Nuclear magnetic resonance atomic gyroscope based on diatomic gas cell and implementation method thereof

Abstract

The application relates to the field of atomic inertial measurement technology and discloses a nuclear magnetic resonance atomic gyroscope based on double-atom gas chambers and an implementation method thereof. 129 Xe and 131 Xe are arranged in the same magnetic shielding barrel and share a heating unit, homologous pumping light is adjusted through light splitting and polarization, actual polarization directions of alkali metal electron spins in the two gas chambers are formed along a common bias magnetic field in opposite directions, homologous detection light respectively propagates in two Herriott multi-reflection cavities and is received by a differential photoelectric detector. Two phase-locked loop modules respectively track resonance frequencies of two kinds of xenon isotopes in the corresponding gas chambers through two frequency tracking branches, and four resonance frequencies are synchronously output by adopting a common reference clock, a signal processing module first solves angular velocity measurement values of the two gas chambers, then superimposes the two angular velocity measurement values, divides the superimposed value by 2 to take an absolute value, and finally outputs the absolute value. The application can reduce residual errors caused by main magnetic field fluctuation, temperature and laser parameter change.

Description

Technical Field

[0001] This invention relates to the fields of atomic inertial measurement and nuclear magnetic resonance precision measurement technology, specifically to a nuclear magnetic resonance atomic gyroscope and its implementation method that utilizes two atomic gas cells containing alkali metal atoms and two xenon isotope atoms to form a dual measurement channel, and utilizes Herriott multi-reflection cavity, differential photodetector, phase-locked loop and dual-channel signal superposition to realize angular velocity measurement. Background Technology

[0002] Gyroscopes are crucial inertial devices in inertial navigation, attitude control, geophysical measurement, and precision rotation detection. Traditional mechanical gyroscopes rely on high-speed rotors or vibrating structures to sense rotation, while optical gyroscopes primarily utilize the phase difference of light propagation to measure angular velocity. As inertial measurement systems evolve towards higher precision, lower drift, and miniaturization, atomic gyroscopes, which utilize atomic spin to sense rotation, are gaining increasing attention. Atomic spin systems do not rely on mechanical rotating parts, are relatively insensitive to vibrations and gravitational disturbances, and can be polarized and detected using optical methods. Therefore, they are suitable for applications requiring high long-term stability and resolution of minute angular velocities.

[0003] Nuclear magnetic resonance (NMR) atomic gyroscopes typically consist of a sealed atomic cell filled with alkali metal atoms and inert gas atoms. Pump light is used to polarize the electron spins of the alkali metal atoms, which then transfer this polarization to the nuclear spins of the inert gas atoms through spin-exchange collisions. Simultaneously, the alkali metal atoms also act as atomic magnetometers within the cell, optically detecting the precession signal of the inert gas nuclear spins. By applying a bias magnetic field and a radio frequency excitation magnetic field to the cell and detecting the change in the nuclear spin precession frequency due to external rotation, the angular velocity to be measured can be obtained. To reduce the influence of main magnetic field fluctuations on the measurement results, existing NMR gyroscopes also use two inert gas isotopes with different gyromagnetic ratios within the same cell, combining them based on their resonance frequencies to separate the magnetic field term from the rotation term.

[0004] The magnetic field generated by the nuclear spin precession within the atomic gas chamber is relatively weak, and the actual detection sensitivity is easily limited by the sensitivity of the alkali metal magnetometer and the effective range of the probe light. To improve the detection signal strength, existing technologies can increase the probe light power, increase the number of atoms in the gas chamber, or set up a multi-reflection optical cavity within the gas chamber to allow the probe light to pass through the atomic medium multiple times. However, increasing the probe light power may increase photoheating and light shift, while increasing the number of atoms will place higher demands on the gas chamber temperature, gas filling process, and collision relaxation. Although a multi-reflection optical cavity can extend the optical path without significantly increasing the gas chamber size, the slow changes in gas chamber temperature, pump light power, pump light frequency, probe light power, probe light frequency, and the polarization state of alkali metal atoms may still be reflected in the resonant frequency or angular velocity output through light shift, contact magnetic field changes, and detection gain variations.

[0005] The dual-isotope combination in a single-cell chamber primarily aims to suppress the main magnetic field and its variations experienced by both isotopes. When the additional frequency shift is not entirely distributed according to the gyromagnetic ratio of the two isotopes, or when the additional frequency shift is related to alkali metal electron spin polarization, laser parameters, and chamber temperature, a certain residual amount may still be retained in the angular velocity results after the dual-isotope combination. Phase-locked loops enable the RF excitation frequency to continuously follow the resonance point, preventing long-term deviations from the resonant operating region. However, the loop can only track changes in the resonant frequency and cannot automatically distinguish whether the change originates from actual rotation or from changes in optical, thermal, and atomic interaction parameters. Furthermore, differences in gain, phase, sampling timing, and RF excitation amplitude may exist between different detection channels.

[0006] Therefore, how to further distinguish between the real rotation signal and the correlation frequency shift that still exists after dual isotope processing, while maintaining the dual isotope closed-loop measurement and multi-reflection enhanced detection capabilities, is a problem that needs to be solved in the long-term stable measurement of nuclear magnetic resonance atomic gyroscopes. Summary of the Invention

[0007] The technical problem to be solved by this invention is to further reduce the residual error caused by changes in magnetic field, temperature and laser parameters in dual isotope nuclear magnetic resonance angular velocity measurement.

[0008] To address the aforementioned technical problems, this invention provides a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas chamber, comprising a first atomic gas chamber and a second atomic gas chamber, which are disposed within the same magnetically shielded environment and share a heating unit. The two atomic gas chambers respectively contain alkali metal atoms, a first xenon isotope atom, a second xenon isotope atom, and a buffer gas. The alkali metal atoms are used to polarize the nuclear spins of the two xenon isotopes through spin-exchange collisions and to detect the nuclear spin precession signals of the two xenon isotopes.

[0009] The nuclear magnetic resonance atomic gyroscope includes a pump optical path. The pump optical path splits the same pump laser into a first beam and a second beam. The first beam is converted into a second beam by a first quarter-wave plate. The circularly polarized light then enters the first atomic gas cell, and the second beam is converted into a second quarter-wave plate. The circularly polarized light is then incident into the second atomic gas cell. The first and second output optical paths extend to opposite sides of the two atomic gas cells, respectively, causing the two circularly polarized pump beams to be incident relative to each other. The first and second beams cause the alkali metal electrons in the two atomic gas cells to form opposite actual polarization directions.

[0010] The nuclear magnetic resonance atomic gyroscope also includes a probe optical path. This path splits the same probe laser into two linearly polarized probe beams. These beams pass through a first atomic gas chamber and a second atomic gas chamber, respectively, before being incident on their corresponding differential photodetectors. A first Herriott multi-reflection cavity is located within the first atomic gas chamber, and a second Herriott multi-reflection cavity is located within the second atomic gas chamber. The two linearly polarized probe beams are incident perpendicularly to their respective circularly polarized pump beams into the two Herriott multi-reflection cavities, undergoing multiple reflections within each cavity before exiting. A polarization beam splitter and a differential photodetector are sequentially arranged on the exit optical path of each multi-reflection cavity. The two output terminals of the polarization beam splitter are connected to the two optical input terminals of the corresponding differential photodetector.

[0011] The first and second Herriott multi-reflection cavities each include a front and a rear cavity mirror arranged opposite to each other, and the front and rear cavity mirrors are fixed on a silicon substrate. The silicon substrate is bonded to a first glass cover and a second glass cover, respectively, to form a first atomic gas chamber and a second atomic gas chamber. A light-blocking silicon wafer is disposed between the two atomic gas chambers, and the surface of the light-blocking silicon wafer has a high-reflectivity coating for reflecting pump light.

[0012] The nuclear magnetic resonance atomic gyroscope further includes a bias magnetic field coil, a first radio frequency excitation coil, a second radio frequency excitation coil, and a magnetic field gradient compensation coil. The bias magnetic field coil is disposed around the first and second atomic gas cells. The first and second radio frequency excitation coils are respectively disposed corresponding to the two atomic gas cells. The magnetic field gradient compensation coil is disposed within a magnetically shielded environment and includes a first-order magnetic field gradient compensation coil and a second-order magnetic field gradient compensation coil.

[0013] The nuclear magnetic resonance atomic gyroscope also includes two phase-locked loop (PLL) modules. Each PLL module is electrically connected to the output of a differential photodetector and adjusts the frequency of the radio frequency excitation magnetic field applied to the corresponding atomic cell based on the detection signal output from the differential photodetector, thereby tracking the resonance frequency of the corresponding xenon isotope. Each PLL module includes a first frequency tracking branch and a second frequency tracking branch. The first frequency tracking branch tracks the resonance frequency of the first xenon isotope atom, and the second frequency tracking branch tracks the resonance frequency of the second xenon isotope atom.

[0014] Two phase-locked loop (PLL) modules are connected to the same clock reference, with the clock output of one PLL module connected to the clock reference of the other. The signal processing module includes a data acquisition board, with the frequency outputs of the two PLL modules connected to different acquisition channels of the data acquisition board, ensuring that the resonant frequencies of the two xenon isotopes in the two atomic gas chambers are acquired according to a common frequency and sampling reference.

[0015] The signal processing module calculates the first angular velocity measurement value based on the resonance frequencies and gyromagnetic ratios of the two xenon isotopes in the first atomic gas chamber, and calculates the second angular velocity measurement value based on the resonance frequencies and gyromagnetic ratios of the two xenon isotopes in the second atomic gas chamber. The first and second angular velocity measurement values ​​are then superimposed, divided by 2, and the absolute value is taken for normalization before being output.

[0016] This invention also provides a method for implementing a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell, comprising the following steps:

[0017] S1. The first atomic gas chamber containing alkali metal atoms, first xenon isotope atoms, second xenon isotope atoms and buffer gas are placed in the same magnetic shielding environment, and the two atomic gas chambers are heated by the same heating unit.

[0018] S2. Divide the same pump laser into a first beam and a second beam, and convert the first beam into... Circularly polarized light then enters the first atomic gas cell, converting the second beam into... The circularly polarized light is then injected into the second atomic gas cell to polarize the alkali metal atoms in the two atomic gas cells respectively, and to make the alkali metal electron spins in the two atomic gas cells form opposite actual polarization directions.

[0019] S3. The same probe laser is split into two linearly polarized probe beams, and the two linearly polarized probe beams are reflected multiple times in the Herriott multi-reflection cavities in the two atomic gas chambers, respectively. Differential photoelectric detection is performed on the outgoing light from the two Herriott multi-reflection cavities to obtain the first probe signal and the second probe signal.

[0020] S4. Perform phase-locked demodulation based on the first detection signal and the second detection signal respectively, and adjust the frequency of the radio frequency excitation magnetic field of the corresponding atomic gas cell based on the demodulated phase signal to obtain the resonance frequency of the two xenon isotopes in the first atomic gas cell and the resonance frequency of the two xenon isotopes in the second atomic gas cell.

[0021] S5. Calculate the first angular velocity measurement value based on the resonance frequencies of the two xenon isotopes in the first atomic gas chamber, calculate the second angular velocity measurement value based on the resonance frequencies of the two xenon isotopes in the second atomic gas chamber, and output the first angular velocity measurement value and the second angular velocity measurement value after superimposing them, dividing by 2 and taking the absolute value.

[0022] The first xenon isotope atom can be 129 Xe, the second xenon isotope atom can be 131 Xe. The angular velocities of the first and second atomic gas chambers are determined according to the following formulas:

[0023] ;

[0024] ;

[0025] in, This is the measured value of the first angular velocity. This is the measured value of the second angular velocity. for 129 The gyromagnetic ratio of Xe for 131 The gyromagnetic ratio of Xe and The first atomic gas chamber 129 Xe and 131 The resonant angular frequency of Xe, and The second atomic gas chamber 129 Xe and 131 The resonant angular frequency of Xe.

[0026] The final output angular velocity amplitudes of the two channels are determined by the following formula: .

[0027] Compared to measurement structures that use only a single dual-isotope atomic chamber, this invention first processes the common magnetic field term within each atomic chamber using a combination of the resonance frequencies of two xenon isotopes. Then, the angular velocity measurements from the two atomic chambers are superimposed, forming a two-stage measurement structure that combines dual-isotope processing within the chambers with dual-channel processing between the chambers. Thus, the main magnetic field variation and the residual frequency shift remaining after dual-isotope processing are handled at different processing levels, avoiding the use of the dual chambers merely as two independent, repetitive measurement channels.

[0028] Simultaneously, the two atomic gas chambers employ co-source pump light, co-source probe light, a shared heating environment, and a shared magnetic shielding environment, enabling changes in temperature, pump light power, pump light frequency, probe light power, and probe light frequency to affect the two channels in a correlated manner; the two pump lights are respectively... and Circularly polarized light, incident from opposite directions, ensures that the two channels maintain consistent measurement directions for the actual rotation, while the residual frequency changes caused by opposite polarization states are in opposite directions. Superimposing the two angular velocity measurements preserves the rotational components in the same direction and weakens the residual error components in the opposite direction.

[0029] Furthermore, the Herriott multi-reflection cavity allows the linearly polarized probe light to pass through the atomic medium multiple times within a smaller cell size, extending the effective interaction path between the probe light and alkali metal atoms. This eliminates the need to simply increase the probe light power or expand the cell volume to obtain a detection signal. The light-blocking silicon wafer can also limit crosstalk between the two pump lights when the two cells are close to each other, allowing each cell to maintain its corresponding atomic polarization state.

[0030] Furthermore, the two phase-locked loop modules use a common clock reference, and the frequency outputs of the two channels are synchronously acquired by the same data acquisition board, reducing additional differences in the two angular velocity measurements caused by differences in frequency reference, phase reference, or sampling timing. By selecting atomic gas cells manufactured in the same batch with similar performance, calibrating the photoelectric conversion coefficient of the differential photodetector, and adjusting the amplitude of the RF excitation signal according to the resistance of the RF excitation coil, the consistency of the operating states of the two channels can be further improved. Attached Figure Description

[0031] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in this specification are briefly described below.

[0032] Figure 1 This is a schematic diagram of the structure of the first atomic gas chamber, the second atomic gas chamber, and the light-blocking silicon wafer;

[0033] Figure 2 This is a schematic diagram of the Herriott multi-reflection cavity structure;

[0034] Figure 3 This is a schematic diagram of the system structure of a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell;

[0035] In the diagram: 1. Front cavity mirror; 2. Rear cavity mirror; 3. Silicon substrate; 4. Light-blocking silicon wafer; 5. First atomic gas chamber; 6. Second atomic gas chamber; 7. Probe laser; 8. Pump laser; 9. Y-axis radio frequency excitation coil group; 10. Heating unit; 11. Z-axis bias and gradient compensation coil group; 12. X-axis magnetic field coil; 13. Magnetic shielding barrel. Detailed Implementation

[0036] The following is combined with Figures 1 to 3 The technical solution of the present invention will be further described below.

[0037] In this embodiment, lasers, optical beam splitters, polarization adjustment devices, lock-in amplifiers, oscillators, radio frequency drive circuits, temperature controllers, and data acquisition devices that are not specifically limited to a particular model can all be devices and connection methods already available in the fields of nuclear magnetic resonance detection and atomic precision measurement. The specifications of each device are selected based on the atomic gas cell size, operating temperature, resonant frequency range, and required detection sensitivity.

[0038] Example 1

[0039] This embodiment provides a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas chamber, including a magnetic shielding barrel 13 for forming a magnetic shielding environment, a first atomic gas chamber 5 and a second atomic gas chamber 6 disposed within the magnetic shielding barrel 13, a heating unit 10 for simultaneously heating the two atomic gas chambers, a magnetic field generating component for establishing a working magnetic field in the region where the two atomic gas chambers are located, and a pump optical path, a probe optical path, two phase-locked loop modules, and a signal processing module arranged in conjunction with the two atomic gas chambers. The first atomic gas chamber 5 and the second atomic gas chamber 6 are disposed adjacent to each other in the middle region of the magnetic shielding barrel 13, and they share the heating unit 10, thus being within the same magnetic shielding environment and the same temperature control environment.

[0040] The magnetic shielding barrel 13 can be made of one or more layers of high magnetic permeability material, with gaps between the layers to reduce the influence of external static magnetic fields, low-frequency magnetic field changes, and magnetic fields generated by nearby electrical equipment on the working area of ​​the atomic gas chamber. The first atomic gas chamber 5 and the second atomic gas chamber 6 are preferably located close to the geometric center of the magnetic shielding barrel 13 to reduce the differences caused by magnetic leakage at the ends of the magnetic shielding barrel 13 and local magnetic field inhomogeneity on the two measurement channels. The magnetic shielding barrel 13 is not part of the two atomic gas chambers themselves, but rather forms a common magnetic shielding environment by surrounding the two atomic gas chambers and their corresponding magnetic field generating components.

[0041] like Figure 1 As shown, the first atomic gas chamber 5 and the second atomic gas chamber 6 are disposed adjacently on the same silicon substrate 3. The silicon substrate 3 provides a common mechanical support and heat conduction path for the two atomic gas chambers. The first glass cover is bonded to the silicon substrate 3 to form the first atomic gas chamber 5, and the second glass cover is bonded to the silicon substrate 3 to form the second atomic gas chamber 6. The first and second glass covers can be respectively equipped with tailpipes connected to a vacuum filling device. After vacuuming, alkali metal atom introduction, and gas filling are completed, the tailpipes are sealed gas-tight, so that the first atomic gas chamber 5 and the second atomic gas chamber 6 form independent sealed spaces.

[0042] The first atomic chamber 5 and the second atomic chamber 6 respectively contain alkali metal atoms, a first xenon isotope atom, a second xenon isotope atom, and a buffer gas. The alkali metal atoms are used to form electron spin polarization under the action of the pump laser 8, and transfer the electron spin polarization to the nuclear spins of the two xenon isotope atoms through spin exchange collisions; at the same time, the alkali metal atoms also serve as atomic magnetometers in the chambers to sense the weak magnetic field generated by the precession of the xenon isotope nuclear spins.

[0043] In one specific embodiment, the alkali metal atom is a naturally abundant rubidium atom, and the first xenon isotope atom is... 129 Xe, the second xenon isotope atom uses 131 Xe, with buffer gases including hydrogen and nitrogen. Each atomic chamber is filled with 3 Torr. 129Xe, 35 Torr 131 Xe, 5 Torr of hydrogen, and 150 Torr of nitrogen. Nitrogen is used to broaden the absorption lines of rubidium atoms and suppress radiative trapping, while hydrogen is used to modulate the collision and relaxation processes within the chamber. This gas composition and pressure constitute a specific configuration for achieving di-xenon isotope nuclear magnetic resonance measurements. The gas pressure can be selected based on the operating temperature, nuclear spin polarization time, relaxation time, and target signal intensity.

[0044] A light-blocking silicon wafer 4 is disposed between the first atomic gas cell 5 and the second atomic gas cell 6. The light-blocking silicon wafer 4 extends along the adjacent sides of the two atomic gas cells, separating the corresponding pump light propagation spaces. High-reflectivity coatings are respectively applied to the two opposing surfaces of the light-blocking silicon wafer 4, preventing the pump laser 8 incident into the first atomic gas cell 5 from directly entering the second atomic gas cell 6, and vice versa. After reaching the high-reflectivity coating, the pump laser 8 is reflected and passes through the corresponding atomic gas cell again, forming a round-trip propagation path within the corresponding gas cell. This structure can limit crosstalk between two oppositely circularly polarized pump lights and reduce atomic polarization inhomogeneities formed along the pump light propagation direction. In one specific embodiment, the thickness of the light-blocking silicon wafer 4 is 0.5 mm, allowing the two atomic gas cells to achieve optical isolation while maintaining a short thermal conduction distance.

[0045] The heating unit 10 is thermally connected to the silicon substrate 3 and can be positioned below, to the side, or at a common support location of the two atomic gas chambers on the silicon substrate 3. The heating unit 10 can employ a non-magnetic heating element, a twisted-pair heater, or other low-magnetic-interference heater, and is driven by the same temperature controller. The heat generated by the heating unit 10 is simultaneously transferred to the first atomic gas chamber 5 and the second atomic gas chamber 6 via the silicon substrate 3, ensuring that the two atomic gas chambers exhibit similar temperature change trends during heating and isothermal processes. The temperature controller can obtain temperature feedback using a thermistor, platinum resistance thermometer, or thermocouple positioned near the silicon substrate 3 or the atomic gas chambers, and adjusts the power of the heating unit 10 using proportional-integral-derivative (PID) control. The two atomic gas chambers are not required to have identical absolute temperatures at any given time, but because they are in the same temperature control loop and have similar heat transfer paths, changes in heating power and external temperature can act simultaneously on the two measurement channels in a correlated manner.

[0046] A first Herriott multi-reflection cavity is provided within the first atomic gas chamber 5, and a second Herriott multi-reflection cavity is provided within the second atomic gas chamber 6. For example... Figure 2As shown, each Herriott multi-reflection cavity includes a front cavity mirror 1 and a rear cavity mirror 2 arranged opposite each other. The two sets of front cavity mirrors 1 and rear cavity mirrors 2 are respectively fixed to a silicon substrate 3 and located within a sealed gas chamber space enclosed by corresponding glass covers. The front cavity mirrors 1 and rear cavity mirrors 2 can be cylindrical mirrors. During assembly, a positioning mold adapted to the shape of the cavity mirrors is first used to define the position, spacing, and relative rotation angle of the front cavity mirrors 1 and rear cavity mirrors 2. Then, they are fixed to the silicon substrate 3 by anodic bonding or other connection methods suitable for silicon materials, glass materials, and optical cavity mirrors. After the cavity mirrors are installed, the first and second glass covers are bonded to the silicon substrate 3 respectively to prevent the subsequent gas chamber sealing process from changing the positional relationship between the cavity mirrors.

[0047] In one specific embodiment, the distance between the front cavity mirror 1 and the rear cavity mirror 2 is 19.2 mm, and the relative rotation angle between their principal axes is 52.2°. The probe laser 7 enters between the front cavity mirror 1 and the rear cavity mirror 2 at a predetermined incident position and angle, and exits from the predetermined position after 21 reflections between the two cavity mirrors. The curvature, distance, relative rotation angle of the principal axes of the front cavity mirror 1 and the rear cavity mirror 2, as well as the incident position of the probe laser 7, jointly determine the spatial distribution of the reflected light spot. Other compatible cavity mirror parameters can also be used as long as a stable multi-reflection path can be formed and the probe laser 7 can exit from the predetermined position.

[0048] The magnetic field generating assembly includes a bias magnetic field coil, a first radio frequency (RF) excitation coil, a second RF excitation coil, and a magnetic field gradient compensation coil. The bias magnetic field coil is positioned around the first atomic gas cell 5 and the second atomic gas cell 6, and is used to establish the static bias magnetic field required for nuclear spin precession in the region where the two gas cells are located. The first RF excitation coil is positioned corresponding to the first atomic gas cell 5, and the second RF excitation coil is positioned corresponding to the second atomic gas cell 6. Both RF excitation coils are electrically connected to the excitation output terminals of their respective phase-locked loop (PLL) modules. The magnetic field gradient compensation coil is positioned within the magnetic shielding barrel 13 and arranged around the common working area of ​​the two atomic gas cells. The magnetic field gradient compensation coil includes a first-order magnetic field gradient compensation coil and a second-order magnetic field gradient compensation coil. The first-order magnetic field gradient compensation coil is used to adjust the first-order variation of the magnetic field along the spatial coordinate direction, and the second-order magnetic field gradient compensation coil is used to adjust the second-order spatial variation of the magnetic field, making the magnetic field strength and magnetic field gradient in the region where the first atomic gas cell 5 and the second atomic gas cell 6 are located as close as possible.

[0049] exist Figure 3 Under the coordinate relationship shown, the Y-direction radio frequency excitation coil group 9 is used to form radio frequency excitation magnetic fields acting on the first atomic gas cell 5 and the second atomic gas cell 6 respectively; the Z-direction bias and gradient compensation coil group 11 is used to form a static bias magnetic field and compensate for the magnetic field gradient in the region where the two gas cells are located; the X-direction magnetic field coil 12 does not participate in the resonant frequency calculation in the conventional angular velocity measurement process of this embodiment.

[0050] The pump optical path includes a pump laser, a tapered amplifier, and a pump beam splitter connected sequentially along the propagation direction of the pump light. It also includes a first quarter-wave plate disposed on the first output optical path and a second quarter-wave plate disposed on the second output optical path. The pump laser generates a pump laser beam 8, the tapered amplifier is used to increase the power of the pump laser beam 8, and the pump beam splitter is used to split the amplified pump laser beam 8 into a first beam and a second beam.

[0051] In one embodiment, a pump beam splitter splits the pump laser 8 into a first beam and a second beam with a 1:1 optical power ratio. The first beam is then converted by a first quarter-wave plate. The circularly polarized light then enters the first atomic gas chamber 5, and the second beam is converted into a second quarter-wave plate. Circularly polarized light is then incident into the second atomic gas cell 6. The first and second output optical paths extend to opposite sides of the two atomic gas cells, causing the two circularly polarized pump beams to be incident relative to each other. The fast axis directions of the first and second quarter-wave plates are set according to the propagation direction of the corresponding beams and the direction of the system magnetic field. During assembly, the installation angle of the two quarter-wave plates is determined by detecting the degree of circular polarization of the two pump beams and the atomic polarization response in the two gas cells, so that the alkali metal electron spins in the two gas cells form opposite actual polarization directions.

[0052] The frequency of the pump laser 8 is set near the D1 line of rubidium atoms. The pump laser can be connected to an existing laser frequency stabilizer. The frequency stabilizer performs closed-loop regulation of the drive current and operating temperature of the pump laser based on the absorption signal of the rubidium atom reference gas cell or other frequency discrimination signals, so that the pump laser 8 is kept near the rubidium atom absorption spectral line after being broadened by the buffer gas.

[0053] In one specific frequency stabilization implementation, a frequency reference is constructed using a FP cavity in conjunction with a high-stability He-Ne laser: the frequency reference of the FP cavity is stabilized using the high-stability He-Ne laser, and then the frequency discrimination signal provided by the stabilized FP cavity is used to lock the frequency of the pump laser 8. This frequency stabilization structure is used to reduce the long-term frequency drift of the pump laser 8; in addition to this method, existing frequency stabilization schemes that can provide equivalent frequency stability can also be used.

[0054] The probe optical path includes a probe laser, an acousto-optic modulator, an optical fiber coupling unit, and a probe optical splitter arranged sequentially along the probe light propagation direction. The probe laser generates a probe laser 7. The acousto-optic modulator is used to adjust the frequency or optical power of the probe laser 7. The optical fiber coupling unit is used to couple the probe laser 7 to the transmission optical fiber. The probe optical splitter is used to split the same probe laser 7 into two linearly polarized probe beams. The two linearly polarized probe beams are perpendicular to their corresponding circularly polarized pump beams and enter the first and second Herriott multi-reflection cavities, respectively. The probe laser 7 is reflected multiple times between the corresponding front cavity mirror 1 and rear cavity mirror 2, and passes through the rubidium atom vapor in the gas chamber multiple times. The weak magnetic field formed by the spin precession of the xenon isotope nuclei changes the spin state of the rubidium atoms. The spin state of the rubidium atoms changes the polarization direction of the probe laser 7 through Faraday rotation. Multiple reflections cause the polarization rotation signal to accumulate along the effective optical path.

[0055] Each Herriott multi-reflection cavity has a polarization beamsplitter and a differential photodetector sequentially positioned in its output optical path. The two outputs of the polarization beamsplitter are connected to the two inputs of the corresponding differential photodetector. During initial adjustment, the polarization direction of the probe laser 7 or the installation angle of the polarization beamsplitter is adjusted to ensure that the two inputs of the differential photodetector receive the same or substantially the same optical power. When the polarization direction of the probe laser 7 changes, a difference in optical power is generated between the two inputs, and the differential photodetector outputs a corresponding electrical signal.

[0056] The outputs of the two differential photodetectors are electrically connected to two phase-locked loop (PLL) modules, respectively. Each PLL module includes a lock-in amplifier, a first frequency tracking branch, a second frequency tracking branch, and an oscillator. The first frequency tracking branch is used for tracking... 129 The resonant frequency of Xe, the second frequency tracking branch is used for tracking 131 The resonant frequency of Xe. The oscillator corresponding to the first atomic gas cell 5 is connected to the first radio frequency excitation coil, and the oscillator corresponding to the second atomic gas cell 6 is connected to the second radio frequency excitation coil. Each oscillator provides a resonant frequency at the resonant frequency of Xe. 129 Xe and 131 The Xe isotope is a radio frequency excitation signal near the Larmor frequency. The lock-in amplifier can be a multi-frequency lock-in amplifier with two reference frequency channels, or two parallel lock-in demodulation branches can be used to process the detection signals of the two xenon isotopes respectively.

[0057] The phase-locked loop (PLL) module adjusts the output frequency of the corresponding oscillator based on the deviation between the demodulated phase and the set phase, ensuring that the frequency of the radio frequency excitation magnetic field applied to the corresponding atomic gas cell continuously tracks the resonance frequency of the xenon isotope. Thus, the first atomic gas cell 5 and the second atomic gas cell 6 respectively form closed-loop measurement channels capable of simultaneously tracking the resonance frequencies of two xenon isotopes. The two PLL modules are connected to the same clock reference. In one embodiment, the 10MHz clock signal output from the rubidium clock is used as the external frequency reference for the first lock-in amplifier corresponding to the first atomic gas cell 5, and the clock signal output from the first lock-in amplifier is input to the second lock-in amplifier corresponding to the second atomic gas cell 6, so that the two lock-in amplifiers and their corresponding oscillators use the same frequency reference.

[0058] The signal processing module includes a data acquisition board and a processor. The frequency outputs of the two phase-locked loop (PLL) modules are connected to different acquisition channels of the data acquisition board. The data acquisition board is controlled by the same data acquisition program, which processes the signal within the first atomic gas chamber 5. 129 Xe and 131 The resonance frequency of Xe and the second atomic gas chamber 6 129 Xe and 131 The resonant frequency of Xe is synchronously acquired. The data acquisition program can be LabVIEW or other programs with multi-channel synchronous acquisition capabilities.

[0059] The first atomic gas chamber 5 and the second atomic gas chamber 6 are preferably made from the same batch of vacuum pipes or microfabricated materials, and employ the same gas chamber forming, cavity mirror mounting, glass cover bonding, and gas filling processes. Before assembly, the resonance signal amplitude, resonance linewidth, nuclear spin relaxation characteristics, and operating temperature of each atomic gas chamber are tested, and two atomic gas chambers with similar performance and meeting the measurement requirements are selected. Before formal use, the photoelectric conversion coefficients of the two differential photodetectors are calibrated. During calibration, a known optical power difference is applied to the two optical input terminals of the differential photodetector, the corresponding output voltage is recorded, and the correspondence between the optical power difference and the output voltage is determined. Based on the calibration results, the optical power of the two probe lasers 7 and the gain of the differential photodetectors are adjusted so that both channels operate within the effective linear range. The first and second radio frequency excitation coils may differ in terms of wire length, number of turns, and installation position. After assembly, the resistance of the two radio frequency excitation coils is measured, and the two radio frequency excitation signals are adjusted in conjunction with the nuclear magnetic resonance signal amplitude of the corresponding gas chambers to form a resonance response with stable amplitude in both gas chambers without causing significant power broadening.

[0060] In a complete operational example, the magnetic field control circuit is first activated to establish the required static bias magnetic field in the Z direction. The magnetic field gradient in the regions containing the two atomic gas chambers is adjusted using first-order and second-order magnetic field gradient compensation coils, while the X-direction magnetic field coil 12 remains in a reserved state. Subsequently, the heating unit 10 is activated, causing the first atomic gas chamber 5 and the second atomic gas chamber 6 to heat up synchronously. After the temperature stabilizes, the pump laser is activated, and the pump laser 8, after amplification and dispersion, forms... Circularly polarized light and Circularly polarized light is incident on two atomic gas cells, causing the electron spin of rubidium atoms to... 129 Xe and 131 The Xe nuclear spin gradually reaches a stable polarization state. Next, the probe lasers are activated, allowing two probe laser beams 7 to enter the two Herriott multi-reflection cavities respectively. The two differential photodetectors output the first and second probe signals accordingly. Subsequently, two oscillators and radio frequency excitation coils are activated to perform frequency scanning near the Larmor frequencies of the two xenon isotopes. After capturing the corresponding resonance signals, the two phase-locked loop modules enter closed-loop tracking mode, outputting signals from the two atomic gas chambers respectively. 129 Xe and 131 The resonant frequency of Xe. The signal processing module synchronously reads four resonant frequencies, obtains two angular velocity measurements for each, and then superimposes the two angular velocity measurements, divides them by 2, and takes the absolute value to form the angular velocity output.

[0061] In this embodiment, a common magnetic shielding environment for accommodating two atomic gas chambers is first formed by the magnetic shielding barrel 13. Then, the two gas chambers, the common heating structure, the same-source pump optical path, the same-source detection optical path, the independent radio frequency excitation circuit, the dual isotope phase-locked tracking circuit, and the synchronous signal processing structure are combined so that the two measurement channels have similar temperature, magnetic field, and optical disturbance conditions, while maintaining independent atomic polarization and resonance measurement states, thereby providing synchronous and comparable measurement data for the superposition processing of the angular velocity results of the two gas chambers.

[0062] Example 2

[0063] This embodiment provides a method for implementing a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas chamber. This method can be executed using the apparatus described in Embodiment 1. The first atomic gas chamber 5 and the second atomic gas chamber 6 respectively contain rubidium atoms, 129 Xe, 131 Xe, hydrogen and nitrogen, each with its own Herriott multi-reflection cavity.

[0064] Before the formal measurement, two atomic gas chambers with similar performance were selected from the same batch of manufactured and filled with gas using the same process, designated as the first atomic gas chamber 5 and the second atomic gas chamber 6, respectively. By detecting the absorption spectra, nuclear magnetic resonance signal amplitude, resonance linewidth, and nuclear spin relaxation characteristics of the two gas chambers, it was confirmed that both gas chambers could meet the predetermined measurement requirements. Simultaneously, the photoelectric conversion coefficients of the two differential photodetectors were calibrated, and the coil resistances of the first and second radio frequency excitation coils were measured. The photoelectric conversion coefficients are used to adjust the detection gain of the two detection channels, and the coil resistances are used to adjust the excitation signal amplitude of the two radio frequency excitation channels, ensuring that both channels are within a stable operating range.

[0065] In step S1, to create the same magnetic shielding environment required for the two atomic gas chambers, the first atomic gas chamber 5 and the second atomic gas chamber 6 are placed together inside the magnetic shielding barrel 13, and the same heating unit 10 is used to heat the two gas chambers. Before heating begins, a static bias magnetic field is established in the Z direction, and the magnetic field gradient in the region where the two gas chambers are located is adjusted by the first-order magnetic field gradient compensation coil and the second-order magnetic field gradient compensation coil in the Z direction; the X-direction magnetic field coil 12 is kept in a reserved state in this embodiment. Then the heating unit 10 is turned on, and the temperature controller adjusts the heating power according to the temperature detection results until the first atomic gas chamber 5 and the second atomic gas chamber 6 reach the set operating temperature and enter a stable state.

[0066] In step S2, the pump laser is turned on. The pump laser 8 is amplified by a cone amplifier and then split into a first beam and a second beam by a pump beam splitter. The first beam is then converted into a second beam after passing through a first quarter-wave plate. Circularly polarized light is incident on the first atomic gas cell 5, and the second beam is converted into a second quarter-wave plate. Circularly polarized light is incident on the second atomic gas chamber 6. Two pump beams are incident from opposite sides of the two atomic gas chambers, and are confined within their respective chamber spaces by the light-blocking silicon wafer 4. The pump laser 8 first polarizes the electron spins of the rubidium atoms, and the polarized rubidium atoms then transfer the polarization to the electrons through spin-exchange collisions. 129 Xe and 131 Xe nuclear spin. Continuous pumping leads to a stable state of electron spin polarization and nuclear spin polarization in the two atomic chambers, and maintains the alkali metal electron spins in the two atomic chambers in opposite actual polarization directions.

[0067] In step S3, the probe laser is activated. The probe laser 7 passes sequentially through the acousto-optic modulator and the fiber coupling unit, and is then split into two linearly polarized probe beams by the probe beam splitter. The two linearly polarized probe beams enter the first Herriott multi-reflection cavity and the second Herriott multi-reflection cavity, respectively, and are reflected multiple times between the corresponding front cavity mirror 1 and rear cavity mirror 2. In the embodiment where the distance between the front cavity mirror 1 and the rear cavity mirror 2 is 19.2 mm and the relative rotation angle of the principal axis is 52.2°, each probe beam undergoes twenty-one reflections within the corresponding multi-reflection cavity. The emitted probe beam is split into two orthogonal polarization components by the corresponding polarization beam splitter, and differential detection is performed by a differential photodetector to obtain the first probe signal and the second probe signal, respectively.

[0068] Before differential detection begins, the power of the two probe beams and the gain of the two differential photodetectors are adjusted according to the pre-obtained photoelectric conversion coefficients, so that the output of the two differential photodetectors is close to zero when no nuclear magnetic resonance signal is detected. When the spin precession of the xenon nucleus causes a change in the polarization direction of the probe laser 7, the two differential photodetectors output electrical signals containing the corresponding nuclear magnetic resonance information.

[0069] In step S4, radio frequency excitation magnetic fields are applied to the two atomic gas cells through the first and second radio frequency excitation coils, respectively. The amplitudes of the two radio frequency excitation signals are adjusted according to the pre-measured coil resistance and the actual resonance signal amplitude, so that both gas cells can obtain clear signals suitable for phase-locked tracking. 129 Xe and 131 Xe resonant response. A first probe signal is input to a first phase-locked loop amplifier, and a second probe signal is input to a second phase-locked loop amplifier. The first frequency tracking branch in each phase-locked loop module tracks... 129 The resonant frequency of Xe, tracked by the second frequency tracking branch. 131 The resonant frequency of Xe. The phase-locked loop module adjusts the output frequency of the corresponding oscillator based on the deviation between the demodulated phase and the set phase, so that the frequency of the radio frequency excitation magnetic field continuously tracks the resonant frequency of the corresponding xenon isotope.

[0070] The 10MHz clock signal output from the rubidium clock is used as the external frequency reference for the first lock-in amplifier, and the clock signal output from the first lock-in amplifier is used as the clock reference for the second lock-in amplifier. The same data acquisition program controls the same data acquisition board to synchronously acquire the resonance frequencies of the two xenon isotopes in the two atomic gas chambers.

[0071] For the The first atomic gas chamber For a given xenon isotope, neglecting the additional frequency shift caused by temperature and laser parameter variations, its reference resonant angular frequency satisfies:

[0072] ;

[0073] in, =1,2, respectively corresponding to 129 Xe and 131 Xe; =a,b, which correspond to the first atomic gas chamber 5 and the second atomic gas chamber 6, respectively; When the common-mode additional frequency shift is not taken into account, the first The first atomic gas chamber The resonance angular frequencies of xenon isotopes; For the first The gyromagnetic ratio of xenon isotopes; For the first The magnetic field within an atomic gas chamber; For the first The angular velocity corresponding to each atomic gas cell.

[0074] When considering the common-mode frequency shift caused by temperature changes, pump laser power and frequency changes, and probe laser power and frequency changes, the actual measured resonant angular frequency is uniformly expressed as:

[0075] ;

[0076] in, The additional frequency shift introduced by the common-mode perturbation to the i-th xenon isotope; The polarity coefficients of the two atomic gas chamber channels are given, with the first atomic gas chamber corresponding to... = +1, the second atomic gas cell corresponds to = -1. Thus, the same type of common-mode disturbance enters the resonant frequency with opposite signs in the two opposite polarization channels, while the magnetic field term and the angular velocity term remain in the same frequency relationship.

[0077] In step S5, based on the first atomic gas chamber 5 129 Xe and 131 The resonant angular frequency of Xe determines the first angular velocity measurement:

[0078] ;

[0079] According to the second atomic gas chamber 6 129 Xe and 131 The resonant angular frequency of Xe determines the second angular velocity measurement:

[0080] ;

[0081] in, This is the measured value of the first angular velocity. This is the measured value of the second angular velocity; for 129 The gyromagnetic ratio of Xe for131 The gyromagnetic ratio of Xe and Each is located in the first atomic gas chamber 5. 129 Xe and 131 The resonant angular frequency of Xe, and The second atomic gas chamber 6 is respectively 129 Xe and 131 The resonant angular frequency of Xe; Let be the ratio of the gyromagnetic ratios of the two xenon isotopes, and satisfy:

[0082] ;

[0083] In obtaining respectively and Finally, the magnitude of the output angular velocity is determined according to the following formula:

[0084] .

[0085] When the two chambers are subjected to the same external rotation, the actual rotational components in the two channels correspond to the same angular velocity amplitude. Therefore, by adding them together, dividing by 2, and taking the absolute value, the superposition of the two channels can be normalized to the actual angular velocity level. The additional frequency shift caused by the combined disturbances of temperature, pump laser power and frequency, and probe laser power and frequency has opposite signs in the two opposite polarization channels. They weaken each other during the summation process, thereby reducing their impact on the final angular velocity output.

[0086] A complete measurement example is as follows:

[0087] First, the nuclear magnetic resonance atomic gyroscope is fixed on a turntable that provides a known angular velocity. With the turntable stationary, the magnetic field control circuit and heating unit 10 are activated. After the temperature and magnetic field environment of the two atomic chambers stabilize, the pump laser 8 and probe laser 7 are activated sequentially to ignite the rubidium atoms in the two chambers. 129 Xe and 131 Xe reaches a stable polarization state. Then, two RF excitation channels are activated. 129 Xe and 131 The Xe is scanned near the Larmor frequency, so that the four frequency tracking branches corresponding to the two gas chambers capture the corresponding resonance signals and enter the closed-loop locking state.

[0088] Data acquisition board synchronous reading , , and The signal processing module calculates according to the above formulas respectively. and Then according to Calculate the final angular velocity amplitude as the output reference under static conditions. After static recording is completed, rotate the turntable along a predetermined direction at a known angular velocity. The two angular velocity measurements change accordingly as the turntable rotates, and the final output changes with the turntable angular velocity.

[0089] While the turntable maintains stable rotation, the set temperature of the heating unit 10, the power or frequency of the pump laser 8, and the power or frequency of the probe laser 7 can be slightly adjusted, and the angular velocity measurements of the two single channels and the final output can be recorded continuously. Because the corresponding common-mode disturbance causes additional frequency shifts in opposite directions in the two channels, the disturbance change in the final average output is less than the disturbance change in a single channel. After completing the disturbance test, all parameters are restored to their original settings, and the turntable is stopped. Four resonant frequencies are continuously acquired to confirm that the final output can return to the vicinity of the stationary output reference.

[0090] In this embodiment, the first atomic gas chamber 5 and the second atomic gas chamber 6 form independent nuclear magnetic resonance measurement channels under common magnetic shielding environment and common temperature control conditions. The two channels utilize... 129 Xe and 131 The resonant frequency of Xe is used to calculate the corresponding angular velocity measurement value to reduce the influence of changes in the main magnetic field in each chamber on the angular velocity measurement. Then, the angular velocity measurements from the two chambers are first superimposed, then divided by 2 and the absolute value is taken. This preserves the same-direction components corresponding to the actual rotation in both channels and weakens the reverse residual frequency components caused by changes in temperature, pump laser, and probe laser power and frequency. Through a common reference clock, synchronous frequency acquisition, chamber performance screening, differential photodetector calibration, and RF excitation amplitude adjustment, the differences in frequency reference, sampling time, detection gain, and excitation intensity between the two measurement channels can be reduced, thereby achieving continuous and stable angular velocity measurement.

[0091] In summary, the first atomic gas chamber 5 and the second atomic gas chamber 6 respectively constitute measurement channels including bi-xenon isotope polarization, excitation, detection, and resonance tracking. The two measurement channels share the heating unit 10, the magnetic shielding environment, the pump laser 8, the detection laser 7, and the clock reference. Each measurement channel first obtains the corresponding angular velocity measurement value based on the resonance frequency of the two xenon isotopes, then the two angular velocity measurements are superimposed, divided by 2, and the absolute value is taken. This structure utilizes the combination of bi-isotope frequencies to reduce the influence of the main magnetic field changes in a single gas chamber, and utilizes the inverse relationship of the additional frequency shifts in the two oppositely polarized channels to reduce the output drift caused by changes in common temperature and optical parameters. At the same time, the Herriott multi-reflection cavity extends the effective interaction path between the detection laser 7 and the alkali metal atoms, realizing closed-loop angular velocity measurement of the bi-atomic gas chamber nuclear magnetic resonance atomic gyroscope.

Claims

1. A nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell, characterized in that, include: The first atomic gas chamber (5) and the second atomic gas chamber (6) are both located in the same magnetic shielding environment and share a heating unit (10); The first atomic gas chamber (5) and the second atomic gas chamber (6) respectively contain alkali metal atoms, first xenon isotope atoms, second xenon isotope atoms, and buffer gas; The pump optical path is used to split the same pump laser (8) into a first beam and a second beam; The first beam becomes after passing through the first quarter-wave plate Circularly polarized light enters the first atomic gas cell (5); The second beam becomes after passing through the second quarter-wave plate. Circularly polarized light enters the second atomic gas chamber (6); The first beam and the second beam cause the alkali metal electrons in the first atomic gas cell (5) and the second atomic gas cell (6) to form opposite actual polarization directions; The detection optical path is used to split the same detection laser (7) into two linearly polarized detection beams, which pass through the first atomic gas cell (5) and the second atomic gas cell (6) respectively and are then incident on their respective differential photodetectors. Two phase-locked loop modules are electrically connected to the output terminals of two differential photodetectors, respectively, to lock the frequency of the radio frequency excitation magnetic field applied to the corresponding atomic gas cell to the resonant frequency; as well as The signal processing module is electrically connected to the output terminals of the two phase-locked loop modules respectively. It is used to calculate the angular velocity measurement values ​​according to the resonance frequencies of the two xenon isotopes in the two gas chambers, and output the two angular velocity measurement values ​​after superimposing them, dividing by 2 and taking the absolute value.

2. The nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 1, characterized in that: The first atomic gas chamber (5) is provided with a first Herriott multi-reflection cavity, and the second atomic gas chamber (6) is provided with a second Herriott multi-reflection cavity; The first Herriott multi-reflection cavity and the second Herriott multi-reflection cavity each include a front cavity mirror (1) and a rear cavity mirror (2) arranged opposite to each other; Each front endoscope (1) and rear endoscope (2) is fixed on the same silicon substrate (3); The silicon substrate (3) is bonded to the first glass cover and the second glass cover respectively to form the first atomic gas chamber (5) and the second atomic gas chamber (6); A light-blocking silicon wafer (4) is disposed between the first atomic gas chamber (5) and the second atomic gas chamber (6), and the surface of the light-blocking silicon wafer (4) is provided with a high-reflectivity coating for reflecting the pump laser (8).

3. The nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 1, characterized in that: The pump optical path includes a pump laser, a cone amplifier, and a pump beam splitter connected sequentially along the pump light propagation direction; The pump optical splitter has a first output optical path and a second output optical path; The first quarter-wave plate is disposed on the first output optical path; The second quarter-wave plate is positioned on the second output optical path; The first output optical path and the second output optical path extend to the opposite sides of the first atomic gas chamber (5) and the second atomic gas chamber (6), respectively, so that Circularly polarized light and Circularly polarized light is incident relative to each other.

4. The nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 2, characterized in that: The detection optical path includes a detection laser, an acousto-optic modulator, an optical fiber coupling unit, and a detection optical splitter arranged sequentially along the direction of detection light propagation. The two linearly polarized probe beams output by the probe beam splitter are respectively perpendicular to the corresponding circularly polarized pump beams and incident on the first Herriott multi-reflection cavity and the second Herriott multi-reflection cavity. Each Herriott multi-reflection cavity has a polarization beam splitter and a differential photodetector sequentially installed in the output optical path; The two outputs of the polarization beam splitter are respectively connected to the two optical inputs of the corresponding differential photodetector.

5. The nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 1, characterized in that: It also includes a bias magnetic field coil, a first radio frequency excitation coil, a second radio frequency excitation coil, and a magnetic field gradient compensation coil; The bias magnetic field coil is disposed around the first atomic gas cell (5) and the second atomic gas cell (6); The first radio frequency excitation coil is set corresponding to the first atomic gas cell (5) and is electrically connected to the excitation output terminal of one of the phase-locked loop modules; The second radio frequency excitation coil is set in relation to the second atomic gas chamber (6) and is electrically connected to the excitation output terminal of another phase-locked loop module; The magnetic field gradient compensation coil is set in a magnetically shielded environment and includes a first-order magnetic field gradient compensation coil and a second-order magnetic field gradient compensation coil.

6. The nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 1, characterized in that: Each phase-locked loop module includes a first frequency tracking branch and a second frequency tracking branch; The first frequency tracking branch is used to track the resonance frequency of the first xenon isotope atom; The second frequency tracking branch is used to track the resonance frequency of the second xenon isotope atom; Two phase-locked loop (PLL) modules are connected to the same clock reference, with the clock output of one PLL module connected to the clock reference of the other PLL module. The signal processing module includes a data acquisition board, and the frequency output terminals of the two phase-locked loop modules are respectively connected to different acquisition channels of the data acquisition board.

7. A method for implementing a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell, characterized in that, Includes the following steps: S1. The first atomic gas chamber (5) containing alkali metal atoms, first xenon isotope atoms, second xenon isotope atoms and buffer gas and the second atomic gas chamber (6) are placed in the same magnetic shielding environment and the two atomic gas chambers are heated by the same heating unit (10); S2. The same pump laser (8) is divided into a first beam and a second beam, and the first beam is converted into... The circularly polarized light then enters the first atomic gas cell (5), converting the second beam into... The circularly polarized light is then injected into the second atomic gas cell (6) to polarize the alkali metal atoms in the two atomic gas cells respectively, and to make the alkali metal electron spins in the two atomic gas cells form opposite actual polarization directions. S3. The same probe laser (7) is split into two linearly polarized probe beams, and the two linearly polarized probe beams are reflected multiple times in the Herriott multi-reflection cavities in the two atomic gas chambers, and differential photoelectric detection is performed on the outgoing light of the two Herriott multi-reflection cavities to obtain the first probe signal and the second probe signal. S4. Perform phase-locked demodulation based on the first detection signal and the second detection signal respectively, and adjust the frequency of the radio frequency excitation magnetic field of the corresponding atomic gas cell according to the demodulated phase signal to obtain the resonance frequency of the two xenon isotopes in the first atomic gas cell (5) and the resonance frequency of the two xenon isotopes in the second atomic gas cell (6). S5. Calculate the first angular velocity measurement value based on the resonance frequency of the two xenon isotopes in the first atomic gas chamber (5), calculate the second angular velocity measurement value based on the resonance frequency of the two xenon isotopes in the second atomic gas chamber (6), and output the first angular velocity measurement value and the second angular velocity measurement value by superimposing them, dividing by 2 and taking the absolute value.

8. The method for implementing a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 7, characterized in that: The first xenon isotope atom is 129 Xe, the second xenon isotope atom is 131 Xe; In step S5, the first angular velocity measurement value and the second angular velocity measurement value are determined according to the following formulas: ； ； in, This is the measured value of the first angular velocity. This is the measured value of the second angular velocity. for 129 The gyromagnetic ratio of Xe for 131 The gyromagnetic ratio of Xe and The first atomic gas chamber (5) is located in the first atomic gas chamber. 129 Xe and 131 The resonant angular frequency of Xe, and The second atomic gas chamber (6) is located inside the second atomic gas chamber. 129 Xe and 131 The resonant angular frequency of Xe; The final output angular velocity amplitude according to Sure.

9. The method for implementing a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 7, characterized in that: In step S4, the 10MHz clock signal output by the rubidium clock is used as the external frequency reference of the first lock-in amplifier corresponding to the first atomic gas cell (5), and the clock signal output by the first lock-in amplifier is used as the clock reference of the second lock-in amplifier corresponding to the second atomic gas cell (6). The same data acquisition program is used to control the same data acquisition board, and the resonance frequencies of two xenon isotopes in two atomic gas chambers are acquired synchronously.

10. The method for implementing a nuclear magnetic resonance atomic gyroscope based on a dual-atom gas cell according to claim 7, characterized in that: Before step S1, select the first atomic gas chamber (5) and the second atomic gas chamber (6) made from the same batch of vacuum pipes, with the same gas filling amount and similar performance, and calibrate the photoelectric conversion coefficient of the differential photodetector corresponding to the two atomic gas chambers respectively. In step S4, the amplitude of the radio frequency excitation signal applied to the first atomic gas cell (5) and the second atomic gas cell (6) is adjusted according to the coil resistance of the corresponding radio frequency excitation coil.

Images