Aom-based single-beam serf atomic magnetometer polarizability online control system and method

Abstract

The application discloses an AOM-based single-beam SERF atomic magnetometer polarizability online control system and method, realizes alkali metal atom pumping and magnetic field detection technology based on one light beam, acquires magnetic field information by collecting light signals, realizes proportional integral PI online control of a direct current component of a magnetometer response signal through a lock-in amplifier, and feeds back a control quantity to a driving module of an acousto-optic modulator AOM to realize a closed loop, so that the polarizability fluctuation can be inhibited to improve system stability, the ability of the magnetometer to resist external disturbances is improved, the problem that the atomic magnetometer cannot work due to light intensity and temperature changes is solved, and the system has great practical application potential.

Description

Technical Field

[0001] The present invention relates to the technical field of atomic magnetometer polarizability control, and in particular to an online polarizability control system and method for a single-beam SERF atomic magnetometer based on an AOM. Alkali metal atom pumping and magnetic field detection technology are implemented using a single beam of light. Magnetic field information is acquired by collecting optical signals, and proportional-integral (PI) online control is implemented for the DC component of the magnetometer response signal via a lock-in amplifier. The controlled quantity is then fed back to a drive module of an acousto-optic modulator (AOM) to implement a closed loop. Polarizability fluctuations can be suppressed, thereby improving system stability, thereby facilitating the magnetometer's ability to resist external disturbances and resolving the problem of atomic magnetometers failing to operate due to changes in light intensity and temperature. The system has great practical application potential. Background Art

[0002] With the advancement of precision measurement technology, optically pumped atomic magnetometers based on the interaction between magnetism, light and atoms have shown great potential in the field of weak magnetic measurement. Among them, atomic magnetometers based on the spin-exchange relaxation-free (SERF) effect can achieve aT / Hz. 1 / 2 Ultra-high magnetic measurement sensitivity of this magnitude has attracted widespread attention. Among SERF atomic magnetometers, the single-beam modulated atomic magnetometer has the characteristics of simple structure, easy miniaturization, and low cost, and has become the mainstream magnetic field sensor in the current new generation of cardio-cerebral magnetic measurement devices.

[0003] However, the highly integrated structure makes the pump light susceptible to fiber jitter and temperature fluctuations, causing the magnetometer output signal to become unstable or even exceed the linear region, rendering it inoperable. This is detrimental to biomagnetic measurement applications requiring long-term stability. Therefore, a method for online control of polarizability, which provides real-time stability, is needed. Currently, research on magnetometer polarizability stability is limited, with most studies focusing on laser performance control without addressing the fundamentals of signal response. This is based on this research, which led the inventors to complete the present invention. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and propose an online control system and method for the polarizability of a single-beam SERF atomic magnetometer based on an AOM. The system realizes alkali metal atom pumping and magnetic field detection technology based on a single beam of light, obtains magnetic field information by collecting optical signals, and realizes proportional integral (PI) online control of the DC component of the magnetometer response signal through a phase-locked amplifier. The control amount is fed back to the driving module of the acousto-optic modulator (AOM) to realize a closed loop. The system can suppress polarizability fluctuations and improve system stability, thereby facilitating the improvement of the magnetometer's ability to resist external disturbances and solving the problem that the atomic magnetometer cannot work due to changes in light intensity and temperature. The system has great practical application potential.

[0005] The technical solutions of the present invention are as follows:

[0006] The invention discloses an online control system for polarizability of a single-beam SERF atomic magnetometer based on an AOM, characterized in that it comprises a single-beam SERF atomic magnetometer system, wherein the single-beam SERF atomic magnetometer system uses a beam of light to realize the pumping of alkali metal atoms and the detection of the magnetic field, collects the optical signal through a photodetector to obtain magnetic field information, realizes proportional integral (PI) online control by passing the DC component of the magnetometer response signal through a phase-locked amplifier, and feeds back the control amount to a driving module of an acousto-optic modulator (AOM) to realize a closed loop, thereby suppressing polarizability fluctuations and improving system stability.

[0007] The single-beam SERF atomic magnetometer system includes a single light beam passing through an alkali metal gas chamber along the z-axis direction. The single light beam incident end of the alkali metal gas chamber is connected to a distributed Bragg reflector (DBR) laser via a quarter-wave plate, a polarization beam splitter, a half-wave plate, a collimator, and an acousto-optic modulator (AOM) in sequence. The single light beam exit end of the alkali metal gas chamber is connected to a photodetector. The photodetector is connected to a lock-in amplifier via a transimpedance amplifier. The lock-in amplifier is respectively connected to a proportional-integral (PI) online control module and a host computer. The proportional-integral (PI) online control module is respectively connected to the acousto-optic modulator (AOM) and the host computer.

[0008] A non-magnetic electric heating system, a three-axis magnetic field coil and a magnetic shielding barrel are sequentially arranged outward from the periphery of the alkali metal gas chamber. The three-axis magnetic field coil is connected to the phase-locked amplifier through a signal generator. The collimator, 1 / 2 wave plate, polarization beam splitter, 1 / 4 wave plate and photodetector are all located in the inner cavity of the magnetic shielding barrel. The acousto-optic modulator (AOM) is connected to the collimator through a polarization-maintaining optical fiber.

[0009] The photodetector collects optical signals containing magnetic field information. The quarter-wave plate converts linearly polarized light into left-handed or right-handed circularly polarized light. The combination of the half-wave plate and the polarization beam splitter ensures that the ratio of the intensity of the transmitted light to the reflected light is 9:1. The optical signal collected by the photodetector is amplified by a transimpedance amplifier and then enters a phase-locked amplifier. The phase-locked amplifier demodulates the signal to obtain the DC component P z DC and the first harmonic component P z ω , the DC component P z DC The proportional integral PI online control module feeds back to the AOM drive module, thereby achieving closed-loop stability and online control of the polarization rate.

[0010] The alkali metal atoms in the alkali metal gas chamber include one of potassium atoms, rubidium atoms, and cesium atoms, and nitrogen gas serving as a buffer gas and a quenching gas.

[0011] The DBR laser emits a beam of light with a frequency at the center of the D1 line of the alkali metal atoms used.

[0012] The signal generator drives the three-axis magnetic field coil to apply a calibration magnetic field with a frequency of 30.5 Hz and an amplitude of 100 pTrms, and applies a modulation magnetic field with a modulation frequency of 1 to 2 kHz and a modulation amplitude of 100 to 150 nT to complete compensation of the three-axis residual magnetism.

[0013]

[0014]

[0015] where R op is the optical pumping rate, R rel is the relaxation rate, γ is the classical electron radius, B x0 is the residual magnetic field in the x-axis direction, J0 is the zero-order Bessel series, J1 is the first-order Bessel series, B m is the modulation magnetic field amplitude, Q is the nuclear slowing factor, ω m is the modulation frequency.

[0016] The invention discloses an online control method for polarizability of a single-beam SERF atomic magnetometer based on AOM, characterized by adopting the above-mentioned online control system for polarizability of a single-beam SERF atomic magnetometer based on AOM.

[0017] The following steps are involved:

[0018] Step 1: Using a non-magnetic electric heating system, the alkali metal gas chamber is heated to between 140°C and 200°C depending on the alkali metal atoms. At this time, the alkali metal atoms are vaporized, achieving the high atomic density conditions required for the SERF state.

[0019] Step 2: Turn on the DBR laser and AOM, adjust the temperature and current of the DBR laser so that the pump laser frequency is the center frequency of the alkali metal atom D1 line, turn on the signal generator, and use the three-axis magnetic field coil to compensate for the three-axis remanent magnetization, so that the alkali metal atoms are in a zero magnetic environment, achieving the extremely weak magnetic field conditions required for the SERF state. At this point, the single-beam SERF atomic magnetometer enters the working state;

[0020] Step 3: Use a signal generator to apply a high-frequency modulated magnetic field using a three-axis magnetic field coil, with a modulation frequency of 1K to 2KHz and a modulation amplitude of 100 to 150nT;

[0021] Step 4: Use the lock-in amplifier to demodulate the DC component P of the magnetometer signal z DC and the first harmonic component

[0022] Step 5: Feedback the demodulated DC component of the magnetometer signal to the AOM drive module through the PI online control module to achieve closed-loop stability and online control of the polarizability;

[0023] In step 6, the first harmonic component of the demodulated magnetometer signal is imported into the host computer. At the same time, a signal generator is used to drive the three-axis magnetic field coil to generate a calibration magnetic field of 30.5 Hz and 100 pTrms. The performance indicators of the magnetometer are calculated in the host computer.

[0024] The technical effects of the present invention are as follows: the present invention provides an online control system and method for the polarizability of a single-beam SERF atomic magnetometer based on an AOM, which uses a beam of light to achieve pumping of alkali metal atoms and detection of the magnetic field, obtains magnetic field information by collecting optical signals, and implements online proportional integral (PI) control of the DC component of the magnetometer response signal through a phase-locked amplifier, and feeds the control amount back to the driving module of the acousto-optic modulator (AOM) to achieve a closed loop. Ultimately, the fluctuation of the polarizability is suppressed, achieving a system stability effect, which is beneficial to improving the magnetometer's ability to resist external disturbances, thereby solving the problem of the atomic magnetometer failing to work due to changes in light intensity and temperature. The present invention has great practical application potential.

[0025] The present invention has the following features: (1) The present invention's solution, based on the nature of the interaction between light and atoms, stabilizes the overall system by suppressing fluctuations in polarizability, resulting in more accurate control and more intuitive results. (2) The present invention's solution is simple and easy to operate, making it particularly suitable for systems such as single-beam atomic magnetometers, where the pump and detection beams cannot be controlled separately. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The schematic diagram of the structure of the online control system of the polarizability of the single-beam SERF atomic magnetometer based on AOM of the present invention is provided.

[0027] The accompanying drawings in the figure are marked as follows: 1-DBR laser (DBR, distributed Bragg reflector); 2-acousto-optic modulator (AOM, acoustic optical modulator); 3-collimator (collimator and acousto-optic modulator are connected by polarization-maintaining fiber); 4-1 / 2 wave plate; 5-polarization beam splitter prism; 6-1 / 4 wave plate; 7-non-magnetic electric heating system; 8-alkali metal gas chamber; 9-three-axis magnetic field coil; 10-photodetector; 11-transimpedance amplifier; 12-phase-locked amplifier; 13-host computer; 14-signal generator; 15-magnetic shielding barrel; PI-proportional integral online control module. DETAILED DESCRIPTION

[0028] Below is the attached figure ( Figure 1) and Examples illustrate the present invention.

[0029] Figure 1 This is a schematic diagram of the structure of the online control system for the polarizability of the single-beam SERF atomic magnetometer based on AOM in the present invention. Figure 1 As shown, an AOM-based single-beam SERF atomic magnetometer polarizability online control system includes a single-beam SERF atomic magnetometer system. The single-beam SERF atomic magnetometer system uses a beam of light to achieve pumping of alkali metal atoms and detection of the magnetic field, and acquires magnetic field information by collecting optical signals through a photodetector. The DC component of the magnetometer response signal is controlled online by a phase-locked amplifier to implement proportional-integral (PI) control, and the control amount is fed back to the driving module of the acousto-optic modulator (AOM) to realize a closed loop, thereby suppressing polarizability fluctuations and improving system stability. The single-beam SERF atomic magnetometer system includes a single light beam passing through the z-axis direction of the alkali metal gas chamber. The single light beam incident end of the alkali metal gas chamber 8 is connected to the distributed Bragg reflector DBR laser 1 through a 1 / 4 wave plate 6, a polarization beam splitter prism 5, a 1 / 2 wave plate 4, a collimator 3 and an acousto-optic modulator AOM2 in sequence. The single light beam exit end of the alkali metal gas chamber 8 is connected to a photodetector 10. The photodetector 10 is connected to a phase-locked amplifier 12 through a transimpedance amplifier 11. The phase-locked amplifier 12 is respectively connected to a proportional-integral PI online control module and a host computer 13. The proportional-integral PI online control module is respectively connected to the acousto-optic modulator AOM2 and the host computer 13.

[0030] The periphery of the alkali metal gas chamber 8 is sequentially provided with a non-magnetic electric heating system 7, a three-axis magnetic field coil 9, and a magnetic shielding barrel 15. The three-axis magnetic field coil 9 is connected to the phase-locked amplifier 12 via a signal generator 14. The collimator 3, 1 / 2 wave plate 4, polarization beam splitter prism 5, 1 / 4 wave plate 6, and photodetector 10 are all located in the inner cavity of the magnetic shielding barrel 15. The acousto-optic modulator AOM2 is connected to the collimator 3 via a polarization-maintaining optical fiber. The photodetector 10 collects optical signals containing magnetic field information. The 1 / 4 wave plate 6 converts linearly polarized light into left-handed or right-handed circularly polarized light. The combination of the 1 / 2 wave plate 4 and the polarization beam splitter prism 5 ensures that the ratio of the intensity of the transmitted light to the reflected light is 9:1. The optical signal collected by the photodetector 10 is amplified by the transimpedance amplifier 11 and then enters the phase-locked amplifier 12. The phase-locked amplifier 12 demodulates the signal to obtain the DC component P z DC and the first harmonic component The DC component P z DC The proportional integral PI online control module feeds back to the AOM drive module, thereby achieving closed-loop stability and online control of the polarization rate.

[0031] The alkali metal atoms in the alkali metal gas chamber 8 include one of potassium, rubidium, and cesium atoms, as well as nitrogen as a buffer gas and quenching gas. The frequency of the light beam emitted by the DBR laser 1 is centered at the D1 line of the alkali metal atoms used. The signal generator 14 drives the three-axis magnetic field coil 9 to apply a calibration magnetic field with a frequency of 30.5 Hz and an amplitude of 100 pTrms, and to compensate for the three-axis residual magnetization, a modulation magnetic field with a modulation frequency of 1 to 2 kHz and a modulation amplitude of 100 to 150 nT.

[0032]

[0033]

[0034] where R op is the optical pumping rate, R rel is the relaxation rate, γ is the classical electron radius, B x0 is the residual magnetic field in the x-axis direction, J0 is the zero-order Bessel series, J1 is the first-order Bessel series, B m is the modulation magnetic field amplitude, Q is the nuclear slowing factor, ω m is the modulation frequency.

[0035] The invention relates to an online control method for polarizability of a single-beam SERF atomic magnetometer based on AOM, which adopts the above-mentioned online control system for polarizability of a single-beam SERF atomic magnetometer based on AOM.

[0036] The method comprises the following steps: step 1, using a non-magnetic electric heating system to heat an alkali metal gas chamber to a temperature between 140° C. and 200° C. according to the different alkali metal atoms, at which time the alkali metal atoms are vaporized, thereby achieving the high atomic density condition required for the SERF state; step 2, turning on a DBR laser and an AOM, adjusting the temperature and current of the DBR laser so that the frequency of the pumping laser is the center frequency of the D1 line of the alkali metal atoms, turning on a signal generator, using a three-axis magnetic field coil to compensate for the three-axis residual magnetism, so that the alkali metal atoms are in a zero magnetic environment, achieving the extremely weak magnetic field condition required for the SERF state, and thus the single-beam SERF atomic magnetometer enters the working state; step 3, using a signal generator to apply a high-frequency modulation magnetic field using the three-axis magnetic field coil, wherein the modulation frequency is 1 kHz to 2 kHz and the modulation amplitude is 100 to 150 nT; step 4, using a phase-locked amplifier to demodulate the DC component P of the magnetometer signal z DC and the first harmonic component In step 5, the DC component of the demodulated magnetometer signal is fed back to the AOM drive module through the PI online control module to achieve closed-loop stabilization and online control of the polarizability. In step 6, the first harmonic component of the demodulated magnetometer signal is imported into the host computer. At the same time, a signal generator is used to drive the three-axis magnetic field coil to generate a calibration magnetic field of 30.5 Hz and 100 pTrms. The performance indicators of the magnetometer are calculated in the host computer.

[0037] The present invention relates to an online control system and method for the polarizability of a single-beam SERF atomic magnetometer based on an AOM. The single-beam SERF atomic magnetometer uses a beam of light to pump alkali metal atoms and detect the magnetic field, and obtains magnetic field information by collecting optical signals. By using a phase-locked amplifier to implement proportional integral (PI) online control of the DC component of the magnetometer response signal, and feeding back the control amount to the drive module of the acousto-optic modulator (AOM) to achieve a closed loop, the fluctuation of the polarizability is ultimately suppressed, achieving a stable system effect. Utilizing this method, the magnetometer's ability to resist external disturbances is improved, solving the problem of the atomic magnetometer being unable to operate due to changes in light intensity and temperature, and having great practical application potential.

[0038] Figure 1 The system includes light emitted by a DBR laser 1, which passes through an acousto-optic modulator (AOM) 2, a collimator 3, a half-wave plate 4, a polarization beam splitter 5, and a quarter-wave plate 6 before entering a non-magnetic electric heating system 7. This system interacts with alkali metal atoms, sensing magnetic field changes. The magnetometer response signal is collected by a photodetector 9, amplified by a transimpedance amplifier 10, and then fed into a lock-in amplifier 11 to demodulate the DC component of the response signal. This DC component is then controlled online using a proportional-integral (PI) algorithm. This control variable is fed back to the driver module of the acousto-optic modulator (AOM) 2, creating a closed-loop system. This ultimately suppresses fluctuations in the polarizability and achieves system stability.

[0039] refer to Figure 1 As shown, an AOM-based single-beam SERF atomic magnetometer polarizability online control system and method includes a single-beam magnetometer system that uses a single beam of light to pump alkali metal atoms and detect magnetic fields. A photodetector 10 collects optical signals to acquire magnetic field information. Proportional-integral (PI) online control is implemented by applying the DC component of the magnetometer response signal through a phase-locked amplifier 12. This control variable is then fed back to the driver module of the acousto-optic modulator (AOM) 2 to achieve a closed-loop control. This ultimately suppresses polarizability fluctuations and achieves system stability.

[0040] A DBR laser 1 is used to emit laser light of a specific wavelength. The light emitted by the DBR laser 1 is transmitted to a collimator 3 via a polarization-maintaining optical fiber, and then passes through a half-wave plate 4, a polarization beam splitter 5, and a quarter-wave plate 6 to enter an alkali metal gas chamber 8. The optical signal containing the magnetic field information is then collected by a photodetector 10.

[0041] The combination of the half wave plate 4 and the polarization beam splitter prism 5 ensures that the ratio of the intensity of the transmitted light to the reflected light is 9: 1. The quarter wave plate 6 is used to convert linearly polarized light into left-handed or right-handed circularly polarized light.

[0042] A non-magnetic electric heating system 7 , a three-axis magnetic field coil 9 and a magnetic shielding barrel 15 are sequentially arranged around the alkali metal gas chamber 8 from the inside to the outside. The three-axis magnetic field coil 9 is connected to a signal generator 14 .

[0043] The optical signal collected by the photodetector 10 is amplified by the transimpedance amplifier 11 and then enters the phase-locked amplifier 12, where it is demodulated to obtain the DC component P of the signal. z DC and the first harmonic component It is described by the following formula:

[0044]

[0045]

[0046] where R op is the optical pumping rate, R rel is the relaxation rate, γ is the classical electron radius, B x0 is the residual magnetic field in the x-axis direction, J0 and J1 are the first-order and zero-order Bessel series respectively, B m is the modulation magnetic field amplitude, Q is the nuclear slowing factor, ω m The DC component is fed back to the AOM2 drive module through the PI online control module to achieve closed-loop stability and online control of the polarization rate.

[0047] The single-beam SERF atomic magnetometer system performs online control and closed-loop stabilization of the electron polarizability based on the AOM, including the following steps:

[0048] Step 1: Use a non-magnetic electric heating system to heat the alkali metal gas chamber to between 140°C and 200°C depending on the alkali metal atoms. At this time, the alkali metal atoms are vaporized, achieving the high atomic density conditions required for the SERF state.

[0049] Step 2: Turn on the DBR laser and AOM. Adjust the DBR laser's temperature and current so that the pump laser frequency is at the center frequency of the alkali metal atom's D1 line. Turn on the signal generator and use a three-axis magnetic field coil to compensate for the three-axis residual magnetization, placing the alkali metal atoms in a zero-magnetic environment and achieving the extremely weak magnetic field conditions required for the SERF state. This puts the single-beam SERF atomic magnetometer into operation.

[0050] Step 3: Use a signal generator to apply a high-frequency modulated magnetic field using a three-axis magnetic field coil, with a modulation frequency of 1k-2kHz and a modulation amplitude of 100-150nT.

[0051] Step 4: Use the lock-in amplifier to demodulate the DC component P of the magnetometer signal z DC and the first harmonic component The formulas are:

[0052]

[0053]

[0054] where R op is the optical pumping rate, R rel is the relaxation rate, γ is the classical electron radius, B x0 is the residual magnetic field in the x-axis direction, J0 and J1 are the first-order and zero-order Bessel series respectively, B m is the modulation magnetic field amplitude, Q is the nuclear slowing factor, ω m is the modulation frequency.

[0055] In step 5, the DC component of the demodulated magnetometer signal is fed back to the AOM drive module through the PI online control module to achieve closed-loop stabilization and online control of the polarizability.

[0056] Step 6: Import the first harmonic component of the demodulated magnetometer signal into the host computer. Simultaneously, use a signal generator to drive the three-axis magnetic field coil to generate a 30.5 Hz, 100 pTrms calibration magnetic field. The host computer then calculates the magnetometer's performance indicators.

[0057] The alkali metal atoms in the alkali metal gas chamber 8 are one of potassium atoms, rubidium atoms, and cesium atoms, and should contain a buffer gas and a quenching gas with a total pressure of about 1 atm (atmospheric pressure). Both the buffer gas and the quenching gas are nitrogen.

[0058] The pumping light frequency emitted by the DBR laser 1 must be at the center of the D1 line of the alkali metal atoms used.

[0059] The signal generator 14 drives the three-axis magnetic field coil 9 to complete the compensation of the three-axis residual magnetism, apply a modulation magnetic field with a modulation frequency of 1-2 kHz and a modulation amplitude of 100-150 nT, and apply a calibration magnetic field of 30.5 Hz and 100 pTrms.

[0060] Any content not described in detail in this specification is prior art known to those skilled in the art. It should be noted that the above description is intended to help those skilled in the art understand the present invention, but does not limit the scope of protection of the present invention. Any equivalent substitution, modification, improvement, and / or simplification of the above description that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. AOM-based single-beam SERF atomic magnetometer polarizability online control system, characterized by: The invention comprises a single-beam SERF atomic magnetometer system, which uses a beam of light to pump alkali metal atoms and detect magnetic fields. The optical signal is collected by a photodetector to obtain magnetic field information. The DC component of the magnetometer response signal is passed through a phase-locked amplifier to implement proportional-integral (PI) online control, and the control amount is fed back to the drive module of the acousto-optic modulator (AOM) to achieve a closed loop, thereby suppressing polarizability fluctuations and improving system stability. The single-beam SERF atomic magnetometer system includes a single light beam passing through an alkali metal gas chamber along the z-axis direction. The single light beam incident end of the alkali metal gas chamber is connected to a distributed Bragg reflector (DBR) laser through a quarter wave plate, a polarization beam splitter, a half wave plate, a collimator, and an acousto-optic modulator (AOM) in sequence. The single light beam exit end of the alkali metal gas chamber is connected to a photodetector. The photodetector is connected to a lock-in amplifier through a transimpedance amplifier. The lock-in amplifier is respectively connected to a proportional-integral (PI) online control module and a host computer. The proportional-integral (PI) online control module is respectively connected to the acousto-optic modulator (AOM) and the host computer. A non-magnetic electric heating system, a three-axis magnetic field coil, and a magnetic shielding barrel are sequentially arranged outward from the periphery of the alkali metal gas chamber. The three-axis magnetic field coil is connected to the phase-locked amplifier via a signal generator. The collimator, 1 / 2 wave plate, polarization beam splitter, 1 / 4 wave plate, and photodetector are all located in the inner cavity of the magnetic shielding barrel. An acousto-optic modulator (AOM) is connected to the collimator via a polarization-maintaining optical fiber. The photodetector collects optical signals containing magnetic field information. The quarter-wave plate converts linearly polarized light into left-handed or right-handed circularly polarized light. The combination of the half-wave plate and the polarization beam splitter ensures that the ratio of the intensity of transmitted light to reflected light is 9:

1. The optical signal collected by the photodetector is amplified by a transimpedance amplifier and then enters a phase-locked amplifier. The phase-locked amplifier demodulates the signal to obtain the DC component. and the first harmonic component The DC component The proportional integral PI online control module feeds back to the AOM drive module, thereby achieving closed-loop stability and online control of the polarization rate; where R op is the optical pumping rate, R rel is the relaxation rate, γ is the classical electron radius, B x0 is the residual magnetic field in the x-axis direction, J0 is the zero-order Bessel series, J1 is the first-order Bessel series, B m is the modulation magnetic field amplitude, Q is the nuclear slowing factor, ω m is the modulation frequency.

2. The AOM-based single-beam SERF atomic magnetometer polarizability online control system according to claim 1, characterized in that: The alkali metal atoms in the alkali metal gas chamber include one of potassium atoms, rubidium atoms, and cesium atoms, and nitrogen gas serving as a buffer gas and a quenching gas.

3. The AOM-based single-beam SERF atomic magnetometer polarizability online control system according to claim 1, characterized in that: The DBR laser emits a beam of light with a frequency at the center of the D1 line of the alkali metal atoms used.

4. The AOM-based single-beam SERF atomic magnetometer polarizability online control system according to claim 1, characterized in that: The signal generator drives the three-axis magnetic field coil to apply a calibration magnetic field with a frequency of 30.5 Hz and an amplitude of 100 pTrms, and applies a modulation magnetic field with a modulation frequency of 1 k to 2 kHz and a modulation amplitude of 100 to 150 nT to complete compensation of the three-axis residual magnetism.

5. A single-beam SERF atomic magnetometer polarizability online control method based on AOM, characterized by: The single-beam SERF atomic magnetometer polarizability online control system based on AOM as described in any one of claims 1 to 4 is adopted.

6. The method for online polarizability control of a single-beam SERF atomic magnetometer based on AOM according to claim 5, characterized in that: The following steps are involved: Step 1: Using a non-magnetic electric heating system, the alkali metal gas chamber is heated to between 140°C and 200°C depending on the alkali metal atoms. At this time, the alkali metal atoms are vaporized, achieving the high atomic density conditions required for the SERF state. Step 2: Turn on the DBR laser and AOM, adjust the temperature and current of the DBR laser so that the pump laser frequency is the center frequency of the alkali metal atom D1 line, turn on the signal generator, and use the three-axis magnetic field coil to compensate for the three-axis remanent magnetization, so that the alkali metal atoms are in a zero magnetic environment, achieving the extremely weak magnetic field conditions required for the SERF state. At this point, the single-beam SERF atomic magnetometer enters the working state; Step 3: Use a signal generator to apply a high-frequency modulated magnetic field using a three-axis magnetic field coil, with a modulation frequency of 1K to 2KHz and a modulation amplitude of 100 to 150nT; Step 4: Use a lock-in amplifier to demodulate the DC component of the magnetometer signal and the first harmonic component Step 5: Feedback the demodulated DC component of the magnetometer signal to the AOM drive module through the PI online control module to achieve closed-loop stability and online control of the polarizability; In step 6, the first harmonic component of the demodulated magnetometer signal is imported into the host computer. At the same time, a signal generator is used to drive the three-axis magnetic field coil to generate a calibration magnetic field of 30.5 Hz and 100 pTrms. The performance indicators of the magnetometer are calculated in the host computer.

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