A single-beam dual-channel atomic magnetometer system

Abstract

A single-beam dual-channel atomic magnetometer system, through a combined polarization beam splitter set in a dual-channel meter head with a single-beam input interface, can split a single beam into a first pump beam and a second pump beam to act on the first alkali metal gas cell and the second alkali metal gas cell respectively. It can simultaneously obtain dual-channel magnetic field information, and has the characteristics of high sensitivity and high integration. It is conducive to forming a high-density magnetometer array and serving fields such as magnetoencephalography and magnetocardiography.

Description

Technical Field

[0001] This invention belongs to the field of magnetometer technology, specifically relating to a single-beam dual-channel atomic magnetometer system. Through a combined polarization beam splitter set within the dual-channel meter head with a single-beam input interface, the single beam can be split into a first pump beam and a second pump beam to act on the first and second alkali metal gas cells respectively. This allows for the simultaneous acquisition of dual-channel magnetic field information, featuring high sensitivity and high integration, which is beneficial for forming high-density magnetometer arrays and serving fields such as magnetoencephalography (MEG) and magnetocardiography (MCC). Background Technology

[0002] Magnetic fields are ubiquitous in the macroscopic universe and microscopic particles. Acquiring and understanding magnetic field information helps us better understand the world. Precise magnetic field measurement plays a crucial role in fields such as biomagnetic field detection, medicine, resource exploration, and anti-submarine warfare. In particular, biomagnetic field measurement will promote the development of life science research. A magnetometer is an instrument for detecting magnetic fields. The most commonly used instruments in the field of magnetic metrology, both domestically and internationally, are fluxgate magnetometers and optically pumped atomic magnetometers. Ordinary fluxgate magnetometers have a sensitivity on the order of nT, while high-precision fluxgate magnetometers produced by foreign companies can reach the pT level. However, due to limitations in its basic principle, fluxgate magnetometers suffer from drawbacks such as large zero bias and drift, and poor temperature stability, thus significantly limiting their accuracy in practical applications. Atomic magnetometers aim to achieve non-destructive passive magnetic field measurement under natural conditions, enabling precise magnetic source location and assessment of weak magnetic properties. With the continuous development of quantum precision measurement technology, a spin-exchange relaxation-free (SERF) atomic magnetometer has emerged, which has extremely high theoretical sensitivity. However, the magnetic field measurement sensitivity of the single-beam SERF atomic magnetometer is close to the limit, the measurement efficiency is low, the single-channel volume is difficult to further reduce, which is not conducive to array-type magnetic field measurement. At the same time, when using multi-channel, a certain degree of external isolation is required, and the density of the magnetometer array is low. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a single-beam dual-channel atomic magnetometer system. Through a combined polarization beam splitter housed within the dual-channel meter head with a single-beam input interface, the single beam can be split into a first pump beam and a second pump beam to act on the first and second alkali metal gas chambers, respectively. This allows for the simultaneous acquisition of dual-channel magnetic field information. The system features high sensitivity and high integration, facilitating the formation of high-density magnetometer arrays for applications such as magnetoencephalography (MEG) and magnetocardiography (MCC).

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

[0005] A single-beam dual-channel atomic magnetometer system is characterized by comprising a dual-channel meter head, wherein the dual-channel meter head has a single-beam input interface, and the inner cavity of the dual-channel meter head is provided with a combined polarization beam splitter, wherein the combined polarization beam splitter splits the single beam into a first pump beam and a second pump beam, wherein the first pump beam is used to pump atoms in a first alkali metal gas chamber, and the second pump beam is used to pump atoms in a second alkali metal gas chamber.

[0006] The combined polarizing beam splitter includes a polarizing beam splitter. The x-axis input side of the polarizing beam splitter is connected to the single-beam input interface. A third λ / 4 waveplate is disposed on the x-axis transmission side. A reflective film is disposed on the outer surface of the third λ / 4 waveplate. A first λ / 4 waveplate is disposed on the positive y-axis reflection side of the polarizing beam splitter, and a second λ / 4 waveplate is disposed on the negative y-axis reflection side. The polarizing beam splitter splits the linearly polarized light incident along the x-axis into a first vertically polarized light reflected along the positive y-axis and a horizontally polarized light transmitted along the x-axis. The first λ / 4 waveplate changes the first vertically polarized light into a first circularly polarized light that serves as the first pump beam. The horizontally polarized light is reflected back by the reflective film after passing through the third λ / 4 waveplate to form a second vertically polarized light reflected along the negative y-axis. The second λ / 4 waveplate changes the second vertically polarized light into a second circularly polarized light that serves as the second pump beam.

[0007] The first λ / 4 waveplate is connected to the first photodetector through the first alkali metal gas chamber, and the second λ / 4 waveplate is connected to the second photodetector through the second alkali metal gas chamber. A first non-magnetic electric heating film is disposed on the outside of the first alkali metal gas chamber, and a second non-magnetic electric heating film is disposed on the outside of the second alkali metal gas chamber. Both the first and second alkali metal gas chambers are located within a three-dimensional magnetic coil. The single-beam input interface is connected to the output end of the fiber collimator, and the input end of the fiber collimator is connected to the pump laser through a polarization-maintaining fiber. The photodetector is used to convert the optical signal into an electrical signal and send it to the lock-in amplifier for demodulation.

[0008] The collimating lens of the fiber collimator converts the divergent polarization-maintaining beam into collimated light with a diameter equivalent to the side length of the outer diameter of the alkali metal gas chamber, and then directs it into the dual-channel meter.

[0009] Both the first and second alkali metal gas chambers contain alkali metal atoms and a buffer gas. The alkali metal atoms are the working atoms, which are in a spin-free exchange relaxation state during operation. The buffer gas is an inert gas used to reduce spin collisions between atoms. The outermost electrons of the alkali metal atoms are macroscopically polarized by laser pumping. Under the action of the external magnetic field B0 to be measured, the macroscopic polarization forms Larmor precession. The light intensity after passing through the atomic gas chamber will change with the magnitude of the magnetic field strength to be measured. By detecting the change in light absorption by the atomic gas chamber caused by the change in magnetic field strength, the magnetic field strength in the x-axis direction is measured.

[0010] When detecting the magnetic field to be measured, a modulated magnetic field with a known magnetic field strength and modulation frequency is added in the direction of the magnetic field to be measured. The intensity of the light beam received by the photodetector is related to the transverse polarizability S along the laser direction. x The intensity signal of the light beam received by the photodetector is directly proportional to the frequency of the applied modulation magnetic field after being demodulated by a lock-in amplifier. The final signal output of the lock-in amplifier is proportional to S. x The first harmonic component S x Mod Proportional, S x Mod Defined by the following formula:

[0011]

[0012] Where u is the modulation index. Ω1 represents the Larmor precession frequency of alkali metal atoms in magnetic field B1, Ω1 = γB1, where γ is the gyromagnetic ratio of the alkali metal atom; Ω0 represents the Larmor precession frequency of alkali metal atoms in the magnetic field B0 to be measured, Ω0 = γB0; ω is the frequency of the applied modulation magnetic field; Q is the slowing factor of the alkali metal atom nucleus under high polarizability conditions; J0(u) and J1(u) are the first-order 0th-order and first-order 1st-order Bessel functions of the first kind with u as a parameter, respectively. Γ' is the transverse relaxation time of the alkali metal atom, Γ' is the transverse relaxation rate, Γ is the spin relaxation rate of the alkali metal atom, and R is the optical pumping rate of the pump light.

[0013] The technical effects of this invention are as follows: This invention provides a single-beam dual-channel atomic magnetometer system, comprising a laser source, a polarization-maintaining fiber, a fiber collimator, and a dual-channel meter head. The dual-channel meter head includes an alkali metal gas chamber, a non-magnetic electric heating film, a three-dimensional magnetic coil, a beam splitting module, and a photodetector. The fiber collimator collimates or focuses the laser beam into a specific beam diameter or spot size before it enters the probe. The alkali metal gas chamber is filled with alkali metal atoms. The non-magnetic electric heating film and the three-dimensional magnetic coil ensure efficient pumping of the alkali metal atoms under high temperature and low magnetic field conditions. The beam splitting module includes a polarization beam splitting prism, a λ / 4 waveplate, and a reflective film. The light emitted from the laser is transmitted through the fiber to the fiber collimator for collimation. The beam splitting module then generates two independent, opposite beams that simultaneously pump atoms in both atomic gas chambers, which are finally received by the photodetector. The light received by the photodetector is demodulated by a lock-in amplifier to obtain the measurement result. The laser is used to detect the magnetic field strength in the axial direction of the atomic magnetometer. Its advantages lie in the fact that the beam splitting module divides the laser into two desired laser paths and obtains the required polarization state, resulting in high laser quality and easy control and adjustment. Simultaneously, the single laser source outputs sufficient power, facilitating the integration of multiple arrayed probes for magnetoencephalography (MEG) and magnetocardiography (MCC) measurement. This invention can simultaneously obtain axial magnetic field information from two-channel atomic magnetometers and features high sensitivity and high integration, showing broad application prospects in MEG and MCC measurement fields. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a single-beam dual-channel atomic magnetometer system implementing the present invention.

[0015] Figure 2 yes Figure 1 A schematic diagram of the structure of a dual-channel meter.

[0016] Figure 3 yes Figure 2 A schematic diagram of the structure of the combined beam splitter prism.

[0017] The reference numerals in the attached figures are listed below: 1-Pump laser; 2-Polarization-maintaining fiber; 3-Fiber collimator; 4-Dual-channel meter; 40-Combined polarization beam splitter; 41-First alkali metal gas cell; 42-Second alkali metal gas cell; 43-First photodetector; 44-Second photodetector; 45-Three-dimensional magnetic coil; 46-First non-magnetic electric heating film; 47-Second non-magnetic electric heating film; 401-Polarization beam splitter; 402-First λ / 4 waveplate; 403-Second λ / 4 waveplate; 404-Third λ / 4 waveplate; 405-Reflective film; xyz-Cartesian coordinate axes. Detailed Implementation

[0018] The following is in conjunction with the attached diagram ( Figures 1-3 The invention will be described in the following sections and examples.

[0019] Figure 1 This is a schematic diagram of the structure of a single-beam dual-channel atomic magnetometer system implementing the present invention. Figure 2 yes Figure 1 A schematic diagram of the structure of a dual-channel meter. Figure 3 yes Figure 2 A schematic diagram of the combined beam-splitting prism. (Reference) Figures 1 to 3 As shown, a single-beam dual-channel atomic magnetometer system includes a dual-channel meter head 4, which has a single-beam input interface. The internal cavity of the dual-channel meter head 4 is provided with a combined polarization beam splitter 40, which splits the single beam into a first pump beam and a second pump beam. The first pump beam is used to pump atoms in a first alkali metal gas chamber 41, and the second pump beam is used to pump atoms in a second alkali metal gas chamber 42. The combined polarizing beam splitter 40 includes a polarizing beam splitter 401. The x-axis input side of the polarizing beam splitter 401 is connected to the single-beam input interface. A third λ / 4 waveplate 404 is disposed on the x-axis transmission side. A reflective film 405 is disposed on the outer surface of the third λ / 4 waveplate 404. A first λ / 4 waveplate 402 is disposed on the positive y-axis reflection side of the polarizing beam splitter 401, and a second λ / 4 waveplate 403 is disposed on the negative y-axis reflection side. The polarizing beam splitter 401 polarizes the linearly incident beam along the x-axis. The beam splits into a first vertically polarized light reflected along the positive y-axis and a horizontally polarized light transmitted along the x-axis. The first λ / 4 waveplate 402 changes the first vertically polarized light into a first circularly polarized light that serves as the first pump beam. The horizontally polarized light passes through the third λ / 4 waveplate 404 and is then reflected back by the reflective film 405 to form a second vertically polarized light reflected along the negative y-axis. The second λ / 4 waveplate 403 changes the second vertically polarized light into a second circularly polarized light that serves as the second pump beam.

[0020] The first λ / 4 waveplate 402 is connected to the first photodetector 43 via the first alkali metal gas chamber 41, and the second λ / 4 waveplate 403 is connected to the second photodetector 44 via the second alkali metal gas chamber 42. A first non-magnetic electric heating film 46 is disposed on the outside of the first alkali metal gas chamber 41, and a second non-magnetic electric heating film 47 is disposed on the outside of the second alkali metal gas chamber 42. Both the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 are located within a three-dimensional magnetic coil 45. The single-beam input interface is connected to the output end of the fiber collimator 3, and the input end of the fiber collimator 3 is connected to the pump laser 1 via a polarization-maintaining fiber 2. The photodetector is used to convert the optical signal into an electrical signal and send it to the lock-in amplifier for demodulation. The collimating lens of the fiber collimator 3 converts the diverging polarization-maintaining beam into collimated light with a diameter equivalent to the outer diameter of the alkali metal gas chamber, and then directs it into the dual-channel meter 4. Both the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 contain alkali metal atoms and buffer gas. The alkali metal atoms are working atoms, which are in a spin-free exchange relaxation state when working. The buffer gas is an inert gas used to reduce spin collisions between atoms. The outermost electron spin of the alkali metal atoms is macroscopically polarized by laser pumping. Under the action of the external magnetic field B0 to be measured, the macroscopic polarization forms Larmor precession. The light intensity after passing through the atomic gas chamber will change with the magnitude of the magnetic field strength to be measured. By detecting the change in light absorption of the atomic gas chamber caused by the change in magnetic field strength, the magnetic field strength in the x-axis direction is measured.

[0021] When detecting the magnetic field to be measured, a modulated magnetic field with a known magnetic field strength and modulation frequency is added in the direction of the magnetic field to be measured. The intensity of the light beam received by the photodetector is related to the transverse polarizability S along the laser direction. x The intensity signal of the light beam received by the photodetector is directly proportional to the frequency of the applied modulation magnetic field after being demodulated by a lock-in amplifier. The final signal output of the lock-in amplifier is proportional to S. x The first harmonic component S x Mod Proportional, S x Mod Defined by the following formula:

[0022]

[0023] Where u is the modulation index. Ω1 represents the Larmor precession frequency of alkali metal atoms in magnetic field B1, Ω1 = γB1, where γ is the gyromagnetic ratio of the alkali metal atom; Ω0 represents the Larmor precession frequency of alkali metal atoms in the magnetic field B0 to be measured, Ω0 = γB0; ω is the frequency of the applied modulation magnetic field; Q is the slowing factor of the alkali metal atom nucleus under high polarizability conditions; J0(u) and J1(u) are the first-order 0th-order and first-order 1st-order Bessel functions of the first kind with u as a parameter, respectively. Γ' is the transverse relaxation time of the alkali metal atom, Γ' is the transverse relaxation rate, Γ is the spin relaxation rate of the alkali metal atom, and R is the optical pumping rate of the pump light.

[0024] A highly integrated single-beam dual-channel atomic magnetometer system is disclosed, capable of simultaneously measuring dual-channel signals, increasing detection density, and improving measurement efficiency and magnetic field measurement sensitivity. The advantages of this invention compared to existing technologies are: it can simultaneously obtain dual-channel vector magnetic field signals, improving measurement efficiency and integration, which is beneficial for forming magnetometer arrays and has broad application prospects in fields such as magnetoencephalography (MEG) and magnetocardiography (MCC).

[0025] A single-beam dual-channel atomic magnetometer system comprises a laser source 1, a polarization-maintaining fiber 2, a fiber collimator 3, and a dual-channel meter head 4. The dual-channel meter head 4 includes a combined polarization beam splitter 40, a first alkali metal gas chamber 41, a second alkali metal gas chamber 42, a first photodetector 43, a second photodetector 44, a first non-magnetic electric heating film 45, and a second non-magnetic electric heating film 46. The first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 are symmetrically mounted on both sides of the combined polarization beam splitter 40 inside the dual-channel magnetometer meter head 4. Their external structures are the first non-magnetic electric heating film 46 and the second non-magnetic electric heating film 47, respectively. Heating of the gas chambers is achieved through non-magnetic electric heating. A magnetic coil 45 achieves magnetic compensation. The pump light enters the dual-channel meter head 4 from the laser 1 via the polarization-maintaining fiber 2 and the fiber collimator 3. Within the dual-channel meter head 4, it is split into a first pump beam and a second pump beam after passing through a combined polarization beam splitter 41. These beams are respectively injected into the first alkali metal gas cell 41 and the second alkali metal gas cell 42. The transmitted light is received by the first photodetector 43 and the second photodetector 44, respectively. The optical signal received by the photodetector is converted into an electrical signal and sent to a lock-in amplifier for demodulation. This demodulation is used to obtain the vector magnetic field strength sensed by the atoms in the first alkali metal gas cell 41 and the second alkali metal gas cell 42. Finally, the demodulated magnetic field strength data is processed and displayed in the signal processor.

[0026] The first and second pump beams generated after being split by the combined polarizing beam splitter 40 are left-handed circularly polarized light with opposite propagation directions. The two pump beams are injected into the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 along the -y axis and y axis directions, respectively. The combined polarizing beam splitter 40 is composed of a polarizing beam splitter 401, a first λ / 4 waveplate 402, a second λ / 4 waveplate 403, a third λ / 4 waveplate 404, and a reflective film 405. The first λ / 4 waveplate 402 and the second λ / 4 waveplate 403 are bonded to the surface of the polarizing beam splitter 401 along the y axis direction, and the third λ / 4 waveplate 404 and the reflective film 405 are bonded to the surface of the polarizing beam splitter 401 along the x axis direction.

[0027] The linearly polarized light incident on the dual-channel meter 4 has its propagation direction and polarization state changed by the combined polarization beam splitter 40. The incident linearly polarized light is split into reflected vertically polarized light and projected horizontally polarized light by the polarization beam splitter 401. The reflected vertically polarized light propagates along the y-axis and is generated by the first pump beam through the first λ / 4 waveplate 402. The transmitted horizontally polarized light is reflected by the third λ / 4 waveplate 404 and the reflective film 405, and then becomes vertically polarized light again after being reflected by the third λ / 4 waveplate 404 and propagates along the -y-axis. It is then generated by the second pump beam through the second λ / 4 waveplate 403.

[0028] The first pump beam and the second pump beam, which are injected into the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42, are used for laser pumping and magnetic field detection.

[0029] The first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 have the same parameters and contain alkali metal atoms and buffer gas.

[0030] The first photodetector 43 and the second photodetector 44 are of the same model.

[0031] The first non-magnetic electric heating film 46 and the second non-magnetic electric heating film 47 heat the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42, and the temperature is measured in real time by a platinum resistance thermometer.

[0032] The laser can output sufficient power to facilitate the later implementation of one laser driving multiple probes.

[0033] The three-dimensional magnetic coil 45 uses three pairs of square Helmholtz coils to compensate for residual magnetism in the x, y, and z axes. The light emitted by the laser 1 is linearly polarized laser light, which is transmitted into the dual-channel meter 4 through the polarization-maintaining fiber 2 and fiber collimator 3 to generate circularly polarized pump light, thereby realizing the polarization of alkali metal atoms and the detection of magnetic fields.

[0034] The linearly polarized laser emitted by laser 1 is coupled into polarization-maintaining fiber 2 through an optical fiber coupler to ensure polarization stability. Polarization-maintaining fiber 2 is connected to optical fiber collimator 3. The linearly polarized laser entering polarization-maintaining fiber 2 is expanded and collimated by the collimating lens of optical fiber collimator 3 to output a polarization-maintaining beam. The linearly polarized light entering the dual-channel meter 4 is split into two pump beams after passing through a combined polarization beam splitter prism 40. One beam enters the first alkali metal gas chamber 41, and the other enters the second alkali metal gas chamber 42, achieving the pumping of atoms.

[0035] The first and second pump lights, emitted from the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42, ultimately enter the first photodetector 43 and the second photodetector 44. The optical signals entering the photodetectors are then converted into electrical signals and sent to the lock-in amplifier for demodulation. The first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 contain alkali metal atoms and a buffer gas. The alkali metal atoms are the working atoms, operating in a spin-free exchange relaxation state. The buffer gas is an inert gas used to reduce spin collisions between atoms.

[0036] The first and second pump beams perform laser pumping of alkali metal atoms in the first alkali metal gas cell 41 and the second alkali metal gas cell 42, respectively. This laser pumping causes macroscopic polarization of the outermost electron spins of a large number of alkali metal atoms. Under the influence of the external magnetic field B0, this macroscopic polarization induces Larmor precession. The light intensity passing through the atomic gas cell then changes with the magnitude of the magnetic field strength. By detecting the change in light absorption by the atomic gas cell caused by the change in magnetic field strength, the magnetic field strength along the x-axis is measured.

[0037] The principle of vector magnetic field detection in the single-beam dual-channel atomic magnetometer system is as follows:

[0038] (1) Start the first non-magnetic electric heating film 46 and the first non-magnetic electric heating film 47 to heat the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 to the set temperature respectively. Then control the current of the three-dimensional magnetic coil 45 and adjust the magnetic field generated by the three-dimensional magnetic coil 46 so that the residual magnetic fields in the x-axis, y-axis and z-axis directions in the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42 are compensated to zero, so as to avoid the influence of the external residual magnetic field on the measurement results and make the alkali metal atoms in the gas chamber no longer have a spin exchange relaxation state.

[0039] (2) When passing through the first alkali metal gas chamber 41 and the second alkali metal gas chamber 42, the pump beams of the dual channels are directed along the y-axis and -y-axis directions, respectively, to polarize the high-temperature alkali metal atoms. After the laser interacts with the alkali metal atoms in the presence of a magnetic field, it operates at high density in a near-zero field condition. The alkali metal atoms operate in the SERF region, and the laser emission is recorded by the photodetector. When detecting the magnetic field to be measured, a modulation magnetic field with a known magnetic field strength and modulation frequency is added in the direction of the magnetic field to be measured. The intensity of the beam received by the first photodetector 43 and the second photodetector 44 is related to the transverse polarizability S along the laser direction. x Proportional. The light intensity signals of the beam received by the first photodetector 43 and the second photodetector 44 are demodulated by a lock-in amplifier at the frequency of the applied modulation magnetic field. The final signal output of the lock-in amplifier is proportional to S. x The first harmonic component S x Mod Proportional, S x ModDefined by the following formula:

[0040]

[0041] Where u is the modulation index. Ω1 represents the Larmor precession frequency of alkali metal atoms in magnetic field B1, Ω1 = γB1, where γ is the gyromagnetic ratio of the alkali metal atom. Ω0 represents the Larmor precession frequency of alkali metal atoms in the magnetic field B0 to be measured, Ω0 = γB0, ω is the frequency of the applied modulation magnetic field, Q is the slowing factor of the alkali metal atom nucleus under high polarizability conditions, and J1(u) and J1(u) are the first-order 0th-order and first-order Bessel functions of the first kind with u as a parameter, respectively. Γ represents the transverse relaxation time of the alkali metal atom, Γ represents the spin relaxation rate of the alkali metal atom, and R represents the optical pumping rate of the pump light.

[0042] 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 single-beam dual-channel atomic magnetometer system, characterized in that, The device includes a dual-channel meter head, which has a single-beam input interface. The inner cavity of the dual-channel meter head is provided with a combined polarization beam splitter, which splits the single beam into a first pump beam and a second pump beam. The first pump beam is used to pump atoms in a first alkali metal gas chamber, and the second pump beam is used to pump atoms in a second alkali metal gas chamber. The combined polarizing beam splitter includes a polarizing beam splitter. The x-axis input side of the polarizing beam splitter is connected to the single-beam input interface. A third λ / 4 waveplate is provided on the x-axis transmission side. A reflective film is provided on the outer surface of the third λ / 4 waveplate. A first λ / 4 waveplate is provided on the positive y-axis reflection side of the polarizing beam splitter, and a second λ / 4 waveplate is provided on the negative y-axis reflection side. The polarizing beam splitter splits linearly polarized light incident along the x-axis into a first vertically polarized light reflected along the positive y-axis and a horizontally polarized light transmitted along the x-axis. The first λ / 4 waveplate changes the first vertically polarized light into a first circularly polarized light that serves as the first pump beam. The horizontally polarized light is reflected back by the reflective film after passing through the third λ / 4 waveplate to form a second vertically polarized light reflected along the negative y-axis. The second λ / 4 waveplate changes the second vertically polarized light into a second circularly polarized light that serves as the second pump beam. When detecting the magnetic field to be measured, a modulated magnetic field with a known magnetic field strength and modulation frequency is added in the direction of the magnetic field to be measured. The intensity of the light beam received by the photodetector is related to the transverse polarizability S along the laser direction. x The intensity signal of the light beam received by the photodetector is directly proportional to the frequency of the applied modulation magnetic field after being demodulated by a lock-in amplifier. The final signal output of the lock-in amplifier is proportional to S. x The first harmonic component S x Mod Proportional, S x Mod Defined by the following formula: Where u is the modulation index. Ω1 represents the Larmor precession frequency of alkali metal atoms in magnetic field B1, Ω1 = γB1, where γ is the gyromagnetic ratio of the alkali metal atom; Ω0 represents the Larmor precession frequency of alkali metal atoms in the magnetic field B0 to be measured, Ω0 = γB0; ω is the frequency of the applied modulation magnetic field; Q is the slowing factor of the alkali metal atom nucleus under high polarizability conditions; J0(u) and J1(u) are the first-order 0th-order and first-order 1st-order Bessel functions of the first kind with u as a parameter, respectively. Γ' is the transverse relaxation time of the alkali metal atom, Γ' is the transverse relaxation rate, Γ is the spin relaxation rate of the alkali metal atom, and R is the optical pumping rate of the pump light.

2. The single-beam dual-channel atomic magnetometer system according to claim 1, characterized in that, The first λ / 4 waveplate is connected to the first photodetector through the first alkali metal gas chamber, and the second λ / 4 waveplate is connected to the second photodetector through the second alkali metal gas chamber. A first non-magnetic electric heating film is disposed on the outside of the first alkali metal gas chamber, and a second non-magnetic electric heating film is disposed on the outside of the second alkali metal gas chamber. Both the first and second alkali metal gas chambers are located within a three-dimensional magnetic coil. The single-beam input interface is connected to the output end of the fiber collimator, and the input end of the fiber collimator is connected to the pump laser through a polarization-maintaining fiber. The photodetector is used to convert the optical signal into an electrical signal and send it to the lock-in amplifier for demodulation.

3. The single-beam dual-channel atomic magnetometer system according to claim 2, characterized in that, The collimating lens of the fiber collimator converts the divergent polarization-maintaining beam into collimated light with a diameter equivalent to the side length of the outer diameter of the alkali metal gas chamber, and then directs it into the dual-channel meter.

4. The single-beam dual-channel atomic magnetometer system according to claim 1, characterized in that, Both the first and second alkali metal gas chambers contain alkali metal atoms and a buffer gas. The alkali metal atoms are the working atoms, which are in a spin-free exchange relaxation state during operation. The buffer gas is an inert gas used to reduce spin collisions between atoms. The outermost electrons of the alkali metal atoms are macroscopically polarized by laser pumping. Under the action of the external magnetic field B0 to be measured, the macroscopic polarization forms Larmor precession. The light intensity after passing through the atomic gas chamber will change with the magnitude of the magnetic field strength to be measured. By detecting the change in light absorption by the atomic gas chamber caused by the change in magnetic field strength, the magnetic field strength in the x-axis direction is measured.

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