Device and method for measuring optical frequency shift virtual magnetic field of single-beam optical pump atom magnetometer

Abstract

The invention discloses a single-beam optical pump atom magnetometer optical frequency shift virtual magnetic field measuring device and method, and belongs to the technical field of atom magnetometers, the single-beam optical pump atom magnetometer comprises a single-beam optical pump atom magnetometer, a shielding cylinder, a three-axis coil and a current source, the single-beam optical pump atom magnetometer comprises a transmitting end, an experiment end and a detection end, the three-axis coil is arranged in the shielding cylinder and close to the inner wall of the shielding cylinder, the current source is connected with the three-axis coil, the experiment end is arranged in the middle of the interior of the shielding cylinder, the transmitting end is located outside the shielding cylinder, and the detection end is connected with the experiment end. Optical parameters of the single-beam optical pump atom magnetometer do not need to be changed, operation is easy and convenient, and meanwhile the influence of pumping light polarization state adjusting precision or wavelength adjusting precision on a measurement result can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of atomic magnetometers, and in particular to an optical frequency shift virtual magnetic field measuring device and method for a single-beam optical pump atomic magnetometer. Background Art

[0002] The single-beam optically pumped atomic magnetometer works in a non-zero magnetic environment. Spin exchange relaxation seriously restricts the improvement of sensitivity. High-power pumping light is needed to suppress spin exchange relaxation through the narrowing effect of optical pressure. High-power pumping light causes a significant increase in optical frequency shift. Optical frequency shift can be equivalent to making atoms feel a virtual magnetic field. Therefore, optical frequency shift becomes an important source of heading error, which reduces the measurement accuracy of the single-beam optically pumped atomic magnetometer. In order to improve the measurement accuracy, it is necessary to suppress the optical frequency shift. Accurately measuring the size of the virtual magnetic field of the optical frequency shift can evaluate the suppression effect, which helps to improve the measurement accuracy of the single-beam optically pumped atomic magnetometer.

[0003] There are two main traditional methods for measuring optical frequency-shifted virtual magnetic fields: one is to measure by changing the polarization state of the pumping light. This method requires adjusting the optical devices of the single-beam optically pumped atomic magnetometer to change the polarization state of the light. The operation steps are complicated and it is not suitable for the assembled single-beam optically pumped atomic magnetometer, especially the miniaturized single-beam optically pumped atomic magnetometer; the other is to change the wavelength of the pumping light for measurement. This method requires first measuring the optical absorption center wavelength of the gas chamber. The measurement accuracy of the optical frequency-shifted virtual magnetic field is subject to the measurement accuracy of the center wavelength and the wavelength adjustment accuracy, and the operation is cumbersome. Based on this, the present invention provides an optical frequency-shifted virtual magnetic field measurement device and method for a single-beam optically pumped atomic magnetometer. Summary of the invention

[0004] The purpose of the present invention is to provide a single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device and method. Through the device and method, measurements can be performed directly in the working state of the single-beam optically pumped atomic magnetometer without changing the optical parameters of the single-beam optically pumped atomic magnetometer. The operation is simple and the influence of the polarization state adjustment accuracy or wavelength adjustment accuracy of the pumping light on the measurement results can be avoided.

[0005] To achieve the above-mentioned purpose, the present invention provides a single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measuring device, comprising a single-beam optically pumped atomic magnetometer, a shielding tube, a three-axis coil and a current source. The single-beam optically pumped atomic magnetometer comprises a transmitting end, an experimental end and a detecting end. The three-axis coil is arranged in the shielding tube and close to the inner wall of the shielding tube. The current source is connected to the three-axis coil. The experimental end is arranged in the middle position inside the shielding tube. The transmitting end is located outside the shielding tube. The detecting end is connected to the experimental end.

[0006] Preferably, the emitting end of the single-beam optically pumped atomic magnetometer is a laser, and connection holes are opened around the shielding tube. The laser emitted by the laser, the experimental end, the detection end, the three-axis coil and the current source are all connected through the connection holes around the shield, and the current source provides a stable DC current for the three-axis coil.

[0007] Preferably, the laser emitted by the laser will sequentially pass through the linear polarizer, 1 / 4 wave plate, heating film, oven, and gas chamber at the experimental end and finally irradiate the photodetector. The gas chamber is arranged inside the oven, and the heating film is arranged outside the oven. The heating film is provided with a port connected to an external circuit. A group of radio frequency coils are also arranged outside the heating film. The radio frequency coils are connected to the detection end to receive the AC voltage at the detection end, and the photodetector is also connected to the detection end.

[0008] Preferably, the experimental end of the single-beam optically pumped atomic magnetometer is designed to be non-magnetized. There are two schemes for emitting lasers. One is to use spatial light incidence, in which case the laser outlet and the center of the gas chamber need to be strictly aligned. The other is to use optical fiber introduction, in which case there is no need to restrict the position of the laser.

[0009] Preferably, the detection end includes a phase-locked amplifier and a transimpedance voltage amplifier, the input end of the transimpedance voltage amplifier is connected to the photodetector, the input end of the phase-locked amplifier is connected to the output end of the transimpedance voltage amplifier, and the output end of the phase-locked amplifier is connected to the radio frequency coil.

[0010] Preferably, the gas chamber is filled with a sensitive medium alkali metal and a buffer gas.

[0011] The present invention also provides a method for measuring a virtual magnetic field using an optical frequency shift of a single-beam optically pumped atomic magnetometer, comprising the following steps:

[0012] S1, installing a virtual magnetic field measurement device, starting a single-beam optically pumped atomic magnetometer, making the single-beam optically pumped atomic magnetometer in a normal working state, and obtaining an output signal of the magnetometer;

[0013] S2, generate the main magnetic field through the three-axis coil, and obtain the magnetic field B1 felt by the sensitive medium alkali metal through the output signal of the magnetometer;

[0014] S3, rotating the single-beam optical pump atomic magnetometer while ensuring that the center position of the gas chamber remains unchanged, and using the same method as S2 to obtain the magnetic field B2 felt by the sensitive medium alkali metal at this time;

[0015] S4. The optical frequency-shifted virtual magnetic field is obtained through the relationship between the magnetic fields felt twice by the sensitive medium alkali metal.

[0016] Preferably, the process of obtaining the output signal in S1 is as follows:

[0017] S11, install a virtual magnetic field measurement device and start the single-beam optically pumped atomic magnetometer;

[0018] S12, using an external circuit to energize the heating film to generate Joule heat, and the generated Joule heat is conducted to the air chamber through the oven to heat the air chamber to a working temperature;

[0019] S13, using a laser to emit laser into the shielding tube, and the generated laser is converted into circularly polarized light after passing through a linear polarizer and a quarter wave plate;

[0020] S14, the phase-locked amplifier provides an excitation signal to the radio frequency coil, and the radio frequency coil generates an excitation magnetic field;

[0021] S15, using circularly polarized light to polarize the alkali metal atoms in the sensitive medium, and then detecting the spin precession signal of the atomic ensemble by detecting the light intensity transmitted through the gas chamber through a photodetector;

[0022] S16, transmitting the detected spin precession signal to a transimpedance voltage amplifier, and the signal is amplified by the transimpedance voltage amplifier and then transmitted to a lock-in amplifier;

[0023] S17. Use a phase-locked amplifier to demodulate the amplified spin precession signal to obtain a magnetometer output signal.

[0024] Preferably, the process of obtaining the magnetic field B1 in S2 is as follows:

[0025] S21. Use a current source to provide a DC current to the three-axis coil, and the three-axis coil provides a main magnetic field into the shielding tube, and the magnitude of the main magnetic field is within 10uT;

[0026] S22, make the direction of the main magnetic field form an angle θ1 with the direction of the circularly polarized light, and obtain the relationship curve between the output signal of the magnetometer and the excitation magnetic field frequency by scanning the excitation magnetic field frequency, and obtain the resonance frequency ω1 by the following formula,

[0027]

[0028] Where R is the output signal of the magnetometer, K is the fitting parameter, γ is the gyromagnetic ratio of the alkali metal atom, and B rf represents the amplitude of the excitation magnetic field, T1 represents the transverse relaxation time, T2 represents the transverse relaxation time, and ω represents the excitation magnetic field frequency;

[0029] S23. The value of the magnetic field B1 felt by the atomic ensemble is obtained based on the resonance frequency and the gyromagnetic ratio of the alkali metal atoms:

[0030]

[0031] S24. The magnetic field B1 felt by the atomic ensemble is also the superposition of the main magnetic field, the residual magnetism in the tube and the virtual magnetic field of optical frequency shift, which can be expressed as:

[0032] B1=B0+B re cos(α)+B LS cos(θ1);

[0033] Where B0 represents the main magnetic field, B re represents the residual magnetism in the shielding tube, α represents the angle between the main magnetic field and the residual magnetism in the tube, B LS represents the optical frequency-shifted virtual magnetic field.

[0034] Preferably, the process of obtaining the optical frequency shift virtual magnetic field in S4 is as follows:

[0035] S41, comprehensively analyzing the process of calculating B1 in S2 and the process of calculating B2 in S3, the calculation expression of the optical frequency shift virtual magnetic field is obtained as follows:

[0036]

[0037] Where ω2 represents the resonant frequency of the single-beam optically pumped atomic magnetometer after rotation, and θ2 represents the angle between the main magnetic field and the direction of the circularly polarized light after rotation;

[0038] S42, inputting the obtained data into the optical frequency shift virtual magnetic field calculation expression to obtain the measurement result of the optical frequency shift virtual magnetic field, and completing the optical frequency shift virtual magnetic field measurement.

[0039] Therefore, the present invention adopts the single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device and method of the above-mentioned structure, which can directly perform measurements in the working state of the single-beam optically pumped atomic magnetometer without changing the optical parameters of the single-beam optically pumped atomic magnetometer. The operation is simple and can avoid the influence of the pumping light polarization state adjustment accuracy or the wavelength adjustment accuracy on the measurement results. It solves the problem that the traditional method performs measurement by changing the pumping light polarization state or the pumping light wavelength, the operation steps are complicated, and it is difficult to apply to the assembled single-beam optically pumped atomic magnetometer, especially the miniaturized single-beam optically pumped atomic magnetometer, and the measurement accuracy is subject to the pumping light polarization state adjustment accuracy or the wavelength adjustment accuracy.

[0040] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure of the device and method for measuring the optical frequency shift virtual magnetic field of the single-beam optically pumped atomic magnetometer of the present invention;

[0042] Figure 2 It is a flow chart of the optical frequency shift virtual magnetic field measurement method of the optical frequency shift virtual magnetic field measurement device and method of the single-beam optical pump atomic magnetometer of the present invention;

[0043] Reference numerals

[0044] 1. Laser; 2. Linear polarizer; 3. 1 / 4 wave plate; 4. Gas chamber; 5. Oven; 6. Heating film; 7. Photodetector; 8. RF coil; 9. Three-axis coil; 10. Shielding tube; 11. Current source; 12. Phase-locked amplifier; 13. Transimpedance voltage amplifier. DETAILED DESCRIPTION

[0045] Example

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0049] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0050] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0052] like Figure 1 and Figure 2 As shown, the present invention provides a single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measuring device, including a single-beam optically pumped atomic magnetometer, a shielding tube 10, a three-axis coil 9 and a current source 11. The single-beam optically pumped atomic magnetometer includes a transmitting end, an experimental end and a detecting end. The three-axis coil 9 is arranged in the shielding tube 10 and close to the inner wall of the shielding tube 10. The current source 11 is connected to the three-axis coil 9. The experimental end is arranged in the middle position inside the shielding tube 10. The transmitting end is located outside the shielding tube 10, and the detecting end is connected to the experimental end.

[0053] The emitting end of the single-beam optically pumped atomic magnetometer is a laser 1. The shielding tube 10 is provided with connecting holes around it. The laser emitted by the laser 1, the experimental end, the detection end, the three-axis coil 9 and the current source 11 are all connected through the connecting holes around the shielding device. The current source 11 provides a stable DC current for the three-axis coil 9.

[0054] The laser emitted by the laser 1 will sequentially pass through the linear polarizer 2, the quarter wave plate 3, the heating film 6, the oven 5, the gas chamber 4 at the experimental end and finally irradiate the photodetector 7. The gas chamber 4 is arranged inside the oven 5, and the heating film 6 is arranged outside the oven 5. The heating film 6 is provided with a port connected to an external circuit. A group of radio frequency coils 8 are also arranged on the outside of the heating film 6. The radio frequency coils 8 are connected to the detection end to receive the AC voltage of the detection end. The photodetector 7 is also connected to the detection end.

[0055] The experimental end of the single-beam optically pumped atomic magnetometer is designed to be non-magnetized, which can avoid the influence of magnetic field interference generated by the experimental end equipment itself on the measurement results. There are two schemes for laser 1 to emit laser. One is to use spatial light incidence, at this time, it is necessary to strictly align the laser outlet and the center of the gas chamber 4, and the other is to use optical fiber introduction, at this time, there is no need to limit the position of the laser.

[0056] The detection end includes a phase-locked amplifier 12 and a transimpedance voltage amplifier 13 , the input end of the transimpedance voltage amplifier 13 is connected to the photodetector 7 , the input end of the phase-locked amplifier 12 is connected to the output end of the transimpedance voltage amplifier 13 , and the output end of the phase-locked amplifier 12 is connected to the radio frequency coil 8 .

[0057] The gas chamber 4 is filled with sensitive medium alkali metal and buffer gas.

[0058] The specific implementation method includes the following steps:

[0059] S1, installing a virtual magnetic field measurement device, starting a single-beam optically pumped atomic magnetometer, making the single-beam optically pumped atomic magnetometer in a normal working state, and obtaining an output signal of the magnetometer;

[0060] S11, install a virtual magnetic field measurement device and start the single-beam optically pumped atomic magnetometer;

[0061] S12, using an external circuit to energize the heating film 6 to generate Joule heat, and the generated Joule heat is conducted to the air chamber 4 through the oven 5, and the air chamber 4 is heated to the working temperature;

[0062] S13, using the laser 1 to emit laser light into the shielding tube 10, and the generated laser light becomes circularly polarized light after passing through the linear polarizer 2 and the quarter wave plate 3;

[0063] S14, the lock-in amplifier 12 provides an excitation signal to the radio frequency coil 8, and the radio frequency coil 8 generates an excitation magnetic field;

[0064] S15, using circularly polarized light to polarize the alkali metal atoms of the sensitive medium, and then detecting the light intensity passing through the gas chamber 4 by the photodetector 7 to detect the spin precession signal of the atomic ensemble;

[0065] S16, transmitting the detected spin precession signal to the transimpedance voltage amplifier 13, and the signal is amplified by the transimpedance voltage amplifier 13 and then transmitted to the lock-in amplifier 12;

[0066] S17, the lock-in amplifier 12 demodulates the amplified spin precession signal to obtain the magnetometer output signal.

[0067] S2, generate the main magnetic field through the three-axis coil 9, and obtain the magnetic field B1 felt by the sensitive medium alkali metal through the output signal of the magnetometer;

[0068] S21, using the current source 11 to provide a direct current to the three-axis coil 9, the three-axis coil 9 provides a main magnetic field into the shielding tube 10, the magnitude of the main magnetic field is within 10uT, and the nonlinear Zeeman effect can be avoided to affect the measurement;

[0069] S22, make the direction of the main magnetic field form an angle θ1 with the direction of the circularly polarized light, and obtain the relationship curve between the output signal of the magnetometer and the excitation magnetic field frequency by scanning the excitation magnetic field frequency, and obtain the resonance frequency ω1 by the following formula,

[0070]

[0071] Where R is the output signal of the magnetometer, K is the fitting parameter, γ is the gyromagnetic ratio of the alkali metal atom, and B rf represents the amplitude of the excitation magnetic field, T1 represents the transverse relaxation time, T2 represents the transverse relaxation time, and ω represents the excitation magnetic field frequency;

[0072] S23. According to the resonance frequency and the gyromagnetic ratio of the alkali metal atoms, the value of the magnetic field B1 felt by the atomic ensemble can be obtained:

[0073]

[0074] S24. The magnetic field B1 felt by the atomic ensemble is also the superposition of the main magnetic field, the residual magnetism in the tube and the virtual magnetic field of optical frequency shift, which can be expressed as:

[0075] B1=B0+B re cos(α)+B LS cos(θ1);

[0076] Where B0 represents the main magnetic field, B re represents the residual magnetism in the shielding tube 10, α represents the angle between the main magnetic field and the residual magnetism in the tube, and B LS represents the optical frequency-shifted virtual magnetic field.

[0077] S3, rotating the single-beam optical pump atomic magnetometer while ensuring that the center position of the gas chamber 4 remains unchanged, and using the same method as S2 to obtain the magnetic field B2 felt by the sensitive medium alkali metal at this time;

[0078] S4. The virtual magnetic field of optical frequency shift is obtained through the relationship between the magnetic fields felt twice by the sensitive medium alkali metal:

[0079] S41, comprehensively analyzing the process of calculating B1 in S2 and the process of calculating B2 in S3, the calculation expression of the optical frequency shift virtual magnetic field is obtained as follows:

[0080]

[0081] Where ω2 represents the resonant frequency of the single-beam optically pumped atomic magnetometer after rotation, and θ2 represents the angle between the main magnetic field and the direction of the circularly polarized light after rotation;

[0082] S42, inputting the obtained data into the optical frequency shift virtual magnetic field calculation expression to obtain the measurement result of the optical frequency shift virtual magnetic field, and completing the optical frequency shift virtual magnetic field measurement.

[0083] When performing optical frequency shift virtual magnetic field measurement, first install the virtual magnetic field measurement device. After the installation is completed, start the single-beam optical pump atomic magnetometer, use an external circuit to energize the heating film 6, and the Joule heat generated by the energization of the heating film 6 is transmitted to the gas chamber 4 through the oven 5, so that the gas chamber 4 is heated to the working temperature. The phase-locked amplifier 12 provides an excitation signal to the radio frequency coil 8 to make the radio frequency coil 8 generate an excitation magnetic field. Then, use the laser 1 to emit laser to the gas chamber 4. The laser passes through the linear polarizer 2 and the 1 / 4 wave plate 3 and becomes circularly polarized light. The circularly polarized light will polarize the alkali metal atoms of the sensitive medium. The photodetector 7 will detect the light intensity passing through the gas chamber 4 at this time, so as to detect the spin precession signal of the atomic ensemble. After amplification and demodulation, the spin precession signal will obtain the magnetometer output signal.

[0084] During the measurement process, a current source 11 is used to provide a DC current to the three-axis coil 9, and a main magnetic field is obtained in the shielding tube 10. At this time, the magnetic field felt by the atomic ensemble is the superposition of the main magnetic field, the residual magnetism in the tube and the optical frequency-shifted virtual magnetic field. The resonance frequency can be obtained based on the relationship curve between the output signal of the magnetometer and the excitation magnetic field frequency, and then the magnetic field felt by the atomic ensemble is obtained. The single-beam optically pumped atomic magnetometer is rotated to obtain a new magnetic field felt by the atomic ensemble. The optical frequency-shifted virtual magnetic field can be obtained based on the relationship between the magnetic fields felt by the atomic ensemble obtained twice, and the optical frequency-shifted virtual magnetic field is measured to complete the measurement of the optical frequency-shifted virtual magnetic field.

[0085] Therefore, the present invention adopts the single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device and method of the above-mentioned structure, which can directly perform measurements in the working state of the single-beam optically pumped atomic magnetometer without changing the optical parameters of the single-beam optically pumped atomic magnetometer. The operation is simple and can avoid the influence of the pumping light polarization state adjustment accuracy or the wavelength adjustment accuracy on the measurement results. It solves the problem that the traditional method performs measurement by changing the pumping light polarization state or the pumping light wavelength, the operation steps are complicated, and it is difficult to apply to the assembled single-beam optically pumped atomic magnetometer, especially the miniaturized single-beam optically pumped atomic magnetometer, and the measurement accuracy is subject to the pumping light polarization state adjustment accuracy or the wavelength adjustment accuracy.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device, characterized in that: The invention comprises a single-beam optically pumped atomic magnetometer, a shielding tube, a three-axis coil and a current source. The single-beam optically pumped atomic magnetometer comprises a transmitting end, an experimental end and a detecting end. The three-axis coil is arranged in the shielding tube and close to the inner wall of the shielding tube. The current source is connected to the three-axis coil. The experimental end is arranged in the middle position inside the shielding tube. The transmitting end is located outside the shielding tube. The detecting end is connected to the experimental end.

2. The single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device according to claim 1 is characterized in that: The transmitting end of the single-beam optically pumped atomic magnetometer is a laser. There are connecting holes around the shielding tube. The laser emitted by the laser, the experimental end, the detection end, the three-axis coil and the current source are all connected through the connecting holes around the shield. The current source provides a stable DC current for the three-axis coil.

3. The single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device according to claim 2, characterized in that: The laser emitted by the laser will pass through the linear polarizer, 1 / 4 wave plate, heating film, oven, gas chamber at the experimental end in turn and finally irradiate the photodetector. The gas chamber is set inside the oven, and the heating film is set outside the oven. The heating film is provided with a port connected to the external circuit. A group of radio frequency coils are also provided on the outside of the heating film. The radio frequency coil is connected to the detection end to receive the AC voltage at the detection end. The photodetector is also connected to the detection end.

4. The single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device according to claim 3, characterized in that: The experimental end of the single-beam optically pumped atomic magnetometer is designed to be non-magnetized. There are two schemes for laser emission. One is to use spatial light incidence, in which case the laser outlet and the center of the gas chamber need to be strictly aligned. The other is to use optical fiber introduction, in which case there is no need to restrict the position of the laser.

5. The single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device according to claim 4, characterized in that: The detection end includes a phase-locked amplifier and a transimpedance voltage amplifier. The input end of the transimpedance voltage amplifier is connected to the photodetector, the input end of the phase-locked amplifier is connected to the output end of the transimpedance voltage amplifier, and the output end of the phase-locked amplifier is connected to the radio frequency coil.

6. The single-beam optically pumped atomic magnetometer optical frequency shift virtual magnetic field measurement device according to claim 5, characterized in that: The gas chamber is filled with sensitive medium alkali metal and buffer gas.

7. A method for measuring virtual magnetic field using optical frequency shift of a single-beam optically pumped atomic magnetometer, applied to the optical frequency shift virtual magnetic field measuring device using a single-beam optically pumped atomic magnetometer as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1, installing a virtual magnetic field measurement device, starting a single-beam optically pumped atomic magnetometer, making the single-beam optically pumped atomic magnetometer in a normal working state, and obtaining an output signal of the magnetometer; S2, generate the main magnetic field through the three-axis coil, and obtain the magnetic field B1 felt by the sensitive medium alkali metal through the output signal of the magnetometer; S3, rotating the single-beam optical pump atomic magnetometer while ensuring that the center position of the gas chamber remains unchanged, and using the same method as S2 to obtain the magnetic field B2 felt by the sensitive medium alkali metal at this time; S4. The optical frequency-shifted virtual magnetic field is obtained through the relationship between the magnetic fields felt twice by the sensitive medium alkali metal.

8. The method for measuring virtual magnetic field using optical frequency shift of a single-beam optically pumped atomic magnetometer according to claim 7, characterized in that: The process of obtaining the output signal in S1 is as follows: S11, install a virtual magnetic field measurement device and start the single-beam optically pumped atomic magnetometer; S12, using an external circuit to energize the heating film to generate Joule heat, and the generated Joule heat is conducted to the air chamber through the oven to heat the air chamber to a working temperature; S13, using a laser to emit laser into the shielding tube, and the generated laser is converted into circularly polarized light after passing through a linear polarizer and a quarter wave plate; S14, the phase-locked amplifier provides an excitation signal to the radio frequency coil, and the radio frequency coil generates an excitation magnetic field; S15, using circularly polarized light to polarize the alkali metal atoms in the sensitive medium, and then detecting the spin precession signal of the atomic ensemble by detecting the light intensity transmitted through the gas chamber through a photodetector; S16, transmitting the detected spin precession signal to a transimpedance voltage amplifier, and the signal is amplified by the transimpedance voltage amplifier and then transmitted to a lock-in amplifier; S17. Use a phase-locked amplifier to demodulate the amplified spin precession signal to obtain a magnetometer output signal.

9. The method for measuring virtual magnetic field using optical frequency shift of a single-beam optically pumped atomic magnetometer according to claim 8, characterized in that: The process of obtaining the magnetic field B1 in S2 is as follows: S21. Use a current source to provide a DC current to the three-axis coil, and the three-axis coil provides a main magnetic field into the shielding tube, and the magnitude of the main magnetic field is within 10uT; S22, make the direction of the main magnetic field form an angle θ1 with the direction of the circularly polarized light, and obtain the relationship curve between the output signal of the magnetometer and the excitation magnetic field frequency by scanning the excitation magnetic field frequency, and obtain the resonance frequency ω1 by the following formula, Where R is the output signal of the magnetometer, K is the fitting parameter, γ is the gyromagnetic ratio of the alkali metal atom, and B rf represents the amplitude of the excitation magnetic field, T1 represents the transverse relaxation time, T2 represents the transverse relaxation time, and ω represents the excitation magnetic field frequency; S23. The value of the magnetic field B1 felt by the atomic ensemble is obtained based on the resonance frequency and the gyromagnetic ratio of the alkali metal atoms: S24, the magnetic field B1 felt by the atomic ensemble is also the superposition of the main magnetic field, the residual magnetism in the tube and the virtual magnetic field of the optical frequency shift, which can be expressed as: B1=B0+B re cos(α)+B LS cos(θ1); Where B0 represents the main magnetic field, B re represents the residual magnetism in the shielding tube, α represents the angle between the main magnetic field and the residual magnetism in the tube, B LS represents the optical frequency-shifted virtual magnetic field.

10. The method for measuring virtual magnetic field using optical frequency shift of a single-beam optically pumped atomic magnetometer according to claim 9, characterized in that: The process of obtaining the optical frequency-shifted virtual magnetic field in S4 is as follows: S41, comprehensively analyzing the process of calculating B1 in S2 and the process of calculating B2 in S3, the calculation expression of the optical frequency shift virtual magnetic field is obtained as follows: Where ω2 represents the resonant frequency of the single-beam optically pumped atomic magnetometer after rotation, and θ2 represents the angle between the main magnetic field and the direction of the circularly polarized light after rotation; S42, inputting the obtained data into the optical frequency shift virtual magnetic field calculation expression to obtain the measurement result of the optical frequency shift virtual magnetic field, and completing the optical frequency shift virtual magnetic field measurement.

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