Method for measuring main magnetic field of nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation

Abstract

The invention provides a nuclear magnetic resonance gyroscope main magnetic field measurement method based on rotating magnetic field phase compensation. The method comprises the following steps: separating magnetic resonance signals of 129Xe nuclear spin and 131Xe nuclear spin in a nuclear magnetic resonance gyroscope; respectively demodulating the frequencies of the separated 129Xe nuclear spin magnetic resonance signal and the 131 Xe nuclear spin magnetic resonance signal by using a high-speed digital phase-locked loop, and carrying out summation operation on the two demodulated frequencies to obtain a sum frequency measurement signal; a rotating magnetic field simulating nuclear spin magnetic resonance is synthesized and generated; measuring a coupling phase error generated when the nuclear spin magnetic resonance signal is measured by electron spin to obtain an error compensation amount; and performing differential operation on the error compensation amount and the sum frequency measurement signal, and calculating to obtain an accurate value of the main magnetic field to be measured. According to the technical scheme, the technical problem that in the prior art, differential mode errors caused by precession phase coupling of paramagnetic resonance electron spinning and nuclear spinning are difficult to effectively restrain, and consequently the main magnetic field measurement precision is low is solved.

Description

Technical Field

[0001] This invention relates to the field of nuclear magnetic resonance gyroscope technology, and in particular to a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation. Background Technology

[0002] In the operation of a nuclear magnetic resonance gyroscope, the accurate measurement of the main magnetic field is crucial, as its accuracy directly affects the overall performance of the gyroscope. Traditional methods for measuring the main magnetic field are usually based on nuclear spin magnetic resonance signals, but in practical applications, various error factors can affect the measurement accuracy.

[0003] On the one hand, the precession phase coupling between electron spin and nuclear spin in paramagnetic resonance can lead to errors in magnetic resonance frequency measurement; on the other hand, different types of nuclear spin (such as...) 129 Xe and 131 (Xe) Due to the Fermi contact interaction, the sensed electron spin polarization magnetic field differs, further introducing errors. In addition, during the detection of electron spin precession signals by the detection light through the optical rotation effect, the detection background noise causes relative error in the calculation of the magnetic resonance signal frequency, and this error is related to the signal-to-noise ratio. When the signal-to-noise ratio is not ideal, the error will increase significantly.

[0004] While summing the two nuclear spin magnetic resonance frequencies can eliminate the influence of angular velocity and suppress common-mode errors to some extent, traditional methods struggle to effectively suppress differential-mode errors caused by coupling phase changes during nuclear spin precession in paramagnetic resonance electron spin measurements. This results in the main magnetic field measurement accuracy failing to meet the application requirements of high-precision nuclear magnetic resonance gyroscopes. Therefore, a method and system that can effectively suppress these differential-mode errors and improve the main magnetic field measurement accuracy is urgently needed. Summary of the Invention

[0005] This invention provides a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation. This method can solve the technical problem in the prior art of effectively suppressing differential mode errors caused by the precession phase coupling of paramagnetic resonance electron spin and nuclear spin, which leads to low accuracy in main magnetic field measurement.

[0006] According to one aspect of the present invention, a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation is provided. The method includes: Step one, based on electron spin paramagnetic resonance modulation and carrier demodulation, measuring the main magnetic field of the nuclear magnetic resonance gyroscope... 129 Xe nuclear spin and 131 The magnetic resonance signal of the Xe nuclear spin is demodulated, and the magnetic resonance signals of the two nuclear spins are separated using a filtering signal processing method. In the second step, a high-speed digital phase-locked loop is used to separate the magnetic resonance signals of the two nuclear spins. 129Xe nucleus spin magnetic resonance signal and 131 The frequency of the Xe nuclear spin magnetic resonance signal is demodulated, and the two demodulated frequencies are summed to obtain the sum-frequency measurement signal. Step three: Using x-axis and y-axis magnetic field coils, sinusoidal magnetic fields with a 90° phase difference, the same frequency, and different from the nuclear spin magnetic resonance signal frequency are applied to the x-axis and y-axis respectively, synthesizing a rotating magnetic field simulating nuclear spin magnetic resonance. Step four: By measuring the phase and frequency changes of the rotating magnetic field generated in step three through paramagnetic resonance electron spin measurement, the coupling phase error generated when measuring the nuclear spin magnetic resonance signal is measured, and the error compensation amount is obtained. Step five: The error compensation amount measured in step four is differentially calculated with the sum-frequency measurement signal obtained in step two to suppress the coupling phase error, calculate the accurate value of the main magnetic field to be measured, and complete the measurement of the main magnetic field of the nuclear magnetic resonance gyroscope.

[0007] Furthermore, step one specifically includes: activating the nuclear magnetic resonance gyroscope, causing its... 129 Xe nuclear spin and 131 The Xe nuclear spin is in a magnetic resonance state; based on electron spin paramagnetic resonance modulation technology, the nuclear spin magnetic resonance signal is modulated, and then the modulated signal is demodulated by a carrier demodulation circuit to obtain a signal containing... 129 Xe and 131 The mixed signal of Xe nuclear spin magnetic resonance is obtained; this mixed signal is input to a filtering circuit, which separates it into two signals based on the frequency difference between the two nuclear spin magnetic resonance signals. 129 Xe nucleus spin magnetic resonance signal and 131 Xe nucleus spin magnetic resonance signal.

[0008] Furthermore, step two specifically includes: separating the... 129 The Xe nucleus spin magnetic resonance signal is fed into the first high-speed digital phase-locked loop, and the separated... 131 The Xe nuclear spin magnetic resonance signal is fed into a second high-speed digital phase-locked loop (PLL). The two high-speed PLLs demodulate the frequency of the input signal, respectively, to obtain the demodulated signal. 129 Xe nucleus spin magnetic resonance frequency f1 and demodulated 131 The Xe nucleus spin magnetic resonance frequency f2 will be demodulated. 129 Xe nucleus spin magnetic resonance frequency f1 and demodulated 131 The Xe nuclear spin magnetic resonance frequency f2 is input to the summation circuit to obtain the sum frequency measurement signal f_sum = f1 + f2. The sum frequency measurement signal f_sum has eliminated the influence of the angular rate ω and suppressed the differential mode error Δf_d of magnetic resonance frequency measurement caused by the coupling phase change during the precession of nuclear spin in paramagnetic resonance electron spin measurement.

[0009] Furthermore, the sum-frequency measurement signal f_sum can be calculated using the formula f_sum=(γ1+γ2)B0+2Δf_c+2Δf_n, where γ1 and γ2 are respectively... 129 Xe and 131 The gyromagnetic ratio of the Xe nuclear spin, Δf_c is the common-mode coupling phase error of the magnetic resonance frequency measurement caused by the coupling phase change during the measurement of nuclear spin precession in paramagnetic resonance electron spin, Δf_n is the coupling phase error caused by the detection background noise during the detection of electron spin precession signal by the detection light through the optical rotation effect, and B0 is the main magnetic field to be measured.

[0010] Further, step three specifically includes: generating two sinusoidal signals through a signal generator; one sinusoidal signal is input to the x-axis magnetic field coil driving circuit, driving the x-axis magnetic field coil to generate a sinusoidal magnetic field Bx = B0x sin(2πft) in the x-axis direction; the other sinusoidal signal, after passing through a 90° phase-shifting circuit, is input to the y-axis magnetic field coil driving circuit, driving the y-axis magnetic field coil to generate a sinusoidal magnetic field By = B0y cos(2πft) in the y-axis direction, where f is the frequency of the sinusoidal signal, and the frequency f is related to... 129 Xe, 131 The Xe nucleus spin magnetic resonance signals have different frequencies, and B0x and B0y are the amplitudes of the sinusoidal magnetic fields along the x-axis and y-axis, respectively; the combination of Bx and By generates a rotating magnetic field B_rot.

[0011] Further, step four specifically includes: after the paramagnetic resonance electron spin senses the rotating magnetic field B_rot, its precession state will change; the precession signal of the electron spin is detected by the optical rotation effect of the detection light (along the x-axis direction), the signal is input to the signal processing unit, the phase and frequency changes of the rotating magnetic field B_rot are analyzed, and the error compensation amount Δf_comp is calculated by combining the pre-calibrated coefficient K.

[0012] Furthermore, in step five, the main magnetic field B0 to be measured can be calculated according to B0 = f_final / (γ1+γ2), where f_final is the difference between the sum-frequency measurement signal f_sum and the error compensation amount Δf_comp.

[0013] According to another aspect of the present invention, a nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation is provided, characterized in that the nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation is used to implement the nuclear magnetic resonance gyroscope main magnetic field measurement method based on rotating magnetic field phase compensation as described above.

[0014] Furthermore, the nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation includes: a signal demodulation and separation module, which is used for electron spin-based paramagnetic resonance modulation and carrier demodulation, to...129 Xe nuclear spin and 131 The magnetic resonance signal of the Xe nuclear spin is demodulated, and the magnetic resonance signals of the two nuclear spins are separated by a filtering signal processing method. The frequency demodulation and preliminary calculation module includes a high-speed digital phase-locked loop (PLL) and a summation unit. The PLL demodulates the frequencies of the separated nuclear spin magnetic resonance signals, and the summation unit sums the two demodulated frequencies to obtain a preliminary sum-frequency measurement signal. The rotating magnetic field generation module consists of a signal generator, a 90° phase-shifting circuit, an x-axis magnetic field coil drive circuit, a y-axis magnetic field coil drive circuit, an x-axis magnetic field coil, and a y-axis magnetic field coil. The signal generator outputs two sinusoidal signals of the same frequency. One input is directly to the x-axis magnetic field coil drive circuit, and the other is input to the y-axis magnetic field coil drive circuit after passing through a 90° phase shift circuit. The x-axis and y-axis magnetic field coils generate sinusoidal magnetic fields under the action of the x-axis and y-axis magnetic field coil drive circuits, respectively, to synthesize a rotating magnetic field. The coupling phase error measurement module is used to measure the phase and frequency changes of the rotating magnetic field through paramagnetic resonance electron spin to obtain the error compensation amount. The phase compensation and precision measurement module is used to perform differential operation on the error compensation amount and the sum-frequency measurement signal to suppress the coupling phase differential mode error and output a precise main magnetic field measurement signal.

[0015] Furthermore, the coupled phase error measurement module includes a detection light emission unit, a light detection unit, and an error calculation unit. The detection light emission unit emits detection light along the x-axis. After passing through a medium containing nuclear spin and electron spin, the light detection unit detects the optical rotation change of the light to obtain the electron spin precession signal. The error calculation unit processes the signal, analyzes the phase and frequency changes of the rotating magnetic field, and calculates the error compensation amount.

[0016] Applying the technical solution of this invention, a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation is provided. This invention achieves this by... 129 Xe and 131Summing the two nuclear spin magnetic resonance frequencies (Xe and Xe) effectively eliminates the influence of the measured angular velocity in the nuclear magnetic resonance gyroscope (NMR gyroscope), while suppressing common-mode errors caused by the precession phase coupling of paramagnetic resonance electron spin and nuclear spin. This enhances the signal-to-noise ratio of the main magnetic field measurement, laying the foundation for subsequent accurate measurements. An innovative method for suppressing coupling phase errors based on rotating magnetic field phase difference is proposed. By generating a rotating magnetic field simulating nuclear spin magnetic resonance, precise measurement and compensation of coupling phase differential-mode errors are achieved, further suppressing differential-mode errors and significantly improving the accuracy of the main magnetic field measurement, meeting the application requirements of high-precision NMR gyroscopes. Therefore, compared with existing technologies, the NMR gyroscope main magnetic field measurement method based on rotating magnetic field phase compensation provided by this invention can achieve accurate measurement of the main magnetic field of the NMR gyroscope, effectively solving the problem of low main magnetic field measurement accuracy caused by the differential-mode error resulting from the difficult suppression of the precession phase coupling of paramagnetic resonance electron spin and nuclear spin in existing technologies. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 A schematic diagram of the main magnetic field measurement system of nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation provided according to a specific embodiment of the present invention is shown. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0022] like Figure 1 As shown, a specific embodiment of the present invention provides a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation. This method includes: Step one, based on electron spin paramagnetic resonance modulation and carrier demodulation, measuring the main magnetic field of the nuclear magnetic resonance gyroscope... 129 Xe nuclear spin and 131 The magnetic resonance signal of the Xe nuclear spin is demodulated, and the magnetic resonance signals of the two nuclear spins are separated using a filtering signal processing method. In the second step, a high-speed digital phase-locked loop is used to separate the magnetic resonance signals of the two nuclear spins. 129 Xe nucleus spin magnetic resonance signal and 131The frequency of the Xe nuclear spin magnetic resonance signal is demodulated, and the two demodulated frequencies are summed to obtain the sum-frequency measurement signal. Step three: Using x-axis and y-axis magnetic field coils, sinusoidal magnetic fields with a 90° phase difference, the same frequency, and different from the nuclear spin magnetic resonance signal frequency are applied to the x-axis and y-axis respectively, synthesizing a rotating magnetic field simulating nuclear spin magnetic resonance. Step four: The phase and frequency changes of the rotating magnetic field generated in step three are measured by paramagnetic resonance electron spin measurement to measure the coupling phase error generated when measuring the nuclear spin magnetic resonance signal, obtaining the error compensation amount. Step five: The error compensation amount measured in step four is differentially calculated with the sum-frequency measurement signal obtained in step two to suppress the coupling phase error, calculate the accurate value of the main magnetic field to be measured, and complete the measurement of the main magnetic field of the nuclear magnetic resonance gyroscope.

[0023] This configuration provides a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation. The invention achieves this by... 129 Xe and 131 Summing the two nuclear spin magnetic resonance frequencies (Xe and Xe) effectively eliminates the influence of the measured angular velocity in the nuclear magnetic resonance gyroscope (NMR gyroscope), while suppressing common-mode errors caused by the precession phase coupling of paramagnetic resonance electron spin and nuclear spin. This enhances the signal-to-noise ratio of the main magnetic field measurement, laying the foundation for subsequent accurate measurements. An innovative method for suppressing coupling phase errors based on rotating magnetic field phase difference is proposed. By generating a rotating magnetic field simulating nuclear spin magnetic resonance, precise measurement and compensation of coupling phase differential-mode errors are achieved, further suppressing differential-mode errors and significantly improving the accuracy of the main magnetic field measurement, meeting the application requirements of high-precision NMR gyroscopes. Therefore, compared with existing technologies, the NMR gyroscope main magnetic field measurement method based on rotating magnetic field phase compensation provided by this invention can achieve accurate measurement of the main magnetic field of the NMR gyroscope, effectively solving the problem of low main magnetic field measurement accuracy caused by the differential-mode error resulting from the difficult suppression of the precession phase coupling of paramagnetic resonance electron spin and nuclear spin in existing technologies.

[0024] Specifically, the purpose of this invention is to provide a method and system for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation, so as to solve the problem in the prior art of effectively suppressing the differential mode error caused by the precession phase coupling of paramagnetic resonance electron spin and nuclear spin, resulting in low accuracy of main magnetic field measurement. To achieve the above objective, this invention adopts the following technical solution, specifically including the following steps:

[0025] 1. Nuclear spin magnetic resonance signal demodulation and separation: Based on electron spin paramagnetic resonance modulation and carrier demodulation, the nuclear magnetic resonance gyroscope signal is demodulated and separated. 129 Xe nuclear spin and 131The magnetic resonance signal of the Xe nuclear spin is demodulated, and then the magnetic resonance signals of the two nuclear spins are separated by signal processing methods such as filtering.

[0026] 2. Nuclear spin magnetic resonance frequency demodulation and preliminary processing: Using a high-speed digital phase-locked loop, the separated nuclear spin magnetic resonance frequencies are demodulated and preliminarily processed. 129 Xe nucleus spin magnetic resonance signal and 131 The frequency of the Xe nuclear spin magnetic resonance signal is demodulated, and the two demodulated frequencies are summed to obtain the preliminary main magnetic field measurement signal.

[0027] In an ideal situation, the demodulated 129 Xe nuclear spin magnetic resonance frequencies f1 and 131 The Xe nuclear spin magnetic resonance frequency f2 satisfies:

[0028] f1 = γ1(B0 + ω / γ1)

[0029] f2=γ2(B0-ω / γ2)

[0030] Wherein, γ1 and γ2 are respectively 129 Xe and 131 The gyromagnetic ratio of the Xe nuclear spin (a constant), ω is the angular velocity to be measured in the nuclear magnetic resonance gyroscope, and B0 is the main magnetic field to be measured. Since γ1 and γ2 have opposite signs, the influence of ω can be eliminated after summation, and the preliminary main magnetic field measurement related signal can be obtained.

[0031] f1+f2=(γ1+γ2)B0

[0032] In practice, after considering the error term, f1 and f2 are expressed as follows:

[0033] f1=γ1(B0+ω / γ1)+Δf_d+Δf_c+Δf_n

[0034] f2=γ2(B0-ω / γ2)-Δf_d+Δf_c+Δf_n

[0035] Wherein, Δf_d represents the differential-mode error in magnetic resonance frequency measurement caused by the coupling phase change during nuclear spin precession in paramagnetic resonance electron spin measurement; Δf_c represents the common-mode coupling phase error in magnetic resonance frequency measurement caused by the coupling phase change during nuclear spin precession in paramagnetic resonance electron spin measurement; and Δf_n represents the coupling phase error caused by the detection background noise during the detection of the electron spin precession signal by the detection light through the optical rotation effect. Summing f1 and f2 yields the sum-frequency measurement signal f_sum = (γ1 + γ2)B0 + 2Δf_c + 2Δf_n. This signal is independent of ω and can serve as the fundamental signal for main magnetic field measurement, effectively suppressing Δf_d and enhancing the signal-to-noise ratio of main magnetic field measurement. To further suppress Δf_c and Δf_n, compensation is further achieved by measuring the coupling phase error using a rotating magnetic field.

[0036] 3. Generation of rotating magnetic field: Using x-axis and y-axis magnetic field coils, sinusoidal magnetic fields with a 90° phase difference, the same frequency, and different frequency from the nuclear spin magnetic resonance signal are applied to the x-axis and y-axis respectively, to synthesize a rotating magnetic field that simulates nuclear spin magnetic resonance.

[0037] 4. Coupling phase error measurement: By measuring the phase and frequency changes of the rotating magnetic field generated in step 3 of the paramagnetic resonance electron spin measurement, the coupling phase error (i.e., the error source related to the differential mode error Δf_c + Δf_n) generated when the electron spin measures the nuclear spin magnetic resonance signal is realized, and the error compensation amount Δf_comp = 2Δf_c + 2Δf_n is obtained.

[0038] 5. Phase compensation and precise main magnetic field measurement: The error compensation amount Δf_comp measured in step 4 is differentially calculated with the sum frequency measurement signal f_sum obtained in step 2, i.e., f_final=f_sum-Δf_comp=(γ1+γ2)B0, to suppress the coupling phase error and obtain a precise main magnetic field measurement signal, thereby determining the magnitude of the main magnetic field B0 to be measured.

[0039] According to another aspect of the invention, a nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation is also included, the system comprising:

[0040] 1. Signal Demodulation and Separation Module: Used for electron spin-based paramagnetic resonance modulation and carrier demodulation, converting... 129 Xe nuclear spin and 131 The magnetic resonance signal of the Xe nuclear spin was demodulated, and the magnetic resonance signals of the two nuclear spins were separated by signal processing methods such as filtering.

[0041] 2. Frequency demodulation and preliminary calculation module: This module includes a high-speed digital phase-locked loop (PLL) and a summation unit. The PLL is used to demodulate the frequencies of the two separated nuclear spin magnetic resonance signals, and the summation unit is used to sum the two demodulated frequencies to obtain a preliminary sum-frequency measurement signal.

[0042] 3. Rotating magnetic field generation module: It consists of an x-axis magnetic field coil, a y-axis magnetic field coil and a signal generation unit. The signal generation unit is used to generate a sinusoidal signal with a 90° phase difference, the same frequency and different frequency from the nuclear spin magnetic resonance signal. The x-axis magnetic field coil and the y-axis magnetic field coil apply sinusoidal magnetic fields on the x-axis and y-axis respectively according to the sinusoidal signal to synthesize a rotating magnetic field.

[0043] 4. Coupled Phase Error Measurement Module: Used to measure the phase and frequency changes of the rotating magnetic field through paramagnetic resonance electron spin to obtain the error compensation amount.

[0044] 5. Phase Compensation and Precision Measurement Module: This module performs differential operations on the error compensation amount and the sum-frequency measurement signal to suppress the coupled phase differential mode error and output a precise main magnetic field measurement signal.

[0045] The present invention has the following beneficial effects:

[0046] 1. This invention, through the... 129 Xe and 131 Summing the two nuclear spin magnetic resonance frequencies of Xe can effectively eliminate the influence of the measured angular velocity of the nuclear magnetic resonance gyroscope, while suppressing the common-mode error caused by the precession phase coupling of the paramagnetic resonance electron spin and nuclear spin, enhancing the signal-to-noise ratio of the main magnetic field measurement, and laying the foundation for subsequent accurate measurements.

[0047] 2. An innovative method for suppressing coupled phase error based on rotating magnetic field phase difference is proposed. By generating a rotating magnetic field that simulates nuclear spin magnetic resonance, the method achieves accurate measurement and compensation of coupled phase differential mode error, further suppressing differential mode error and significantly improving the accuracy of main magnetic field measurement, thus meeting the application requirements of high-precision nuclear magnetic resonance gyroscopes.

[0048] 3. The measurement system of the present invention has a clear structure, well-defined functions of each module, is easy to implement and integrate, and has good practicality and scalability. It can be widely used in various nuclear magnetic resonance gyroscope devices that require high-precision main magnetic field measurement.

[0049] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0050] Example 1

[0051] A method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation, the specific steps of which are as follows:

[0052] 1. Demodulation and separation of nuclear spin magnetic resonance signals: Activate the nuclear magnetic resonance gyroscope, causing its... 129 Xe nuclear spin and 131 The Xe nuclear spin is in a magnetic resonance state. Based on electron spin paramagnetic resonance modulation (SMRM), the nuclear spin magnetic resonance signal is modulated, and then demodulated using a carrier demodulation circuit to obtain a signal containing... 129 Xe and 131 The mixed signal of Xe nuclear spin magnetic resonance is input into a filtering circuit (such as a bandpass filter). Based on the frequency difference between the two nuclear spin magnetic resonance signals, it is separated into two signals. 129 Xe nucleus spin magnetic resonance signal and 131 Xe nucleus spin magnetic resonance signal.

[0053] 2. Nuclear spin magnetic resonance frequency demodulation and preliminary processing: The separated nuclear spin magnetic resonance frequencies are then... 129The Xe nuclear spin magnetic resonance signal is fed into a high-speed digital phase-locked loop 1. 131 The Xe nuclear spin magnetic resonance signal is input into a high-speed digital phase-locked loop (PLL) 2. Two PLLs demodulate the frequencies of the input signal, yielding f1 and f2 respectively. f1 and f2 are then input to a summation circuit to obtain f_sum = f1 + f2. At this point, f_sum has eliminated the influence of the angular rate ω and suppressed the differential-mode error Δf_d in magnetic resonance frequency measurement caused by the coupling phase change during nuclear spin precession in paramagnetic resonance electron spin measurement.

[0054] 3. Rotating Magnetic Field Generation: Two sinusoidal signals are generated by a signal generator. One sinusoidal signal is input to the x-axis magnetic field coil drive circuit, driving the x-axis magnetic field coil to generate a sinusoidal magnetic field Bx = B0x sin(2πft) in the x-axis direction. The other sinusoidal signal, after passing through a 90° phase-shifting circuit, is input to the y-axis magnetic field coil drive circuit, driving the y-axis magnetic field coil to generate a sinusoidal magnetic field By = B0y cos(2πft) in the y-axis direction, where f is the frequency of the sinusoidal signal, and f is related to... 129 Xe, 131 The Xe nucleus spin magnetic resonance signals have different frequencies, and B0x and B0y are the amplitudes of the sinusoidal magnetic fields along the x and y axes, respectively. The combination of Bx and By produces a rotating magnetic field B_rot.

[0055] 4. Coupling Phase Error Measurement: After the paramagnetic resonance electron spin senses the rotating magnetic field B_rot, its precession state changes. The precession signal of the electron spin is detected by the optical rotation effect of detection light (along the x-axis). This signal is input to the signal processing unit to analyze the phase and frequency changes of the rotating magnetic field B_rot. Combined with a pre-calibrated coefficient K (obtained experimentally and used to convert the phase and frequency changes of the rotating magnetic field into corresponding error compensation amounts), the error compensation amount Δf_comp = K × Δ (related parameters of the phase and frequency changes of B_rot) is calculated.

[0056] 5. Phase Compensation and Precise Main Magnetic Field Measurement: Δf_comp is input to the differential operation circuit and differentially calculated with f_sum to obtain f_final = f_sum - Δf_comp. Based on the correspondence between f_final and the main magnetic field B0 (from...),... 129 Xe and 131 The gyromagnetic ratio of Xe is determined, i.e., f_final=(γ1+γ2)B0+2Δf_c+2Δf_n1-Δf_comp. After compensation, the error term is greatly reduced, and it can be considered that f_final≈(γ1+γ2)B0. The accurate value of the main magnetic field B0 to be measured is calculated, i.e., B0=f_final / (γ1+γ2).

[0057] Example 2

[0058] Figure 1 This is a block diagram of the main magnetic field measurement system based on rotating magnetic field phase compensation in an embodiment of the present invention. Figure 1 In the process, the signal generation unit is connected to the x-axis magnetic field coil and the y-axis magnetic field coil respectively. The magnetic fields generated by the x-axis magnetic field coil and the y-axis magnetic field coil act on the paramagnetic resonance electron spin measurement module. The output terminal of the paramagnetic resonance electron spin measurement module is connected to the error measurement unit. The output terminal of the error measurement unit is connected to the differential operation module. The differential operation module simultaneously receives the sum frequency measurement signal output by the summation operation module. The output of the differential operation module is the accurate main magnetic field measurement signal.

[0059] This embodiment provides a nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation. The system includes a signal demodulation and separation module, a frequency demodulation and preliminary calculation module, a rotating magnetic field generation module, a coupling phase error measurement module, and a phase compensation and precise measurement module.

[0060] The signal demodulation and separation module consists of a paramagnetic resonance modulation circuit, a carrier demodulation circuit, and a filtering circuit. The paramagnetic resonance modulation circuit modulates the nuclear spin magnetic resonance signal, the carrier demodulation circuit demodulates the modulated signal, and the filtering circuit uses a bandpass filter for separation. 129 Xe and 131 Xe nucleus spin magnetic resonance signal.

[0061] The frequency demodulation and preliminary calculation module includes two high-speed digital phase-locked loops (PLLs) and a summation circuit (composed of operational amplifiers acting as adders). The two high-speed digital PLLs are connected to the two outputs of the filter circuit, respectively, to demodulate the frequencies of the two nuclear spin magnetic resonance signals. The two inputs of the summation circuit are connected to the outputs of the two high-speed digital PLLs, respectively, to sum the demodulated frequencies.

[0062] The rotating magnetic field generation module consists of a signal generator, a 90° phase-shifting circuit, an x-axis magnetic field coil drive circuit, a y-axis magnetic field coil drive circuit, an x-axis magnetic field coil, and a y-axis magnetic field coil. The signal generator outputs two sinusoidal signals of the same frequency. One signal is directly input to the x-axis magnetic field coil drive circuit, and the other signal is input to the y-axis magnetic field coil drive circuit after passing through the 90° phase-shifting circuit. The x-axis and y-axis magnetic field coils generate sinusoidal magnetic fields under the action of the drive circuits, which combine to form a rotating magnetic field.

[0063] The coupled phase error measurement module includes a detection light emitting unit (such as a laser), a light detection unit (such as a photodiode), and an error calculation unit (composed of a microprocessor). The detection light emitting unit emits detection light along the x-axis. After passing through a medium containing nuclear spin and electron spin, the light detection unit detects the optical rotation change of the light to obtain the electron spin precession signal. The error calculation unit processes this signal, analyzes the phase and frequency changes of the rotating magnetic field, and calculates the error compensation amount.

[0064] The phase compensation and precision measurement module consists of a differential operation circuit (composed of operational amplifiers forming a subtractor) and a main magnetic field calculation unit (sharing a microprocessor with the error calculation unit). The two inputs of the differential operation circuit are connected to the outputs of the summation operation circuit and the error calculation unit, respectively, to perform differential calculation on the sum-frequency measurement signal and the error compensation amount. The main magnetic field calculation unit calculates the precise value of the main magnetic field to be measured based on the differential signal and outputs the measurement result through a communication interface (such as RS232).

[0065] When the system is in operation, the modules work together to accurately measure the main magnetic field of the nuclear magnetic resonance gyroscope by following the measurement method and steps in Example 1 above.

[0066] In summary, this invention provides a method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation. This invention achieves this by... 129 Xe and 131 Summing the two nuclear spin magnetic resonance frequencies (Xe and Xe) effectively eliminates the influence of the measured angular velocity in the nuclear magnetic resonance gyroscope, while suppressing the common-mode error caused by the precession phase coupling of paramagnetic resonance electron spin and nuclear spin, thus enhancing the signal-to-noise ratio of the main magnetic field measurement and laying the foundation for subsequent accurate measurements. An innovative coupling phase error suppression method based on rotating magnetic field phase difference is proposed. By generating a rotating magnetic field simulating nuclear spin magnetic resonance, accurate measurement and compensation of coupling phase differential mode error are achieved, further suppressing differential mode error and significantly improving the accuracy of the main magnetic field measurement, meeting the application requirements of high-precision nuclear magnetic resonance gyroscopes. The measurement system of this invention has a clear structure, well-defined functions for each module, is easy to implement and integrate, and possesses good practicality and scalability. It can be widely applied to various nuclear magnetic resonance gyroscope devices requiring high-precision main magnetic field measurement.

[0067] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0068] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

Claims

1. A method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation, characterized in that, The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation includes: Step one: Based on electron spin paramagnetic resonance modulation and carrier demodulation, the NMR gyroscope... 129 Xe nuclear spin and 131 The magnetic resonance signal of the Xe nuclear spin was demodulated, and the magnetic resonance signals of the two nuclear spins were separated by a filtering signal processing method. Step two: Using a high-speed digital phase-locked loop, the separated components are... 129 Xe nucleus spin magnetic resonance signal and 131 The frequency of the Xe nuclear spin magnetic resonance signal is demodulated, and the sum of the two demodulated frequencies is calculated to obtain the sum frequency measurement signal. Step 3: Using the x-axis magnetic field coil and the y-axis magnetic field coil, sinusoidal magnetic fields with a 90° phase difference, the same frequency, and different frequency from the nuclear spin magnetic resonance signal are applied to the x-axis and y-axis respectively, to synthesize a rotating magnetic field that simulates nuclear spin magnetic resonance. Step four: By measuring the phase and frequency changes of the rotating magnetic field generated in step three through paramagnetic resonance electron spin measurement, the coupling phase error generated when measuring nuclear spin magnetic resonance signals by electron spin is realized, and the error compensation amount is obtained. Step 5: Perform differential calculation between the error compensation amount measured in Step 4 and the sum-frequency measurement signal obtained in Step 2 to suppress the coupling phase error, calculate the accurate value of the main magnetic field to be measured, and complete the measurement of the main magnetic field of the nuclear magnetic resonance gyroscope.

2. The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation according to claim 1, characterized in that, Step one specifically includes: activating the nuclear magnetic resonance gyroscope, causing its... 129 Xe nuclear spin and 131 The Xe nuclear spin is in a magnetic resonance state; based on electron spin paramagnetic resonance modulation technology, the nuclear spin magnetic resonance signal is modulated, and then the modulated signal is demodulated by a carrier demodulation circuit to obtain a signal containing... 129 Xe and 131 The mixed signal of Xe nuclear spin magnetic resonance is obtained; this mixed signal is input to a filtering circuit, which separates it into two signals based on the frequency difference between the two nuclear spin magnetic resonance signals. 129 Xe nucleus spin magnetic resonance signal and 131 Xe nucleus spin magnetic resonance signal.

3. The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation according to claim 2, characterized in that, Step two specifically includes: separating the... 129 The Xe nucleus spin magnetic resonance signal is fed into the first high-speed digital phase-locked loop, and the separated... 131 The Xe nuclear spin magnetic resonance signal is fed into a second high-speed digital phase-locked loop (PLL). The two high-speed PLLs demodulate the frequency of the input signal, respectively, to obtain the demodulated signal. 129 Xe nucleus spin magnetic resonance frequency f1 and demodulated 131 The Xe nucleus spin magnetic resonance frequency f2 will be demodulated. 129 Xe nucleus spin magnetic resonance frequency f1 and demodulated 131 The Xe nuclear spin magnetic resonance frequency f2 is input to the summation operation circuit to obtain the sum frequency measurement signal f_sum = f1 + f2; the sum frequency measurement signal f_sum has eliminated the influence of angular rate ω and suppressed the differential mode error Δf_d of magnetic resonance frequency measurement caused by the coupling phase change during the precession of nuclear spin in paramagnetic resonance electron spin measurement.

4. The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation according to claim 3, characterized in that, The sum-frequency measurement signal f_sum can be calculated based on f_sum=(γ1+γ2)B0+2Δf_c+2Δf_n, where γ1 and γ2 are respectively 129 Xe and 131 The gyromagnetic ratio of the Xe nuclear spin, Δf_c is the common-mode coupling phase error of the magnetic resonance frequency measurement caused by the coupling phase change during the measurement of nuclear spin precession in paramagnetic resonance electron spin, Δf_n is the coupling phase error caused by the detection background noise during the detection of electron spin precession signal by the detection light through the optical rotation effect, and B0 is the main magnetic field to be measured.

5. The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation according to claim 4, characterized in that, Step three specifically includes: generating two sinusoidal signals using a signal generator; one sinusoidal signal is input to the x-axis magnetic field coil driving circuit, driving the x-axis magnetic field coil to generate a sinusoidal magnetic field Bx = B0x sin(2πft) in the x-axis direction; the other sinusoidal signal, after passing through a 90° phase-shifting circuit, is input to the y-axis magnetic field coil driving circuit, driving the y-axis magnetic field coil to generate a sinusoidal magnetic field By = B0y cos(2πft) in the y-axis direction, where f is the frequency of the sinusoidal signal, and the frequency f is related to... 129 Xe, 131 The Xe nucleus spin magnetic resonance signals have different frequencies, and B0x and B0y are the amplitudes of the sinusoidal magnetic fields along the x-axis and y-axis, respectively; the combination of Bx and By generates a rotating magnetic field B_rot.

6. The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation according to claim 5, characterized in that, Step four specifically includes: after the paramagnetic resonance electron spin senses the rotating magnetic field B_rot, its precession state will change; the precession signal of the electron spin is detected by the optical rotation effect of the detection light (along the x-axis direction), the signal is input to the signal processing unit, the phase and frequency changes of the rotating magnetic field B_rot are analyzed, and the error compensation amount Δf_comp is calculated by combining the pre-calibrated coefficient K.

7. The method for measuring the main magnetic field of a nuclear magnetic resonance gyroscope based on rotating magnetic field phase compensation according to claim 6, characterized in that, In step five, the main magnetic field B0 to be measured can be calculated according to B0 = f_final / (γ1+γ2), where f_final is the difference between the sum-frequency measurement signal f_sum and the error compensation amount Δf_comp.

8. A nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation, characterized in that, The nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation is used to implement the nuclear magnetic resonance gyroscope main magnetic field measurement method based on rotating magnetic field phase compensation as described in claims 1 to 7.

9. The nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation according to claim 8, characterized in that, The nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation includes: The signal demodulation and separation module is used for electron spin-based paramagnetic resonance modulation and carrier demodulation, and to... 129 Xe nuclear spin and 131 The magnetic resonance signal of the Xe nuclear spin was demodulated, and the magnetic resonance signals of the two nuclear spins were separated by a filtering signal processing method. The frequency demodulation and preliminary calculation module includes a high-speed digital phase-locked loop and a summation unit. The high-speed digital phase-locked loop is used to demodulate the frequencies of the two separated nuclear spin magnetic resonance signals, and the summation unit is used to sum the two demodulated frequencies to obtain a preliminary sum-frequency measurement signal. A rotating magnetic field generation module is provided, comprising a signal generator, a 90° phase-shifting circuit, an x-axis magnetic field coil driving circuit, a y-axis magnetic field coil driving circuit, an x-axis magnetic field coil, and a y-axis magnetic field coil. The signal generator outputs two sinusoidal signals of the same frequency. One signal is directly input to the x-axis magnetic field coil driving circuit, and the other signal is input to the y-axis magnetic field coil driving circuit after passing through the 90° phase-shifting circuit. The x-axis magnetic field coil and the y-axis magnetic field coil generate sinusoidal magnetic fields under the action of the x-axis magnetic field coil driving circuit and the y-axis magnetic field coil driving circuit, respectively, thus synthesizing a rotating magnetic field. A coupled phase error measurement module is used to measure the phase and frequency changes of a rotating magnetic field through paramagnetic resonance electron spin to obtain the error compensation amount; The phase compensation and precise measurement module is used to perform differential operations on the error compensation amount and the sum-frequency measurement signal to suppress the coupled phase differential mode error and output a precise main magnetic field measurement signal.

10. The nuclear magnetic resonance gyroscope main magnetic field measurement system based on rotating magnetic field phase compensation according to claim 9, characterized in that, The coupled phase error measurement module includes a detection light emission unit, a light detection unit, and an error calculation unit. The detection light emission unit emits detection light along the x-axis. After passing through a medium containing nuclear spin and electron spin, the light detection unit detects the optical rotation change of the light to obtain the electron spin precession signal. The error calculation unit processes the signal, analyzes the phase and frequency changes of the rotating magnetic field, and calculates the error compensation amount.

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