Decoupling phase closed-loop locking nuclear magnetic resonance gyroscope

Abstract

The invention provides a decoupling phase closed-loop locking nuclear magnetic resonance gyroscope, and particularly relates to a nuclear magnetic resonance gyroscope based on modulation and demodulation of an alternating current reference line magnetic field, which is characterized in that an alternating current reference modulation magnetic field different from nuclear spin resonance frequency is applied along the direction of detection light; meanwhile, alternating current modulation is conducted on the decoupling phase of the nuclear magnetic resonance gyroscope electron paramagnetic resonance magnetometer, alternating current reference modulation amplitude changes are demodulated, a decoupling phase error signal is obtained, and real-time closed-loop locking of the decoupling phase is achieved through a closed-loop control system based on the error signal. According to the invention, real-time closed-loop locking of the decoupling phase of the nuclear magnetic resonance gyroscope can be realized, and decoupling phase fluctuation caused by fluctuation of system parameters such as laser power, frequency and air chamber temperature is inhibited, so that the angular rate measurement precision and long-term stability of the nuclear magnetic resonance gyroscope are improved. According to the technical scheme, the technical problems that in the prior art, a double-shaft differential detection method is prone to being affected by amplitude fluctuation, large errors exist, and operation is complex are solved.

Description

Technical Field

[0001] The invention relates to the field of quantum sensing technology, and in particular to a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope. Background Art

[0002] The nuclear magnetic resonance gyroscope is a type of atomic spin gyroscope that uses the invariance of the magnetic resonance frequency of the spin of inert gas nuclei in inertial space to measure the angular velocity of the carrier. It has the advantages of high theoretical accuracy, small size and low cost. With the development of quantum precision control, micromachining and laser technology, the nuclear magnetic resonance gyroscope is expected to break through the bottleneck of large size and high cost of traditional mechanical and optical gyroscopes, and is an important development direction of miniaturized high-precision gyroscope technology.

[0003] In a nuclear magnetic resonance gyroscope, since it is not easy to directly manipulate the nuclear spin with a light field, the magnetic resonance signal of the nuclear spin needs to be detected by a paramagnetic resonance magnetometer composed of the electron spins of alkali metal atoms, and a self-excited oscillation loop is formed. In this process, it is necessary to adjust the demodulation phase of the electron paramagnetic resonance magnetometer to achieve decoupled measurement of the precession signal and magnetic field excitation signal of the nuclear spin along the direction of the detection light and perpendicular to the direction of the detection light. This phase is usually called the decoupling phase. When the laser power, frequency and gas chamber temperature fluctuate, the decoupling phase will fluctuate accordingly, which will cause the self-excited oscillation phase to fluctuate, causing the nuclear spin magnetic resonance frequency to fluctuate, and then causing a large error when the gyroscope measures the angular velocity, and the long-term stability of the gyroscope deteriorates. How to achieve real-time closed-loop locking of the decoupling phase is a key problem in improving the accuracy of the nuclear magnetic resonance gyroscope. In the existing technology [1] (Lei, Guanqun, et al. The key to the accuracy of the vibrating gyroscope is me stabilization of the alkali-metal transverse axis orientation in nuclear spin comagnetometer by biaxial differential detection.” AIP Advances 11.9 (2021): 095016.), the decoupling phase change is mainly monitored by the dual-axis differential detection method, that is, by monitoring the amplitude difference of the rotating magnetic field projection and performing online compensation. However, this method is easily affected by amplitude fluctuations in practice and has large errors. The improvement of the long-term stability of the nuclear magnetic gyroscope is relatively limited, and the operation is relatively complicated. Summary of the invention

[0004] The present invention provides a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope, which can solve the technical problems that the dual-axis differential detection method in the prior art is easily affected by amplitude fluctuations in practice, has large errors, has limited improvement on the long-term stability of the nuclear magnetic gyroscope, and is relatively complicated to operate.

[0005] The invention provides a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope, which comprises a detection light source module, a driving light source module, a magnetic shielding tube, a three-dimensional magnetic field coil, a heating film, an atomic gas chamber, a polarization balance beam splitting detection module, a first paramagnetic resonance magnetometer carrier demodulation module, a Bxr AC modulation reference line magnetic field response amplitude demodulation module, a decoupled phase error signal demodulation module, a decoupled phase modulator, a phase shifter, a decoupled phase PID controller, a Bz magnetic field generator, a second paramagnetic resonance magnetometer carrier demodulation module, an angular rate ... Linear magnetic field generator and nuclear spin excitation magnetic field Bxj generator, heating film and magnetic shielding barrel are arranged outside the atomic gas chamber, the heating film is used to heat the atomic gas chamber, and the magnetic shielding barrel is used to shield external magnetic interference; the driving light source module emits circularly polarized driving laser, the frequency of which is tuned to the alkali metal atom D1 line contained in the atomic gas chamber, and the spin-polarized alkali metal atom electron spin is pumped by spin exchange light, and the spin-polarized alkali metal atom electron spin is then hyperpolarized by spin exchange collision to cause the inert gas atomic nucleus spin; the detection light source module emits linear polarization detection laser, which enters the polarization balance beam splitting detection module after passing through the atomic gas chamber. The polarization balanced beam splitting detection module includes a λ / 2 wave plate, a polarization beam splitter prism, a first photodetector and a second photodetector. The detection light emitted from the atomic gas chamber is divided into two beams after passing through the λ / 2 wave plate and the polarization beam splitter prism and enters the first photodetector and the second photodetector respectively. The precession signal of the electron spin of the alkali metal atom is obtained according to the differential signal detected by the first photodetector and the second photodetector. Since there is a Fermi interaction between the electron spin of the alkali metal atom and the nuclear spin of the inert gas atom, the signal carries a nuclear spin magnetic resonance signal, thereby indirectly realizing the detection of the nuclear spin magnetic resonance signal. The measuring frequency is detuned by 0.1 to 0.3 nm relative to the D1 line of alkali metal atoms to ensure that the intensity of the optical rotation detection response signal at the detuning position is at the maximum point; the Bz magnetic field generator, the Bxr AC modulation reference line magnetic field generator, the phase shifter, the first paramagnetic resonance magnetometer carrier demodulation module, the Bxr AC modulation reference line magnetic field response amplitude demodulation module, the decoupling phase error signal demodulation module, the decoupling phase modulator and the decoupling phase PID controller constitute a nuclear magnetic resonance gyroscope decoupling phase closed-loop locking system; the Bz magnetic field generator outputs a current signal to generate a main magnetic field B along the z-axis direction through the z-axis magnetic field coil z0 and paramagnetic resonance modulated magnetic field B c cos(ω c t), the amplitude of the modulated magnetic field B c Can be set to main magnetic field B z The frequency is between 1 and 1.8 times of that of the electron spin of the alkali metal atom in the main magnetic field B. z0 The magnetic resonance frequency in the magnetic field makes the electron spin in the paramagnetic resonance state, and on the other hand, it generates the carrier demodulation reference signal cos(ω ct), carrier demodulation reference signal cos(ω c t) The decoupled phase is superimposed on the signal phase after the phase shifter to obtain the carrier demodulation reference signal of the carrier demodulation module of the second paramagnetic resonance magnetometer The reference signal is simultaneously passed through a decoupling phase modulator to generate a carrier demodulation reference signal of a first paramagnetic resonance magnetometer carrier demodulation module. The Bxr AC modulated reference line magnetic field generator generates an AC modulated current signal of the reference line magnetic field, and the nuclear spin excitation magnetic field Bxj generator generates a nuclear spin excitation magnetic field current signal. The reference line magnetic field AC modulated current signal and the nuclear spin excitation magnetic field current signal are superimposed and applied to the coil in the x-axis direction to generate an AC modulated reference line magnetic field Bxr and a nuclear spin excitation magnetic field Bxj along the x-axis direction. At the same time, the Bxr AC modulated reference line magnetic field generator also generates an AC modulated reference signal that enters the Bxr AC modulated reference line magnetic field response amplitude demodulation module for demodulating the response amplitude of the paramagnetic resonance magnetometer to the AC modulated reference line magnetic field Bxr. The nuclear spin excitation magnetic field Bxj generator also generates a nuclear spin excitation signal that enters the angular rate demodulation module; the differential signal detected by the first photodetector and the second photodetector simultaneously enters the first paramagnetic resonance magnetometer carrier demodulation module and the second paramagnetic resonance magnetometer carrier demodulation module, and the first paramagnetic resonance magnetometer carrier demodulation module compares the received differential signal with the carrier demodulation reference signal. After mixing and low-pass filtering, it enters the Bxr AC modulation reference line magnetic field response amplitude demodulation module, mixes and low-pass filters with the AC modulation reference signal generated by the Bxr AC modulation reference line magnetic field generator, and finally enters the decoupled phase error signal demodulation module to mix and low-pass filter with the decoupled phase modulation reference signal generated by the decoupled phase modulator, thereby obtaining a decoupled phase error signal. The decoupled phase error signal Enter the decoupling phase PID controller to generate a control signal through the PID algorithm to adjust the decoupling phase generated by the phase shifter to decouple the phase error signal The second paramagnetic resonance magnetometer carrier demodulation module compares the received differential signal with the carrier demodulation reference signal. After mixing and low-pass filtering, it enters the angular rate demodulation module and is mixed and low-pass filtered with the nuclear spin excitation signal generated by the nuclear spin excitation magnetic field Bxj generator to obtain the gyro angular rate ω R The measurement signal.

[0006] Furthermore, the nuclear spin excitation magnetic field Bxj generator generates an output current signal to generate a nuclear spin magnetic resonance excitation magnetic field along the x-axis direction through the x-axis magnetic field coil, continuously exciting the nuclear spins to be in a magnetic resonance state in the main magnetic field.

[0007] Furthermore, the frequency of the Bxr AC modulation reference line magnetic field generator is greater than the nuclear spin resonance frequency by more than 50 Hz to facilitate phase-locked demodulation.

[0008] Furthermore, the first paramagnetic resonance magnetometer carrier demodulation module and the second paramagnetic resonance magnetometer carrier demodulation module are both composed of a digital mixer and a digital low-pass filter, the first paramagnetic resonance magnetometer carrier demodulation module is used to demodulate the magnetometer signal after decoupling phase modulation, and provide signal input for Bxr AC modulation reference line magnetic field response amplitude demodulation and decoupling phase error signal demodulation; the second paramagnetic resonance magnetometer carrier demodulation module is used to demodulate the electron paramagnetic resonance magnetometer signal whose decoupling phase is not modulated, and is used to demodulate the nuclear spin magnetic resonance signal to avoid the influence of decoupling phase modulation on it.

[0009] Furthermore, the decoupling phase modulation frequency generated by the decoupling phase modulator is within the carrier demodulation low-pass filter bandwidth of the paramagnetic resonance magnetometer to ensure that the carrier demodulation output signal of the paramagnetic resonance magnetometer contains the response signal generated by the decoupling phase modulation.

[0010] Furthermore, the decoupled phase modulation amplitude generated by the decoupled phase modulator It can be set within ±5° to avoid excessive modulation amplitude causing nonlinear effects in the carrier demodulation of the paramagnetic resonance magnetometer.

[0011] Furthermore, the decoupled phase error signal demodulation module is composed of a digital mixer and a digital low-pass filter, and is used to demodulate the decoupled phase error signal.

[0012] Furthermore, the angular rate demodulation module is composed of a digital mixer, a digital low-pass filter and an inverse tangent operator, and the gyro angular rate ω is obtained by orthogonal demodulation. R The measurement signal.

[0013] By applying the technical solution of the present invention, a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope is provided. In the nuclear magnetic resonance gyroscope, the decoupled phase represents a demodulation phase in which a paramagnetic resonance magnetometer is least sensitive to a magnetic field along a detection light direction and most sensitive to a magnetic field along a direction perpendicular to the detection light and the driving light. By utilizing the characteristic that the paramagnetic resonance magnetometer is insensitive to the detection light direction at the decoupled phase, an AC modulated reference magnetic field is applied in the detection light direction, and the decoupled phase is modulated at the same time. The response amplitude change of the demodulated paramagnetic resonance magnetometer to the AC modulated magnetic field is used as an error signal of the decoupled phase. When the error signal is zero, the response amplitude of the AC modulated magnetic field remains unchanged, and the demodulated phase is at the decoupled phase. By utilizing the signal, real-time closed-loop locking of the decoupled phase can be achieved, thereby suppressing the measurement error of the nuclear magnetic resonance gyroscope caused by the fluctuation of the decoupled phase. The modulation and demodulation method of the present invention can realize real-time closed-loop locking of the decoupling phase of the nuclear magnetic resonance gyroscope. The locking point is the only zero-crossing point where the change in the magnetic field response degree of the AC modulation line in the direction of the detection light of the electronic paramagnetic resonance magnetometer is the smallest. It is not easily affected by the fluctuation of the amplitude of the response signal, has higher locking accuracy, and is relatively simple in structure and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 A schematic structural diagram of a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope provided according to a specific embodiment of the present invention is shown.

[0016] The above drawings include the following reference numerals:

[0017] 1-detection laser module, 2-driving laser module, 3-magnetic shielding tube, 4-magnetic field coil, 5-heating film, 6-atomic gas chamber, 7-polarization balance detection module, 8-first paramagnetic resonance magnetometer carrier demodulation module, 9-Bxr AC modulation reference line magnetic field response amplitude demodulation module, 10-decoupling phase error signal demodulation module, 11-decoupling phase modulator, 12-phase shifter, 13-decoupling phase PID controller, 14-Bz magnetic field generator, 15-second paramagnetic resonance magnetometer carrier demodulation module, 16-angular rate demodulation module, 17-Bxr AC modulation reference line magnetic field generator, 18-nuclear spin excitation magnetic field Bxj generator. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0021] like Figure 1As shown, according to a specific embodiment of the present invention, a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope is provided, and the decoupled phase closed-loop locked nuclear magnetic resonance gyroscope includes a detection light source module 1, a driving light source module 2, a magnetic shielding tube 3, a three-dimensional magnetic field coil 4, a heating film 5, an atomic gas chamber 6, a polarization balance beam splitting detection module 7, a first paramagnetic resonance magnetometer carrier demodulation module 8, a Bxr AC modulation reference line magnetic field response amplitude demodulation module 9, a decoupled phase error signal demodulation module 10, a decoupled phase modulator 11, a phase shifter 12, a decoupled phase PID controller 13, a Bz magnetic field generator 14, a second paramagnetic resonance magnetometer carrier demodulation module 15, an angular rate The demodulation module 16, the Bxr AC modulation reference line magnetic field generator 17 and the nuclear spin excitation magnetic field Bxj generator 18, the heating film 5 and the magnetic shielding barrel 3 are arranged outside the atomic gas chamber 6, the heating film 5 is used to heat the atomic gas chamber 6, and the magnetic shielding barrel 3 is used to shield the external magnetic interference; the driving light source module 2 emits a circularly polarized driving laser, the frequency of which is tuned to the alkali metal atom D1 line contained in the atomic gas chamber, and the spin-polarized alkali metal atom electron spin is pumped by spin exchange light, and the spin-polarized alkali metal atom electron spin is then hyperpolarized by spin exchange collision. The spin of the inert gas nucleus is hyperpolarized; the detection light source module 1 emits a linear polarization detection laser, which enters the polarization laser after passing through the atomic gas chamber 6. The polarization-balanced beam splitting detection module 7 comprises a λ / 2 wave plate a, a polarization beam splitting prism b, a first photodetector c and a second photodetector d. The detection light emitted from the atomic gas chamber 6 is divided into two beams after passing through the λ / 2 wave plate a and the polarization beam splitting prism b, and enters the first photodetector c and the second photodetector d respectively. The precession signal of the electron spin of the alkali metal atom is obtained according to the differential signal detected by the first photodetector c and the second photodetector d. Since there is a Fermi interaction between the electron spin of the alkali metal atom and the nuclear spin of the inert gas atom, the signal carries a nuclear spin magnetic resonance signal, thereby indirectly realizing the nuclear spin magnetic resonance signal detection. The detection frequency is detuned by 0.1 to 0.3 nm relative to the alkali metal atom D1 line to ensure that the intensity of the optical rotation detection response signal at the detuned position is at the maximum point; the Bz magnetic field generator 14, the Bxr AC modulation reference line magnetic field generator 17, the phase shifter 12, the first paramagnetic resonance magnetometer carrier demodulation module 8, the Bxr AC modulation reference line magnetic field response amplitude demodulation module 9, the decoupling phase error signal demodulation module 10, the decoupling phase modulator 11 and the decoupling phase PID controller 13 constitute a nuclear magnetic resonance gyro decoupling phase closed-loop locking system; the Bz magnetic field generator 14 outputs a current signal through the z-axis magnetic field coil to generate a main magnetic field B along the z-axis direction z0 and paramagnetic resonance modulated magnetic field B c cos(ω c t), the amplitude of the modulated magnetic field B c Can be set to main magnetic field B z The frequency is between 1 and 1.8 times of that of the electron spin of the alkali metal atom in the main magnetic field B.z0 The magnetic resonance frequency in the magnetic field makes the electron spin in the paramagnetic resonance state, and on the other hand, it generates the carrier demodulation reference signal cos(ω c t), carrier demodulation reference signal cos(ω c t) The decoupled phase is superimposed on the signal phase after the phase shifter 12 to obtain the carrier demodulation reference signal of the second paramagnetic resonance magnetometer carrier demodulation module 15 The reference signal is simultaneously passed through the decoupling phase modulator 11 to generate a carrier demodulation reference signal of the first paramagnetic resonance magnetometer carrier demodulation module 8 The Bxr AC modulated reference line magnetic field generator 17 generates a reference line magnetic field AC modulated current signal, and the nuclear spin excitation magnetic field Bxj generator 18 generates a nuclear spin excitation magnetic field current signal. The reference line magnetic field AC modulated current signal and the nuclear spin excitation magnetic field current signal are superimposed and applied to the coil in the x-axis direction to generate an AC modulated reference line magnetic field Bxr and a nuclear spin excitation magnetic field Bxj along the x-axis direction. At the same time, the Bxr AC modulated reference line magnetic field generator 17 also generates an AC modulated reference signal and enters the Bxr AC modulated reference line magnetic field response amplitude demodulation module 9 for demodulating the response amplitude of the paramagnetic resonance magnetometer to the AC modulated reference line magnetic field Bxr. The nuclear spin excitation magnetic field Bxj generator 18 also generates a nuclear spin excitation signal and enters the angular rate demodulation module 16; the differential signal detected by the first photodetector c and the second photodetector d simultaneously enters the first paramagnetic resonance magnetometer carrier demodulation module 8 and the second paramagnetic resonance magnetometer carrier demodulation module 15, and the first paramagnetic resonance magnetometer carrier demodulation module 8 compares the received differential signal with the carrier demodulation reference signal. After mixing and low-pass filtering, it enters the Bxr AC modulation reference line magnetic field response amplitude demodulation module 9, mixes and low-pass filters with the AC modulation reference signal generated by the Bxr AC modulation reference line magnetic field generator 17, and finally enters the decoupled phase error signal demodulation module 10 to mix and low-pass filter with the decoupled phase modulation reference signal generated by the decoupled phase modulator 11, thereby obtaining a decoupled phase error signal The decoupled phase error signal Entering the decoupling phase PID controller 13 generates a control signal through the PID algorithm to adjust the decoupling phase generated by the phase shifter 12 to decouple the phase error signal The second paramagnetic resonance magnetometer carrier demodulation module 15 compares the received differential signal with the carrier demodulation reference signal After mixing and low-pass filtering, it enters the angular rate demodulation module 16, and is mixed and low-pass filtered with the nuclear spin excitation signal generated by the nuclear spin excitation magnetic field Bxj generator 18 to obtain the gyro angular rate ω R The measurement signal.

[0022] By applying this configuration, a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope is provided. In the nuclear magnetic resonance gyroscope, the decoupled phase represents the demodulation phase at which the paramagnetic resonance magnetometer is least sensitive to the magnetic field along the direction of the detection light, but most sensitive to the magnetic field along the perpendicular direction of the detection light and the driving light. By utilizing the characteristic that the paramagnetic resonance magnetometer is insensitive to the direction of the detection light at the decoupled phase, an AC modulated reference magnetic field is applied in the direction of the detection light, and the decoupling phase is modulated at the same time. The response amplitude change of the demodulated paramagnetic resonance magnetometer to the AC modulated magnetic field is used as an error signal of the decoupling phase. When the error signal is zero, the response amplitude of the AC modulated magnetic field remains unchanged, and the demodulated phase is at the decoupling phase. By utilizing this signal, real-time closed-loop locking of the decoupling phase can be achieved, thereby suppressing the measurement error of the nuclear magnetic resonance gyroscope caused by the fluctuation of the decoupling phase. The modulation and demodulation method of the present invention can realize real-time closed-loop locking of the decoupling phase of the nuclear magnetic resonance gyroscope. The locking point is the only zero-crossing point where the change in the magnetic field response degree of the AC modulation line in the direction of the detection light of the electronic paramagnetic resonance magnetometer is the smallest. It is not easily affected by the fluctuation of the amplitude of the response signal, has higher locking accuracy, and is relatively simple in structure and operation.

[0023] Furthermore, the nuclear spin excitation magnetic field Bxj generator 18 generates an output current signal to generate a nuclear spin magnetic resonance excitation magnetic field along the x-axis direction through the x-axis magnetic field coil, continuously exciting the nuclear spins to be in a magnetic resonance state in the main magnetic field.

[0024] The frequency of the Bxr AC modulation reference line magnetic field generator 17 is greater than the nuclear spin resonance frequency by more than 50 Hz to facilitate phase-locked demodulation.

[0025] Furthermore, in the present invention, the first paramagnetic resonance magnetometer carrier demodulation module 8 and the second paramagnetic resonance magnetometer carrier demodulation module 15 are both composed of a digital mixer. and a digital low-pass filter, the first paramagnetic resonance magnetometer carrier demodulation module 8 is used to demodulate the magnetometer signal after decoupling phase modulation, and provide signal input for Bxr AC modulation reference line magnetic field response amplitude demodulation and decoupling phase error signal demodulation; the second paramagnetic resonance magnetometer carrier demodulation module 15 is used to demodulate the electron paramagnetic resonance magnetometer signal whose decoupling phase is not modulated, and is used to demodulate the nuclear spin magnetic resonance signal to avoid the influence of decoupling phase modulation on it.

[0026] In addition, the decoupling phase modulation frequency generated by the decoupling phase modulator 11 is within the paramagnetic resonance magnetometer carrier demodulation low-pass filter bandwidth to ensure that the paramagnetic resonance magnetometer carrier demodulation output signal contains the response signal generated by the decoupling phase modulation.

[0027] Furthermore, the decoupling phase modulation amplitude generated by the decoupling phase modulator 11 is It can be set within ±5° to avoid excessive modulation amplitude causing nonlinear effects in the carrier demodulation of the paramagnetic resonance magnetometer.

[0028] In addition, the decoupled phase error signal demodulation module 10 is composed of a digital mixer and a digital low-pass filter, and is used to demodulate the decoupled phase error signal.

[0029] Specifically, in the present invention, the angular rate demodulation module 16 is composed of a digital mixer, a digital low-pass filter and an inverse tangent operator, and the gyro angular rate ω is obtained by orthogonal demodulation. R The measurement signal.

[0030] In order to further understand the present invention, the following Figure 1 The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope provided by the present invention is described in detail.

[0031] like Figure 1 As shown, in order to overcome the shortcomings of the prior art, the present invention proposes to use a nuclear magnetic resonance gyro electronic paramagnetic resonance magnetometer to measure the amplitude change of the AC reference line magnetic field under decoupled phase modulation, and realize a method for real-time closed-loop locking of the decoupled phase based on the characteristic that the amplitude change at the phase decoupling point is zero, thereby avoiding the introduction of a large amplitude error in the decoupled phase closed-loop locking process and realizing high-precision real-time closed-loop locking of the decoupled phase.

[0032] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope based on AC reference line magnetic field modulation and demodulation, so as to improve the locking accuracy and stability of the decoupled phase, so as to suppress the influence of the decoupled phase fluctuation caused by the laser power, frequency and gas chamber temperature fluctuation on the stability of the nuclear magnetic resonance gyroscope, thereby improving the long-term stability of the nuclear magnetic resonance gyroscope.

[0033] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0034] A decoupled phase closed-loop locked nuclear magnetic resonance gyroscope, characterized in that it includes: a detection light source module 1, a driving light source module 2, a magnetic shielding tube 3, a three-dimensional magnetic field coil 4, a heating film 5, an atomic gas chamber 6, a polarization balanced beam splitting detection module 7, a first paramagnetic resonance magnetometer carrier demodulation module 8, a Bxr AC modulation reference line magnetic field response amplitude demodulation module 9, a decoupled phase error signal demodulation module 10, a decoupled phase modulator 11, a phase shifter 12, a decoupled phase PID controller 13, a Bz magnetic field generator 14, a second paramagnetic resonance magnetometer carrier demodulation module 15, an angular rate demodulation module Block 16, Bxr AC modulated reference line magnetic field generator 17 and nuclear spin excitation magnetic field Bxj generator 18, wherein the driving light source module 2 emits circularly polarized driving laser, the frequency of which is tuned to the alkali metal atom D1 line contained in the atomic gas chamber, and the spin-polarized alkali metal atom electron spin is pumped by spin exchange light, and the spin-polarized alkali metal atom electron spin is then hyperpolarized by spin exchange collision to cause the inert gas atomic nucleus spin; the detection light source module 1 emits a linear polarization detection laser, which enters the balanced beam splitting polarization detection module 7 after passing through the gas chamber, and the module includes a λ / 2 wave plate a, a polarization beam splitter prism b, and a first photoelectric The detection light emitted from the atomic gas chamber 6 passes through λ, 2 wave plates a and polarization beam splitter prism b, and is divided into two beams, which enter the first photodetector c and the second photodetector d respectively. The precession signal of the electron spin of the alkali metal atom is obtained according to the differential signal detected by the first photodetector and the second photodetector. Since there is a Fermi interaction between the electron spin of the alkali metal atom and the nuclear spin of the inert gas atom, the signal carries the nuclear spin magnetic resonance signal, and thus the nuclear spin magnetic resonance signal detection can be indirectly realized. The detection frequency is detuned by 0.1 to 0.1 relative to the D1 line of the alkali metal atom. 0.3nm, to ensure that the intensity of the optical rotation detection response signal at the detuning position is at the maximum point; Bz magnetic field generator 14, Bxr AC modulation reference line magnetic field generator 17, phase shifter 12, first paramagnetic resonance magnetometer carrier demodulation module 8, Bxr AC modulation reference line magnetic field response amplitude demodulation module 9, decoupling phase error signal demodulation module 10, decoupling phase modulator 11, decoupling phase PID controller 13 constitute a nuclear magnetic resonance gyro decoupling phase closed-loop locking system; Bz magnetic field generator 14 outputs a current signal through the z-axis magnetic field coil to generate a main magnetic field B along the z-axis direction z0 and paramagnetic resonance modulated magnetic field B c cos(ω c t), the amplitude of the modulated magnetic field B c Can be set to main magnetic field B z The frequency is between 1 and 1.8 times of that of the electron spin of the alkali metal atom in the main magnetic field B. z0 The magnetic resonance frequency in the magnetic field makes the electron spin in the paramagnetic resonance state, and on the other hand, it generates the carrier demodulation reference signal cos(ω ct), the signal is superimposed on the decoupled phase after passing through the phase shifter 12 to obtain the carrier demodulation reference signal of the second paramagnetic resonance magnetometer carrier demodulation module 15 The reference signal is simultaneously passed through the decoupling phase modulator 11 to generate a carrier demodulation reference signal of the first paramagnetic resonance magnetometer carrier demodulation module 8 The Bxr AC modulated reference line magnetic field generator 17 and the nuclear spin excitation magnetic field Bxj generator 18 generate a reference line magnetic field AC modulated current signal and a nuclear spin excitation magnetic field current signal respectively. The two are superimposed and applied to the coil in the x-axis direction to generate an AC modulated reference line magnetic field Bxr and a nuclear spin excitation magnetic field Bxj along the x-axis direction. At the same time, the Bxr AC modulated reference line magnetic field generator 17 also generates an AC modulated reference signal that enters the Bxr AC modulated reference line magnetic field response amplitude demodulation module 9 for the paramagnetic resonance magnetometer to demodulate the response amplitude of the AC modulated reference line magnetic field Bxr. The nuclear spin excitation magnetic field Bxj generator 18 also generates a nuclear spin excitation signal that enters the angular velocity demodulation module 16. The differential signal detected by the first photodetector and the second photodetector simultaneously enters the first paramagnetic resonance magnetometer carrier demodulation module 8 and the second paramagnetic resonance magnetometer carrier demodulation module 15. The first paramagnetic resonance magnetometer carrier demodulation module 8 compares the received differential signal with the carrier demodulation reference signal. After mixing and low-pass filtering, it enters the Bxr AC modulation reference line magnetic field response amplitude demodulation module 9, mixes and low-pass filters with the AC modulation reference signal generated by the Bxr AC modulation reference line magnetic field generator 17, and finally enters the decoupled phase error signal demodulation module 10 to mix and low-pass filter with the decoupled phase modulation reference signal generated by the decoupled phase modulator 11, thereby obtaining a decoupled phase error signal The error signal enters the decoupling phase PID controller and generates a control signal through the PID algorithm to adjust the decoupling phase generated by the phase shifter to decouple the phase error signal The second paramagnetic resonance magnetometer carrier demodulation module 15 compares the received differential signal with the carrier demodulation reference signal After mixing and low-pass filtering, it enters the angular rate demodulation module 16, and is mixed and low-pass filtered with the nuclear spin excitation signal generated by the nuclear spin excitation magnetic field Bxj generator 18 to obtain the gyro angular rate ω R The measurement signal.

[0035] The nuclear spin excitation magnetic field Bxj generator 18 generates an output current signal to generate a nuclear spin magnetic resonance excitation magnetic field along the x-axis direction through the x-axis magnetic field coil, continuously exciting the nuclear spins to be in a magnetic resonance state in the main magnetic field.

[0036] The frequency of the Bxr AC modulation reference line magnetic field generator 17 is greater than the nuclear spin resonance frequency by more than 50 Hz to facilitate phase-locked demodulation, and the amplitude is substantially the same as the nuclear spin excitation magnetic field amplitude to ensure that it is within the linear region of the electron paramagnetic resonance magnetometer.

[0037] The first and second paramagnetic resonance magnetometer carrier demodulation modules 8 and 15 are composed of digital mixers. and a digital low-pass filter, and is used to extract the nuclear spin magnetic resonance signal detected by the paramagnetic resonance magnetometer composed of the electron spin of the alkali metal atom. The first paramagnetic resonance magnetometer carrier demodulation module 8 is used to demodulate the magnetometer signal after the decoupling phase modulation, and provide signal input for the Bxr AC modulation reference line magnetic field response amplitude demodulation and the decoupling phase error signal demodulation; the second paramagnetic resonance magnetometer carrier demodulation module 15 is used to demodulate the electron paramagnetic resonance magnetometer signal whose decoupling phase is not modulated, and is used to demodulate the nuclear spin magnetic resonance signal to avoid the influence of the decoupling phase modulation on it.

[0038] The decoupling phase modulation frequency generated by the decoupling phase modulator 11 is within the carrier demodulation low-pass filter bandwidth of the paramagnetic resonance magnetometer to ensure that the carrier demodulation output signal of the paramagnetic resonance magnetometer contains the response signal generated by the decoupling phase modulation.

[0039] The decoupling phase modulation amplitude generated by the decoupling phase modulator 11 It can be set within ±5° to avoid excessive modulation amplitude causing nonlinear effects in the carrier demodulation of the paramagnetic resonance magnetometer.

[0040] The decoupling phase error demodulation module 10 is composed of a digital mixer and a digital low-pass filter, and is used to demodulate the decoupling phase error signal;

[0041] The angular rate demodulation module 16 is composed of a digital mixer, a digital low-pass filter and an inverse tangent operator, and obtains the gyro angular rate ω by orthogonal demodulation. R The measurement signal.

[0042] The principle of the present invention is that in a nuclear magnetic resonance gyroscope, a decoupling phase represents a demodulation phase in which a paramagnetic resonance magnetometer is least sensitive to a magnetic field along a detection light direction and is most sensitive to a magnetic field along a direction perpendicular to the detection light and the driving light. By utilizing the characteristic that the paramagnetic resonance magnetometer is insensitive to the detection light direction at the decoupling phase, an AC modulated reference magnetic field is applied in the detection light direction, and the decoupling phase is modulated at the same time. The response amplitude change of the demodulated paramagnetic resonance magnetometer to the AC modulated magnetic field is used as an error signal of the decoupling phase. When the error signal is zero, the response amplitude of the AC modulated magnetic field remains unchanged, and the demodulation phase is at the decoupling phase. By utilizing the signal, real-time closed-loop locking of the decoupling phase can be achieved, thereby suppressing the measurement error of the nuclear magnetic resonance gyroscope caused by the fluctuation of the decoupling phase.

[0043] The advantages of the present invention over the prior art are that the modulation and demodulation method of the present invention can realize real-time closed-loop locking of the decoupling phase of the nuclear magnetic resonance gyroscope, the locking point is the only zero-crossing point where the response degree of the AC modulation line magnetic field in the direction of the detection light of the electronic paramagnetic resonance magnetometer is the smallest, it is not easily affected by the amplitude fluctuation of the response signal, the locking accuracy is higher, and the structure and operation are relatively simple.

[0044] In summary, the present invention provides a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope, in particular, a decoupled phase closed-loop locked nuclear magnetic resonance gyroscope based on AC reference line magnetic field modulation and demodulation, wherein an AC reference modulation magnetic field different from the nuclear spin resonance frequency is applied along the detection light direction, and the decoupled phase of the nuclear magnetic resonance gyroscope electronic paramagnetic resonance magnetometer is AC modulated at the same time, and the AC reference modulation amplitude change is demodulated to obtain a decoupled phase error signal, and the real-time closed-loop locking of the decoupled phase is achieved through a closed-loop control system based on the error signal. The present invention can achieve real-time closed-loop locking of the decoupled phase of the nuclear magnetic resonance gyroscope, suppress the decoupled phase fluctuation caused by the fluctuation of system parameters such as laser power, frequency, and gas chamber temperature, and thus improve the angular velocity measurement accuracy and long-term stability of the nuclear magnetic resonance gyroscope.

[0045] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0046] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A decoupled phase closed-loop locked nuclear magnetic resonance gyroscope, characterized in that: The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope comprises a detection light source module (1), a driving light source module (2), a magnetic shielding cylinder (3), a three-dimensional magnetic field coil (4), a heating film (5), an atomic gas chamber (6), a polarization balanced beam splitting detection module (7), a first paramagnetic resonance magnetometer carrier demodulation module (8), a Bxr AC modulation reference line magnetic field response amplitude demodulation module (9), a decoupled phase error signal demodulation module (10), a decoupled phase modulator (11), a phase shifter (12), a decoupled phase PID controller (13), a Bz magnetic field generator (14), a second paramagnetic resonance magnetometer carrier demodulation module (15), an angular rate demodulation module (16), a Bxr AC modulation reference line magnetic field generator (17) and a nuclear spin excitation magnetic field Bxj generator (18); the heating film (5) and the magnetic shielding cylinder (3) are arranged outside the atomic gas chamber (6); the heating film (5) is used to heat the atomic gas chamber (6); and the magnetic shielding cylinder (3) is used to shield external magnetic interference; The driving light source module (2) emits circularly polarized driving laser light, the frequency of which is tuned to the alkali metal atom D1 line contained in the atomic gas chamber, and the spin-polarized alkali metal atom electron spins are pumped by spin exchange light, and the spin-polarized alkali metal atom electron spins are then hyperpolarized by spin exchange collision to cause the inert gas atomic nucleus spins; the detection light source module (1) emits linear polarization detection laser light, which enters the polarization balanced beam splitting detection module (7) after passing through the atomic gas chamber (6), and the polarization balanced beam splitting detection module (7) comprises a λ / 2 wave plate (a), a polarization beam splitting prism (b), a first photodetector (c) and a second photodetector (d), and the detection laser light emitted from the atomic gas chamber (6) After passing through the λ / 2 wave plate (a) and the polarization beam splitter (b), the measured light is divided into two beams and enters the first photodetector (c) and the second photodetector (d) respectively. The precession signal of the electron spin of the alkali metal atom is obtained according to the differential signal detected by the first photodetector (c) and the second photodetector (d). Since there is a Fermi interaction between the electron spin of the alkali metal atom and the nuclear spin of the inert gas atom, the signal carries a nuclear spin magnetic resonance signal, thereby indirectly realizing the detection of the nuclear spin magnetic resonance signal. The detection frequency is detuned by 0.1 to 0.3 nm relative to the D1 line of the alkali metal atom to ensure that the intensity of the optical rotation detection response signal at the detuning point is at a maximum point. The Bz magnetic field generator (14), the Bxr AC modulation reference line magnetic field generator (17), the phase shifter (12), the first paramagnetic resonance magnetometer carrier demodulation module (8), the Bxr AC modulation reference line magnetic field response amplitude demodulation module (9), the decoupling phase error signal demodulation module (10), the decoupling phase modulator (11) and the decoupling phase PID controller (13) constitute a nuclear magnetic resonance gyro decoupling phase closed-loop locking system; the Bz magnetic field generator (14) outputs a current signal to generate a main magnetic field B along the z-axis direction through the z-axis magnetic field coil. z0 and paramagnetic resonance modulated magnetic field B c cos(ω c t), the amplitude of the modulated magnetic field B c Can be set to main magnetic field B z The frequency is between 1 and 1.8 times of that of the electron spin of the alkali metal atom in the main magnetic field B. z0 The magnetic resonance frequency in the magnetic field makes the electron spin in the paramagnetic resonance state, and on the other hand, it generates the carrier demodulation reference signal cos(ω c t), the carrier demodulation reference signal cos(ω c t) The decoupled phase is superimposed on the signal phase after passing through the phase shifter (12) to obtain a carrier demodulation reference signal cos(ω) of the carrier demodulation module (15) of the second paramagnetic resonance magnetometer c t+φ), the reference signal is simultaneously passed through the decoupling phase modulator (11) to generate a carrier demodulation reference signal cos(ω) of the carrier demodulation module (8) of the first paramagnetic resonance magnetometer c t+φ+φ c cos(ωt)); The Bxr AC modulation reference line magnetic field generator (17) generates a reference line magnetic field AC modulation current signal, and the nuclear spin excitation magnetic field Bxj generator (18) generates a nuclear spin excitation magnetic field current signal. The reference line magnetic field AC modulation current signal and the nuclear spin excitation magnetic field current signal are superimposed and applied to the coil in the x-axis direction to generate an AC modulation reference line magnetic field Bxr and a nuclear spin excitation magnetic field Bxj along the x-axis direction. At the same time, the Bxr AC modulation reference line magnetic field generator (17) also generates an AC modulation reference signal that enters the Bxr AC modulation reference line magnetic field response amplitude demodulation module (9) for demodulating the paramagnetic resonance magnetometer's response amplitude to the AC modulation reference line magnetic field Bxr. The nuclear spin excitation magnetic field Bxj generator (18) also generates a nuclear spin excitation signal that enters the angular velocity demodulation module (16); The differential signals detected by the first photodetector (c) and the second photodetector (d) simultaneously enter the first paramagnetic resonance magnetometer carrier demodulation module (8) and the second paramagnetic resonance magnetometer carrier demodulation module (15), and the first paramagnetic resonance magnetometer carrier demodulation module (8) compares the received differential signal with a carrier demodulation reference signal. After mixing and low-pass filtering, it enters the Bxr AC modulation reference line magnetic field response amplitude demodulation module (9), mixes and low-pass filters with the AC modulation reference signal generated by the Bxr AC modulation reference line magnetic field generator (17), and finally enters the decoupled phase error signal demodulation module (10) to mix and low-pass filter with the decoupled phase modulation reference signal generated by the decoupled phase modulator (11), thereby obtaining a decoupled phase error signal. The decoupled phase error signal The decoupling phase PID controller (13) generates a control signal through a PID algorithm to adjust the decoupling phase generated by the phase shifter (12) to decouple the phase error signal Control to zero position, thereby realizing closed-loop locking of the decoupling phase of the NMR gyro; The second paramagnetic resonance magnetometer carrier demodulation module (15) combines the received differential signal with a carrier demodulation reference signal After frequency mixing and low-pass filtering, it enters the angular rate demodulation module (16) and is mixed and low-pass filtered with the nuclear spin excitation signal generated by the nuclear spin excitation magnetic field Bxj generator (18) to obtain the gyro angular rate ω R The measurement signal.

2. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 1, characterized in that: The nuclear spin excitation magnetic field Bxj generator (18) generates an output current signal to generate a nuclear spin magnetic resonance excitation magnetic field along the x-axis direction through the x-axis magnetic field coil, continuously exciting the nuclear spin to be in a magnetic resonance state in the main magnetic field.

3. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 2, characterized in that: The frequency of the Bxr AC modulation reference line magnetic field generator (17) is greater than the nuclear spin resonance frequency by more than 50 Hz, so as to facilitate phase-locked demodulation.

4. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 3, characterized in that: The first paramagnetic resonance magnetometer carrier demodulation module (8) and the second paramagnetic resonance magnetometer carrier demodulation module (15) are both composed of a digital mixer. and a digital low-pass filter, wherein the first paramagnetic resonance magnetometer carrier demodulation module (8) is used to demodulate the magnetometer signal after the decoupling phase modulation, and provide signal input for the Bxr AC modulation reference line magnetic field response amplitude demodulation and the decoupling phase error signal demodulation; the second paramagnetic resonance magnetometer carrier demodulation module (15) is used to demodulate the electron paramagnetic resonance magnetometer signal whose decoupling phase is not modulated, and is used to demodulate the nuclear spin magnetic resonance signal to avoid the influence of the decoupling phase modulation on it.

5. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 4, characterized in that: The decoupling phase modulation frequency generated by the decoupling phase modulator (11) is within the paramagnetic resonance magnetometer carrier demodulation low-pass filter bandwidth to ensure that the paramagnetic resonance magnetometer carrier demodulation output signal contains the response signal generated by the decoupling phase modulation.

6. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 5, characterized in that: The decoupling phase modulation amplitude generated by the decoupling phase modulator (11) It can be set within ±5° to avoid excessive modulation amplitude causing nonlinear effects in the carrier demodulation of the paramagnetic resonance magnetometer.

7. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 6, characterized in that: The decoupled phase error signal demodulation module (10) is composed of a digital mixer and a digital low-pass filter, and is used for demodulating the decoupled phase error signal.

8. The decoupled phase closed-loop locked nuclear magnetic resonance gyroscope according to claim 7, characterized in that: The angular rate demodulation module (16) is composed of a digital mixer, a digital low-pass filter and an inverse tangent operator, and obtains the gyro angular rate ω by orthogonal demodulation. R The measurement signal.

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