A small dual-beam dual-channel atomic magnetometer system

Abstract

A small dual-beam dual-channel atomic magnetometer system is provided by arranging a first combined polarization beam splitter prism and a second combined polarization beam splitter prism in a dual-axis dual-channel meter head with a pumping beam input interface and a detection beam input interface. The first combined polarization beam splitter prism splits the pumping beam into a first pumping beam and a second pumping beam to act on a first alkali metal gas chamber and a second alkali metal gas chamber respectively. The second combined polarization beam splitter prism splits the detection beam into a first detection beam and a second detection beam to irradiate the first alkali metal gas chamber and the second alkali metal gas chamber respectively. The dual beams are used to realize pumping and detection separation, and a beam splitting module and differential detection are introduced to simultaneously obtain high-precision dual-channel magnetic field information. The system has the characteristics of high sensitivity, high integration and high detection efficiency, and is conducive to forming a high-precision and high-density magnetometer array to serve the fields of brain magnetism and heart magnetism measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetometers, and specifically relates to a dual-beam dual-channel atomic magnetometer. A first combined polarization beam splitter prism and a second combined polarization beam splitter prism are arranged in a dual-axis dual-channel meter head with a pumping beam input interface and a detection beam input interface. The first combined polarization beam splitter prism splits the pumping beam into a first pumping beam and a second pumping beam to act on a first alkali metal gas chamber and a second alkali metal gas chamber respectively. The second combined polarization beam splitter prism splits the detection beam into a first detection beam and a second detection beam to irradiate the first alkali metal gas chamber and the second alkali metal gas chamber respectively. The dual beams are used to realize pumping and detection separation, and a beam splitting module and differential detection are introduced. High-precision dual-channel magnetic field information can be obtained simultaneously. The magnetometer has the characteristics of high sensitivity, high integration and high detection efficiency, which is conducive to forming a high-precision and high-density magnetometer array to serve the fields of brain magnetism and heart magnetism measurement. Background Art

[0002] The application of magnetic field information is widely present in modern science and technology and human life. Accurate magnetic field measurement can help us better understand the world, especially high-precision weak magnetic field measurement is widely used in biological magnetic field detection, geomagnetic detection, deep space magnetic detection, magnetic anomaly detection and other fields. The ability to measure extremely weak magnetic fields depends on the technical level of magnetic sensors. Therefore, the development of ultra-high sensitivity magnetometers is closely related to the improvement of national comprehensive strength and people's life and health. With the continuous development of quantum precision measurement technology, spin-exchange relaxation free regime (SERF) atomic magnetometers have emerged, which have extremely high theoretical sensitivity. However, the magnetic field measurement sensitivity of single-beam SERF atomic magnetometers is close to the limit, which is difficult to improve significantly, and the measurement efficiency is low. Although dual-beam atomic magnetometers can improve accuracy, they will inevitably increase the volume and reduce the density of magnetometer arrays. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a dual-beam dual-channel atomic magnetometer. A first combined polarization beam splitter prism and a second combined polarization beam splitter prism are arranged in a dual-axis dual-channel meter head with a pumping beam input interface and a detection beam input interface. The first combined polarization beam splitter prism splits the pumping beam into a first pumping beam and a second pumping beam to act on a first alkali metal gas chamber and a second alkali metal gas chamber respectively. The second combined polarization beam splitter prism splits the detection beam into a first detection beam and a second detection beam to irradiate the first alkali metal gas chamber and the second alkali metal gas chamber respectively. The dual beams are used to realize pumping and detection separation, and a beam splitting module and differential detection are introduced. High-precision dual-channel magnetic field information can be obtained simultaneously. The magnetometer has the characteristics of high sensitivity, high integration and high detection efficiency, which is conducive to forming a high-precision and high-density magnetometer array to serve the fields of brain magnetism and heart magnetism measurement.

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

[0005] A dual-beam dual-channel atomic magnetometer, characterized in that it includes a dual-axis dual-channel header, the dual-axis dual-channel header has a pumping beam input interface and a detection beam input interface, the inner cavity of the dual-axis dual-channel header is provided with a first combined polarization beam splitter prism and a second combined polarization beam splitter prism, the first combined polarization beam splitter prism corresponds to the position of the pumping beam input interface, the second combined polarization beam splitter prism corresponds to the position of the detection beam input interface, the first combined polarization beam splitter prism splits the pumping beam into a first pumping beam and a second pumping beam, the first pumping beam is used to pump atoms in a first alkali metal gas chamber, the second pumping beam is used to pump atoms in a second alkali metal gas chamber, the second combined polarization beam splitter prism splits the detection beam into a first detection beam and a second detection beam, the first detection beam is used to irradiate the first alkali metal gas chamber, and the second detection beam is used to irradiate the second alkali metal gas chamber.

[0006] The second combined polarization beam splitter prism includes a fourth polarization beam splitter prism, the x-axis input side of the fourth polarization beam splitter prism is connected to the detection beam input interface, the x-axis transmission side is provided with a fourth λ / 4 wave plate, the outer surface of the fourth λ / 4 wave plate is provided with a second reflection film, the z-axis negative reflection side is provided with a first combined triangular prism, the first combined triangular prism transmits the first detection beam to the first polarization beam splitter prism through the first alkali metal gas chamber along the negative direction of the y-axis, the second combined triangular prism transmits the second detection beam to the second polarization beam splitter prism through the second alkali metal gas chamber along the negative direction of the y-axis, the z-axis positive reflection side of the fourth polarization beam splitter prism is provided with a second combined triangular prism, and the second combined triangular prism transmits the second detection beam to the second polarization beam splitter prism through the second alkali metal gas chamber along the negative direction of the y-axis.

[0007] A fifth photodetector is arranged on the negative reflection side of the z-axis of the second polarization beam splitter prism, and a sixth photodetector is arranged on the negative transmission side of the y-axis. A third photodetector is arranged on the negative reflection side of the z-axis of the first polarization beam splitter prism, and a fourth photodetector is arranged on the negative transmission side of the y-axis. The magnetic field intensity measurement in the x-axis or z-axis direction is achieved by detecting the change in the polarization direction of the detection light caused by the change in the magnetic field intensity.

[0008] The first combined polarization beam splitter prism includes a third polarization beam splitter prism, the x-axis input side of the third polarization beam splitter prism is connected to the pumping beam input interface, the x-axis transmission side is provided with a third λ / 4 wave plate, the outer surface of the third λ / 4 wave plate is provided with a first reflection film, and the z-axis negative reflection side is provided with a first λ / 4 wave plate, the polarization beam splitter prism splits the linear polarized light incident in the x-axis direction into a first vertical polarized light negatively reflected along the z-axis and a horizontal polarized light transmitted along the x-axis, the first λ / 4 wave plate changes the first vertical polarized light into a first circularly polarized light as the first pumping beam, the horizontally polarized light passes through the third λ / 4 wave plate and is reflected back by the first reflection film to form a second vertical polarized light positively reflected along the z-axis, and the second λ / 4 wave plate changes the second vertical polarized light into a second circularly polarized light as the second pumping beam.

[0009] A first photodetector is provided on the negative side of the z-axis of the first alkali metal gas chamber, and a second photodetector is provided on the positive side of the z-axis of the second alkali metal gas chamber. The first photodetector and the second photodetector are both used to detect the absorption change of the pumping light signal to obtain the polarization degree of the alkali metal atoms.

[0010] The first combined triangular prism and the second combined triangular prism each include a triangular prism, and a polarizing plate is bonded to a negative side of the y-axis of the triangular prism.

[0011] A first non-magnetic electric heater and a first three-dimensional magnetic coil structure are installed outside the first alkali metal gas chamber, and a second non-magnetic electric heater and a second three-dimensional magnetic coil structure are installed outside the second alkali metal gas chamber.

[0012] The pumping beam input interface is connected to a first fiber collimator, which is connected to a pumping laser via a first polarization-maintaining fiber. The detection beam input interface is connected to a second fiber collimator, which is connected to a detection laser via a second polarization-maintaining fiber.

[0013] The magnitude of the magnetic field in the x-axis direction is related to the electron polarization rate P in the y-axis direction of the magnetometer. y Related:

[0014]

[0015] Where P0 is the steady-state polarizability of the electron spin in the z-axis direction, R p is the optical pumping efficiency of the pumping beam on the alkali metal electrons in the z-axis direction, R rel is the relaxation rate of alkali metal electrons, β x , β y , β z are the equivalent vector magnetic fields in the x, y, and z directions, β x =γ e B x / (R p +R rel ), β y =γ e B y / (R p +R rel ), β z =γ e B z / (R p +R rel ), γ e is the electron gyromagnetic ratio, B x , B y , B z They are the environmental magnetic field strengths to be measured in the x, y and z directions respectively.

[0016] The magnitude of the magnetic field in the x-axis direction is related to the electron polarization rate P in the y-axis direction of the magnetometer. y Related:

[0017]

[0018] This formula shows that P y The magnetic field B to be measured in the x-axis direction x The magnetic field strength to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.

[0019] The technical effects of the present invention are as follows: The present invention is a dual-beam dual-channel atomic magnetometer, including a pumping laser, a detection laser, a collimation module, and a dual-axis dual-channel header. The dual-axis dual-channel header includes an alkali metal gas chamber, non-magnetic electric heating, a three-dimensional magnetic coil, a beam splitting module, and a differential detection module. Among them, the collimation module is composed of two polarization-maintaining optical fibers with optical fiber collimators at the tail, so that the light emitted by the pumping laser and the detection laser is collimated and focused into a specific spot size and injected into the dual-axis dual-channel meter head; there are alkali metal atoms in the alkali metal gas chamber; non-magnetic electric heating and three-dimensional magnetic coils make the alkali metal atoms work in a high temperature and low magnetic field environment to ensure their efficient pumping; the beam splitting module is composed of a combined polarization beam splitter prism, a combined beam splitter prism, and a combined triangular prism, so that the pumping light and the detection light are split; the differential detection module is composed of a polarization beam splitter prism and a photoelectric detector; the pumping laser is used to polarize the alkali metal atoms, and the pumping light collimated by the collimation module passes through the beam splitting module to generate two independent pumping lasers and are injected into the alkali metal gas chamber to polarize the alkali metal atoms; the detection laser is used to sense the magnetic field intensity in the axial direction of the atomic magnetometer, and the detection light collimated by the collimation module passes through the beam splitting module to generate two independent and reverse detection lasers and are simultaneously injected into the alkali metal gas chamber to detect the magnetic field intensity of the two channels, and the measurement result is demodulated by the phase-locked amplifier through the differential detection method. The present invention utilizes dual-beam differential detection to obtain high precision, and adds a beam splitting module to simultaneously obtain the magnetic field information of two channels and two axes. It has the characteristics of high sensitivity, high integration, and high detection efficiency, and has broad application prospects in the fields of brain magnetism and heart magnetism measurement.

[0020] The advantages of the present invention compared with the prior art are: the present invention uses light of different wavelengths as pumping light and detection light, introduces a differential detection method, and has high magnetic field measurement sensitivity and stability; and introduces a beam splitting system to drive a dual gas chamber, which can simultaneously obtain a dual-channel vector magnetic field signal, improve measurement efficiency and integration, and is conducive to forming a magnetometer array, and has broad application prospects in the fields of brain magnetism, heart magnetism measurement, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic diagram of the structure of a small dual-beam dual-channel atomic magnetometer system.

[0022] Figure 2 yes Figure 1 Schematic diagram of the structure of the dual-axis dual-channel meter head.

[0023] Figure 3 yes Figure 2 Schematic diagram of the structure of the combined beam splitter prism. Figure 3 The left side in the middle is the first combined beam splitter prism, and the right side is the second combined beam splitter prism.

[0024] The reference numerals are listed as follows: 1-pumping laser; 2-detection laser; 3-first polarization-maintaining fiber; 4-second polarization-maintaining fiber; 5-first fiber collimator; 6-second fiber collimator; 7-dual-axis dual-channel meter; 700-first combined polarization beam splitter prism; 701-first alkali metal gas chamber; 702-second alkali metal gas chamber; 703-first photodetector; 704-second photodetector; 705-second combined polarization beam splitter prism; 706-first combined triangular prism; 707-second combined triangular prism; 708-first polarization beam splitter prism; 709-second polarization beam splitter prism; 710- The third photodetector; 711-the fourth photodetector; 712-the fifth photodetector; 713-the sixth photodetector; 715-the first non-magnetic electric heater; 716-the first three-dimensional magnetic coil structure; 717-the second non-magnetic electric heater; 718-the second three-dimensional magnetic coil structure; 7001-the third polarization beam splitter prism; 7002-the first λ / 4 wave plate; 7003-the second λ / 4 wave plate; 7004-the third λ / 4 wave plate; 7005-the first reflection film; 7051-the fourth polarization beam splitter prism; 7052-the fourth λ / 4 wave plate; 7053-the second reflection film (or the second reflection mirror). DETAILED DESCRIPTION

[0025] Below is the attached figure ( Figure 1-Figure 3 ) and Examples illustrate the present invention.

[0026] Figure 1 The present invention is a schematic diagram of the structure of a small dual-beam dual-channel atomic magnetometer system. Figure 2 yes Figure 1 Schematic diagram of the structure of the dual-axis dual-channel meter head. Figure 3 yes Figure 2 Schematic diagram of the structure of the combined beam splitter prism. Figures 1 to 3As shown, a dual-beam dual-channel atomic magnetometer includes a dual-axis dual-channel header 7, wherein the dual-axis dual-channel header 7 has a pumping beam input interface and a detection beam input interface, and the inner cavity of the dual-axis dual-channel header is provided with a first combined polarization beam splitter prism 700 and a second combined polarization beam splitter prism 705, wherein the first combined polarization beam splitter prism 700 corresponds to the position of the pumping beam input interface, and the second combined polarization beam splitter prism 705 corresponds to the position of the detection beam input interface, and the first combined polarization beam splitter prism 700 splits the pumping beam into a first pumping beam and a second pumping beam, wherein the first pumping beam is used to pump atoms in a first alkali metal gas chamber 701, and the second pumping beam is used to pump atoms in a second alkali metal gas chamber 702, and the second combined polarization beam splitter prism 705 splits the detection beam into a first detection beam and a second detection beam, wherein the first detection beam is used to irradiate the first alkali metal gas chamber 701, and the second detection beam is used to irradiate the second alkali metal gas chamber 702.

[0027] The second combined polarization beam splitter prism 705 includes a fourth polarization beam splitter prism 7051, the x-axis input side of the fourth polarization beam splitter prism 7051 is connected to the detection beam input interface, the x-axis transmission side is provided with a fourth λ / 4 wave plate 7052, the outer surface of the fourth λ / 4 wave plate 7052 is provided with a second reflection film 7053, the z-axis negative reflection side is provided with a first combined triangular prism 706, the first combined triangular prism 706 transmits the first detection beam through the first alkali metal gas chamber 701 to the first polarization beam splitter prism 708 along the negative direction of the y-axis, the second combined triangular prism 707 is provided on the z-axis positive reflection side of the fourth polarization beam splitter prism 7051, and the second combined triangular prism 707 transmits the second detection beam through the second alkali metal gas chamber 702 to the second polarization beam splitter prism 709 along the negative direction of the y-axis. A fifth photodetector 712 is provided on the negative reflection side of the z-axis of the second polarization beam splitter prism 709, and a sixth photodetector 713 is provided on the negative transmission side of the y-axis. A third photodetector 710 is provided on the negative reflection side of the z-axis of the first polarization beam splitter prism 708, and a fourth photodetector 711 is provided on the negative transmission side of the y-axis. The magnetic field intensity measurement in the x-axis or z-axis direction is achieved by detecting the change in the polarization direction of the detection light caused by the change in the magnetic field intensity.

[0028] The first combined polarization beam splitter prism 700 includes a third polarization beam splitter prism 7001, the x-axis input side of the third polarization beam splitter prism 7001 is connected to the pumping beam input interface, the x-axis transmission side is provided with a third λ / 4 wave plate 7004, the outer surface of the third λ / 4 wave plate 7004 is provided with a first reflection film 7005, and the z-axis negative reflection side is provided with a first λ / 4 wave plate 7002, the polarization beam splitter prism 7001 splits the linear polarized light incident in the x-axis direction into a first vertical polarized light negatively reflected along the z-axis and a horizontal polarized light transmitted along the x-axis, the first λ / 4 wave plate 7002 changes the first vertical polarized light into a first circularly polarized light serving as the first pumping beam, the horizontally polarized light passes through the third λ / 4 wave plate 7004 and is then reflected back by the first reflection film 7005 to form a second vertical polarized light positively reflected along the z-axis, and the second λ / 4 wave plate 7003 changes the second vertical polarized light into a second circularly polarized light serving as the second pumping beam.

[0029] A first photodetector 703 is provided on the negative side of the z-axis of the first alkali metal gas chamber 701, and a second photodetector 704 is provided on the positive side of the z-axis of the second alkali metal gas chamber 702. The first photodetector 703 and the second photodetector 704 are both used to detect the absorption change of the pumping light signal to obtain the polarization degree of the alkali metal atom. The first combined triangular prism 706 and the second combined triangular prism 707 both include triangular prisms, and a polarizer is bonded to the negative side of the y-axis of the triangular prism. A first non-magnetic electric heater 715 and a first three-dimensional magnetic coil structure 716 are installed on the outside of the first alkali metal gas chamber 701, and a second non-magnetic electric heater 717 and a second three-dimensional magnetic coil structure 718 are installed on the outside of the second alkali metal gas chamber 702. The pumping beam input interface is connected to the first fiber collimator 5, and the first fiber collimator 5 is connected to the pumping laser 1 through the first polarization-maintaining fiber 3. The detection beam input interface is connected to the second fiber collimator 6, and the second fiber collimator 6 is connected to the detection laser 2 through the second polarization-maintaining fiber 4.

[0030] The magnitude of the magnetic field in the x-axis direction is related to the electron polarization rate P in the y-axis direction of the magnetometer. y Related:

[0031]

[0032] Where P0 is the steady-state polarizability of the electron spin in the z-axis direction, R p is the optical pumping efficiency of the pumping beam on the alkali metal electrons in the z-axis direction, R rel is the relaxation rate of alkali metal electrons, β x , β y , β zare the equivalent vector magnetic fields in the x, y, and z directions, β x =γ e B x / (R p +R rel ), β y =γ e B y / (R p +R rel ), β z =γ e B z / (R p +R rel ), γ e is the electron gyromagnetic ratio, B x , B y , B z They are the environmental magnetic field strengths to be measured in the x, y and z directions respectively.

[0033] The magnitude of the magnetic field in the x-axis direction is related to the electron polarization rate P in the y-axis direction of the magnetometer. y Related:

[0034]

[0035] This formula shows that P y The magnetic field B to be measured in the x-axis direction x The magnetic field strength to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.

[0036] A small dual-beam dual-channel atomic magnetometer system, the system is composed of a pumping laser 1, a detection laser 2, a first polarization-maintaining optical fiber 3, a second polarization-maintaining optical fiber 4, a first collimator 5, a second collimator 6, and a dual-axis dual-channel meter head 7; wherein the dual-axis dual-channel meter head 7 includes a first combined polarization beam splitter prism 700, a first alkali metal gas chamber 701, a second alkali metal gas chamber 702, a first photodetector 703, a second photodetector 704, a second combined polarization beam splitter prism 705, a first combined triangular prism 706, a second combined triangular prism 707, a first polarization beam splitter prism 708, a second polarization beam splitter prism 709, a third photodetector 710, and a fourth photodetector 711. The electric detector 711, the fifth photodetector 712, the sixth photodetector 713, the first non-magnetic electric heater 715, the first three-dimensional magnetic coil structure 716, the second non-magnetic electric heater 717 and the second three-dimensional magnetic coil structure 718; the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are symmetrically installed on both sides of the dual-axis dual-channel meter head 7, and the middle is the first combined polarization splitter prism 700, whose external structures are the first non-magnetic electric heater 715, the first three-dimensional magnetic coil structure 716 and the second non-magnetic electric heater 717, and the second three-dimensional magnetic coil structure 718, respectively. The gas chamber heating is achieved by the non-magnetic electric heating, and the magnetic compensation is achieved by the three-dimensional magnetic coil; the pumping light is pumped by the pumping pump. Light 1 enters the dual-axis dual-channel header 7 through the first polarization-maintaining optical fiber 3 and the first collimator 5, and is split into a first pumping beam and a second pumping beam after passing through the first combined polarization beam splitter prism 700 in the dual-axis dual-channel header 7, and is respectively incident on the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702. The light passing through the alkali metal gas chamber is received by the first photodetector 703 and the second photodetector 704. The detection light enters the dual-axis dual-channel header 7 through the second polarization-maintaining optical fiber 4 and the second collimator 6 from the detection laser 2, and is split into a first detection beam and a second detection beam by the second combined polarization beam splitter prism 705 in the dual-axis dual-channel header 7. The first detection beam passes through the first group After the combined triangular prism 706, the first alkali metal gas chamber 701 and the first polarization beam splitter prism 708, the light beam is split into the third photodetector 710 and the fourth photodetector 711. The second detection light beam passes through the second combined triangular prism 707, the second alkali metal gas chamber 702 and the second polarization beam splitter prism 709 in sequence and then is split into the fifth photodetector 712 and the sixth photodetector 713. The light signal entering the photodetector is converted into an electrical signal and transmitted to the phase-locked amplifier for demodulation, so as to obtain the vector magnetic field intensity sensed by the atoms in the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702. Finally, the magnetic field intensity data obtained by demodulation is processed and displayed in the signal processor.

[0037] The first pumping light beam and the second pumping light beam generated by the first combined polarization beam splitting prism 700 are left-handed circularly polarized lights with opposite propagation directions. The two pumping light beams are respectively injected into the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 along the -z axis and the z axis directions, and the emitted light beams are finally received by the first photodetector 703 and the second photodetector 704; wherein the first combined polarization beam splitting prism 700 is composed of a polarization beam splitting prism 7001, a first λ / 4 wave plate 7002, a second λ / 4 wave plate 7003, and a third λ / 4 wave plate 7004. / 4 wave plate 7004, and a first reflective film 7005, and along the z-axis are the first λ / 4 wave plate 7002, the polarization beam splitter prism 7001, and the second λ / 4 wave plate 7003, the λ / 4 wave plate is bonded to the surface of the polarization beam splitter prism 7001, and the surface of the polarization beam splitter prism 7001 along the x-axis direction is bonded to the third λ / 4 wave plate 7004 and the first reflective film 7005; the pumping beam optical signal received by the photodetector is used to obtain the polarization efficiency of the alkali metal atoms in the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702.

[0038] The first detection light beam and the second detection light beam generated by the beam splitting after passing through the second combined polarization beam splitter prism 705 are linear polarized lights with opposite propagation directions. The propagation directions and polarization states of the two detection light beams are changed by the first combined triangular prism 706 and the second combined triangular prism 707. The two detection light beams emitted from the combined triangular prism pass through the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 along the -y axis direction, respectively, and pass through the first polarization beam splitter prism 708 and the second polarization beam splitter prism 709 in sequence, and enter the third photodetector 710, the fourth photodetector 711, the fifth photodetector 712, and the sixth photodetector 713; wherein the second combined polarization beam splitter prism 705 is composed of a polarization beam splitter prism 7051, a fourth λ / 4 wave plate 7052, and a second reflective film 7053, and the fourth λ / 4 wave plate 7052 and the second reflective film 7053 are bonded to the outer surface of the polarization beam splitter prism 7051 along the x-axis.

[0039] The first detection light beam and the second detection light beam are both linearly polarized lasers. The detection light detects changes in the polarization direction of the detection light caused by changes in the magnetic field intensity. The first polarization beam splitter prism 708, the third photodetector 710, the fourth photodetector 711, the second polarization beam splitter prism 709, the fifth photodetector 712, and the sixth photodetector 713 respectively differentiate the two-channel detection light, and a part of the noise is filtered out by the differential method. The optical signal received by the photodetector is converted into an electrical signal and demodulated by a phase-locked amplifier to measure the magnetic field intensity in the x-axis direction and the z-axis direction, thereby improving the detection sensitivity.

[0040] The first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 have the same parameters and contain alkali metal atoms and buffer gas.

[0041] The first photodetector 703 , the second photodetector 704 , the third photodetector 710 , the fourth photodetector 711 , the fifth photodetector 712 , and the sixth photodetector 713 are of the same model.

[0042] The first combined triangular prism 706 and the second combined triangular prism 707 have the same structural parameters, and both are triangular prisms with polarizers bonded to the surface along the -y axis.

[0043] The first polarization beam splitter prism 708 and the second polarization beam splitter prism 709 are of the same model.

[0044] The pumping laser 1 and the detection laser 2 can output sufficient power to facilitate the simultaneous driving of multiple probes in the later stage.

[0045] The first pumping beam and the second pumping beam propagate along the -y and y axis directions respectively, and the first detection beam and the second detection beam propagate along the -z axis direction. The pumping beam and the detection beam propagate perpendicularly and intersect at the center of the corresponding alkali metal gas chamber. The first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are filled with alkali metal atoms and buffer gas. The alkali metal atoms are working atoms, generally alkali metal elements such as K, Rb, Cs, etc., and are in a spin-free exchange relaxation state when working; the buffer gas is an inert gas used to reduce spin collisions between atoms.

[0046] The principle of a high-precision miniaturized dual-channel atomic magnetometer system for vector magnetic field detection is:

[0047] 1. Start the first non-magnetic electric heating 715, the first three-dimensional magnetic coil structure 716 and the second non-magnetic electric heating 717, the second three-dimensional magnetic coil structure 718, and heat the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 to the set temperature respectively, and then control the current of the three-dimensional magnetic coil, adjust the magnetic field generated by the three-dimensional magnetic coil, so that the residual magnetic field in the x-axis, y-axis and z-axis directions in the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 is compensated to zero to avoid the influence of the external residual magnetic field on the measurement result. At this time, the alkali metal atoms in the alkali metal gas chamber work in a spin-exchange relaxation state.

[0048] 2. When passing through the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702, the dual-channel pumping beams are respectively along the -z axis and the z axis directions, which are used to polarize the high-temperature alkali metal atoms; the dual-channel detection beams are both along the -y axis and the y axis directions, which are used to detect the magnitude of the magnetic field in the x-axis direction, which is related to the electron polarization rate P in the y-axis direction of the magnetometer. y Related:

[0049]

[0050] Where P0 is the steady-state polarizability of the electron spin in the z-axis direction, R p is the optical pumping efficiency of the pumping beam on the alkali metal electrons in the z-axis direction, R rel is the relaxation rate of alkali metal electrons, β x , β y , β z are the equivalent vector magnetic fields in the x, y, and z directions, β x =γ e B x / (R p +R rel ), β y =γ e B y / (R p +R rel ), β z =γ e B z / (R p +R rel ), γ e is the electron gyromagnetic ratio, B x , B y , B z They are the environmental magnetic field strengths to be measured in the x, y and z directions respectively.

[0051] Since the alkali metal atoms are in a state of no spin exchange relaxation, the ambient magnetic field B x , B y , B z Generally in the nanometer scale, that is, |β x |<<1,|β y |<<1,|β z |<<1, ignoring the second-order small quantities, the transverse polarizability of electrons in the y-axis direction can be simplified to:

[0052]

[0053] This formula shows that P y The magnetic field B to be measured in the x-axis direction x The magnetic field strength to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.

[0054] The present invention provides a small dual-beam dual-channel atomic magnetometer system, such as Figure 1 As shown, it is mainly composed of pumping laser 1, detection laser 2, first polarization-maintaining fiber 3, second polarization-maintaining fiber 4, first collimator 5, second collimator 6, and dual-axis dual-channel header 7. The pumping laser provides a polarized alkali metal atom light source, and the detection laser provides a light source for detecting magnetic field changes. The pumping laser and the detection laser are transmitted through the corresponding polarization-maintaining fiber and collimator respectively, and the light that is collimated and expanded to the required size enters the dual-axis dual-channel header 7.

[0055] like Figure 2 As shown, the dual-axis dual-channel probe 7 includes a first combined polarization beam splitter prism 700, a first alkali metal gas chamber 701, a second alkali metal gas chamber 702, a first photodetector 703, a second photodetector 704, a second combined polarization beam splitter prism 705, a first combined triangular prism 706, a second combined triangular prism 707, a first polarization beam splitter prism 708, a second polarization beam splitter prism 709, a third photodetector 710, a fourth photodetector 711, a fifth photodetector 712, a sixth photodetector 713, a first non-magnetic electric heater 715, a first three-dimensional magnetic coil structure 716, a second non-magnetic electric heater 717, and a second three-dimensional magnetic coil structure 718.

[0056] like Figure 2 As shown, the pumping light entering the dual-axis dual-channel probe 7 is divided into two circularly polarized pumping lights after passing through the first combined polarization beam splitter prism 700, one beam entering the first alkali metal gas chamber 701, and the other beam entering the second alkali metal gas chamber 702, thereby achieving pumping of atoms.

[0057] like Figure 3 As shown, the first combined polarization beam splitter prism 700 is composed of a third polarization beam splitter prism 7001, a first λ / 4 wave plate 7002, a second λ / 4 wave plate 7003, a third λ / 4 wave plate 7004, and a first reflective film 7005. The x-axis outer surface of the third polarization beam splitter prism 7001 is plated with the first reflective film 7005, and the first λ / 4 wave plate 7002 and the second λ / 4 wave plate 7003 are symmetrically bonded to the two x-axis outer surfaces. The long axis of the λ / 4 wave plate is 45° with the vertical polarization. The light emitted through the first combined polarization beam splitter prism 700 is circularly polarized light, and enters the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 in the -z axis and z axis directions respectively. After transmission, it is received by the first photodetector 703 and the second photodetector 704. The light signal entering the photodetector is converted into an electrical signal, and the polarization degree of the alkali metal atom is obtained by detecting the absorption change.

[0058] like Figure 2 , 3 As shown, the detection light entering the dual-axis dual-channel probe 7 is divided into two beams of linearly polarized detection light after passing through the second combined polarization beam splitter prism 705. The second combined polarization beam splitter prism 705 is composed of a fourth polarization beam splitter prism 7051, a fourth λ / 4 wave plate 7052, and a second reflective film 7053. The fourth λ / 4 wave plate 7052 and the second reflective film 7053 are bonded to the x-axis outer surface of the fourth polarization beam splitter prism 7051. The long axis of the λ / 4 wave plate is 45° with the vertical polarization, and the two outgoing detection lights are both vertically polarized.

[0059] like Figure 2As shown, two beams of vertical polarized detection light are respectively changed in propagation direction and polarization state through a combined triangular prism. A polarizer is bonded to the y-axis surface of the combined triangular prism to generate the required linear polarized detection light. The light emitted from the combined triangular prism enters the alkali metal gas chamber. The light of the two channels passing through the alkali metal gas chamber is respectively split by the first polarization beam splitter prism 708 and the second polarization beam splitter prism 709 and enters the corresponding photoelectric detector. By detecting the change in the polarization direction of the detection light caused by the change in magnetic field intensity, the magnetic field intensity measurement in the z-axis direction is achieved. The change in the polarization direction of the detection light will cause the change in the polarization component of the light. The change in the optical signal after the splitting by the first polarization beam splitter prism 708 and the second polarization beam splitter prism 709 can be measured to obtain the change in the polarization direction of the detection light. After passing through the photoelectric detector, the optical signal is converted into an electrical signal and transmitted to the phase-locked amplifier for modulation and demodulation. The demodulated magnetic field intensity data is processed and displayed in the signal processor after differential.

[0060] The first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are filled with alkali metal atoms and buffer gas. The alkali metal atoms are working atoms, generally alkali metal elements such as K, Rb, Cs, etc., and work at high temperatures. The temperature varies depending on the different alkali metal elements, and is generally greater than 100°C. When working, the alkali metal atoms are in a spin-free exchange relaxation state; the buffer gas is an inert gas used to reduce spin collisions between atoms.

[0061] The working temperature is achieved by non-magnetic electric heating. The first non-magnetic electric heating 715 and the second non-magnetic electric heating 717 are started to heat the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 to the set temperature. The current of the three-dimensional magnetic coil is controlled and the magnetic field generated by the first three-dimensional magnetic coil structure 716 and the second three-dimensional magnetic coil structure 718 is adjusted to compensate the residual magnetic fields in the x-axis, y-axis and z-axis directions in the two-channel alkali metal gas chambers to zero, thereby avoiding the influence of the external residual magnetic field on the measurement results.

[0062] When passing through the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702, the dual-channel pumping beams are respectively along the -z axis and the z axis directions, which are used to polarize the high-temperature alkali metal atoms; the dual-channel detection beams are both along the -y axis direction, which are used to detect the magnitude of the magnetic field in the x-axis direction, which is related to the electron polarization rate P in the y-axis direction of the magnetometer. y Related.

[0063] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. It is pointed out here that the above description helps those skilled in the art to understand the invention, but does not limit the protection scope of the invention. Any equivalent replacement, modification and / or simplification of the above description without departing from the essence of the invention falls within the protection scope of the invention.

Claims

1. A dual-beam dual-channel atomic magnetometer, characterized in that: The invention comprises a dual-axis dual-channel meter head, wherein the dual-axis dual-channel meter head has a pumping beam input interface and a detection beam input interface, wherein an inner cavity of the dual-axis dual-channel meter head is provided with a first combined polarization beam splitter prism and a second combined polarization beam splitter prism, wherein the first combined polarization beam splitter prism corresponds to the position of the pumping beam input interface, and the second combined polarization beam splitter prism corresponds to the position of the detection beam input interface, wherein the first combined polarization beam splitter prism splits the pumping beam into a first pumping beam and a second pumping beam, wherein the first pumping beam is used to pump atoms in a first alkali metal gas cell, and the second pumping beam is used to pump atoms in a second alkali metal gas cell, and the second combined polarization beam splitter prism splits the detection beam into a first detection beam and a second detection beam, wherein the first detection beam is used to irradiate the first alkali metal gas cell, and the second detection beam is used to irradiate the second alkali metal gas cell; The second combined polarization beam splitter prism comprises a fourth polarization beam splitter prism, the input side of the fourth polarization beam splitter prism in the x-axis direction is connected to the detection beam input interface, a fourth λ / 4 wave plate is arranged on the transmission side in the x-axis direction, a second reflection film is arranged on the outer surface of the fourth λ / 4 wave plate, a first combined triangular prism is arranged on the negative reflection side in the z-axis direction, the first combined triangular prism transmits the first detection beam to the first polarization beam splitter prism through the first alkali metal gas chamber along the negative direction of the y-axis, a second combined triangular prism is arranged on the positive reflection side in the z-axis direction of the fourth polarization beam splitter prism, and the second combined triangular prism transmits the second detection beam to the second polarization beam splitter prism through the second alkali metal gas chamber along the negative direction of the y-axis; The first combined polarization beam splitter prism is composed of a third polarization beam splitter prism, a first λ / 4 wave plate, a second λ / 4 wave plate, a third λ / 4 wave plate, and a first reflection film, and the first λ / 4 wave plate, the third polarization beam splitter prism, and the second λ / 4 wave plate are arranged in sequence along the z-axis. The x-axis input side of the third polarization beam splitter prism is connected to the pumping beam input interface, the x-axis transmission side is provided with a third λ / 4 wave plate, the outer surface of the third λ / 4 wave plate is provided with a first reflection film, the z-axis negative reflection side is provided with the first λ / 4 wave plate, and the polarization beam splitter prism is provided with a first λ / 4 wave plate. The beam splitter prism splits the linear polarized light incident along the x-axis into a first vertical polarized light negatively reflected along the z-axis and a horizontal polarized light transmitted along the x-axis, the first λ / 4 wave plate changes the first vertical polarized light into a first circular polarized light as the first pumping beam, the horizontal polarized light passes through the third λ / 4 wave plate and is then reflected back by the first reflective film to form a second vertical polarized light positively reflected along the z-axis, and the second λ / 4 wave plate changes the second vertical polarized light into a second circular polarized light as the second pumping beam; The magnitude of the magnetic field in the x-axis direction is related to the electron polarization R in the y-axis direction of the magnetometer. y Related: Where P0 is the steady-state polarizability of the electron spin in the z-axis direction, R p is the optical pumping efficiency of the pumping beam on the alkali metal electrons in the z-axis direction, R rel is the relaxation rate of alkali metal electrons, β x , β y , β z are the equivalent vector magnetic fields in the x, y, and z directions, β x =γ e B x / (R p +R rel ), β y =γ e B y / (R p +R rel ), β z =γ e B z / (R p +R rel ), γ e is the electron gyromagnetic ratio, B x , B y , B z They are the environmental magnetic field strength to be measured in the x, y and z directions respectively; This formula shows that P y The magnetic field B to be measured in the x-axis direction x The magnetic field strength to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.

2. The dual-beam dual-channel atomic magnetometer according to claim 1, characterized in that: A fifth photodetector is arranged on the negative reflection side of the z-axis of the second polarization beam splitter prism, and a sixth photodetector is arranged on the negative transmission side of the y-axis. A third photodetector is arranged on the negative reflection side of the z-axis of the first polarization beam splitter prism, and a fourth photodetector is arranged on the negative transmission side of the y-axis. The magnetic field intensity measurement in the x-axis or z-axis direction is achieved by detecting the change in the polarization direction of the detection light caused by the change in the magnetic field intensity.

3. The dual-beam dual-channel atomic magnetometer according to claim 1, characterized in that: A first photodetector is provided on the negative side of the z-axis of the first alkali metal gas chamber, and a second photodetector is provided on the positive side of the z-axis of the second alkali metal gas chamber. The first photodetector and the second photodetector are both used to detect the absorption change of the pumping light signal to obtain the polarization degree of the alkali metal atoms.

4. The dual-beam dual-channel atomic magnetometer according to claim 1, characterized in that: The first combined triangular prism and the second combined triangular prism each include a triangular prism, and a polarizing plate is bonded to a negative side of the y-axis of the triangular prism.

5. The dual-beam dual-channel atomic magnetometer according to claim 1, characterized in that: A first non-magnetic electric heater and a first three-dimensional magnetic coil structure are installed outside the first alkali metal gas chamber, and a second non-magnetic electric heater and a second three-dimensional magnetic coil structure are installed outside the second alkali metal gas chamber.

6. The dual-beam dual-channel atomic magnetometer according to claim 1, characterized in that: The pumping beam input interface is connected to a first fiber collimator, which is connected to a pumping laser via a first polarization-maintaining fiber. The detection beam input interface is connected to a second fiber collimator, which is connected to a detection laser via a second polarization-maintaining fiber.

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