Method and system for controlling lockout interval of passive laser gyroscope

Abstract

The invention discloses a passive laser gyroscope lockout interval control method and a passive laser gyroscope lockout interval control system, and relates to the field of laser gyroscopes, and the passive laser gyroscope lockout interval control method comprises the following steps: measuring lockout intervals in different states by adjusting the light intensity ratio of two beams of incident laser of a passive laser gyroscope; drawing a locking interval curve changing along with the light intensity ratio, performing nonlinear fitting through an expression of a locking threshold value, and obtaining locking intervals corresponding to different light intensity ratios from the fitted curve; and the light intensity proportion of the corresponding incident laser is adjusted to reduce the locking interval. According to the invention, the locking interval can be reduced without introducing additional devices or additional technologies to the passive laser gyroscope, and the rotation angular velocity measurement range of the passive laser gyroscope is enlarged.

Description

Technical Field

[0001] The present invention relates to the field of laser gyroscopes, and particularly to a method and system for controlling the lock-in range of a passive laser gyroscope. Background Art

[0002] As a rotational angular velocity measurement sensor, the laser gyroscope is widely used in the fields of inertial navigation, geodesy, rotational seismology, etc. due to its high rotational speed resolution, good stability, wide dynamic range, etc. The main difference between a passive laser gyroscope and an active laser gyroscope is that the passive laser gyroscope uses an external laser to inject laser light into a ring cavity and uses a laser frequency stabilization system to achieve operation. However, the passive laser gyroscope has a lock-in effect introduced by backscattering.

[0003] In the prior art, the article “Observation of lock-in behavior in a passive resonator gyroscope” published in Optics Letters, Vol. 11, p. 401 in 1986 disclosed a method of phase modulating the incident laser so that the frequency of the backscattered signal is much larger than the laser frequency locking bandwidth, thereby avoiding the lock-in effect in the passive laser gyroscope. However, this method has great limitations. It is necessary to ensure that the phase modulation sideband can enter the ring cavity and that the modulation frequency is larger than the locking bandwidth, which is not conducive to the development of high rotation sensitivity and high stability of passive laser gyroscopes. The article “Passive, free-space heterodyne laser gyroscope” published in Classical and Quantum Gravity, Vol. 33, p. 035004 in 2016 disclosed a passive laser gyroscope based on differential mode operation. By locking two lasers with opposite propagation directions to two adjacent longitudinal modes of the ring cavity, that is, differential mode operation, the backscattered signal is converted into a high-frequency signal, which also exceeds the locking bandwidth and avoids the lock-in of the gyroscope. However, this method cannot directly obtain the Sagnac frequency signal, so that the beat frequency detection signal of the gyroscope includes the signal of the free spectrum range, which increases the cavity length drift noise. Patent CN115406429A discloses a passive laser gyroscope based on three-loop differential locking. On the basis of differential mode locking, a laser beam is added for locking to realize real-time detection of the free spectrum range, and the free spectrum range signal in the beat frequency signal is subtracted to obtain the Sagnac frequency. However, this method increases the complexity of the entire gyroscope system, and there is a subtraction residual. Similarly, patent document CN111780738A discloses a passive laser gyroscope based on phase-sensitive heterodyne measurement, which is also achieved through differential mode locking of three incident laser beams. The electrical signal obtained by the beat frequency measurement is self-demodulated by the extraction device to obtain the Sagnac signal. This method also increases the complexity of the system, adding a locking system and a more complex signal extraction device than the traditional measurement scheme.

[0004] In summary, how to reduce the lockout interval without increasing the complexity of the laser gyroscope system is an important issue that needs to be solved urgently. Summary of the invention

[0005] The embodiment of the present invention provides a control method and system for a passive laser gyroscope lockout interval, which can solve the problem in the prior art that the lockout interval cannot be reduced.

[0006] An embodiment of the present invention provides a method for controlling a locking interval of a passive laser gyroscope, comprising the following steps: When the passive laser gyroscope operates in the common mode, the intensity of one incident laser beam remains unchanged while the intensity of the other incident laser beam is changed, and the intensity ratio of the two incident laser beams is obtained; A linearly varying bias voltage is added to the error signal generated by the passive laser gyroscope, and the range of the bias voltage when the passive laser gyroscope locks is recorded; according to the ratio of the range of the bias voltage to the discriminant frequency slope affected by the error signal, the locking frequency threshold is obtained; According to the fitting formula, the variation curves of multiple intensity ratios and multiple locking frequency thresholds are fitted; wherein, the fitting formula is: ; represents the locking frequency threshold as the dependent variable, represents the intensity ratio as the independent variable, , are fitting parameters; The minimum value of the locking frequency threshold is obtained from the variation curve , and the intensity ratio corresponding to the minimum value ; The intensity ratio of the two incident laser beams is adjusted to , so that the influence of the locking interval of the passive laser gyroscope on the minimum value is reduced to ± .

[0007] Further, the adding of the linearly varying bias voltage specifically includes the following steps: Determine whether the intensity of the changed incident laser belongs to the clockwise optical path or the counterclockwise optical path; Add a linearly varying bias voltage to the locking loop of the determined optical path.

[0008] Further, the adding of the linearly varying bias voltage to the error signal generated by the passive laser gyroscope specifically includes the following steps: Use an external signal generator to generate a linearly varying voltage signal; Input the linearly varying voltage signal into the error signal of the locking system of the passive laser gyroscope, so that the linearly varying voltage signal is superimposed on the original error signal.

[0009] Further, the variation range of the intensity ratio of the two incident laser beams is from 0.1 to 10.

[0010] An embodiment of the present invention provides a control system for the locking interval of a passive laser gyroscope, including: An intensity ratio acquisition module, configured to, when the passive laser gyroscope operates in the common mode, keep the intensity of one incident laser beam unchanged and change the intensity of the other incident laser beam, and acquire the intensity ratio of the two incident laser beams; A locking frequency threshold acquisition module, configured to add a linearly varying bias voltage to the error signal generated by a passive ring laser gyroscope, and record the range of the bias voltage when the passive ring laser gyroscope locks; obtain the locking frequency threshold according to the ratio of the range of the bias voltage to the frequency discrimination slope affected by the error signal; A variation curve fitting module, configured to fit the variation curves of multiple light intensity ratios and multiple locking frequency thresholds according to a fitting formula; A locking interval control module, configured to obtain the minimum value of the locking frequency threshold in the variation curve , and the minimum value corresponding light intensity ratio ; adjust the light intensity ratio of the two incident laser beams to , so that the influence of the locking interval of the passive ring laser gyroscope on the minimum value is reduced to ± .

[0011] An embodiment of the present invention provides a method and system for controlling the locking interval of a passive ring laser gyroscope. Compared with the prior art, the beneficial effects are as follows: When the passive ring laser gyroscope operates in a common mode, keep the light intensity of one incident laser beam unchanged and change the light intensity of the other incident laser beam, and obtain the light intensity ratio of the two incident laser beams; add a linearly varying bias voltage to the error signal generated by the passive ring laser gyroscope, and record the range of the bias voltage when the passive ring laser gyroscope locks; obtain the locking frequency threshold according to the ratio of the range of the bias voltage to the frequency discrimination slope affected by the error signal; fit the variation curves of multiple light intensity ratios and multiple locking frequency thresholds according to a fitting formula; obtain the minimum value of the locking frequency threshold in the variation curve , and the minimum value corresponding light intensity ratio ; adjust the light intensity ratio of the two incident laser beams to , so that the influence of the locking interval of the passive ring laser gyroscope on the minimum value is reduced to ± .

[0012] Among them, according to multiple light intensity ratios and multiple locking frequency thresholds, use a fitting formula to fit the variation curve. The curve reflects the relationship between the light intensity ratio and the locking frequency threshold, and the light intensity ratio corresponding to the minimum value of the locking frequency threshold can be determined through the variation curve. Therefore, adjusting the light intensity ratio in the passive ring laser gyroscope can reduce the locking interval without introducing additional devices or technologies into the passive ring laser gyroscope. Since the locking interval refers to the range in which the gyroscope cannot measure the rotational angular velocity, reducing the locking interval expands the range for measuring the rotational angular velocity, and finally realizes optimizing the measurement range while reducing the locking interval. Description of the Drawings

[0013] Figure 1Flow chart of a method for controlling the locking range of a passive laser gyroscope provided by an embodiment of the present invention; Figure 2 Schematic diagram of adding a bias voltage to the error signal of a passive laser gyroscope in a method for controlling the locking range of a passive laser gyroscope provided by an embodiment of the present invention; Figure 3 Schematic diagram for measuring the frequency discrimination slope of a passive laser gyroscope provided by an embodiment of the present invention; Figure 4 Theoretical simulation curve graph of the frequency locking threshold of a passive laser gyroscope in a method for controlling the locking range of a passive laser gyroscope provided by an embodiment of the present invention.

[0014] Figure 5 Overall system structure diagram of a passive laser gyroscope provided by an embodiment of the present invention.

[0015] Reference numerals: 100 - Light source system, 1011 - Laser, 1012 - First frequency shifter, 1013 - Second frequency shifter, 200 - Sagnac interferometer, 2011 - First mirror, 2012 - Second mirror, 2013 - Third mirror, 300 - Laser frequency stabilization system, 3011 - PID control system, 3012 - Laser frequency stabilization error signal, 3013 - Bias voltage, 400 - Beat frequency detection system, 4011 - Mach-Zehnder interference optical path, 4012 - Photoelectric detector, 4013 - Voltage signal acquisition device. Detailed implementation manners

[0016] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following describes the detailed implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0017] Refer to Figure 1 , an embodiment of the present invention provides a method for controlling the locking range of a passive laser gyroscope, including the following steps: Step 1: When the passive laser gyroscope operates in a common mode, keep the light intensity of one incident laser unchanged and change the light intensity of the other incident laser, and obtain the light intensity ratio of the two incident lasers.

[0018] Step 2: Add a linearly varying bias voltage to the error signal generated by the passive laser gyroscope, and record the range of the bias voltage when the passive laser gyroscope locks; obtain the locking frequency threshold according to the ratio of the range of the bias voltage to the frequency discrimination slope affected by the error signal.

[0019] Step 3: Fit the variation curves of multiple light intensity ratios and multiple locking frequency thresholds according to the fitting formula; where the fitting formula is: ; represents the locking frequency threshold as the dependent variable, represents the light intensity ratio as the independent variable, 、 are fitting parameters.

[0020] Step 4: Obtain the minimum value of the locking frequency threshold in the variation curve , and the light intensity ratio corresponding to the minimum value ; Adjust the light intensity ratio of the two incident laser beams to , so that the influence of the locking interval of the passive laser gyroscope on the minimum value is reduced to ± .

[0021] The specific content analysis is as follows: For Steps 1 and 2, the passive laser gyroscope operates in a common mode. Keep the intensity of one incident laser beam unchanged and change the intensity of the other incident laser beam, and record the light intensity ratio of the two laser beams at this time. Add a linearly varying bias voltage to the error signal of the locking system, and at the same time detect the beat frequency output of the laser gyroscope, and record the range of the bias voltage corresponding to when the gyroscope is locked, that is, when there is no beat frequency signal output.

[0022] The bias voltage added to the error signal, the locking with the added bias voltage, can be the locking loop of the clockwise optical path or the counterclockwise locking loop. However, it should be noted that for the subsequent measurement of the frequency discrimination slope, the loop selected in this step is also required to ensure that the correct locking interval is calculated. Preferably, the loop that changes the incident light intensity in Step 1 should be selected. In the locking loop, an external signal generator can be used to input a linearly varying voltage to the locking system, or the function of adding a bias voltage inside the locking system can be used. As shown in Figure 2 , it is a schematic diagram of adding a bias voltage to the error signal of the passive laser gyroscope. A passive laser gyroscope system mainly includes four parts: a light source system 100, a Sagnac interferometer 200, a laser frequency stabilization system 300, and a beat frequency detection system 400. The laser frequency stabilization system 300 receives the laser frequency stabilization error signal 3012 and performs feedback control on the laser frequency of the light source system through the PID control system 3011. At this time, a bias voltage is added to the laser frequency stabilization error signal 3012 from to The linearly varying bias voltage 3013 causes a corresponding linear change in the laser frequency. The range of the voltage change needs to ensure that the beat frequency detection system 400 can detect the two states of the passive laser gyroscope being locked and unlocked. The beat frequency detection system 400 monitors the frequency output of the passive laser gyroscope and records the voltage bias range when the frequency output is 0, that is, when the gyroscope is in the locked range. 。

[0023] In step two, the error signal of the locking system is collected to obtain the frequency discrimination slope. ,Using the formula ,The locking frequency threshold of the gyroscope at this time is obtained. 。

[0024] Collecting the error signal of the locking system does not require locking the laser frequency. The frequency discrimination slope is a coefficient characterizing the frequency discrimination ability of the laser frequency stabilization system 300, but the loop for measuring the frequency discrimination slope needs to be the same as the loop for adding the bias voltage in step S2. As Figure 3 shown, it is a schematic diagram of the frequency discrimination slope measurement scheme for a passive laser gyroscope. In the light source system 100, the laser 1011 emits laser light, which passes through the first frequency shifter 1012 for frequency shifting the laser frequency. Preferably, the frequency shifter uses an acousto-optic modulator as the frequency shifting device. The first frequency shifter 1012 linearly shifts the frequency of the laser light incident on the Sagnac interferometer 200 to obtain a linear change in the laser frequency stabilization error signal 3012, and the frequency discrimination slope is obtained by linear fitting. ,The unit is V / Hz. Through the frequency discrimination slope ,The locking frequency interval corresponding to the voltage bias range can be obtained, that is, the frequency locking threshold is 。 。

[0025] For step three, steps one and two need to be repeated to obtain a series of locking frequency thresholds corresponding to the laser light intensity ratios. 。 。

[0026] Adjusting the number of times of the incident laser light intensity ratio corresponds to the number of cycles of steps one and two. The adjusted light intensity ratio and the locking frequency threshold The more data, the smaller the fitting error of the theoretical curve. Preferably, more than five groups of light intensity ratios are selected, and the variation range of the light intensity ratio is in 。

[0027] Plot the variation curve of the locking frequency threshold with respect to the light intensity ratio ,Fit the plotted curve through the formula ,where Taking as the independent variable, and as the fitting parameters, the minimum value of the fitting curve and the corresponding light intensity ratio at this time are obtained.

[0028] The expression used for fitting is the theoretical expression of the locking frequency threshold of the passive ring laser gyroscope . The locking frequency threshold varies with the change of the incident laser light intensity ratio, and there is a specific incident laser light intensity ratio such that is the minimum value. Figure 4 This is the theoretical simulation curve of the frequency locking threshold of the passive ring laser gyroscope in this step. There is one and only one minimum value on this curve, corresponding to the minimum value of the frequency locking threshold , and the corresponding light intensity ratio is . and are fitting parameters, and their results are directly given by fitting. They characterize the various parameters of the ring cavity, including the backscattering coefficient.

[0029] The source of this fitting formula is the frequency difference expression of the laser gyroscope: Essentially, a laser gyroscope is a ring laser that uses the Sagnac effect to measure the change in the laser resonance frequency caused by external rotation, so as to achieve angle perception. Although there is no gain medium in a passive ring laser gyroscope and laser is injected from the outside, the laser frequency is locked to the ring cavity resonance peak through a locking system. However, due to the crosstalk of the backscattered light field to the locking system, when the external rotation speed signal input to the laser gyroscope is too small, a locking phenomenon will occur, that is, the corresponding positive / negative beam frequency difference cannot be output. The theoretical value of the laser gyroscope frequency difference under normal operating conditions can be calculated from the self-consistent equation:

[0030] 。

[0031] .

[0032] In the formula: and are the frequency difference and phase difference of the forward / backward traveling waves; is the Sagnac frequency; is a constant related to the size of the laser gyroscope and the parameters of the cavity mirrors, with the dimension of frequency; is the locking frequency threshold of the laser gyroscope; and are the light intensities of the forward / backward traveling waves; and are the complex amplitude backscattering coefficients; The phase change caused by backscattering. When the measured rotational speed of the gyroscope is too small, it causes the Sagnac frequency , then the laser gyroscope locks, and there is no rotational speed output, that is ; conversely, then the laser gyroscope breaks away from the locked area. And it can be seen from the expression that the locking frequency threshold is related to the light intensity ratio of the forward / backward traveling waves.

[0033] Such as Figure 5 shown, the passive laser gyroscope mainly includes four parts, a light source system 100, a Sagnac interferometer 200, a laser frequency stabilization system 300, and a beat frequency detection system 400. The light source system 100 includes a laser 1011. After the laser light source is split into two, one beam of laser passes through a first frequency shifter 1012, and one beam of laser passes through a second frequency shifter 1013. The Sagnac interferometer is composed of four high-reflectivity cavity mirrors. The first cavity mirror 2011 is the clockwise laser incident cavity mirror, the second cavity mirror 2012 is the counterclockwise laser incident cavity mirror, and the third cavity mirror 2013 is used as the transmission cavity mirror for the two beams of laser to detect the laser beat frequency. The laser frequency stabilization system 300 includes a photodetector 3012 for detecting the reflected light, a PID controller 3011 for laser frequency feedback control, and a voltage bias 3013 for the error signal. The beat frequency detection system 400 includes a Mach-Zehnder interference optical path 4011, a photodetector 4012 for detecting the beat frequency signal, and a voltage signal acquisition device 4013.

[0034] The present invention aims at optimizing the measurement range of the passive laser gyroscope. For the applied passive laser gyroscope, as long as it is a passive laser gyroscope operating in the common mode, there are no special requirements for the geometric size of the gyroscope and the laser frequency locking method.

[0035] In the passive laser gyroscope operating in the common mode of the present invention, by measuring the locking intervals under different incident light intensity ratios and fitting the theoretical curve to obtain the minimum locking interval of the gyroscope, a method for reducing the locking interval of the passive laser gyroscope is realized, and the measurement range of the rotational angular velocity is increased. At the same time, the implementation of this method does not require the introduction of additional devices or technologies, and only needs to adjust the light intensity ratio of the two incident laser beams, which is basically applicable to the passive laser gyroscope operating in the common mode.

[0036] An embodiment of the present invention provides a control system for the locking interval of a passive laser gyroscope, including: A light intensity ratio acquisition module, which is used to keep the light intensity of one incident laser beam unchanged and change the light intensity of the other incident laser beam when the passive laser gyroscope operates in the common mode, and acquire the light intensity ratio of the two incident laser beams.

[0037] The locking frequency threshold acquisition module is used to add a linearly varying bias voltage to the error signal generated by the passive ring laser gyroscope, and record the range of the bias voltage when the passive ring laser gyroscope locks; according to the ratio of the range of the bias voltage to the frequency discrimination slope affected by the error signal, the locking frequency threshold is obtained.

[0038] The variation curve fitting module is used to fit the variation curves of multiple light intensity ratios and multiple locking frequency thresholds according to the fitting formula.

[0039] The locking interval control module is used to obtain the minimum value of the locking frequency threshold in the variation curve , and the minimum value corresponding light intensity ratio ; adjust the light intensity ratio of the two incident laser beams to , so that the locking interval of the passive ring laser gyroscope is affected by the minimum value reduced to ± .

[0040] A specific embodiment is as follows: This embodiment discloses a method for controlling the locking interval of a passive ring laser gyroscope, and the specific steps are as follows: S1. Keep the intensity of the counterclockwise laser injected into the second mirror 2012 unchanged, and adjust the intensity of the clockwise laser of the first mirror 2011 so that the ratio of the intensity of the clockwise incident laser to the intensity of the counterclockwise incident laser . The method of adjusting the laser intensity and measuring the laser intensity is not limited. Preferably, the RF modulation amplitudes of the first frequency shifter 1012 and the second frequency shifter 1013 in the light source system 100 are adjusted to adjust the intensities of the two laser beams; preferably, a light power meter is used to directly measure the laser power.

[0041] S2. Add a linearly varying bias voltage 3013 to the error signal of the locking system, and the variation range is to , and monitor the beat frequency signal of the gyroscope through the voltage signal acquisition device 4013. Record the voltage variation range corresponding to the beat frequency signal being 0 . The bias voltage 3013 is not a fixed value and is adjusted according to different gyroscope systems so that the passive gyroscope can switch between the locking and unlocking area ranges. Preferably, the bias voltage is directly added inside the PID control system 3011 for convenient measurement of the required voltage variation range . The voltage signal acquisition device 4013 requires a voltage sampling rate greater than twice the Sagnac frequency.

[0042] S3. Adjust the frequency shift magnitude of the first frequency shifter 1012, collect the error signal extracted by the photodetector 3012 at this time, and obtain the frequency discrimination slope through linear fitting , using the formula , the gyroscope locking frequency threshold at this time is obtained .

[0043] S4. Repeat steps S1, S2, and S3 to obtain a series of laser light intensity ratios , including 0.1, 0.5, 1, 5, 10, and the corresponding locking frequency thresholds .

[0044] S5. Plot the curve of the locking frequency threshold versus the light intensity ratio . Fit the plotted curve through the formula , where is the independent variable, is the dependent variable, , are fitting parameters, and the minimum value of the fitted curve and the corresponding light intensity ratio at this time are obtained. The light intensity ratio satisfies the relationship .

[0045] S6. Adjust the light intensity ratio of the two laser beams to , and at this time the system locking interval is reduced to .

[0046] In view of the current locking effect problem of passive ring laser gyroscopes, the present invention proposes a method for reducing the locking interval of passive ring laser gyroscopes, which can optimize the measurement range of passive ring laser gyroscopes without adding additional devices. In addition, this method is applied to passive ring laser gyroscopes operating in common mode, without restricting the size of the ring cavity and the laser frequency stabilization scheme used, and has universality for passive ring laser gyroscopes.

[0047] The above embodiments merely represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for controlling a passive laser gyroscope locking interval, characterized in that: The following steps are involved: When the passive laser gyroscope is operated in common mode, the light intensity of one incident laser beam is kept constant and the light intensity of another incident laser beam is changed to obtain the light intensity ratio of the two incident laser beams; A linearly varying bias voltage is added to the error signal generated by the passive laser gyroscope, and the bias voltage range when the passive laser gyroscope is locked is recorded; a locking frequency threshold is obtained according to the ratio of the bias voltage range to the frequency discrimination slope affected by the error signal; The variation curves of multiple light intensity ratios and multiple locking frequency thresholds are fitted according to a fitting formula; wherein the fitting formula is: ； represents the lockout frequency threshold as the dependent variable, represents the light intensity ratio as the independent variable, , is the fitting parameter; Get the minimum value of the blocking frequency threshold in the change curve , and the minimum value The corresponding light intensity ratio ; Adjust the light intensity ratio of the two incident laser beams to , which makes the locking interval of the passive laser gyroscope subject to the minimum value The influence of .

2. A method for controlling a passive laser gyroscope locking interval as claimed in claim 1, characterized in that: The step of adding a linearly varying bias voltage comprises: Determine whether the changed incident laser light intensity belongs to the clockwise light path or the counterclockwise light path; A linearly varying bias voltage is added in a locking loop that determines the optical path.

3. A method for controlling a passive laser gyroscope locking interval as claimed in claim 1, characterized in that: The method of adding a linearly varying bias voltage to the error signal generated by the passive laser gyroscope specifically comprises the following steps: Generate a linearly varying voltage signal using an external signal generator; The linearly varying voltage signal is input into the error signal of the locking system of the passive laser gyroscope, so that the linearly varying voltage signal is superimposed on the original error signal.

4. A method for controlling a passive laser gyroscope locking interval as claimed in claim 1, characterized in that: The light intensity ratio of the two incident laser beams varies in a range of 0.1 to 10.

5. A control system for a passive laser gyroscope locking interval, characterized in that: include: A light intensity ratio acquisition module is used to obtain the light intensity ratio of the two incident laser beams by changing the light intensity of another incident laser beam while the passive laser gyroscope is operating in common mode; The locking frequency threshold acquisition module is used to add a linearly changing bias voltage to the error signal generated by the passive laser gyroscope, record the bias voltage range when the passive laser gyroscope is locked; and obtain the locking frequency threshold according to the ratio of the bias voltage range to the frequency discrimination slope affected by the error signal; A variation curve fitting module, used for fitting variation curves of a plurality of light intensity ratios and a plurality of locking frequency thresholds according to a fitting formula; The locking interval control module is used to obtain the minimum value of the locking frequency threshold in the change curve , and the minimum value The corresponding light intensity ratio ; Adjust the light intensity ratio of the two incident laser beams to , which makes the locking interval of the passive laser gyroscope subject to the minimum value The influence of .

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