CN-121995275-A - Method and system for resisting longitudinal magnetic field interference of atomic magnetometer based on zero offset control

CN121995275ACN 121995275 ACN121995275 ACN 121995275ACN-121995275-A

Abstract

The method and the system for resisting the longitudinal magnetic field interference of the atomic magnetometer based on zero offset control are characterized in that a system response model containing zero offset errors is established, zero offset points of first harmonic and second harmonic response signals are respectively set as closed-loop control targets of x-axis magnetic fields and y-axis magnetic fields, and further output response of a double-loop closed-loop feedback control system is stabilized at the zero offset points, so that interference of longitudinal magnetic field fluctuation on transverse magnetic field measurement is isolated in principle, and real-time decoupling measurement of a transverse magnetic field to be measured is realized. The invention solves the problem that the prior art can not simultaneously inhibit quasi-static and dynamic longitudinal magnetic field interference, and has the beneficial effects of being completely free from longitudinal magnetic field interference, double-shaft decoupling measurement and long-term stable operation.

Inventors

LU JIXI
ZHAN DI
WANG YAOGUO
FANG JIANCHENG

Assignees

北京航空航天大学
合肥国家实验室

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (9)

1. The method for resisting the longitudinal magnetic field interference by the atomic magnetometer based on zero offset control is characterized by comprising the following steps of: step 1, a system response model for resisting longitudinal magnetic field interference is established based on a SERF atomic magnetometer system, wherein the system response model comprises zero offset errors output by the system; step 2, setting And , Is that Is used for the zero offset point of the (a), Is that Is used for the zero offset point of the (a), Is the first harmonic of the response signal, Is the second harmonic of the response signal; Step 3, by As a closed loop control target of the first sensitive axis, i.e. the x-axis, to As a closed-loop control target of a second sensitive axis, namely a y axis; step 4, based on the closed-loop control target, implementing independent closed-loop feedback control on the first sensitive axis and the second sensitive axis respectively to dynamically control the first sensitive axis and the second sensitive axis Locked at And put up and put down the Locked at And obtain by feedback signal And , Is the x-axis magnetic field or the first sensitive axis magnetic field, The y-axis magnetic field is the second sensitive axis magnetic field, so that real-time decoupling measurement of the sensitive axis magnetic field is realized.
2. The method for resisting longitudinal magnetic field interference by an atomic magnetometer based on zero offset control according to claim 1, characterized by comprising the steps of calibrating by a cross-axis magnetic field compensation method before implementing closed loop feedback control in step 4 And 。
3. The method for resisting longitudinal magnetic field interference of an atomic magnetometer based on zero offset control according to claim 2, characterized in that said method for compensating a cross-axis magnetic field comprises the following steps: Step 4.1, sequentially compensating a plurality of axial residual magnetic fields by applying an alternating magnetic field and adjusting a direct-current bias magnetic field of an orthogonal axis to minimize the same-frequency oscillation amplitude caused by the alternating magnetic field in a system response signal; Step 4.2, reading and recording the magnetic field in the compensated zero magnetic field environment As output value of (2) Reading and recording the As output value of (2) 。
4. The method of claim 1, wherein the closed loop feedback control in step 4 is implemented by a first PID controller for the x-axis feedback signal and a second PID controller for the y-axis feedback signal.
5. The method of anti-longitudinal magnetic field interference based on zero offset control of atomic magnetometer according to claim 1, characterized in that step 4 comprises using a closed loop rejection ratio As an evaluation index, the expression is as follows: Wherein the method comprises the steps of For the system in open loop condition, the frequency of application is Response signal amplitude caused by the magnetic field to be measured; the system is in a closed loop state, and the amplitude of the feedback control signal is applied to the system, wherein the amplitude and the frequency of the feedback control signal are completely the same as those of the magnetic field to be detected in the open loop test.
6. The method for resisting longitudinal magnetic field interference by using an atomic magnetometer based on zero offset control according to claim 1, wherein the system response model expression in step 1 is as follows: Wherein the method comprises the steps of Is a direct current component response signal output by the system, Is the zero offset point corresponding to the direct current component of the response signal output by the system, Is a transfer matrix from a magnetic field input to a response signal output, Is by Measurement of Is used for the scale factor of (a), Is a measurement of Time of day Corresponding to Is used for the coupling coefficient of the (c), Is a measurement of Time of day Corresponding to Is used for the coupling coefficient of the (c), Is by Measurement of Is used for the scale factor of (a), Is by Measurement of Is used for the scale factor of (a), Is a measurement of Time of day Corresponding to Is used for the coupling coefficient of the (c), Representing the conversion coefficient from the polarization component to the response signal, Is a zero-order Bessel function in The function value of the position, Is a modulation parameter of the longitudinal modulated magnetic field, Is the electron gyromagnetic ratio, Is a first order Bessel function in The function value of the position, Is a second order Bessel function in The function value of the position, Is the magnetic field of the z-axis, Is the overall relaxation rate and is therefore the result, Is the modulation field amplitude, q is the slow down factor, Is the modulated magnetic field frequency.
7. The method of claim 1, wherein step 1 includes deriving the expression from a system response model as follows: When the system output is controlled at the zero offset point, And Is a result of the solution of (2) Is independent of fluctuations in (c).
8. The method for resisting longitudinal magnetic field interference based on zero offset control of atomic magnetometer according to claim 1, characterized in that the SERF atomic magnetometer system in step 1 is a dual-beam SERF magnetometer system comprising a pumping optical path and a detection optical path, the pumping optical path having a pumping laser, a first polarization maintaining optical fiber, a first collimating lens, a first linear polarizer, a first mirror, a 1/4 wave plate and an alkali metal gas cell connected in sequence, the alkali metal gas cell being located in a boron nitride oven having a magneto-free heating film, the boron nitride oven being located in a triaxial magnetic field coil, the triaxial magnetic field coil being located in a low noise manganese zinc ferrite magnetic shielding barrel, the low noise manganese zinc ferrite magnetic shielding barrel being located in a multilayer permalloy magnetic shielding barrel, the detection optical path having a detection laser, a second polarization maintaining optical fiber, a second collimating lens, a second linear polarizer, an alkali metal gas cell, a 1/2 and a PBS beam splitting prism connected in sequence, the reflection side of the PBS beam-splitting prism is connected with a first photoelectric detector through a second reflecting mirror, the transmission side of the PBS beam-splitting prism is connected with a second photoelectric detector, the first photoelectric detector and the second photoelectric detector are respectively connected with two input ends of a differentiator, the output end of the differentiator is connected with a first input end of a phase-locked amplifier through a transimpedance amplifier, the first output end of the phase-locked amplifier is respectively connected with a first PID controller and a data collector, the second output end of the phase-locked amplifier is respectively connected with a second PID controller and a data collector, the second input end of the phase-locked amplifier is connected with a modulated magnetic field signal end of a signal generator, the output end of the first PID controller is respectively connected with a first input end of a first comparator and the data collector, the output end of the second PID controller is respectively connected with the first input end of the second comparator and the data acquisition device, the second input end of the first comparator is connected with the x-axis magnetic field signal end of the signal generator, the second input end of the second comparator is connected with the y-axis magnetic field signal end of the signal generator, and the output end of the first comparator, the output end of the second comparator and the z-axis magnetic field signal end of the signal generator are respectively connected with the triaxial magnetic field coil.
9. An atomic magnetometer longitudinal magnetic field interference resisting system based on zero offset control, characterized by being used for executing the method for resisting longitudinal magnetic field interference based on zero offset control according to one of the claims 1-8.

Description

Method and system for resisting longitudinal magnetic field interference of atomic magnetometer based on zero offset control Technical Field The invention relates to the technical field of quantum precision measurement, in particular to a method and a system for resisting longitudinal magnetic field interference of an atomic magnetometer based on zero offset control, which can effectively inhibit longitudinal magnetic field interference and eliminate cross axis coupling effect. Background Spin-exchange Relaxation-free (SERF) magnetometer operating at zero field is one of the most sensitive magnetic measuring instruments at present, and has wide application in the fields of biomagnetic measurement, material magnetic analysis, basic physical research and the like. In the SERF mode of operation, the alkali metal atomic electron spins in the atomic gas cell are polarized by the pumping light, with the polarization vector tending to be parallel to the pumping light propagation direction (z-axis). In the presence of an external magnetic field, this polarization vector will produce larmor precession about the magnetic field vector, making the system most sensitive to transverse magnetic fields (x-axis and y-axis) perpendicular to the polarization vector, and theoretically insensitive to longitudinal magnetic fields (z-axis) parallel to the polarization vector. However, in actual biaxial or triaxial vector measurements, the longitudinal magnetic field affects the measurement results of the transverse sensitive axes (x-axis and y-axis) by the cross-axis coupling effect, resulting in a significant decrease in measurement accuracy. This effect makes longitudinal magnetic field interference one of the main technical bottlenecks in achieving high accuracy and high stability vector magnetometers. In order to solve the problem, the prior art mainly adopts two methods, namely an active compensation method, a real-time compensation method for a longitudinal magnetic field is adopted through closed-loop control to enable the longitudinal magnetic field to be kept near zero, but the method is limited by the bandwidth and the response speed of a compensation loop, the compensation effect on the fluctuation of a high-frequency magnetic field is limited, and the second method is to calibrate the influence of the longitudinal magnetic field on the output of a transverse sensitive axis in advance through system correction and then decouple, wherein the method generally assumes that the longitudinal magnetic field is quasi-static and cannot effectively cope with the fluctuation of the longitudinal magnetic field which is time-varying. In summary, the prior art, whether based on real-time compensation or system correction, has inherent limitations in that the former suffers from dynamic response performance and the latter suffers from static assumptions of the model. Therefore, there is an urgent need in the art for a novel method that can break through the above limitations in principle, and simultaneously and effectively suppress the cross-axis coupling effect caused by quasi-static or even dynamically changing longitudinal magnetic fields, so as to achieve stable and accurate biaxial magnetic field measurement in a complex magnetic field environment. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a longitudinal magnetic field interference resistance method and a longitudinal magnetic field interference resistance system for an atomic magnetometer based on zero offset control, which can effectively inhibit longitudinal magnetic field interference and eliminate cross axis coupling effect. The technical scheme of the invention is as follows: The method for resisting the longitudinal magnetic field interference by the atomic magnetometer based on zero offset control is characterized by comprising the following steps of: step 1, a system response model for resisting longitudinal magnetic field interference is established based on a SERF atomic magnetometer system, wherein the system response model comprises zero offset errors output by the system; step 2, setting And,Is thatIs used for the zero offset point of the (a),Is thatIs used for the zero offset point of the (a),Is the first harmonic of the response signal,Is the second harmonic of the response signal; Step 3, by As a closed loop control target of the first sensitive axis, i.e. the x-axis, toAs a closed-loop control target of a second sensitive axis, namely a y axis; step 4, based on the closed-loop control target, implementing independent closed-loop feedback control on the first sensitive axis and the second sensitive axis respectively to dynamically control the first sensitive axis and the second sensitive axis Locked atAnd put up and put down theLocked atAnd obtain by feedback signalAnd,Is the x-axis magnetic field or the first sensitive axis magnetic field,The y-axis magnetic field is the second sensitive axis magnetic fiel