CN-121995276-A - Double-beam SERF atomic magnetometer triaxial precision magnetic compensation method based on double observables

CN121995276ACN 121995276 ACN121995276 ACN 121995276ACN-121995276-A

Abstract

A three-axis precise magnetic compensation method of a double-beam SERF atomic magnetometer based on double observables simultaneously generates two observables of a direct current component and a first harmonic under single magnetic field modulation, wherein the two observables of the direct current component and the first harmonic are realized by using the single-peak characteristic wide magnetic field range of the first harmonic observables to realize rapid interval positioning, the effective magnetic field searching range of a magnetic compensation point is obviously enlarged by determining a near zero point and a neighborhood thereof, the zero point is rapidly determined in a compensation interval, the complexity and the compensation time of a system are reduced, the magnetic field transverse coordinate zero crossing point of the direct current component observables is used as a residual magnetic point, and the residual magnetic point is rapidly locked in a thin compensation window positioned by the direct current component to realize the compensation precision of pT magnitude. And by combining triaxial iteration, the cross coupling influence is eliminated, and the system compensation error is reduced, so that the robustness and the compensation precision are simultaneously satisfied under the light magnetic shielding or drift magnetic environment. Convergence can be achieved by iteration round=3 times under a typical experiment.

Inventors

CUI PEILING
Xu Nuozhou
LU JIXI
WANG SHUYING
GAO XIAOYAN
QI YIBO
YE XIHUI

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. A three-axis precise magnetic compensation method of a double-beam SERF atomic magnetometer based on double observables is characterized by comprising the steps of applying a single modulation magnetic field in the sensitive axis direction in a double-beam SERF atomic magnetometer system to achieve simultaneous acquisition of direct current component observables and first-order harmonic observables in the same demodulation frame, utilizing the single-peak characteristic of the first-order harmonic to conduct interval rapid positioning on each axis in a wide magnetic field range, determining a near zero point and a neighborhood thereof as a magnetic compensation fine scanning window, demodulating the direct current component, searching a transverse coordinate zero crossing point of the first-order harmonic in the magnetic compensation fine scanning window as a direct current component residual magnetic point, sequentially completing first-order harmonic interval positioning by three axes, conducting three-axis iteration after the three-axis residual magnetic point of the direct current component is determined, updating and applying the three-axis residual magnetic field of the first wheel as an initial value to a three-axis coil, entering the next round of iteration on the basis of an applied result until an iteration convergence condition is met, and achieving pT magnitude compensation precision.
2. The dual-beam SERF atomic magnetometer triaxial precision magnetic compensation method based on dual observables according to claim 1, characterized by comprising the following steps: step 1, establishing a right-hand coordinate system by taking a pumping light direction as a z-axis, a detection light direction as an x-axis and a sensitive axis as a y-axis, and applying a single modulation magnetic field on the y-axis B mod is the amplitude of the modulated magnetic field, ω is the frequency of the modulated magnetic field, t is the time, and the observed quantity of the direct current component and the observed quantity of the first harmonic are simultaneously established under the same demodulation frame; Step 2, demodulating first-order harmonic components of the response of the dual-beam SERF magnetometer system by using a lock-in amplifier under the condition of maintaining the single modulated magnetic field In a y-axis absorption curve with a y-axis magnetic field as an abscissa and a response signal amplitude as an ordinate, finding out the range of the maximum point of the y-axis absorption curve, wherein the range is the y-axis remanence point The magnetic field compensation interval of (2), i.e. the y-axis interval , The left and right boundary values of the compensation area where the remanence point is located are the same, and the range where the maximum point of the x-axis absorption curve is located is found from the x-axis absorption curve to obtain the x-axis interval , The z-axis interval is obtained by finding out the minimum value point of the z-axis absorption curve from the z-axis absorption curve , Is the z-axis residual magnetic point; Step 3, keeping the single modulation magnetic field unchanged, scanning a y-axis magnetic field area, and demodulating direct current components of the response of the double-beam SERF magnetometer system In a y-axis dispersion curve taking a y-axis magnetic field as an abscissa and a response signal amplitude as an ordinate, taking the y-axis interval as a fine compensation window, and finding out zero crossings of the y-axis dispersion curve in the compensation window to obtain a y-axis remanence value ; Step 4, keeping the single modulation magnetic field unchanged, and additionally applying a direct current bias magnetic field on the z axis Demodulating the DC component of a dual beam SERF magnetometer system response Scanning the x-axis interval, taking the x-axis interval as a fine compensation window in an x-axis dispersion curve taking an x-axis magnetic field as an abscissa and a response signal amplitude as an ordinate, and finding out a zero crossing point of the x-axis dispersion curve in the compensation window to obtain a remanence value of an x-axis Then zeroing the direct-current bias magnetic field of the z-axis, additionally applying a direct-current bias magnetic field on the x-axis, and obtaining the residual magnetic value of the z-axis by utilizing the zero crossing point of the dispersion curve of the z-axis Then, the direct current bias magnetic field of the x axis is zeroed; step 5, the triaxial residual magnetic value As the initial value of the system, the system is applied to a triaxial coil, and the triaxial iteration is started by repeating the steps 2 to 4 until the triaxial residual magnetic value of the last round, i.e. the ith round When the system convergence requirement is completely met, taking As the final remanence value output, the iteration is terminated.
3. The method for three-axis precise magnetic compensation of a double-beam SERF atomic magnetometer based on double observables according to claim 2, wherein step 1 comprises the following formula: Wherein, the Is the spin polarization component of electrons in the x-axis direction, Is a direct current component response value demodulated by the detection signal, Beta is an intermediate quantity, p is a preset value, The value of (3) determines the series expansion of the analytic solution, K 1 is the first order harmonic response value demodulated by the detection signal, Is 2p+1 order Bessel function, K 2 is the harmonic response value corresponding to the even order harmonic, Is a bessel function of order 2p, Is the optical pumping rate at which the optical power is to be extracted, Is the rate of relaxation and the degree of relaxation, Is the electron gyromagnetic ratio, Is the widening of the range of the device, Is the x, y, z-axis residual magnetic field, q is the nuclear slowdown factor.
4. The method for three-axis precise magnetic compensation of the double-beam SERF atomic magnetometer based on double observables according to claim 2, wherein the following expression is included in the step 1: the DC component And first order harmonics Resolving and resolving pairs Sensitive.
5. The method for three-axis precise magnetic compensation of the double-beam SERF atomic magnetometer based on double observables according to claim 2, wherein the following formula is included in the step 2: Wherein, the Is the first order response harmonic value demodulated after the y-axis field scanning, Is the y-axis scanning magnetic field, Is the first order response harmonic value demodulated after the x-axis field scanning, Is the x-axis scanning magnetic field, Is a first order response harmonic value demodulated after the z-axis field scanning, Is the z-axis scanning magnetic field.
6. The method for three-axis precise magnetic compensation of a double-beam SERF atomic magnetometer based on double observance according to claim 2, wherein the following formula is included in step 3: Wherein, the Is the first order response harmonic value demodulated after the y-axis field scanning, Is the y-axis scanning magnetic field.
7. The method for three-axis precise magnetic compensation of a double-beam SERF atomic magnetometer based on double observables according to claim 2, wherein step 4 comprises the following formula: Wherein the method comprises the steps of Is the first order response harmonic value demodulated after the x-axis field scanning, Is the x-axis scanning magnetic field, An additional dc bias magnetic field is applied in the z-axis, Is a first order response harmonic value demodulated after the z-axis field scanning, Is the z-axis scanning magnetic field, An additional dc bias magnetic field is applied in the x-axis.
8. The method for three-axis precise magnetic compensation of double-beam SERF atomic magnetometer based on double observance according to claim 2, wherein step5 comprises the steps of The following formula has been applied in practice: Repeating the steps 2-4, namely sequentially calculating the residual magnetic values of all axes in a fine compensation window according to the sequence of y-x-z to obtain the three-axis residual magnetic value of the 2 nd round Iterating the system according to the method, and when the triaxial remanence values of two iterations are different Less than or equal to a threshold value The method comprises the following steps: Wherein the method comprises the steps of Is the number of iterations, wherein B th = 0.5-5 pT is determined according to the magnetic shielding environment of the system and the resolution of the coil current source, and if the triaxial residual magnetic values all meet the system convergence requirement, the method is adopted As the final remanence value output, the iteration is terminated.
9. The three-axis precise magnetic compensation method of the double-beam SERF atomic magnetometer based on the double observables is characterized in that the double-beam SERF atomic magnetometer system comprises a double-beam SERF atomic magnetometer shell positioned in a magnetic shielding barrel, the double-beam SERF atomic magnetometer shell comprises a pumping laser collimator, a pumping light polarizer, a reflecting mirror, a 1/4 wave plate and an alkali metal air chamber in an air chamber heating oven which are sequentially connected, the input end of the pumping laser collimator is connected with a first channel of a double-beam SERF atomic magnetometer two-channel laser, and a second channel of the double-beam SERF atomic magnetometer two-channel laser is sequentially connected with an output acquisition display system through a detection laser collimator, a detection light polarizer, an alkali metal air chamber, a lateral displacement splitting prism and a photoelectric detector.

Description

Double-beam SERF atomic magnetometer triaxial precision magnetic compensation method based on double observables Technical Field The invention belongs to the technical field of quantum precision measurement and magnetic field compensation, relates to triaxial remanence compensation of an atomic magnetometer in a weak magnetic environment, and particularly relates to a double-beam SERF atomic magnetometer triaxial precision magnetic compensation method based on double observables, wherein the rapid positioning and zero locking of zero magnetic points can be completed through the distribution and use of the double observables by a modulation-analysis solution-iteration method, and the robustness and the precision are both realized, wherein the double observables are first-order harmonic observables and direct current component observables. Background The SERF atomic magnetometer can obtain extremely high sensitivity (SERF, spin-Exchange Relaxation-Free, no Spin-exchange relaxation) in extremely weak magnetic environment, but still has factors such as low-frequency drift and the like in a shielding system, so that the working point of the SERF atomic magnetometer is easily deviated from a linear working area, and stable and rapid triaxial active compensation is needed. The existing technology comprises a cross-axis modulation scheme, a non-modulated zero-field resonance scheme, a high-frequency modulation scheme under coarse compensation and the like, but the problems that robustness and compensation precision are difficult to be simultaneously considered, convergence is slow and the like are common. The method proposed by the prior patent document related to the technical object of the invention is characterized in that quasi-static coarse compensation is firstly performed, then high-frequency modulation is applied, and three-axis fine compensation is realized by using the zero crossing point of the demodulation first-order harmonic dispersion curve. The method is only oriented to a single-beam configuration SERF atomic magnetometer, and the observed quantity mainly depends on first-order harmonic as a criterion and is not suitable for a double-beam SERF atomic magnetometer. Disclosure of Invention The invention provides a three-axis precise magnetic compensation method of a double-beam SERF atomic magnetometer based on double observables, which is used for obtaining a complete analytical model of atomic spin response under high-frequency magnetic field modulation based on perturbation iteration, generating two observables of a direct current component and a first harmonic at the same time under single high-frequency magnetic field modulation, realizing rapid interval positioning in a wide magnetic field range by using the unimodal characteristic of the first harmonic observables, determining a near zero point and a neighborhood thereof, remarkably expanding an effective search range, reducing system complexity and compensation time, and rapidly locking the residual magnetic point in a thin compensation window positioned by the direct current component by taking a zero crossing point of the direct current component observables as the residual magnetic point, thereby realizing pT magnitude compensation precision. And the three-axis iteration is combined, so that the cross coupling influence is eliminated, the system compensation error is reduced, and the robustness and the compensation precision are simultaneously met. And (3) carrying out iteration for 3 times under a typical experiment to realize convergence. The technical scheme of the invention is as follows: A three-axis precise magnetic compensation method of a double-beam SERF atomic magnetometer based on double observables is characterized by comprising the steps of applying a single modulation magnetic field in the sensitive axis direction in a double-beam SERF atomic magnetometer system to achieve simultaneous acquisition of direct current component observables and first-order harmonic observables in the same demodulation frame, utilizing the single-peak characteristic of the first-order harmonic to conduct interval rapid positioning on each axis in a wide magnetic field range, determining a near zero point and a neighborhood thereof as a magnetic compensation fine scanning window, demodulating the direct current component, searching a transverse coordinate zero crossing point of the first-order harmonic in the magnetic compensation fine scanning window as a direct current component residual magnetic point, sequentially completing first-order harmonic interval positioning by three axes, conducting three-axis iteration after the three-axis residual magnetic point of the direct current component is determined, updating and applying the three-axis residual magnetic field of the first wheel as an initial value to a three-axis coil, entering the next round of iteration on the basis of an applied result until an iteration convergence condition is met, and