ΔΩ=k·(x cw -x ccw ) (2)

[0045] Among them, ΔΩ is the rotation speed information of the gyroscope, x cw 、x ccw is the peak position of the demodulated CW direction fitting curve 13 and the CCW direction fitting curve 15, and k is the scale factor.

[0046] This invention addresses the low demodulation accuracy and narrow dynamic range of existing resonant optical gyroscopes based on broad-spectrum light sources. By proposing a high-precision, large-dynamic-range demodulation method for resonant optical gyroscopes based on broad-spectrum light sources, the method employs spatial optical demodulation to separately demodulate the clockwise and counterclockwise resonant optical frequency variations. By comparing the optical frequency variations in these two directions, the gyroscope's rotational speed and direction of rotation are determined. This method significantly improves the demodulation accuracy and dynamic detection range of resonant optical gyroscopes based on broad-spectrum light sources.

Claims

1. A demodulation method for a resonant optical gyroscope based on a wide-spectrum light source, characterized in that: The method comprises: Step 1: For a resonant optical gyroscope based on a wide-spectrum light source, resonant light in the CW direction and CCW direction is respectively induced through an optical circulator; the CW direction is a clockwise direction, and the CCW direction is a counterclockwise direction; Step 2: The resonant light in the CW direction and CCW direction is optically demodulated by respective optical demodulation modules, and the optical demodulation forms white light interference fringes; In step 2, the optical demodulation module includes: a point light source (6), a collimating lens (7), a polarizing plate (8), an optical wedge (9), an analyzer polarizer (10), and a linear array CCD (11) arranged in sequence; In step 2, the Sagnac effect is optically demodulated using an optical demodulation module; The optical demodulation method includes: the resonant light signal emitted by the circulator is a point light source (6), the light signal is collimated by a collimating lens (7), the incident light is converged into a long line to improve the illumination, the collimated light passes through a polarizing plate (8) to be polarized, the polarization direction is 45 degrees to the optical axis direction of the rear end birefringent wedge (9), the polarized light signal is incident on the wedge (9) to be divided into e light and o light, the e light and o light generate an optical path difference in the wedge (9), and then the vibration direction of the light signal is projected to the same direction through the polarizing plate (10), the polarization direction of the polarizing plate (10) is consistent with the polarization direction of the front end polarizing plate (8), the light signal passing through the polarizing plate (10) generates self-coherent interference of the e light and the o light on the CCD11, and generates white light interference fringes; Step 3: Use the photoelectric conversion device in the optical demodulation module to convert the white light interference fringes in the CW direction and CCW direction into electrical signals, and collect them into the data processing unit through the signal acquisition system; Step 4: The data processing unit performs algorithmic demodulation on the white light interference fringe signals in the CW and CCW directions to obtain the relative changes in the positions of the respective white light interference peaks; the difference between the changes in the positions of the respective white light interference peaks in the CW and CCW directions is calculated to obtain the speed and rotation direction information of the gyroscope.

2. The demodulation method of a resonant optical gyroscope based on a wide-spectrum light source according to claim 1, characterized in that: In step 1, a circulator is used on the optical paths in the CW and CCW directions to extract the resonant light in the CW and CCW directions respectively.

3. The demodulation method of a resonant optical gyroscope based on a wide-spectrum light source according to claim 1, characterized in that: In step 3: the white light interference fringes in the CW and CCW directions are converted into electrical signals by the linear array CCD.

4. The demodulation method of a resonant optical gyroscope based on a wide-spectrum light source according to claim 1, characterized in that: In step 4, the least squares fitting algorithm is used to demodulate the peak positions of the white light interference 、 , the least squares fitting formula is as follows (1) （1） Where y is the light intensity signal, is the pixel coordinate of the linear array CCD, is the coordinate of the peak point in the CW direction, 、 It is a coefficient related to light intensity and has no effect on the demodulation of the white light interference peak position.

5. The demodulation method of a resonant optical gyroscope based on a wide-spectrum light source according to claim 4, characterized in that: In step 4, the difference between the peak position changes of the white light interference in the CW direction and the CCW direction is calculated as shown in formula (2) to obtain the speed and rotation direction information of the gyroscope; （2） in, is the gyroscope's rotation speed information, 、 is the peak position of the demodulated white light interference in the CW and CCW directions, is the scale factor.

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