Nuclear magnetic resonance gyroscope detection light intensity and frequency synchronous closed loop control method and system

Abstract

The application provides a nuclear magnetic resonance gyroscope detection laser intensity and frequency synchronous closed loop control method, which first utilizes a beam splitter prism to split part of detection laser probe power fluctuation, adjusts detection laser tube injection current to realize detection laser power closed loop stable control, secondly utilizes a polarization balance beam splitting detection system to extract a detection detection power signal after gas chamber absorption, which reflects detection laser frequency fluctuation, finally takes the signal as a closed loop feedback signal to adjust detection laser tube temperature to realize detection laser frequency synchronous closed loop stable control. The application can realize nuclear magnetic resonance gyroscope detection laser power and frequency synchronous closed loop stable control, suppresses nuclear magnetic resonance gyroscope output signal drift caused by detection laser power and frequency fluctuation, and improves long term stability of the gyroscope output signal. The technical scheme of the application solves the technical problem that the prior art cannot meet the demand of nuclear magnetic resonance gyroscope miniaturization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum sensing (nuclear magnetic resonance gyro), in particular to a nuclear magnetic resonance gyro detection light intensity and frequency synchronous closed-loop control method and system. BACKGROUND

[0002] The nuclear magnetic resonance gyro is a kind of atomic spin gyro that uses the invariance of the inertial space of the inert gas atomic nucleus spin magnetic resonance frequency to realize the carrier angular rate measurement. In the nuclear magnetic resonance gyro, the magnetic resonance signal of the nuclear spin needs to be detected indirectly through the detection of the precession signal of the alkali metal atomic electron spin based on the optical rotation effect of the linearly polarized detection laser, because the optical field is not easy to directly manipulate the nuclear spin. In this process, the detection laser power and frequency fluctuation will directly produce the magnetic resonance signal detection error, and then affect the accuracy and stability of the angular rate measurement of the nuclear magnetic resonance gyro, so it is necessary to perform closed-loop stable control on the power and frequency of the detection laser.

[0003] However, the existing laser power and frequency synchronous closed-loop control method based on atomic absorption peak by adjusting the current and temperature of the laser (Mu W., Hu Z., Wang J., et al. Intensity and frequency stabilization of a laser diode by simultaneously controlling its temperature and current [C]. Applied Optics and Photonics China (AOPC2017), 2017: 1045728) is only applicable to the power and frequency closed-loop control of the driving laser. For the detection laser, the detection laser frequency needs to be greatly detuned, far away from the atomic absorption peak, so it is difficult to realize the detuned frequency stable control of the detection laser; the existing laser detuning frequency stabilization method based on transfer cavity (Zhai Yueyang, Li Xiufei, Quan Wei, et al. A laser double stable frequency optical path system for SERF atomic inertial measurement device [P]. ZL201910034846. X) and the laser power closed-loop control method based on optical modulator (Fang Jiancheng, Huang Jiong, Xing Li, et al. A SERF atomic spin gyro all-optical light intensity stabilization control system [P]. 201710916926. 9) need to additionally increase F-P cavity, electro-optical or acousto-optical optical devices, which is difficult to meet the miniaturization requirement of the nuclear magnetic resonance gyro. SUMMARY

[0004] The present application provides a nuclear magnetic resonance gyro detection light intensity and frequency synchronous closed-loop control method and system, which can solve the technical problem that the prior art is difficult to meet the miniaturization requirement of the nuclear magnetic resonance gyro.

[0005] According to an aspect of the present application, a nuclear magnetic resonance gyroscope detection laser intensity and frequency synchronous closed-loop control method is provided, which comprises: sequentially arranging a first half-wave plate, a first polarization beam splitter prism, a polarization-independent beam splitter prism, an alkali metal atom cell, a second half-wave plate and a second polarization beam splitter prism along the direction of the light beam emitted by a collimated and expanded detection laser source, arranging a three-dimensional magnetic field coil and a magnetic shielding cylinder outside the alkali metal atom cell, arranging a first photodetector, a second photodetector, a first operational amplifier, a second operational amplifier, a third photodetector and a signal processing and control unit, the first photodetector, the second photodetector, the first operational amplifier and the second operational amplifier forming a balanced differential summing detector, the first operational amplifier being used to calculate the differential signal between the first photodetector and the second photodetector, the second operational amplifier being used to calculate the summing signal between the first photodetector and the second photodetector, the polarization-independent beam splitter prism splitting a detection laser to enter the third photodetector, and the second polarization beam splitter prism splitting the detection laser after passing through the alkali metal atom cell into two beams to enter the first photodetector and the second photodetector, respectively; the detection laser emitted by the collimated and expanded detection laser source is split into two beams after passing through the first half-wave plate, the first polarization beam splitter prism and the polarization-independent beam splitter prism, one of the two beams enters the third photodetector, the third photodetector converts the optical signal into an electrical signal and sends the electrical signal into the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimated and expanded detection laser source; the other beam enters the balanced differential summing detector after passing through the alkali metal atom cell, the differential signal is used to detect the atomic spin precession signal, the summing signal reflects the change of the detection light frequency, the summing signal is sent into the signal processing and control unit, and the synchronous closed-loop stable control of the detection laser frequency is realized by adjusting the temperature of the laser tube of the collimated and expanded detection laser source.

[0006] Further, the relationship between the detection laser power entering the alkali metal atom cell and the detection laser power emitted after passing through the alkali metal atom cell is as follows:

[0007] I = I0e -nσ(v)L

[0008] In the formula, I0 is the detection laser power before entering the alkali metal atom cell, I is the detection laser power emitted after passing through the alkali metal atom cell, n is the alkali metal atom number density, L is the length of the laser passing through the alkali metal atom cell, and σ(ν) is the absorption cross section and satisfies the following formula:

[0009]

[0010] In the formula, ν0 is the resonance absorption frequency of the alkali metal atom, ν-ν0 describes the amount of mismatch between the pumping laser frequency and the resonance absorption frequency of the alkali metal atom, c is the speed of light, and r is the radius of the alkali metal atom cell.e is the electronic radius, f is the oscillator strength, Γ is the spectral line broadening, I0 and n can be approximately constant under the condition of closed-loop stable control of detection light intensity and cell temperature, and the change of the detection laser power I out of the alkali metal atom cell is approximately proportional to the change of the detection laser frequency v due to a certain frequency shift of the detection laser frequency v relative to the alkali metal atom resonance absorption frequency v0, which can be used to measure the fluctuation of the detection laser frequency and further perform frequency stabilization control.

[0011] The laser powers of the two beams separated by the polarizing beam splitter prism and entering the first photodetector and the second photodetector can be represented as:

[0012]

[0013] where θ is the optical rotation angle generated by the atomic spin precession in the alkali metal atom cell, I9 is the laser power detected by the first photodetector, I 10 is the laser power detected by the second photodetector, and the sum of the laser powers detected by the two photodetectors I9+I 10 is the detection laser power I out of the alkali metal atom cell, which can be used to measure the fluctuation of the detection laser frequency and further perform frequency stabilization control.

[0014] Further, a non-magnetic electric heating film is arranged outside the alkali metal atom cell, and the alkali metal atom cell contains Rb or Cs alkali metal atoms, buffer gas N2, inert gas atoms 129 Xe and 131 Xe.

[0015] Further, the wavelength of the laser light out of the collimated and expanded detection laser light source 1 is tuned to be 0.1-0.3 nm off the wavelength corresponding to the D1 line pair of the alkali metal atom absorption spectrum.

[0016] Further, the first polarizing beam splitter prism 3 is a calcite-made Glan-Taylor polarizing prism, and the second polarizing beam splitter prism 8 is a PBS polarizing beam splitter prism, and the splitting ratio of the polarization-independent beam splitter is 1:1, so as to achieve the best detection laser power fluctuation monitoring effect.

[0017] Further, the three-dimensional magnetic field coil and the magnetic shielding cylinder are composed of a Helmholtz coil and a permalloy magnetic shielding cylinder, which provide the necessary magnetic field environment for nuclear spin magnetic resonance.

[0018] Further, the signal processing and control module is composed of a digital signal processor, a digital-to-analog converter and an analog-to-digital converter, signals output by the third photoelectric detector and the second operational amplifier are converted into digital signals by the analog-to-digital converter, the digital signals are input into the digital signal processor for processing to realize filtering processing of the detection laser power and frequency monitoring signals and generation of the injection current and temperature PID decoupling control signals of the collimated and expanded detection laser source, the current and temperature PID decoupling control signals output by the digital signal processor are converted into analog signals by the digital-to-analog converter and output to the collimated and expanded detection laser source to complete current and temperature control of the collimated and expanded detection laser source.

[0019] According to another aspect of the present application, a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system is provided, which is characterized in that the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system uses the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control method as described above to perform nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control, and the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system comprises a collimated and expanded detection laser light source, a first half-wave plate, a first polarization beam splitter prism, a polarization-independent beam splitter prism, an alkali metal atom cell, a three-dimensional magnetic field coil and a magnetic shielding cylinder, a second half-wave plate, a second polarization beam splitter prism, a first photoelectric detector, a second photoelectric detector, a first operational amplifier, a second operational amplifier, a third photoelectric detector and a signal processing and control unit; wherein the first photoelectric detector, the second photoelectric detector, the first operational amplifier and the second operational amplifier constitute a balanced differential summing detector, the first operational amplifier is used to calculate a differential signal between the first photoelectric detector and the second photoelectric detector, and the second operational amplifier is used to calculate a summing signal between the first photoelectric detector and the second photoelectric detector, detection laser light emitted by the collimated and expanded detection laser light source is split into two beams after passing through the first half-wave plate, the polarization beam splitter prism and the polarization-independent beam splitter prism, one beam enters the third photoelectric detector, the third photoelectric detector converts the optical signal into an electrical signal and sends the electrical signal to the signal processing and control unit, and stable control of the detection laser power is realized by adjusting the injection current of the collimated and expanded detection laser light source; the other beam enters the balanced differential summing detector after passing through the alkali metal atom cell, the differential signal is used to detect an atomic spin precession signal, the summing signal reflects changes in the detection light frequency, the summing signal is sent to the signal processing and control unit, and synchronous closed-loop stable control of the detection laser frequency is realized by adjusting the temperature of the laser tube of the collimated and expanded detection laser light source.

[0020] According to another aspect of the present application, a method for synchronous closed-loop control of laser intensity and frequency of a nuclear magnetic resonance gyroscope is provided. The method comprises: arranging a first half-wave plate, a first polarization beam splitter prism, a first polarization-independent beam splitter prism, an alkali metal atom cell, a second half-wave plate, a second polarization-independent beam splitter prism, and a second polarization beam splitter prism in sequence along the direction of a light beam emitted by a collimated and expanded detection laser source; arranging a three-dimensional magnetic field coil and a magnetic shielding cylinder outside the alkali metal atom cell; arranging a first photodetector, a second photodetector, an operational amplifier, a third photodetector, a fourth photodetector, and a signal processing and control unit; using the operational amplifier to calculate a differential signal between the first photodetector and the second photodetector, and using the differential signal to detect an atomic spin precession signal; using the first polarization-independent beam splitter prism to split a detection laser into a beam entering the third photodetector; and using the second polarization beam splitter prism to split the detection laser after passing through the alkali metal atom cell into two beams entering the first photodetector and the second photodetector, respectively; splitting the detection laser emitted by the collimated and expanded detection laser source into two beams after passing through the first half-wave plate, the first polarization beam splitter prism, and the polarization-independent beam splitter prism, using one of the two beams to enter the third photodetector, converting an optical signal into an electrical signal by the third photodetector, and sending the electrical signal to the signal processing and control unit to achieve stable control of the detection laser power by adjusting the injection current of the collimated and expanded detection laser source; and using the other beam to enter the fourth photodetector after passing through the alkali metal atom cell and the second polarization-independent beam splitter prism, using the fourth photodetector to detect the detection laser power emitted by the alkali metal atom cell, sending a signal output by the fourth photodetector to the signal processing and control unit, and achieving synchronous closed-loop stable control of the detection laser frequency by adjusting the temperature of a laser tube of the collimated and expanded detection laser source.

[0021] According to another aspect of the present application, a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system is provided, which uses the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method as described above to perform nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control. The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system comprises a collimated and expanded detection laser light source, a first half-wave plate, a first polarization beam splitter prism, a first polarization independent beam splitter prism, an alkali metal atom cell, a three-dimensional magnetic field coil and a magnetic shielding cylinder, a second half-wave plate, a second polarization independent beam splitter prism, a fourth photodetector, a second polarization beam splitter prism, a first photodetector, a second photodetector, an operational amplifier, a third photodetector, and a signal processing and control unit. The operational amplifier is used to calculate the difference signal between the first photodetector and the second photodetector, and the difference signal is used to detect the atomic spin precession signal. The detection laser light emitted by the collimated and expanded detection laser light source is split into two beams after passing through the first half-wave plate, the first polarization beam splitter prism, and the first polarization independent beam splitter prism. One beam enters the third photodetector, which converts the optical signal into an electrical signal and sends it to the signal processing and control unit. The stable control of the detection laser power is achieved by adjusting the injection current of the collimated and expanded detection laser light source. The other beam passes through the alkali metal atom cell and then enters the fourth photodetector through the second polarization independent beam splitter prism. The fourth photodetector is used to detect the detection laser power emitted by the alkali metal atom cell, and the signal output by the fourth photodetector is sent to the signal processing and control unit. The synchronous closed loop stable control of the detection laser frequency is achieved by adjusting the temperature of the laser tube of the collimated and expanded detection laser light source.

[0022] The technical solution of the present application provides a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method. The method first uses a beam splitter prism to split part of the detection laser light to detect power fluctuations, adjusts the injection current of the detection laser tube to achieve closed loop stable control of the detection laser power. Secondly, it uses the sum signal of the polarization balance beam splitting detection system to extract the detection power signal after the cell absorption. This signal reflects the fluctuations of the detection laser frequency. Finally, it uses this signal as a closed loop feedback signal to adjust the temperature of the detection laser tube to achieve synchronous closed loop stable control of the detection laser frequency. The present application can achieve synchronous closed loop stable control of the detection laser power and frequency of the nuclear magnetic resonance gyroscope, suppress the drift of the nuclear magnetic resonance gyroscope output signal caused by the fluctuations of the detection laser power and frequency, and improve the long-term stability of the gyroscope output signal. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is readily understood that the drawings are merely illustrative of some embodiments of the application and therefore are not to be construed as limiting the scope of the application as described herein.

[0024] Figure 1 Fig. 1 shows a structure diagram of a laser intensity and frequency synchronous closed-loop control system of a NMR gyroscope according to a first embodiment of the present application;

[0025] Figure 2 Fig. 2 shows a structure diagram of a laser intensity and frequency synchronous closed-loop control system of a NMR gyroscope according to a second embodiment of the present application.

[0026] In the drawings, the following reference signs are used:

[0027] 1, collimated and expanded detection laser source; 2, first half-wave plate; 3, first polarization beam splitter prism; 4, polarization independent beam splitter prism; 5, alkali metal atom cell; 6, three-dimensional magnetic field coil and magnetic shielding cylinder; 7, second half-wave plate; 8, second polarization beam splitter prism; 9, first photodetector; 10, second photodetector; 11, third photodetector; 12, second polarization independent beam splitter prism; 13, fourth photodetector. DETAILED DESCRIPTION

[0028] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not intended to limit the application and use of the present application in any way. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0029] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of the features, steps, operations, devices, components and / or combinations thereof.

[0030] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0031] like Figure 1As shown, the first embodiment of the application provides a nuclear magnetic resonance gyroscope detection laser intensity and frequency synchronous closed-loop control method, which comprises: sequentially arranging a first half-wave plate 2, a first polarization beam splitter prism 3, a polarization-independent beam splitter prism 4, an alkali metal atom cell 5, a second half-wave plate 7, and a second polarization beam splitter prism 8 along the direction of the light beam emitted by the collimated and expanded detection laser source 1, arranging a three-dimensional magnetic field coil and a magnetic shielding cylinder 6 outside the alkali metal atom cell 5, arranging a first photodetector 9, a second photodetector 10, a first operational amplifier, a second operational amplifier, a third photodetector 11, and a signal processing and control unit, the first photodetector 9, the second photodetector 10, the first operational amplifier, and the second operational amplifier constitute a balanced differential summing detector, the first operational amplifier is used to calculate the differential signal between the first photodetector 9 and the second photodetector 10, and the second operational amplifier is used to calculate the summing signal between the first photodetector 9 and the second photodetector 10, the polarization-independent beam splitter prism 4 splits a detection laser into a third photodetector 11, and the second polarization beam splitter prism 8 splits the detection laser after passing through the alkali metal atom cell 5 into two beams entering the first photodetector 9 and the second photodetector 10, respectively; the detection laser emitted by the collimated and expanded detection laser source 1 is split into two beams after passing through the first half-wave plate 2, the first polarization beam splitter prism 3, and the polarization-independent beam splitter prism 4, one beam enters the third photodetector 11, the third photodetector 11 converts the optical signal into an electrical signal and sends it to the signal processing and control unit, and the detection laser power is stably controlled by adjusting the injection current of the collimated and expanded detection laser source 1; the other beam enters the balanced differential summing detector after passing through the alkali metal atom cell, the differential signal is used to detect the atomic spin precession signal, the summing signal reflects the change of the detection light frequency, the summing signal is sent to the signal processing and control unit, and the detection laser frequency is synchronously and stably controlled by adjusting the laser tube temperature of the collimated and expanded detection laser source 1.

[0032] The application provides a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method.

[0033] Specifically, in the application, the relationship between the detection laser power entering the alkali metal atom cell 5 through the polarization-independent light splitting prism 4 and the detection laser power emitted from the alkali metal atom cell 5 is as follows:

[0034] I = I0e -nσ(v)L

[0035] In the formula, I0 is the detection laser power before entering the alkali metal atom cell 5, I is the detection laser power emitted from the alkali metal atom cell 5, n is the alkali metal atom number density, L is the length of the laser passing through the alkali metal atom cell 5, and sigma (v) is the absorption cross section and satisfies the following formula:

[0036]

[0037] In the formula, v0 is the alkali metal atom resonance absorption frequency, v-v0 describes the amount of mismatch between the pumping laser frequency and the alkali metal atom resonance absorption frequency, and G is the spectral line broadening. Under the condition of closed loop stable control of the detection light intensity and the cell temperature, I0 and n can be approximated as constants. Since there is a certain amount of mismatch between the detection laser frequency v and the alkali metal atom resonance absorption frequency v0, the change of the detection laser power I out of the alkali metal atom cell 5 is approximately proportional to the change of the detection laser frequency v, which can be used to measure the fluctuation of the detection laser frequency and further perform frequency stabilization control.

[0038] The laser powers of the two beams split by the polarizing beam splitter prism 8 into the first photodetector 9 and the second photodetector 10 can be represented as:

[0039]

[0040] In the formula, Q is the optical rotation angle generated by the atomic spin precession in the alkali metal atom cell 5, I9 is the laser power detected by the first photodetector 9, I 10 is the laser power detected by the second photodetector 10, and the sum of the laser powers detected by the two detectors I9+I 10 is the detection laser power I out of the alkali metal atom cell 5, which can be used to measure the fluctuation of the detection laser frequency and further perform frequency stabilization control.

[0041] Further, in the present application, a non-magnetic electric heating film is arranged outside the alkali metal atom cell 5, and the alkali metal atom cell 5 contains Rb or Cs alkali metal atoms, buffer gas N2, inert gas atoms 129 Xe, and 131 Xe.

[0042] In addition, in the present application, the wavelength of the laser light out of the collimated and expanded detection laser light source 1 is tuned to be mismatched by 0.1-0.3 nm relative to the wavelength corresponding to the D1 line of the alkali metal atom absorption spectrum, so as to ensure that the optical rotation signal generated after the detection light passes through the cell is the strongest.

[0043] Further, in the present application, the first polarizing beam splitter prism 3 is a calcite-made Glan-Taylor polarizing prism, which has an extinction ratio better than 10-5, and is used to purify the linear polarization purity of the detection laser light out of the collimated and expanded detection laser light source 1. The splitting ratio of the polarization-independent beam splitter prism 4 is 1:1, so as to achieve the best detection laser power fluctuation monitoring effect. The second polarizing beam splitter prism 8 is a PBS polarizing beam splitter prism. The three-dimensional magnetic field coil and the magnetic shielding cylinder 6 are composed of a Helmholtz coil and a permalloy magnetic shielding cylinder, and provide the necessary magnetic field environment for nuclear spin magnetic resonance.

[0044] In the present application, the signal processing and control module is composed of a digital signal processor, a digital-to-analog converter and an analog-to-digital converter. The signals output by the third photoelectric detector 11 and the second operational amplifier are converted into digital signals by the analog-to-digital converter, and the digital signals are input into the digital signal processor for processing, so as to realize the filtering processing of the detection laser power and the frequency monitoring signal and the generation of the injection current and temperature PID decoupling control signal of the collimated and expanded detection laser source 1. The current and temperature PID decoupling control signal output by the digital signal processor is converted into an analog signal by the digital-to-analog converter and is output to the collimated and expanded detection laser source 1, so as to complete the current and temperature control of the collimated and expanded detection laser source 1.

[0045] According to another aspect of the present application, a nuclear magnetic resonance gyro detection laser light intensity and frequency synchronous closed loop control system is provided, which uses the nuclear magnetic resonance gyro detection laser light intensity and frequency synchronous closed loop control method as described in the first embodiment to perform nuclear magnetic resonance gyro detection laser light intensity and frequency synchronous closed loop control. The nuclear magnetic resonance gyro detection laser light intensity and frequency synchronous closed loop control system comprises a collimated and expanded detection laser light source 1, a first half-wave plate 2, a first polarization beam splitter prism 3, a polarization independent beam splitter prism 4, an alkali metal atom cell 5, a three-dimensional magnetic field coil and magnetic shielding cylinder 6, a second half-wave plate 7, a second polarization beam splitter prism 8, a first photoelectric detector 9, a second photoelectric detector 10, a first operational amplifier, a second operational amplifier, a third photoelectric detector 11 and a signal processing and control unit. The first photoelectric detector 9, the second photoelectric detector 10, the first operational amplifier and the second operational amplifier constitute a balanced differential summing detector. The first operational amplifier is used to calculate the differential signal between the first photoelectric detector 9 and the second photoelectric detector 10, and the second operational amplifier is used to calculate the summing signal between the first photoelectric detector 9 and the second photoelectric detector 10. The detection laser light emitted by the collimated and expanded detection laser light source 1 is split into two beams after passing through the first half-wave plate 2, the first polarization beam splitter prism 3 and the polarization independent beam splitter prism 4. One beam enters the third photoelectric detector 11, which converts the optical signal into an electrical signal and sends it to the signal processing and control unit, so as to realize the stable control of the detection laser power by adjusting the injection current of the collimated and expanded detection laser light source 1. The other beam enters the balanced differential summing detector after passing through the alkali metal atom cell 5. The differential signal is used to detect the atomic spin precession signal, and the summing signal reflects the change of the detection light frequency. The summing signal is sent to the signal processing and control unit, so as to realize the synchronous closed loop stable control of the detection laser frequency by adjusting the temperature of the laser tube of the collimated and expanded detection laser light source 1.

[0046] With the configuration, a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system is provided, when detecting laser power fluctuation, a photoelectric detector detects the detection laser power fluctuation signal separated by the polarization independent beam splitter prism as a feedback signal to realize closed loop stable control of the detection laser power by adjusting the injection current of the laser, at the same time, when detecting laser frequency fluctuation, the detection laser power fluctuation emitted from the alkali metal atom cell directly represents the detection laser frequency fluctuation, the sum signal of the polarization balance beam splitting detection measures the detection laser power fluctuation signal emitted from the alkali metal atom cell to realize indirect measurement of the detection laser frequency fluctuation, and the sum signal is taken as a feedback signal to realize synchronous closed loop stable control of the detection laser frequency by synchronously adjusting the controlled temperature of the laser. The system has simple and compact structure, is easy to operate, and can meet the miniaturization requirement of the nuclear magnetic resonance gyroscope. Therefore, compared with the prior art, the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system has simple and convenient operation, simple and compact structure, uses the detection laser separated by the polarization independent beam splitter prism as a measurement signal of the detection laser power, uses the power sum signal of the polarization balance beam splitting detection as a measurement signal of the detection laser frequency, and realizes synchronous closed loop control of the detection laser by adjusting the injection current and the controlled temperature of the detection laser.

[0047] According to a second embodiment of the present application, Figure 2As shown, a polarization-independent light splitting prism and a photoelectric detector can be added in front of the second polarization light splitting prism 8 in the present application, and the photoelectric detector is used to detect the detection laser power change after passing through the gas cell, to replace the extraction of the sum signal, and also to achieve the extraction of the detection laser frequency fluctuation signal. Specifically, in the second embodiment, the nuclear magnetic resonance gyro detection laser intensity and frequency synchronous closed-loop control method comprises: a first half-wave plate 2, a first polarization light splitting prism 3, a first polarization-independent light splitting prism 4, an alkali metal atom gas cell 5, a second half-wave plate 7, a second polarization-independent light splitting prism 12, and a second polarization light splitting prism 8 are arranged in sequence along the direction of the light beam emitted by the collimated and expanded detection laser source, a three-dimensional magnetic field coil and a magnetic shielding cylinder 6 are arranged outside the alkali metal atom gas cell 5, a first photoelectric detector 9, a second photoelectric detector 10, an operational amplifier, a third photoelectric detector 11, a fourth photoelectric detector 13, and a signal processing and control unit are arranged, the operational amplifier is used to calculate the differential signal between the first photoelectric detector 9 and the second photoelectric detector 10, the first polarization-independent light splitting prism 4 divides a detection laser into a beam entering the third photoelectric detector 11, and the second polarization light splitting prism 8 divides the detection laser after passing through the alkali metal atom gas cell into two beams entering the first photoelectric detector 9 and the second photoelectric detector 10, respectively; the detection laser emitted by the collimated and expanded detection laser source passes through the first half-wave plate 2, the first polarization light splitting prism 3, and the first polarization-independent light splitting prism 4, and is divided into two beams, one of which enters the third photoelectric detector 11, the third photoelectric detector 11 converts the optical signal into an electrical signal and sends it to the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimated and expanded detection laser source; the other beam passes through the alkali metal atom gas cell and enters the fourth photoelectric detector 13 through the second polarization-independent light splitting prism 12, the differential signal is used to detect the atomic spin precession signal, the fourth photoelectric detector is used to detect the detection laser power emitted by the alkali metal atom gas cell, and the signal output by the fourth photoelectric detector is sent to the signal processing and control unit, and the synchronous closed-loop stable control of the detection laser frequency is realized by adjusting the laser tube temperature of the collimated and expanded detection laser source.

[0048] With the configuration, a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method is provided, when detecting laser power fluctuation, a photoelectric detector detects a detection laser power fluctuation signal split by the first polarization independent beam splitter prism as a feedback signal to realize closed loop stable control of the detection laser power by adjusting the injection current of the laser, at the same time, when detecting laser frequency fluctuation, the detection laser power fluctuation emitted by the alkali metal atom cell directly represents the detection laser frequency fluctuation, the fourth photoelectric detector measures the detection laser power fluctuation signal emitted by the alkali metal atom cell to indirectly realize measurement of the detection laser frequency fluctuation, and the signal is taken as a feedback signal to realize synchronous closed loop stable control of the detection laser frequency by synchronously adjusting the controlled temperature of the laser. The system has simple and compact structure, is easy to operate, and can meet the miniaturization requirement of the nuclear magnetic resonance gyroscope. Therefore, compared with the prior art, the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system has simple and convenient operation, simple and compact structure, uses the detection laser split by the first polarization independent beam splitter prism as a detection laser power measurement signal, uses the power signal detected by the fourth photoelectric detector as a detection laser frequency measurement signal, and realizes synchronous closed loop control of the detection laser by adjusting the injection current and the controlled temperature of the detection laser.

[0049] According to a further aspect of the present application, as Figure 2As shown, a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system is provided, which uses the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method provided by the second embodiment of the present application to perform nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control. The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system includes a collimated beam detection laser light source 1, a first half-wave plate 2, a first polarization beam splitter prism 3, a first polarization independent beam splitter prism 4, an alkali metal atom cell 5, a three-dimensional magnetic field coil and magnetic shielding cylinder 6, a second half-wave plate 7, a second polarization beam splitter prism 8, a first photodetector 9, a second photodetector 10, a third photodetector 11, a signal processing and control unit, a second polarization independent beam splitter prism 12, and a fourth photodetector 13. An operational amplifier is used to calculate the differential signal between the first photodetector and the second photodetector, and the differential signal is used to detect the atomic spin precession signal. The detection laser emitted by the collimated beam detection laser light source passes through the first half-wave plate 2, the first polarization beam splitter prism 3, and the first polarization independent beam splitter prism 4, and is divided into two beams. One beam enters the third photodetector 11, which converts the optical signal into an electrical signal and sends it to the signal processing and control unit. The injection current of the collimated beam detection laser light source is adjusted to achieve stable control of the detection laser power. The other beam passes through the alkali metal atom cell 5 and then enters the fourth photodetector 13 through the second polarization independent beam splitter prism 12. The fourth photodetector 13 is used to detect the detection laser power emitted by the alkali metal atom cell. The signal output by the fourth photodetector 13 is sent to the signal processing and control unit, and the temperature of the laser tube of the collimated beam detection laser light source is adjusted to achieve synchronous closed loop stable control of the detection laser frequency.

[0050] In order to have a further understanding of the present application, the following Figure 1 The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method provided by the first embodiment of the present application is described in detail.

[0051] As Figure 1As shown, a nuclear magnetic resonance gyroscope detection laser power and frequency synchronous closed loop stable control system, the system comprises collimating beam expanding detection laser light source 1, first half wave plate 2, first polarization beam splitter prism 3, polarization independent beam splitter prism 4, alkali metal atom cell 5, three-position magnetic field coil and magnetic shield cylinder 6, second half wave plate 7, second polarization beam splitter prism 8, first photodetector 9, second photodetector 10, third photodetector 11, first operational amplifier, second operational amplifier and signal processing and control unit; wherein the first photodetector 9, second photodetector 10, first operational amplifier and second operational amplifier constitute a balanced differential sum detector, the first operational amplifier is used to calculate the differential signal between the first photodetector 9 and the second photodetector 10, and the second operational amplifier is used to calculate the sum signal between the first photodetector 9 and the second photodetector 10; the detection laser emitted along the collimating beam expanding detection laser light source 1 is divided into two beams after the first half wave plate 2, polarization beam splitter prism 3 and polarization independent beam splitter prism 4, one of which enters the third photodetector 11, and the third photodetector 11 converts the optical signal into an electrical signal and sends it to the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimating beam expanding detection laser light source 1; the other beam enters the balanced differential sum detector after passing through the atom cell 5, the differential signal is used to detect the atomic spin precession signal, and the sum signal reflects the change of the detection light frequency, and the sum signal is sent to the signal processing and control unit, and the stable control of the detection laser frequency is realized by adjusting the laser tube temperature of the collimating beam expanding detection laser light source 1.

[0052] The laser emitted by the collimating beam expanding detection laser light source 1 is approximately linearly polarized laser, and the first half wave plate 2 adjusts the polarization direction to horizontal polarization direction, which is consistent with the direction of the light transmission axis of the polarization beam splitter prism 3.

[0053] The second half wave plate 7 adjusts the polarization direction of the detection laser emitted through the alkali metal atom cell 5 to a direction of about 45° with the horizontal direction, and after entering the polarization beam splitter prism 8, it is divided into two beams with approximately equal power, which are then differentially summed by the first photodetector 9 and the second photodetector 10.

[0054] The alkali metal atom cell contains Rb or Cs alkali metal atoms, buffer gas N2, inert gas atoms 129Xe and 131Xe, and is heated to about 120℃ (corresponding to the working temperature of Rb atoms) or 90℃ (corresponding to the working temperature of Cs atoms) by a magnetic-free electric heating film, so that the cell contains a high density of alkali metal atom vapor;

[0055] The laser wavelength emitted by the collimated and expanded detection laser source 1 is tuned to be about 0.1-0.3 nm detuned from the corresponding wavelength of the alkali metal atom absorption spectral line D1 line, so as to ensure that the optical rotation signal generated by the detection light after passing through the gas chamber is the strongest.

[0056] The detection laser is split by the polarization-independent beam splitter prism 4 into one beam entering the third photodetector, the splitting ratio of the polarization-independent beam splitter prism 4 is 1:1, and the third photodetector 11 converts the optical signal into an electrical signal and sends it to the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimated and expanded detection laser source 1, that is, the laser power of the other beam split by the polarization-independent beam splitter prism 4 entering the atomic gas chamber is stable;

[0057] The relationship between the detection laser power split by the polarization-independent beam splitter prism 4 and entering the alkali metal atom gas chamber 5 and the detection laser power emitted after passing through the alkali metal atom gas chamber 5 is:

[0058] I=I0e -nσ (ν) L

[0059] In the formula, I0 is the detection laser power before entering the alkali metal atom gas chamber 5, I is the detection laser power emitted after passing through the alkali metal atom gas chamber 5, n is the number density of alkali metal atoms, L is the length of the laser passing through the alkali metal atom gas chamber 5, and σ(ν) is the absorption cross section and satisfies the following formula:

[0060]

[0061] In the formula, ν0 is the resonance absorption frequency of the alkali metal atom, ν-ν0 describes the detuning between the pumping laser frequency and the resonance absorption frequency of the alkali metal atom, c is the speed of light, r e is the electron radius, f is the oscillator strength, and Γ is the spectral line broadening (full width at half maximum). Under the condition that the detection light intensity and the gas chamber temperature are closed-loop stable controlled, I0 and n can be approximately constant, and since the detection laser frequency ν is detuned from the resonance absorption frequency ν0 of the alkali metal atom, the change of the detection laser power I emitted after passing through the alkali metal atom gas chamber 5 is approximately proportional to the change of the detection laser frequency ν in a small range, which can be used to measure the fluctuation of the detection laser frequency and further perform frequency stable control.

[0062] The laser powers of the two beams split by the polarization beam splitter prism 8 and entering the first photodetector 9 and the second photodetector 10 can be represented as:

[0063]

[0064] Wherein θ is the optical rotation angle generated by the atomic spin precession in the alkali metal atom cell 5, the sum of the laser power detected by the two detectors is the detection laser power I emitted by the alkali metal atom cell 5, which can be used to measure the fluctuation of the detection laser frequency and then perform frequency stabilization control.

[0065] The position relationship of the NMR gyroscope detection laser power and frequency synchronous closed loop stable control system is as follows:

[0066] The light beam emitted by the collimated and expanded detection laser source 1 is sequentially in the advancing direction of the light beam: the first half-wave plate 2, the first polarization beam splitter prism 3, the polarization-independent beam splitter prism 4, the alkali metal atom cell 5, the second half-wave plate 7, and the second polarization beam splitter prism 8. The polarization-independent beam splitter prism 4 divides a detection laser into a third photodetector 11. The second polarization beam splitter prism 8 divides the detection laser after the alkali metal atom cell 5 into two beams, which enter the first photodetector 9 and the second photodetector 10, respectively. The detection laser emitted by the collimated and expanded detection laser source 1 is divided into two beams after the first half-wave plate 2, the first polarization beam splitter prism 3, and the polarization-independent beam splitter prism 4. One beam enters the third photodetector 11, which converts the optical signal into an electrical signal and sends it to the signal processing and control unit. The injection current of the collimated and expanded detection laser source 1 is adjusted to achieve stable control of the detection laser power. The other beam passes through the alkali metal atom cell and enters the balanced differential summing detector composed of the first photodetector 9, the second photodetector 10, the first operational amplifier, and the second operational amplifier. The differential signal is used to detect the atomic spin precession signal, and the summing signal reflects the change of the detection laser frequency. The summing signal is sent to the signal processing and control unit, and the temperature of the laser tube of the collimated and expanded detection laser source 1 is adjusted to achieve synchronous closed loop stable control of the detection laser frequency.

[0067] The structural diagram of the preferred embodiment of the present application is shown in Figure 1 The specific structure is as follows: the collimated and expanded detection laser source 1 is a DFB semiconductor laser with a wavelength of 795 nm, the first polarization beam splitter prism 3 is a calcite-made Glan-Taylor polarization prism with an extinction ratio better than 10 -5, for purifying the polarization purity of the detection laser line emitted by the collimated extended beam detection laser source 1, the splitting ratio of the polarization-independent beam splitter prism 4 is 1:1 to achieve the best detection laser power fluctuation monitoring effect, the second polarization beam splitter prism 8 selects a PBS polarization beam splitter prism, the signal processing and control module is composed of a digital signal processor, a digital-to-analog converter and an analog-to-digital converter, the third photoelectric detector 11 and the signal output by the second operational amplifier are converted into digital signals by the analog-to-digital converter, the digital signals are processed in the digital signal processor to realize the filtering processing of the detection laser power and frequency monitoring signals and the generation of the injection current and temperature PID decoupling control signals of the collimated extended beam detection laser source (1), the current and temperature PID decoupling control signals output by the digital signal processor are converted into analog signals by the digital-to-analog converter and output to the collimated extended beam detection laser source (1), completing the current and temperature control of the collimated extended beam detection laser source (1), and the three-dimensional magnetic field coil and the magnetic shielding cylinder 6 are composed of a Helmholtz coil and a permalloy magnetic shielding cylinder, providing a necessary magnetic field environment for nuclear spin magnetic resonance.

[0068] The working principle of the present application is as follows:

[0069] When detecting the laser power fluctuation, the photoelectric detector 11 detects the detection laser power fluctuation signal split by the polarization-independent beam splitter prism 4 as a feedback signal to realize the closed-loop stable control of the detection laser power by adjusting the injection current of the collimated extended beam detection laser source 1, and at the same time, when detecting the laser frequency fluctuation, the detection laser power emitted by the alkali metal atom cell 5 fluctuates, directly representing the detection laser frequency fluctuation, and the sum signal of the polarization balance beam splitting detection is used to measure the detection laser power fluctuation signal emitted by the alkali metal atom cell 5 to indirectly realize the measurement of the detection laser frequency fluctuation, and as a feedback signal, the synchronous closed-loop stable control of the detection laser frequency is realized by synchronously adjusting the controlled temperature of the collimated extended beam detection laser source 1.

[0070] In summary, the present application provides a nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method, when detecting laser power fluctuation, the photoelectric detector detects the detection laser power fluctuation signal as a feedback signal through the polarization independent beam splitter prism, and adjusts the injection current of the laser to realize the closed loop stable control of the detection laser power, at the same time, when detecting laser frequency fluctuation, the detection laser power fluctuation signal emitted from the alkali metal atom cell directly represents the detection laser frequency fluctuation, the sum signal of the polarization balance beam splitting detection measures the detection laser power fluctuation signal emitted from the alkali metal atom cell to indirectly realize the measurement of the detection laser frequency fluctuation, and the synchronous adjustment of the controlled temperature of the laser is used as a feedback signal to realize the synchronous closed loop stable control of the detection laser frequency. The system structure is simple and compact, easy to operate, and can meet the miniaturization demand of the nuclear magnetic resonance gyroscope. Therefore, compared with the prior art, the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method provided by the present application is simple and convenient to operate, the system structure is simple and compact, the detection laser power measurement signal is obtained by using the detection laser separated by the polarization independent beam splitter prism, the detection laser frequency measurement signal is obtained by using the power sum signal of the polarization balance beam splitting detection, and the synchronous closed loop control of the detection laser is realized by adjusting the injection current and the controlled temperature of the detection laser.

[0071] For the purposes of the description hereinafter, spatially relative terms, such as "above", "below", "up", "down", "between", "within", "left", "right", "rear", "front", "upper", "lower", "horizontal", "vertical", "above", "below", "on", "under", "in", "out", "right", "left", "forward", "backward", "upward", "downward", "up", "down", "front", "back", "side", "under" and the like, are used for ease of description to describe one element's or feature's spatial position relative to another element or feature as illustrated in the figures. It is to be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is inverted, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The terms "first", "second", "third", etc., do not necessarily indicate any ordinal, chronological or other sequence unless expressly stated to do so.

[0072] In addition, it should be noted that the use of "first", "second", and the like words to qualify components is merely for the convenience of distinguishing the corresponding components, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.

[0073] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A method for laser intensity and frequency synchronous closed-loop control of a nuclear magnetic resonance gyroscope, characterized in that, The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method comprises: A first half wave plate (2), a first polarization beam splitter prism (3), a polarization independent beam splitter prism (4), an alkali metal atom cell (5), a second half wave plate (7) and a second polarization beam splitter prism (8) are sequentially arranged along the direction of the light beam emitted by the collimated and expanded detection laser light source (1), a three-dimensional magnetic field coil and a magnetic shielding cylinder (6) are arranged outside the alkali metal atom cell (5), a first photodetector (9), a second photodetector (10), a first operational amplifier, a second operational amplifier, a third photodetector (11) and a signal processing and control unit are arranged, the first photodetector (9), the second photodetector (10), the first operational amplifier and the second operational amplifier constitute a balanced differential summing detector, the first operational amplifier is used for calculating the differential signal between the first photodetector (9) and the second photodetector (10), the second operational amplifier is used for calculating the summing signal between the first photodetector (9) and the second photodetector (10), the polarization independent beam splitter prism (4) splits a detection laser beam into the third photodetector (11), and the second polarization beam splitter prism (8) splits the detection laser beam after the alkali metal atom cell (5) into two beams which enter the first photodetector (9) and the second photodetector (10) respectively; The detection laser beam emitted by the collimated and expanded detection laser light source (1) is split into two beams after the first half wave plate (2), the first polarization beam splitter prism (3) and the polarization independent beam splitter prism (4), one beam enters the third photodetector (11), the third photodetector (11) converts the optical signal into an electrical signal and sends the electrical signal into the signal processing and control unit, and the injection current of the collimated and expanded detection laser light source (1) is adjusted to realize stable control of the detection laser power; the other beam enters the balanced differential summing detector after passing through the alkali metal atom cell, the differential signal is used for detecting the atomic spin precession signal, the summing signal reflects the change of the detection light frequency, the summing signal is sent into the signal processing and control unit, and the temperature of the laser tube of the collimated and expanded detection laser light source (1) is adjusted to realize synchronous closed loop stable control of the detection laser frequency.

2. The NMR gyroscope detection laser light intensity and frequency synchronous closed-loop control method according to claim 1, characterized in that, The relationship between the detection laser power entering the alkali metal atom cell (5) and the detection laser power emitted from the alkali metal atom cell (5) is as follows: I = I0e -nσ(v)L In the formula, I0 is the detection laser power before entering the alkali metal atom cell (5), I is the detection laser power emitted from the alkali metal atom cell (5), n is the alkali metal atom number density, L is the length of the laser passing through the alkali metal atom cell (5), and sigma (v) is an absorption cross section and satisfies the following formula: wherein v0 is the alkali metal atom resonance absorption frequency, v-v0 describes the amount of mismatch between the pumping laser frequency and the alkali metal atom resonance absorption frequency, c is the speed of light, r e is the electronic radius, f is the oscillator strength, Γ is the spectral line broadening, under the condition that the detection light intensity and the cell temperature are closed-loop stable control, I0 and n can be approximately constant, since there is a certain mismatch between the detection laser frequency v and the alkali metal atom resonance absorption frequency v0, the change of the detection laser power I emitted by the alkali metal atom cell (5) is approximately proportional to the change of the detection laser frequency v, which can be used to measure the fluctuation of the detection laser frequency and further perform frequency stabilization control. The laser powers of the two beams entering the first photodetector (9) and the second photodetector (10) through the polarization beam splitter prism (8) can be respectively represented as: where θ is the optical rotation angle generated by the atomic spin precession in the alkali metal atom cell (5), I9 is the laser power detected by the first photodetector (9), I 10 I10 is the laser power detected by the second photodetector (10), and I9+I10 is the sum of the laser powers detected by the two photodetectors. 10 That is, the detected laser power I emitted from the alkali metal atom cell (5) can be used to measure the fluctuation of the frequency of the detected laser and to perform frequency stabilization control.

3. The NMR gyroscope detection laser light intensity and frequency synchronous closed-loop control method according to claim 1, characterized in that, On the outside of the alkali metal atom cell (5) which contains Rb or Cs alkali metal atoms, buffer gas N2, inert gas atoms, a non-magnetic electric heating film is provided 129 Xe and 131 Xe.

4. The NMR gyroscope detection laser light intensity and frequency synchronous closed-loop control method according to claim 1, characterized in that, The laser wavelength emitted by the collimated extended beam detection laser source (1) is tuned to be 0.1-0.3 nm detuned from the corresponding wavelength of the alkali atom absorption spectral line D1 line.

5. The NMR gyroscope detection laser light intensity and frequency synchronous closed-loop control method according to claim 4, characterized in that, The first polarization beam-splitting prism (3) is a calcite-made Glan-Taylor polarization prism, the second polarization beam-splitting prism (8) is a PBS polarization beam-splitting prism, and the polarization-independent beam-splitting prism (4) has a beam-splitting ratio of 1:1, so as to achieve the best detection laser power fluctuation monitoring effect.

6. The NMR gyroscope detection laser light intensity and frequency synchronous closed-loop control method according to claim 5, characterized in that, The three-dimensional magnetic field coil and the magnetic shielding cylinder (6) are composed of a Helmholtz coil and a permalloy magnetic shielding cylinder, and provide a necessary magnetic field environment for nuclear spin magnetic resonance.

7. The NMR gyroscope laser intensity and frequency synchronous closed-loop control method of claim 6, wherein, The signal processing and control module is composed of a digital signal processor, a digital-to-analog converter and an analog-to-digital converter. The signal output by the third photoelectric detector (11) and the second operational amplifier is converted into a digital signal by the analog-to-digital converter, and the digital signal enters the digital signal processor for processing, so as to realize the filtering processing of the detection laser power and frequency monitoring signal and the generation of the injection current and temperature PID decoupling control signal of the collimated extended beam detection laser source (1). The current and temperature PID decoupling control signal output by the digital signal processor is converted into an analog signal by the digital-to-analog converter and output to the collimated extended beam detection laser source (1), so as to complete the current and temperature control of the collimated extended beam detection laser source (1).

8. A nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system, characterized in that, The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system uses the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control method of any one of claims 1 to 7 to perform nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control, and the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system comprises a collimated beam detection laser light source (1), a first half-wave plate (2), a first polarization beam splitter prism (3), a polarization-independent beam splitter prism (4), an alkali metal atom cell (5), a three-dimensional magnetic field coil and magnetic shielding cylinder (6), a second half-wave plate (7), a second polarization beam splitter prism (8), a first photodetector (9), a second photodetector (10), a first operational amplifier, a second operational amplifier, a third photodetector (11), and a signal processing and control unit; wherein the first photodetector (9), the second photodetector (10), the first operational amplifier, and the second operational amplifier constitute a balanced differential summing detector, the first operational amplifier is used to calculate the differential signal between the first photodetector (9) and the second photodetector (10), and the second operational amplifier is used to calculate the summing signal between the first photodetector (9) and the second photodetector (10); the detection laser emitted by the collimated beam detection laser light source (1) is split into two beams after passing through the first half-wave plate (2), the polarization beam splitter prism (3), and the polarization-independent beam splitter prism (4), one of the two beams enters the third photodetector (11), the third photodetector (11) converts the optical signal into an electrical signal and sends it to the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimated beam detection laser light source (1); the other beam enters the balanced differential summing detector after passing through the alkali metal atom cell (5), the differential signal is used to detect the atomic spin precession signal, the summing signal reflects the change of the detection light frequency, the summing signal is sent to the signal processing and control unit, and the synchronous closed-loop stable control of the detection laser frequency is realized by adjusting the laser tube temperature of the collimated beam detection laser light source (1).

9. A method for laser intensity and frequency synchronous closed-loop control of a nuclear magnetic resonance gyroscope, characterized in that, The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control method comprises: A first half-wave plate, a first polarization beam splitter prism, a first polarization independent beam splitter prism, an alkali metal atom cell, a second half-wave plate, a second polarization independent beam splitter prism and a second polarization beam splitter prism are arranged in sequence along the direction of the light beam emitted by the collimated and expanded detection laser source, a three-dimensional magnetic field coil and a magnetic shielding cylinder are arranged outside the alkali metal atom cell, a first photodetector, a second photodetector, an operational amplifier, a third photodetector, a fourth photodetector and a signal processing and control unit are arranged, the operational amplifier is used to calculate the differential signal between the first photodetector and the second photodetector, the differential signal is used to detect the atomic spin precession signal, the first polarization independent beam splitter prism splits a detection laser beam to enter the third photodetector, and the second polarization beam splitter prism splits the detection laser beam after passing through the alkali metal atom cell into two beams to enter the first photodetector and the second photodetector respectively; The detection laser emitted by the collimated and expanded detection laser source passes through the first half-wave plate, the first polarization beam splitter prism and the polarization independent beam splitter prism to be split into two beams, one of which enters the third photodetector, the third photodetector converts the optical signal into an electrical signal and sends it to the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimated and expanded detection laser source; the other beam passes through the alkali metal atom cell and then enters the fourth photodetector through the second polarization independent beam splitter prism, the fourth photodetector is used to detect the detection laser power emitted by the alkali metal atom cell, and the signal output by the fourth photodetector is sent to the signal processing and control unit, and the synchronous closed-loop stable control of the detection laser frequency is realized by adjusting the temperature of the laser tube of the collimated and expanded detection laser source.

10. A nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed-loop control system, characterized in that, The nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system uses the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control method as claimed in claim 9 to perform nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control, and the nuclear magnetic resonance gyroscope detection laser light intensity and frequency synchronous closed loop control system comprises a collimated beam expanding detection laser light source, a first half wave plate, a first polarization beam splitter prism, a first polarization independent beam splitter prism, an alkali metal atom gas cell, a three-dimensional magnetic field coil and a magnetic shielding cylinder, a second half wave plate, a second polarization independent beam splitter prism, a fourth photodetector, a second polarization beam splitter prism, a first photodetector, a second photodetector, an operational amplifier, a third photodetector and a signal processing and control unit; the operational amplifier is used to calculate the differential signal between the first photodetector and the second photodetector, and the differential signal is used to detect the atomic spin precession signal; the detection laser emitted by the collimated beam expanding detection laser light source is split into two beams after passing through the first half wave plate, the first polarization beam splitter prism and the first polarization independent beam splitter prism, one of the two beams enters the third photodetector, the third photodetector converts the optical signal into an electrical signal and sends the electrical signal to the signal processing and control unit, and the stable control of the detection laser power is realized by adjusting the injection current of the collimated beam expanding detection laser light source; the other beam enters the fourth photodetector after passing through the alkali metal atom gas cell and the second polarization independent beam splitter prism, the fourth photodetector is used to detect the detection laser power emitted by the alkali metal atom gas cell, and the signal output by the fourth photodetector is sent to the signal processing and control unit, and the synchronous closed loop stable control of the detection laser frequency is realized by adjusting the laser tube temperature of the collimated beam expanding detection laser light source.

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