Method for precisely compensating three-dimensional residual magnetism of single-beam SERF atomic magnetometer

Abstract

The application discloses a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, which is based on the principle of high-frequency magnetic field modulation and comprises the following steps: after rough compensation of three-dimensional residual magnetism of a single-beam SERF magnetometer based on a quasi-static magnetic field, performing precise compensation of three-dimensional residual magnetism, wherein the precise compensation of three-dimensional residual magnetism comprises the following steps: applying a high-frequency modulation magnetic field, respectively scanning XYZ three-axis magnetic fields, and making the zero-crossing point of a dispersion curve corresponding to a demodulated first-order harmonic coincide with a zero-field point, so as to realize precise magnetic field compensation of a single-beam SERF magnetometer system. The method effectively improves the precision of magnetic compensation, solves the problems that a traditional magnetic compensation mode is not applicable to a single-beam SERF atomic magnetometer or the precision of magnetic field compensation in the direction of pumping light is too low, and is reasonable and simple to operate, thus playing a great promoting role in the development of atomic magnetometers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of three-dimensional remanence compensation of atomic magnetometer system, and particularly relates to a method for precisely compensating three-dimensional remanence of single-beam SERF (Spin-Exchange Relaxation-Free) atomic magnetometer. Based on the principle of high-frequency magnetic field modulation, after the three-dimensional remanence coarse compensation of the single-beam SERF atomic magnetometer based on quasi-static magnetic field is completed, the three-dimensional remanence fine compensation is performed, the three-dimensional remanence fine compensation comprises applying a high-frequency modulation magnetic field, respectively scanning XYZ three-axis magnetic fields, and making the zero-crossing point of the dispersion curve corresponding to the demodulated first-order harmonic coincide with the zero-field point, so as to realize the precise magnetic field compensation of the single-beam SERF atomic magnetometer system. This method effectively improves the precision of magnetic compensation, and solves the problems that the traditional magnetic compensation method is not applicable to the single-beam SERF atomic magnetometer or the magnetic field compensation precision in the pumping light direction is too low. BACKGROUND

[0002] In recent years, the atomic magnetometer based on the principle of Spin-Exchange Relaxation-Free (SERF) has attracted widespread attention, and the related technologies have developed unprecedentedly. The environmental remanence and the light frequency shift virtual magnetic field in the pumping light direction of the SERF atomic magnetometer can broaden the magnetic resonance linewidth, thereby weakening the response capability, so that a magnetic shielding technology is needed to obtain an extremely low magnetic field environment. The magnetic shielding technology is divided into passive magnetic shielding and active magnetic compensation, and the commonly used magnetic shielding barrel or magnetic shielding room can only attenuate the geomagnetic field of tens of thousands of nT to the order of several nT. In order to further reduce the remanence in the barrel, active magnetic compensation is needed. The traditional modulation type magnetic field compensation method with the configuration of pumping light and detection light orthogonal or the non-modulation type magnetic field compensation method based on the single-beam configuration has the problems that it is not applicable to the single-beam magnetometer or the magnetic field compensation resolution in the pumping light direction is too low. Based on this, the present application provides a method for precisely compensating three-dimensional remanence of single-beam SERF atomic magnetometer. Based on the principle of high-frequency magnetic field modulation, after the three-dimensional remanence coarse compensation of the single-beam SERF atomic magnetometer based on quasi-static magnetic field is completed, a high-frequency modulation magnetic field is applied, the magnetic fields of XYZ three axes are respectively scanned, and the zero-crossing point of the dispersion curve corresponding to the demodulated first-order harmonic is made to coincide with the zero-field point, so as to realize the precise magnetic field compensation of the single-beam SERF atomic magnetometer system. This method can be applicable to the single-beam SERF atomic magnetometer, and effectively improves the precision of magnetic compensation. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, which is based on the principle of high-frequency magnetic field modulation and performs three-dimensional residual magnetism fine compensation after three-dimensional residual magnetism coarse compensation based on a quasi-static magnetic field in a single-beam SERF atomic magnetometer system, the three-dimensional residual magnetism fine compensation comprising applying a high-frequency modulation magnetic field, respectively scanning XYZ three-axis magnetic fields, and making the zero-crossing point of a demodulated first-order harmonic corresponding dispersion curve coincide with a zero field point, so as to realize precise magnetic field compensation of the single-beam SERF atomic magnetometer system.

[0004] The technical solution of the present application is as follows:

[0005] A method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, characterized by comprising the following steps:

[0006] Step A: performing three-dimensional residual magnetism coarse compensation based on a quasi-static magnetic field in a single-beam SERF atomic magnetometer system, and the coarse compensation precision reaches the order of 0.1 nT;

[0007] Step B: performing three-dimensional residual magnetism fine compensation based on high-frequency magnetic field modulation on the basis of the three-dimensional residual magnetism coarse compensation, and the fine compensation precision reaches the order of 0.1 pT.

[0008] Step A comprises the following steps:

[0009] Step A1: defining the pumping light direction of the single-beam SERF atomic magnetometer system as the Z-axis direction, the X and Y directions as non-pumping axis directions, and XYZ as a right-handed coordinate system; applying a low-frequency quasi-static magnetic field B osc cos(2πf·t) in the X-axis direction, B osc is a low-frequency quasi-static magnetic field amplitude, B osc is greater than 0 and less than or equal to 10 nT, f is a low-frequency quasi-static magnetic field frequency, f is 1-6 Hz, and t is time; adjusting the direct current bias magnetic field applied in the X-axis direction, when the single-beam SERF atomic magnetometer system output signal appears approximately double frequency phenomenon is observed on an oscilloscope, that is, the frequency of the output signal is dominated by the 2f component instead of the f component, so as to complete the coarse compensation of the system X-axis direction residual magnetism, and then the quasi-static magnetic field applied in the X-axis direction is zeroed;

[0010] Step A2: since the X and Y axes have symmetry, a low-frequency quasi-static magnetic field B osccos(2πf·t), adjust the DC bias magnetic field applied in the Y-axis direction. When the output signal of the single-beam SERF atomic magnetometer system is observed to have an approximate frequency doubling phenomenon on the oscilloscope, that is, the frequency of the output signal changes from the f component dominating to the 2f component dominating, thus completing the coarse compensation of the remanence of the system in the Y-axis direction. Then, the quasi-static magnetic field applied in the Y-axis direction is reduced to zero.

[0011] Step A3: Apply a low-frequency quasi-static magnetic field B in the Z-axis direction. osc cos(2πf·t), and simultaneously apply a DC bias magnetic field B in the X or Y axis direction. bias Adjust the DC bias magnetic field applied along the Z-axis. When an approximate frequency doubling phenomenon is observed in the output signal of the single-beam SERF atomic magnetometer system on the oscilloscope, i.e., the frequency of the output signal changes from being dominated by the f component to being dominated by the 2f component, then the coarse compensation for the remanence of the system along the Z-axis is completed. Finally, the quasi-static magnetic field applied along the Z-axis and the DC bias magnetic field B applied along the X or Y axis are adjusted. bias Everything is reset to zero.

[0012] Step B includes the following steps:

[0013] Step B1: Apply a high-frequency modulated magnetic field B in the non-pumping axis X direction. mod cos(2πf mod t), B mod It is the amplitude of the high-frequency modulated magnetic field, f mod It is the frequency of the high-frequency modulated magnetic field, f mod The signal is on the order of kHz; the magnetic field along the X-axis is scanned, and the output signal of the single-beam SERF atomic magnetometer system is demodulated using a lock-in amplifier corresponding to f. mod In a two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, the zero-crossing point of the dispersion curve corresponding to the first harmonic component is found, which is the intersection point with the x-axis. The DC bias magnetic field applied to the X-axis is adjusted so that the zero-crossing point coincides with the zero field point, which is the origin of the two-dimensional coordinate system, thereby achieving precise compensation for the remanence of the X-axis.

[0014] Step B2, maintain the high-frequency modulated magnetic field B applied in the X-axis direction as in step B1. mod cos(2πf mod With t) unchanged, an additional DC bias magnetic field is applied along the Z-axis, while simultaneously scanning the magnetic field along the Y-axis. The demodulated atomic magnetometer system output signal corresponds to the frequency f. modthe first harmonic component, in the two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, find the zero-crossing point of the dispersion curve corresponding to the first harmonic component, adjust the direct current bias magnetic field applied in the Y-axis direction and make the zero-crossing point coincide with the zero field point, so as to realize the precise compensation of the residual magnetism in the Y-axis direction, and then zero the additional direct current bias magnetic field applied in the Z-axis direction;

[0015] Step B3, keep the high-frequency modulation magnetic field B mod cos(2πf mod t) unchanged, additionally apply a direct current bias magnetic field in the Y-axis direction, and scan the magnetic field in the Z-axis direction, demodulate the output signal of the atomic magnetometer system corresponding to the frequency f mod , find the zero-crossing point of the dispersion curve corresponding to the first harmonic component in the two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, adjust the direct current bias magnetic field applied in the Z-axis direction and make the zero-crossing point coincide with the zero field point, so as to realize the precise compensation of the residual magnetism in the Z-axis direction, and finally zero the high-frequency modulation magnetic field B mod cos(2πf mod t) applied in the X-axis direction and the additional direct current bias magnetic field applied in the Y-axis direction.

[0016] Step A1 includes the following formula:

[0017]

[0018] Where k1 is a coefficient, V PD-X is the voltage signal output by the system after applying a quasi-static magnetic field in the X-axis direction, P z-x is the z-direction component of the electronic polarizability of the atom after applying a quasi-static magnetic field in the X-axis direction, R op is the optical pumping rate, R rel is the relaxation rate, γ e is the electronic gyromagnetic ratio, B x0 is the residual magnetism in the X-axis direction, B y0 is the residual magnetism in the Y-axis direction, B z0 is the residual magnetism in the Z-axis direction, when the X-axis residual magnetism B x0 is large, the frequency doubling f component in V PD-X dominates, and the signal observed on the oscilloscope is approximately f in frequency, when the direct current bias magnetic field applied in the X-axis direction is adjusted to offset the original residual magnetism in the X-axis direction, that is, B x0 is zeroed, the frequency doubling 2f component in V PD-X dominates, and the signal observed on the oscilloscope is approximately 2f in frequency, and the rough compensation of the X-axis residual magnetism is realized according to the appearance of the frequency doubling phenomenon on the oscilloscope.

[0019] Step A3 includes the following formula:

[0020]

[0021] Where V PD-Z It is the voltage signal output by the system after a quasi-static magnetic field is applied along the Z-axis, p z-z It is the z-axis component of the electronic polarizability of an atom when a quasi-static magnetic field is applied along the Z-axis, and when the Z-axis remanence B z0 When V is large, PD-Z The first harmonic component f dominates, and the signal observed on the oscilloscope is the signal with frequency f. When the DC bias magnetic field applied to the Z-axis is adjusted to cancel the original residual magnetism of the Z-axis, that is, B... z0 When V is reset to zero PD-Z The second harmonic component (2f) dominates, and the signal observed on the oscilloscope is approximately 2f. Coarse compensation for Z-axis remanence is achieved based on the appearance of the second harmonic phenomenon on the oscilloscope. The appearance of the second harmonic phenomenon on the oscilloscope is used to apply an additional DC bias magnetic field B on the X or Y axis. bias This is a prerequisite.

[0022] Step B1 includes the following formula:

[0023]

[0024] Where k2 is a coefficient. It is the output signal corresponding to the first harmonic component after applying a high-frequency modulated magnetic field along the X-axis. f is the electron spin polarizability of an atom. mod The first harmonic component, Δω is the magnetic resonance linewidth, Δω=(R op +R rel ) / γ e J0 is a 0th-order Bessel series term, and J1 is a 1st-order Bessel series term. A scanning magnetic field is applied along the X-axis. In a two-dimensional coordinate system with the X-axis as the magnitude of the scanning magnetic field and the y-axis as the amplitude of the system output signal, the demodulated output... The signal is represented by a dispersion curve, and the intersection of the dispersion curve and the x-axis is approximately the remanence B along the x-axis. x0 When B x0 When the field is zeroed, the intersection point coincides with the origin of the two-dimensional coordinate system, i.e., the zero field point. Thus, precise magnetic compensation of the X-axis is achieved by using the sweep field dispersion curve after demodulating the first harmonic as it passes through the origin of the two-dimensional coordinate system.

[0025] The formulas included in steps B2 and B3 are the same as those in step B1. When performing precise compensation for residual magnetism in the Y-axis direction, an additional DC bias magnetic field needs to be applied in the Z-axis direction; when performing precise compensation for residual magnetism in the Z-axis direction, an additional DC bias magnetic field needs to be applied in the Y-axis direction.

[0026] The single-beam SERF atomic magnetometer system comprises a pumping laser connected with a laser collimation head through a polarization maintaining optical fiber, laser emitted by the laser collimation head passes through a polarizer and a 1 / 4 wave plate, and then passes through a Z-axis alkali metal cell and reaches a photodetector, the photodetector is connected with a transimpedance amplifier through a cable, the transimpedance amplifier is connected with an oscilloscope and a lock-in amplifier respectively, the lock-in amplifier is connected with an acquisition output display system, the alkali metal cell is located in a cell heating oven, the cell heating oven is located in a magnetic compensation coil skeleton, the magnetic compensation coil skeleton is located in a magnetic shielding barrel, and the magnetic compensation coil is connected with a signal generator through a cable.

[0027] The technical effect of the present application is as follows: the method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer can realize precise magnetic field compensation of the single-beam SERF magnetometer system, effectively improve the precision of magnetic compensation, and effectively solve the problems that the traditional magnetic compensation method is not applicable to the single-beam SERF atomic magnetometer or the resolution of magnetic field compensation in the pumping light direction is too low. After the three-dimensional residual magnetism of the single-beam SERF magnetometer based on the quasi-static magnetic field is coarsely compensated, a high-frequency modulation magnetic field is applied, the magnetic fields of X, Y and Z axes are scanned respectively, and the zero-crossing point of the dispersion curve corresponding to the demodulated first-order harmonic coincides with the zero field point, so that the precise magnetic field compensation of the single-beam SERF magnetometer system is realized.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) Based on the principle of high-frequency magnetic field modulation, after the three-dimensional residual magnetism of the single-beam SERF magnetometer based on the quasi-static magnetic field is coarsely compensated, a high-frequency modulation magnetic field is applied, the magnetic fields of X, Y and Z axes are scanned respectively, and the zero-crossing point of the dispersion curve corresponding to the demodulated first-order harmonic coincides with the zero field point, so that the precise magnetic field compensation of the single-beam SERF magnetometer system is realized. Since the magnetic field is scanned point by point, the resolution of magnetic field compensation is limited by the resolution of the scanned magnetic field and the coil constant. The theoretical magnetic compensation resolution can be infinitely small, so this method can effectively improve the precision of magnetic compensation.

[0030] (2) The present application has the advantages that the experimental operation is simple, the three-dimensional residual magnetism of the single-beam SERF magnetometer system can be precisely compensated, and the development of the SERF atomic magnetometer is promoted. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a single-beam SERF magnetometer system structure schematic diagram related to the method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer system.

[0032] Figure 2is a flowchart of a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer system according to the present application. Figure 2 The method comprises steps A (carried out in a single-beam SERF atomic magnetometer system) of three-dimensional residual magnetism coarse compensation based on quasi-static magnetic field (coarse compensation accuracy reaches 0.1 nT level) and B (carried out on the basis of the three-dimensional residual magnetism coarse compensation) of three-dimensional residual magnetism fine compensation based on high-frequency magnetic field modulation (fine compensation accuracy reaches 0.1 pT level). Step A comprises sub-steps A1, X-axis low-frequency quasi-static magnetic field is applied (for example, frequency is 1-6 Hz), direct current bias magnetic field applied to the X-axis is adjusted until approximately 2 times frequency phenomenon appears on an oscilloscope (that is, output signal frequency changes from f component dominant to 2f component dominant), thereby completing X-axis residual magnetism coarse compensation, and then quasi-static magnetic field applied to the X-axis direction is zeroed; A2, Y-axis low-frequency quasi-static magnetic field is applied, Y-axis bias magnetic field is adjusted until approximately 2 times frequency phenomenon appears on the oscilloscope, and then Y-axis quasi-static magnetic field is zeroed; A3, Z-axis low-frequency quasi-static magnetic field is applied, at the same time, additional direct current bias magnetic field is applied to the X or Y axis, Z-axis bias magnetic field is adjusted until approximately 2 times frequency phenomenon appears on the oscilloscope, and finally Z-axis quasi-static magnetic field and the additional direct current bias magnetic field applied to the X or Y axis are zeroed. Step B comprises sub-steps B1, X-axis high-frequency modulation magnetic field (magnetic field frequency is kHz level) is applied, X-axis magnetic field is scanned, first harmonic component of a demodulated output signal is adjusted, X-axis bias magnetic field is adjusted until zero-crossing point of a dispersion curve (intersection with the x-axis) and zero field point (origin of a two-dimensional coordinate system including the x-axis and output signal amplitude axis y) coincide; B2, X-axis high-frequency modulation magnetic field is kept unchanged, Z-axis direct current bias magnetic field is applied, Y-axis magnetic field is scanned, first harmonic component of the demodulated output signal is adjusted, Y-axis bias magnetic field is adjusted until zero-crossing point of the dispersion curve (intersection with the x-axis) and the zero field point (origin of the two-dimensional coordinate system) coincide, and then the bias magnetic field applied to the Z-axis is zeroed; B3, X-axis high-frequency modulation magnetic field is kept unchanged, Y-axis direct current bias magnetic field is applied, Z-axis magnetic field is scanned, first harmonic component of the demodulated output signal is adjusted, Z-axis bias magnetic field is adjusted until zero-crossing point of the dispersion curve (intersection with the x-axis) and the zero field point (origin of the two-dimensional coordinate system) coincide, and finally the high-frequency modulation magnetic field applied to the X-axis and the bias magnetic field applied to the Y-axis are both zeroed.

[0033] Reference signs are explained as follows: 1 - magnetic shielding barrel; 2 - magnetic compensation coil skeleton; 3 - pumping laser; 4 - polarizer; 5 - 1 / 4 wave plate; 6 - alkali metal cell; 7 - cell heating oven; 8 - photodetector; 9 - signal generator; 10 - transimpedance amplifier; 11 - oscilloscope; 12 - lock-in amplifier; 13 - acquisition output display system; 14 - laser collimation head; 15 - cable; 16 - polarization maintaining optical fiber. DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with the drawings.Figures 1-2 ) and the examples illustrate the application.

[0035] Figure 1 is a schematic diagram of a single-beam SERF magnetometer system structure involved in a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer system. Figure 2 is a flowchart of a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer system according to the application. Referring to Figures 1-2 the method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, comprising the following steps: step A, performing three-dimensional residual magnetism coarse compensation based on quasi-static magnetic field in a single-beam SERF atomic magnetometer system, and the coarse compensation precision reaches 0.1 nT level; step B, performing three-dimensional residual magnetism fine compensation based on high-frequency magnetic field modulation on the basis of the three-dimensional residual magnetism coarse compensation, and the fine compensation precision reaches 0.1 pT level.

[0036] Step A comprises the following steps:

[0037] Step A1, defining the pumping light direction of the single-beam SERF atomic magnetometer system as the Z-axis direction, and the X and Y directions as non-pumping axis directions, and the XYZ forms a right-handed coordinate system; applying a low-frequency quasi-static magnetic field B osc cos(2πf·t) in the X-axis direction, B osc is the low-frequency quasi-static magnetic field amplitude, B osc is greater than 0 and less than or equal to 10 nT, f is the low-frequency quasi-static magnetic field frequency, f is 1-6 Hz, and t is time; adjusting the direct current bias magnetic field applied in the X-axis direction, when the single-beam SERF atomic magnetometer system output signal appears approximately double frequency phenomenon is observed on the oscilloscope, that is, the frequency of the output signal is dominated by the f component to the 2f component, thereby completing the coarse compensation of the system X-axis direction residual magnetism, and then the quasi-static magnetic field applied in the X-axis direction is zeroed;

[0038] Step A2, since the X and Y axes have symmetry, a low-frequency quasi-static magnetic field B osc cos(2πf·t) is applied in the Y-axis direction; adjusting the direct current bias magnetic field applied in the Y-axis direction, when the single-beam SERF atomic magnetometer system output signal appears approximately double frequency phenomenon is observed on the oscilloscope, that is, the frequency of the output signal is dominated by the f component to the 2f component, thereby completing the coarse compensation of the system Y-axis direction residual magnetism, and then the quasi-static magnetic field applied in the Y-axis direction is zeroed;

[0039] Step A3, applying a low-frequency quasi-static magnetic field B osc cos(2πf·t) in the Z-axis direction, and simultaneously applying a direct current bias magnetic field B bias, the direct current bias magnetic field applied in the Z-axis direction is adjusted, when the approximate frequency doubling phenomenon occurs in the output signal of the single-beam SERF atomic magnetometer system observed on the oscilloscope, that is, the frequency of the output signal is dominated by the 2f component instead of the f component, the coarse compensation of the residual magnetism in the Z-axis direction is completed, finally the quasi-static magnetic field applied in the Z-axis direction and the direct current bias magnetic field B bias All zero.

[0040] The step B includes the following steps:

[0041] Step B1, a high-frequency modulation magnetic field B mod cos(2πf mod t) is applied in the X-axis direction mod B is the amplitude of the high-frequency modulation magnetic field, f mod f is the frequency of the high-frequency modulation magnetic field, f mod is in the order of kHz; the magnetic field in the X-axis direction is scanned, and the first harmonic component of the output signal of the single-beam SERF atomic magnetometer system corresponding to f mod is demodulated by using a lock-in amplifier, in a two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, the zero-crossing point of the dispersion curve corresponding to the first harmonic component is found, and the direct current bias magnetic field applied in the X-axis direction is adjusted so that the zero-crossing point coincides with the zero-field point, i.e., the origin of the two-dimensional coordinate system, thereby realizing the precise compensation of the residual magnetism in the X-axis direction;

[0042] Step B2, the high-frequency modulation magnetic field B mod cos(2πf mod t) applied in the X-axis direction in step B1 is kept unchanged, a direct current bias magnetic field is additionally applied in the Z-axis direction, the magnetic field in the Y-axis direction is scanned, and the first harmonic component of the output signal of the atomic magnetometer system corresponding to f mod is demodulated, in a two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, the zero-crossing point of the dispersion curve corresponding to the first harmonic component is found, and the direct current bias magnetic field applied in the Y-axis direction is adjusted so that the zero-crossing point coincides with the zero-field point, thereby realizing the precise compensation of the residual magnetism in the Y-axis direction, and then the additional direct current bias magnetic field applied in the Z-axis direction is zeroed;

[0043] Step B3, the high-frequency modulation magnetic field B mod cos(2πf mod t) applied in the X-axis direction in step B1 is kept unchanged, a direct current bias magnetic field is additionally applied in the Y-axis direction, the magnetic field in the Z-axis direction is scanned, and the first harmonic component of the output signal of the atomic magnetometer system corresponding to f modthe first harmonic component, in the two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, find the zero-crossing point of the dispersion curve corresponding to the first harmonic component, adjust the direct current bias magnetic field applied by the Z-axis and make the zero-crossing point coincide with the zero field point, so as to realize the precise compensation of the remanence of the Z-axis, and finally the high-frequency modulation magnetic field B mod cos(2πf mod t) and the direct current bias magnetic field additionally applied in the Y-axis direction is zeroed.

[0044] The following formula is included in step A1:

[0045]

[0046] Where K1 is a coefficient, V PD-X is the voltage signal output by the system after a quasi-static magnetic field is applied in the X-axis direction, P z-x is the z-direction component of the electronic polarizability of the atom after a quasi-static magnetic field is applied in the X-axis direction, R op is the optical pumping rate, R rel is the relaxation rate, γ e is the electronic gyromagnetic ratio, B x0 is the remanence in the X-axis direction, B y0 is the remanence in the Y-axis direction, B z0 is the remanence in the Z-axis direction, when the remanence B x0 X is large, the frequency f component in V PD-X dominates, and the signal observed on the oscilloscope is approximately f, when the direct current bias magnetic field applied in the X-axis is adjusted to offset the original remanence in the X-axis, i.e., B x0 is zeroed, the 2f component in V PD-X dominates, and the signal observed on the oscilloscope is approximately 2f, and the rough compensation of the remanence in the X-axis is realized according to the appearance of the 2f phenomenon on the oscilloscope.

[0047] The following formula is included in step A3:

[0048]

[0049] Where V PD-Z is the voltage signal output by the system after a quasi-static magnetic field is applied in the Z-axis direction, P z-z is the z-direction component of the electronic polarizability of the atom when a quasi-static magnetic field is applied in the Z-axis direction, when the remanence B z0 Z is large, the frequency f component in V PD-Z dominates, and the signal observed on the oscilloscope is approximately f, when the direct current bias magnetic field applied in the Z-axis is adjusted to offset the original remanence in the Z-axis, i.e., B z0 is zeroed, the 2f component in V PD-ZThe second harmonic component (2f) dominates, and the signal observed on the oscilloscope is approximately 2f. Coarse compensation for Z-axis remanence is achieved based on the appearance of the second harmonic phenomenon on the oscilloscope. The appearance of the second harmonic phenomenon on the oscilloscope is used to apply an additional DC bias magnetic field B on the X or Y axis. bias This is a prerequisite.

[0050] Step B1 includes the following formula:

[0051]

[0052] Where k2 is a coefficient. It is the output signal corresponding to the first harmonic component after applying a high-frequency modulated magnetic field along the X-axis. f is the electron spin polarizability of an atom. mod The first harmonic component, Δω is the magnetic resonance linewidth, Δω=(R op +R rel ) / γ e J0 is a 0th-order Bessel series term, and J1 is a 1st-order Bessel series term. A scanning magnetic field is applied along the X-axis. In a two-dimensional coordinate system with the X-axis as the magnitude of the scanning magnetic field and the y-axis as the amplitude of the system output signal, the demodulated output... The signal is represented by a dispersion curve, and the intersection of the dispersion curve with the x-axis approximates the remanence B along the x-axis. x0 When B x0 When the field is zeroed, the intersection point coincides with the origin of the two-dimensional coordinate system, i.e., the zero field point. Thus, precise magnetic compensation of the X-axis is achieved by using the sweep field dispersion curve after demodulating the first harmonic as it passes through the origin of the two-dimensional coordinate system.

[0053] The formulas included in steps B2 and B3 are the same as those in step B1. When performing precise compensation for residual magnetism in the Y-axis direction, an additional DC bias magnetic field needs to be applied in the Z-axis direction; when performing precise compensation for residual magnetism in the Z-axis direction, an additional DC bias magnetic field needs to be applied in the Y-axis direction.

[0054] The single-beam SERF atomic magnetometer system includes a pump laser 3, which is connected to a laser collimator 14 via a polarization-maintaining fiber 16. The laser emitted from the collimator 14 passes through a polarizer 4 and a quarter-wave plate 5, then travels along the Z-axis through an alkali metal gas chamber 6 and reaches a photodetector 8. The photodetector 8 is connected to a transimpedance amplifier 10 via a cable 15. The transimpedance amplifier 10 is connected to an oscilloscope 11 and a lock-in amplifier 12, which is connected to an acquisition, output, and display system 13. The alkali metal gas chamber 6 is located inside a gas chamber heating oven 7, which is located inside a magnetic compensation coil frame 2, which is located inside a magnetic shielding barrel 1. The magnetic compensation coil is connected to a signal generator 9 via a cable 15.

[0055] Figure 1 The outermost layer is a magnetic shielding barrel, the magnetic compensation coil skeleton is close to the magnetic shielding barrel, an alkali metal cell is placed in the central region of the barrel, the cell is placed in a heating oven, pumping light is emitted from a collimation head, sequentially passes through a polarizer, a 1 / 4 wave plate and the alkali metal cell, and is finally captured and detected by a photodetector.

[0056] The application relates to a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF (Spin-Exchange Relaxation-Free) atomic magnetometer, which is based on the principle of high-frequency magnetic field modulation. After coarse compensation of three-dimensional residual magnetism of the single-beam SERF magnetometer based on a quasi-static magnetic field, a high-frequency modulation magnetic field is applied to scan magnetic fields of X, Y and Z axes respectively, and the zero-crossing point of a first-order harmonic demodulation dispersion curve is made to coincide with a zero field point, so that precise magnetic field compensation of the single-beam SERF magnetometer system is realized. The method effectively improves the precision of magnetic compensation, solves the problem that the traditional magnetic compensation method is not applicable to the single-beam SERF atomic magnetometer or the precision of magnetic field compensation in the pumping light direction is too low, and is reasonable and simple to operate, thus greatly promoting the development of atomic magnetometers.

[0057] A method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, which comprises coarse compensation of three-dimensional residual magnetism based on a quasi-static magnetic field with a compensation precision of 0.1 nT and precise compensation of three-dimensional residual magnetism based on high-frequency magnetic field modulation with a compensation precision of 0.1 pT.

[0058] The coarse compensation of three-dimensional residual magnetism based on the quasi-static magnetic field comprises the following steps:

[0059] Step A1, the pumping light direction of the single-beam SERF atomic magnetometer system is defined as the Z-axis direction, then the X and Y directions are non-pumping axis directions, and XYZ constitutes a right-handed coordinate system. A low-frequency quasi-static magnetic field B osc cos(2pi f*t): B osc is the amplitude of the quasi-static magnetic field, B osc is greater than 0 and less than 10 nT; f is the frequency of the quasi-static magnetic field, and low frequency means that the value of f is small, and f is usually 1-6 Hz; t is time. The direct current bias magnetic field applied in the X-axis direction is adjusted, when the single-beam SERF atomic magnetometer system output signal appears approximately double frequency phenomenon is observed on an oscilloscope, that is, the frequency of the output signal is dominated by the 2f component instead of the f component, then the coarse compensation of the residual magnetism of the system in the X-axis direction is completed, and then the quasi-static magnetic field applied in the X-axis direction is zeroed.

[0060] Step A2, since the X and Y axes have symmetry, a low-frequency quasi-static magnetic field B osccos(2πf·t), adjust the direct current bias magnetic field applied in the Y-axis direction, when the approximate frequency doubling phenomenon appears in the output signal of the single-beam SERF atomic magnetometer system observed on the oscilloscope, i.e. the frequency of the output signal is dominated by the 2f component instead of the f component, then the coarse compensation of the residual magnetism in the Y-axis direction of the system is completed, and then the quasi-static magnetic field applied in the Y-axis direction is zeroed;

[0061] Step A3, the coarse compensation process of the residual magnetism in the pumping direction Z-axis is different from that in the X and Y axes, a low-frequency quasi-static magnetic field B osc cos(2πf·t) is applied in the Z-axis direction, and a direct current bias magnetic field B bias is applied in the X or Y axis direction at the same time bias , adjust the direct current bias magnetic field applied in the Z-axis direction, when the approximate frequency doubling phenomenon appears in the output signal of the single-beam SERF atomic magnetometer system observed on the oscilloscope, i.e. the frequency of the output signal is dominated by the 2f component instead of the f component, then the coarse compensation of the residual magnetism in the Z-axis direction of the system is completed, and finally the quasi-static magnetic field applied in the Z-axis direction and the direct current bias magnetic field B bias are all zeroed.

[0062] The three-dimensional residual magnetism fine compensation based on high-frequency magnetic field modulation includes the following steps:

[0063] Step B1, complete the three-dimensional residual magnetism coarse compensation based on the quasi-static magnetic field, apply a high-frequency modulation magnetic field B mod cos(2πf mod t) in the non-pumping axis X direction mod , B mod is the amplitude of the modulation magnetic field; f mod is the frequency of the modulation magnetic field, f mod is of the order of kHz; t is time. Scan the magnetic field in the X-axis direction, demodulate the first harmonic component of the output signal of the single-beam SERF atomic magnetometer system corresponding to the frequency f mod using a lock-in amplifier, find the zero-crossing point (intersection with the x-axis) of the dispersion curve corresponding to the first harmonic component in the two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, and adjust the direct current bias magnetic field applied in the X-axis direction to make the zero-crossing point coincide with the zero-field point (origin of the two-dimensional coordinate system), so as to realize the fine compensation of the residual magnetism in the X-axis direction;

[0064] Step B2, keep the high-frequency modulation magnetic field B mod cos(2πf mod t) applied in the X-axis direction unchanged in step B1, additionally apply a direct current bias magnetic field in the Z-axis direction, and scan the magnetic field in the Y-axis direction, demodulate the output signal of the atomic magnetometer system corresponding to the frequency f moda zero point (intersection with the x-axis) of the dispersion curve corresponding to the first harmonic component, adjusting the direct current bias magnetic field applied in the Z-axis direction and making the zero point coincide with the zero field point (origin of the two-dimensional coordinate system), precise compensation of the residual magnetism in the Z-axis direction can be realized, and finally the high frequency modulation magnetic field B

[0065] Step B3, maintaining the high frequency modulation magnetic field B mod cos(2πf mod unchanged, an additional direct current bias magnetic field is applied in the Y-axis direction, and the magnetic field in the Z-axis direction is scanned, the output signal of the atomic magnetometer system is demodulated, and the first harmonic component corresponding to the frequency f mod is found, in a two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, a zero point (intersection with the x-axis) of the dispersion curve corresponding to the first harmonic component, adjusting the direct current bias magnetic field applied in the Z-axis direction and making the zero point coincide with the zero field point (origin of the two-dimensional coordinate system), precise compensation of the residual magnetism in the Z-axis direction can be realized, and finally the high frequency modulation magnetic field B mod cos(2πf mod and the additional direct current bias magnetic field applied in the Y-axis direction are zeroed.

[0066] The single-beam SERF atomic magnetometer system experimental device includes a magnetic shielding barrel, a three-dimensional magnetic compensation coil and a coil skeleton, a laser, a polarizer, a 1 / 4 wave plate, an alkali metal cell, a heating oven, a photodetector, a signal generator, a transimpedance amplifier, an oscilloscope, a lock-in amplifier and a signal acquisition and display system. The magnetic shielding barrel is used for passive shielding of external magnetic fields (including the earth's magnetic field, etc.); the three-dimensional magnetic compensation coil and the signal generator are used in combination to generate a controlled magnetic field, so that active magnetic compensation can be performed; the laser generates a laser beam and satisfies that the laser wavelength is at the center of the D1 line of the alkali metal atom, and is used for pumping the alkali metal atom and obtaining the magnetic field information sensed by the atom; the polarizer is used to adjust the polarization state of the laser beam to linearly polarized light; the 1 / 4 wave plate is used to adjust the linearly polarized light to circularly polarized light; the alkali metal cell is the main unit of the sensitive magnetic field of the SERF atomic magnetometer; the heating oven is used to heat the alkali metal cell, so that the alkali metal atom reaches the required temperature for the SERF state; the photodetector is used to detect the light intensity change of the transmitted laser beam to obtain the magnetic field information; the signal generator is used to generate a waveform; the transimpedance amplifier is used to convert a current signal into a voltage signal and amplify; the oscilloscope is used to observe the waveform; the lock-in amplifier is used for field scanning and demodulation; the signal acquisition and display system is used to acquire the voltage signals output by the transimpedance amplifier and the lock-in amplifier and perform information processing and display.

[0067] After the step A1 single-beam SERF atomic magnetometer system is normally running, under the action of the pumping light in the Z-axis direction, the alkali metal atoms reach a steady state in a very short time. The pumping light transmits through the alkali metal cell and carries the polarization information of the atoms to be detected by the photodetector. A low-frequency quasi-static magnetic field B osc cos(2πf·t) is applied in the X-axis direction. The photodetector detects the light intensity information of the pumping light transmitting through the alkali metal cell and converts it into a photocurrent, which is converted into a voltage signal by a transimpedance amplifier and input into an oscilloscope. Under the action of the quasi-static magnetic field, the output signal V PD-X of the single-beam SERF atomic magnetometer system observed by the oscilloscope can approximately comply with the following formula:

[0068]

[0069] where k1 is a coefficient, V PD-X is the voltage signal output by the system after the quasi-static magnetic field is applied in the X-axis direction, P z-x is the z-direction component of the electronic polarization of the atom after the quasi-static magnetic field is applied in the X-axis direction, R op is the optical pumping rate, R rel is the relaxation rate, γ e is the electronic gyromagnetic ratio, B x0 is the remanence in the X-axis direction, B y0 is the remanence in the Y-axis direction, B z0 is the remanence in the Z-axis direction. As can be seen from the formula, when the X-axis remanence B x0 is large, the frequency component of one octave f in V PD-X dominates, and the signal with a frequency of approximately f observed on the oscilloscope is the signal with a frequency of approximately f. When the direct-current bias magnetic field applied in the X-axis is adjusted to offset the original remanence in the X-axis, i.e., B x0 is set to zero, the frequency component of two octaves 2f in V PD-X dominates, and the signal with a frequency of approximately 2f observed on the oscilloscope is the signal with a frequency of approximately 2f. Therefore, the rough compensation of the remanence in the X-axis can be realized according to the appearance of the two-octave phenomenon on the oscilloscope. Since the X and Y axes are both non-pumping axis directions, they have symmetry, and the analysis of the rough compensation of the remanence in the Y-axis is completely consistent with that of the X-axis.

[0070] The related principle of the step A3 rough compensation of the remanence in the Z-axis direction is as follows. Unlike the X and Y axes, the Z-axis is the direction of the pumping light. After the quasi-static magnetic field B osc cos(2πf·t) is applied in the Z-axis direction, an additional direct-current bias magnetic field B bias must be applied in the X or Y axis. The output signal V PD-Z of the single-beam SERF atomic magnetometer system observed on the oscilloscope can approximately comply with the following formula:

[0071]

[0072] where V PD-Z is the output voltage signal of the system after applying quasi-static magnetic field on Z axis, P z-z is the z component of electronic polarizability of the atom when quasi-static magnetic field is applied on Z axis, from the formula, when the remanence B z0 of Z axis is large, the first harmonic f component in V PD-Z dominates, the signal observed on the oscilloscope is of frequency f, when the DC bias magnetic field applied on Z axis is adjusted to cancel the remanence of Z axis, i.e. B z0 is zero, the second harmonic 2f component in V PD-Z dominates, the signal observed on the oscilloscope is of frequency approximately 2f, so the rough compensation of the remanence of Z axis can be realized according to the appearance of the second harmonic phenomenon on the oscilloscope, it is worth noting that if an additional DC bias magnetic field B bias is not applied on X or Y axis, the appearance of the second harmonic phenomenon cannot be observed on the oscilloscope.

[0073] The step B1 should be performed after the rough compensation of the remanence of Z axis is completed, a high frequency modulation magnetic field B mod cos(2πf mod t) is applied on X direction of the non-pumping axis, it is worth noting that due to the symmetry of X and Y axes, the high frequency modulation magnetic field applied on Y axis is also feasible, the principle analysis is consistent with that of X axis. When the remanence of three axes is not completely zero, and after the high frequency modulation magnetic field B mod cos(2πf mod t) is applied on X direction, the z component of electronic spin polarizability P z is a signal superimposed by high order harmonics of f mod , the pumping light information received by the photodetector is converted into a photoelectric current signal, then the signal is converted into a voltage signal by a transimpedance amplifier, and then the signal is input into a lock-in amplifier for modulation and demodulation, finally the first harmonic component corresponding to frequency f mod is output approximately in accordance with the following formula:

[0074]

[0075] where k2 is a coefficient between and is the output signal of the demodulated first harmonic component after the high frequency modulation magnetic field is applied on X axis, is the first harmonic component of the electronic spin polarizability of the atom corresponding to frequency f mod , R op is the optical pumping rate, R rel is the relaxation rate, and Δω is the magnetic resonance linewidth, Δω = (R op + Rrel ) / γ e γ e It represents the electron gyromagnetic ratio, J0 is the 0th order Bessel series term, J1 is the 1st order Bessel series term, and f is the frequency of the high-frequency modulated magnetic field. mod Generally, the value is in the kHz range, B x0 It is the X-axis remanence of the atomic magnetometer system, B y0 It is the remanence along the Y-axis, B z0 This refers to the Z-axis remanence. As the formula shows, when a scanning magnetic field (with continuously varying magnitude) is applied along the X-axis, in a two-dimensional coordinate system with the X-axis representing the magnitude of the scanning magnetic field and the y-axis representing the amplitude of the system output signal, the demodulated output... The signal is represented by a dispersion curve, and the intersection of the dispersion curve and the x-axis (magnetic field axis) can be approximated as the remanence B along the x-axis. x0 When B x0 When the field is zeroed, the intersection point will coincide with the origin (zero field point) of the two-dimensional coordinate system. Therefore, precise magnetic compensation of the X-axis can be achieved by using the fact that the sweep field dispersion curve after demodulating the first harmonic passes through the origin of the two-dimensional coordinate system.

[0076] Steps B2 and B3 precisely compensate for the residual magnetism of the Y and Z axes, by... As can be seen from the formula, the Y and Z axes are symmetrical. Unlike the precise magnetic compensation in the X-axis direction, when precisely compensating for the residual magnetism in the Y-axis, an additional DC bias magnetic field needs to be applied in the Z-axis direction; when precisely compensating for the residual magnetism in the Z-axis, an additional DC bias magnetic field needs to be applied in the Y-axis direction.

[0077] like Figure 1 As shown. The alkali metal gas chamber 6 is installed within the magnetically shielded barrel 1 and heated until the alkali metal atomic number density reaches 10. 13 ~10 14 cm -3 The order of magnitude is used to ensure that the atoms operate in the SERF state. The laser frequency of the pump laser 3 is tuned to the D1 line of the alkali metal atoms. The output laser light is collimated, then polarized by the polarizer 4 and the quarter-wave plate 5, and then adjusted to circularly polarized light. The circularly polarized laser pumps and polarizes the alkali metal atoms. It passes through the alkali metal gas cell 6, is detected by the photodetector 8, and is converted into a photocurrent signal. This signal contains the electronic polarizability information of the alkali metal atoms. The photocurrent signal is converted into a voltage signal by the transimpedance amplifier for subsequent processing and analysis.

[0078] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, and / or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A method for precisely compensating three-dimensional remanence of a single-beam SERF atomic magnetometer, characterized in that, The method comprises the following steps: Step A: performing three-dimensional remanence coarse compensation based on quasi-static magnetic field in a single-beam SERF atomic magnetometer system, and the coarse compensation precision reaches 0.1 nT level; Step B: performing three-dimensional remanence fine compensation based on high-frequency magnetic field modulation on the basis of the three-dimensional remanence coarse compensation, and the fine compensation precision reaches 0.1 pT level; Step B comprises the following steps: Step B1, applying a high-frequency modulation magnetic field in the non-pumping axis X direction , is the high-frequency modulation magnetic field amplitude, is the high-frequency modulation magnetic field frequency, is of the order of kHz; scanning the magnetic field in the X axis direction, using a lock-in amplifier to demodulate the first harmonic component of the output signal of the single-beam SERF atomic magnetometer system corresponding to , in a two-dimensional coordinate system with the x axis as the magnetic field axis and the y axis as the output signal amplitude axis, finding the zero-crossing point of the dispersion curve corresponding to the first harmonic component, i.e. the intersection with the x axis, and adjusting the DC bias magnetic field applied in the X axis to make the zero-crossing point coincide with the zero-field point, i.e. the origin of the two-dimensional coordinate system, thereby realizing precise compensation of the X axis remanence. Step B2, keep the high frequency modulation magnetic field applied in the X axis direction in step B1 Invariable, in addition to a DC bias magnetic field applied in the Z axis, while scanning the magnetic field in the Y axis direction, demodulate the first harmonic component of the output signal of the atomic magnetometer system corresponding to the frequency of In the two-dimensional coordinate system with the x axis as the magnetic field axis and the y axis as the output signal amplitude axis, find the zero-crossing point of the dispersion curve corresponding to the first harmonic component, adjust the DC bias magnetic field applied in the Y axis and make the zero-crossing point coincide with the zero field point, so as to realize the precise compensation of the residual magnetism in the Y axis, and then return the additional DC bias magnetic field applied in the Z axis to zero. Step B3: Maintain the high-frequency modulated magnetic field applied in the X-axis direction as in step B1. Without changing the direction of the magnetic field, an additional DC bias magnetic field is applied in the Y-axis direction, while simultaneously scanning the magnetic field in the Z-axis direction to demodulate the frequency corresponding to the output signal of the atomic magnetometer system. In a two-dimensional coordinate system with the x-axis as the magnetic field axis and the y-axis as the output signal amplitude axis, the zero-crossing point of the dispersion curve corresponding to the first harmonic component is found. The DC bias magnetic field applied along the Z-axis is adjusted so that the zero-crossing point coincides with the zero field point, thereby achieving precise compensation of the Z-axis remanence. Finally, a high-frequency modulation magnetic field is applied along the X-axis. The additional DC bias magnetic field applied in the Y-axis direction is reduced to zero.

2. The method of claim 1, wherein the method is a method of precisely compensating for three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, characterized in that, Step A comprises the following steps: Step A1, the pumping light direction of the single-beam SERF atomic magnetometer system is defined as the Z-axis direction, and the X and Y directions are non-pumping axis directions, which constitute a right-handed coordinate system; a low-frequency quasi-static magnetic field is applied in the X-axis direction , is the low-frequency quasi-static magnetic field amplitude, is greater than 0 and less than or equal to 10 nT, f is the low-frequency quasi-static magnetic field frequency, f is 1-6 Hz, is time; adjust the direct current bias magnetic field applied in the X-axis direction, when the output signal of the single-beam SERF atomic magnetometer system is observed on the oscilloscope to appear approximately double frequency phenomenon, that is, the frequency of the output signal is dominated by the f component to the 2f component, thereby completing the rough compensation of the residual magnetism in the X-axis direction of the system, and then the quasi-static magnetic field applied in the X-axis direction is zeroed. Step A2, due to the symmetry of X and Y axes, a low frequency quasi-static magnetic field is applied in Y axis direction ; adjusting the direct current bias magnetic field applied in Y axis direction, when observing the approximate frequency multiplication phenomenon of the single beam SERF atomic magnetometer system output signal on the oscilloscope, i.e. the frequency of the output signal is dominated by 2f component instead of f component, thus completing the rough compensation of the remanence in Y axis direction of the system, and then the quasi-static magnetic field applied in Y axis direction is zeroed. Step A3, applying a low frequency quasi-static magnetic field in Z axis direction , while applying a DC bias magnetic field in X or Y axis direction ; adjusting the DC bias magnetic field applied in Z axis direction, when observing the approximate frequency multiplication phenomenon of the output signal of the single-beam SERF atomic magnetometer system on the oscilloscope, i.e. the frequency of the output signal is dominated by the 2f component instead of the f component, the coarse compensation of the residual magnetism in the Z axis direction of the system is completed, then the quasi-static magnetic field applied in the Z axis direction and the DC bias magnetic field applied in the X or Y axis are all zeroed.

3. The method of claim 2, wherein the method is a method of precisely compensating for three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, characterized in that, Step A1 comprises the following formula: ； wherein is a coefficient, is the voltage signal outputted by the system after applying quasi-static magnetic field in X axis direction, is the z component of electronic polarizability of the atom after applying quasi-static magnetic field in X axis direction, is the optical pumping rate, is the relaxation rate, is the electronic gyromagnetic ratio, is the remanence in X axis direction, is the remanence in Y axis direction, is the remanence in Z axis direction, when the remanence in X axis is larger, the first harmonic f component dominates in the above equation, the signal observed on the oscilloscope is of frequency approximately f, when the DC bias magnetic field applied on X axis is adjusted to cancel the original remanence in X axis, i.e. to make zero, the second harmonic 2f component dominates in the above equation, the signal observed on the oscilloscope is of frequency approximately 2f, the rough compensation of the remanence in X axis is realized according to the appearance of second harmonic phenomenon on the oscilloscope.

4. The method of claim 2, wherein the method is a method of precisely compensating for three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, characterized in that, Step A3 comprises the following formula: ； in It is the voltage signal output by the system after a quasi-static magnetic field is applied along the Z-axis. It is the z-axis component of the electronic polarizability of an atom when a quasi-static magnetic field is applied along the Z-axis, and the remanence along the Z-axis. When it is large, The first harmonic component f dominates, and the signal observed on the oscilloscope is the signal with frequency f. When the DC bias magnetic field applied to the Z-axis is adjusted to cancel the original residual magnetism of the Z-axis, that is... When reset to zero, The second harmonic component (2f) dominates, and the signal observed on the oscilloscope is approximately 2f in frequency. Coarse compensation for Z-axis remanence is achieved based on the appearance of the second harmonic phenomenon on the oscilloscope. The observation of the second harmonic phenomenon on the oscilloscope is used to apply an additional DC bias magnetic field to the X or Y axis. This is a prerequisite.

5. The method of claim 1, wherein the method is a method of precisely compensating for three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, characterized in that, Step B1 comprises the following formula: ； in It is a coefficient. It is the output signal corresponding to the first harmonic component after applying a high-frequency modulated magnetic field along the X-axis. It corresponds to the electron spin polarization of the atom. The first harmonic component, It is the magnetic resonance linewidth. , It is a 0th-order Bessel series term. It is a first-order Bessel series term. A scanning magnetic field is applied in the X-axis direction. In a two-dimensional coordinate system with the X-axis as the magnitude of the scanning magnetic field and the y-axis as the amplitude of the system output signal, the demodulated output is... The signal is represented by a dispersion curve, and the intersection of the dispersion curve with the x-axis approximates the remanence along the x-axis. ,when When the field is zeroed, the intersection point coincides with the origin of the two-dimensional coordinate system, i.e., the zero field point. Thus, precise magnetic compensation of the X-axis is achieved by using the sweep field dispersion curve after demodulating the first harmonic as it passes through the origin of the two-dimensional coordinate system.

6. The method of claim 1, wherein, The formula included in steps B2 and B3 is consistent with the formula in claim 5, and an additional direct-current bias magnetic field needs to be applied to the Z axis when performing fine compensation of the remanence in the Y axis direction; An additional direct-current bias magnetic field needs to be applied to the Y axis when performing fine compensation of the remanence in the Z axis direction.

7. The method of claim 1, wherein the method is a method of precisely compensating for three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, and wherein the method comprises: applying a magnetic field to the single-beam SERF atomic magnetometer; and applying a magnetic field to the single-beam SERF atomic magnetometer. The single-beam SERF atomic magnetometer system comprises a pumping laser, the pumping laser is connected with a laser collimation head through a polarization maintaining optical fiber, the pumping laser emitted by the laser collimation head passes through a polarizer and a 1 / 4 wave plate, and then passes through an alkali metal cell along the Z axis and reaches a photodetector, the photodetector is connected with a transimpedance amplifier through a cable, the transimpedance amplifier is connected with an oscilloscope and a lock-in amplifier respectively, the lock-in amplifier is connected with an acquisition output display system, the alkali metal cell is located in a cell heating oven, the cell heating oven is located in a magnetic compensation coil framework, the magnetic compensation coil framework is located in a magnetic shielding barrel, and a magnetic compensation coil is connected with a signal generator through a cable.

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