Miniaturized hot atom vector magnetometer based on S-wave plate

Abstract

The invention discloses a miniaturized hot atom vector magnetometer based on an S wave plate. According to the invention, radial polarized light with a space polarization structure can be rapidly and stably generated by using the miniature S-wave polarization conversion sheet. Meanwhile, in a constant magnetic field, a single beam of radial polarized light is used for pumping a hot atom ensemble, the polarization selective absorption effect and the optical magnetic resonance effect of polarized hot atoms on the radial polarized light are detected, magnetic field direction and intensity information is obtained, and the optical path structure is very simple. According to the invention, the high-precision charge coupler sensing chip is integrated to accurately acquire the transmission light intensity distribution pattern, and the transmission light intensity distribution pattern with the magnetic field direction information is spatially distinguished and detected, so that the accurate detection of the magnetic field vector direction is realized. In order to obtain magnetic field intensity information at the same time, a high-sensitivity photoelectric detector chip is integrated, and the interaction process of radial polarized light and polarized atoms is utilized to collect optical magnetic resonance signals so as to realize accurate detection of the magnetic field intensity.

Description

Technical Field

[0001] The present invention belongs to the technical field of atomic vector magnetometers, and in particular relates to a miniaturized thermal atomic vector magnetometer based on an S-wave plate, which can be used to detect the three-dimensional vector direction information of a magnetic field and detect the magnetic field strength. Background Art

[0002] A vector polarized light beam has a spatially varying non-uniform polarization distribution in a transverse plane perpendicular to the propagation direction, and the polarization structure has rich controllability. This unique polarization structure has attracted extensive academic interest. In the past, most studies on the light-atom interaction have been oriented towards scalar polarized light, but in fact this is a vector process that depends on the external magnetic field direction and the light polarization direction, and the polarization state of the atom is closely related to the magnetic field direction.

[0003] Most atomic magnetometers based on atomic vapor can accurately measure the magnetic field strength in combination with scalar light beams, but they cannot simultaneously obtain the vector direction of the magnetic field. The accurate measurement of the magnetic field direction is also of great value in various research and production activities. In recent years, a scheme for a single-beam three-axis atomic magnetometer has been proposed. This scheme generates a rotating magnetic field in the X-Y plane and applies a modulated magnetic field along the Z axis, and realizes the synchronous measurement of the three-axis magnetic field components in combination with a lock-in amplifier. However, this scheme is highly dependent on the precise control of the magnetic field and has a high technical difficulty. Another magnetometer based on the ground-state Hanle resonance uses four laser beams to pump and detect the cesium atom spin, and can measure the vector directions of the magnetic field components in two orthogonal directions. This scheme adopts a multi-beam design, which increases the complexity of the system and has poor stability. The vector atomic magnetometer scheme based on the electromagnetically induced transparency effect uses two coherent light fields to excite the energy level transition of the rubidium atom Λ structure, and obtains the direction angle of the magnetic field to realize the measurement of the magnetic field vector by measuring the transmission intensity and relative position of the electromagnetically induced transparency resonance peak. However, the measurement result is susceptible to environmental noise and requires high-precision experimental conditions. The structures of the above magnetic field measurement schemes are relatively complex, have high conditions requirements, and cannot simultaneously obtain the magnetic field strength and vector direction information. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a miniaturized thermal atomic vector magnetometer based on an S-waveplate. This miniaturized magnetometer uses a micro S-waveplate polarization conversion sheet, i.e., an S-waveplate, to quickly and stably generate a radially polarized light beam with a spatial polarization structure. Under a constant magnetic field, the magnetometer pumps a thermal atomic ensemble using a single beam of radially polarized light and detects the polarization selective absorption effect and optical magnetic resonance effect of polarized hot atoms on the radially polarized light. The optical path structure is very simple. The present invention integrates a high-precision charge-coupled device sensing chip (CCD) to accurately collect the transmission light intensity distribution pattern, and realizes the precise detection of the magnetic field vector direction by spatially resolving and detecting the transmission light intensity distribution pattern with magnetic field direction information. To obtain the magnetic field strength information simultaneously, this magnetometer integrates a high-sensitivity photodetector chip (PD), and uses the interaction process between the radially polarized light and the polarized atoms to collect the optical magnetic resonance signal to achieve the precise detection of the magnetic field strength.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A miniaturized thermal atomic vector magnetometer based on an S-waveplate, comprising a light source part, an optical path part, an atomic gas cell part, a magnetic field part, and an optical imaging detection part;

[0006] The laser frequency of the VCSEL laser selected for the light source part is tuned to the transition frequency of the atomic medium;

[0007] The optical path part generates radially polarized light by passing the light emitted by the VCSEL laser through a micro S-waveplate polarization conversion sheet and incident on the atomic gas cell, pumps and polarizes the atoms in the atomic gas cell and conducts magnetic field detection;

[0008] The magnetic field part includes two sets of orthogonal Helmholtz coils, a set of solenoid coils, and a set of radio frequency coils; the two sets of orthogonal Helmholtz coils are used to generate transverse magnetic fields along the X and Y axes respectively, a set of solenoid coils is used to generate a longitudinal magnetic field along the Z axis of the light propagation direction, and a set of radio frequency coils is used to generate a radio frequency magnetic field along the Y axis;

[0009] The atomic gas cell part includes an atomic gas cell located at the center of the Helmholtz coils;

[0010] The optical imaging detection part uses a high-precision charge-coupled device sensing chip to photograph the transverse light intensity distribution of the radially polarized light transmitted through the atomic gas cell, and obtains the three-dimensional magnetic field vector information by detecting the spatial light intensity absorption response of the polarized atoms to the radially polarized light; a high-sensitivity photodetector chip is used to collect the optical magnetic resonance signal to achieve magnetic field strength detection by using the interaction process between the radially polarized light and the polarized atoms.

[0011] Further, the light source part includes a VCSEL laser; the frequency of the VCSEL laser is locked at 6 of the D1 line of Cs 2 S 1 / 2 , F = 4 → 6 2 P 1 / 2 , on the F = 3 transition, with a wavelength of 894 nm and the optical power set at 60 μW.

[0012] Further, the optical path part includes a half-wave plate, a micro S-waveplate polarization conversion sheet, a beam splitting prism, and a mirror; the laser passes through the half-wave plate and the micro S-waveplate polarization conversion sheet to generate radially polarized light with a topological charge number L = 1; the radially polarized light is split into two beams by the beam splitting prism after passing through the atomic gas cell, one beam of light is incident on the charge-coupled device sensing chip, and the other beam of light is reflected by the mirror and enters the photodetector chip.

[0013] Further, the atomic gas cell in the atomic gas cell part is filled with Cs atomic vapor, and the outer wall of the atomic gas cell is wound with high-resistance twisted pairs to uniformly heat the atomic gas cell, and a thermocouple is provided for real-time detection of the gas cell temperature.

[0014] Further, the charge-coupled device sensing chip captures the spot of the radially polarized light passing through the atomic gas cell and outputs it to the computer to display the transmitted spot pattern; the photodetector chip collects the optical magnetic resonance signal and outputs it.

[0015] Further, assuming that the distribution of the external vector magnetic field is B = B xoy +B z = B0(sinθ B cosφ B e x +sinθ B sinφ B e y +cosθ B e z ); where B xoy = B0(sinθ B cosφ B e x +sinθ B sinφ B e y ) is the transverse component of the magnetic field, B z = B0cosθ B e z is the longitudinal component of the magnetic field, B0 is the magnitude of the magnetic field modulus, θ B and φ B are respectively the inclination angle and azimuth angle of the magnetic field, e x , e y and e zis the unit vector of the coordinate axis; due to the polarization-selective absorption effect of the polarized atom, the polarization component of the radially polarized light parallel to B will be transmitted after passing through the polarized atom, while the polarization component perpendicular to B will be absorbed, forming two separated light spots; at this time, turn on the charge-coupled device sensing chip to capture the transmitted light spot, and identify the azimuth angles of the two separated light spots in the transmitted light spot pattern, then the azimuth angle φ of the magnetic field can be determined. xoy If the polarization component of the radially polarized light parallel to B will be transmitted after passing through the polarized atom, while the polarization component perpendicular to B will be absorbed, forming two separated light spots; at this time, turn on the charge-coupled device sensing chip to capture the transmitted light spot, and identify the azimuth angles of the two separated light spots in the transmitted light spot pattern, then the azimuth angle φ of the magnetic field can be determined. xoy ; if the azimuth angle φ of the magnetic field B changes, that is, the direction of the B vector changes, then the transmitted light spot will rotate at the same angle as B, and the shape of the light spot remains basically unchanged during the rotation process, and the absorption ratio of the light spot changes little; by identifying and calculating the absorption ratio R of the perpendicular polarization component and the parallel polarization component of the transmitted light spot, combined with the curve relationship formula (1) of the absorption ratio R with respect to the magnetic field inclination angle θ B , the corresponding magnetic field inclination angle θ can be determined. xoy ; xoy where, B Ω B = g

[0016]

[0017] where, Ω L = g F μ B B0 represents the Larmor precession frequency of the atom, g F represents the Landé factor, μ B represents the Bohr magneton; introducing the parameter Γ represents the spontaneous relaxation rate from the excited state to the ground state, γ represents the coherent relaxation rate of the atomic ground state, and Ω R is the Rabi frequency of the radially polarized light.

[0018] Furthermore, after obtaining the transmitted light spot pattern by the charge-coupled device sensing chip, apply an alternating frequency-sweeping signal in the radio frequency coil to generate a radio frequency magnetic field along the Y axis; gradually increase the center frequency with a fixed step size until the photodetector chip collects the optical magnetic resonance signal, and then gradually reduce the frequency-sweeping range to obtain a clear optical magnetic resonance signal; according to the center frequency of the optical magnetic resonance signal (that is, the Larmor precession frequency of the atom), the magnitude of the applied magnetic field can be determined.

[0019] The present invention adopts the above technical solution, demonstrating a miniaturized thermal atomic vector magnetometer based on an S-wave plate, demonstrating a new method for simultaneously detecting the magnetic field strength and orientation based on a thermal atomic ensemble, enabling the three-dimensional information of the magnetic field to be inferred from the transverse light intensity distribution after the radially polarized light beam passes through the polarized atom, and determining the magnetic field inclination angle θ using the absorption ratio of the transverse light intensity distribution B , and at the same time determining the azimuth angle φ of the magnetic field in combination with the direction of the light spot. BThe intensity of the magnetic field can be reflected from the optical magnetic resonance signal, and the intensity of the magnetic field can be determined based on the central frequency of the optical magnetic resonance signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings forming a part of this application are used to provide a further understanding of the application. The schematic embodiments and descriptions thereof of the application are used to explain the application and do not constitute a limitation to the application.

[0021] Figure 1 It is a device diagram of the present invention;

[0022] Figure 2 It is a schematic diagram of the present invention;

[0023] Figure 3 It is a transmission spot pattern when the magnetic field changes the angle on the XOY plane photographed by the present invention;

[0024] Figure 4 It is a transmission spot pattern when the magnetic field changes the angle on the plane where θ B = 80° photographed by the present invention;

[0025] Figure 5 It is a diagram showing the relationship between the extraction of the light intensity information of the transmission spot pattern area photographed by the present invention and the change of the magnetic field angle on the XOZ plane and the normalized absorption ratio of the transmission spot;

[0026] Figure 6 It is an optical magnetic resonance signal diagram collected by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed description is illustrative and is intended to provide further description of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0029] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0030] In the description of the present invention, unless otherwise clearly specified in the context, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0032] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

[0033] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under" and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0035] Example 1:

[0036] As Figure 1 shown, a miniaturized thermal atomic vector magnetometer based on an S-wave plate includes a light source part, an optical path part, an atomic gas cell part, a magnetic field part, and an optical imaging detection part;

[0037] The light source part includes a VCSEL laser 1; the laser frequency of the selected VCSEL laser 1 is tuned to the 6 2 S 1 / 2 , F = 4 → 6 2 P 1 / 2 , F = 3 transition, with a wavelength of 894 nm.

[0038] The optical path part includes a half-wave plate 2, a micro S-waveplate polarization conversion plate 3, a beam splitter prism 9 and a mirror 10; the laser passes through the half-wave plate 2 and the micro S-waveplate polarization conversion plate 3 to generate a radially polarized light 4 with a topological charge number L = 1 and enters the atomic cell 6, where it pumps and polarizes the Cs atoms and is detected; after the radially polarized light 4 passes through the atomic cell 6, it is split into two beams by a beam splitter prism 9 with a splitting ratio of 50:50. One beam of light enters a charge-coupled device sensing chip 11, and the other beam of light is reflected by the mirror 10 and enters a photodetector chip 12.

[0039] The magnetic field part includes two sets of orthogonal Helmholtz coils 5, a set of solenoid coils 7 and a set of radio frequency coils 8; the two sets of orthogonal Helmholtz coils 5 can respectively generate transverse magnetic fields along the X and Y axes, a set of solenoid coils 7 generates a longitudinal magnetic field along the optical propagation direction Z axis, and a set of radio frequency coils 8 generates a radio frequency magnetic field along the Y axis.

[0040] The atomic cell part includes an atomic cell 6 filled with Cs atomic vapor, located at the center of the Helmholtz coils 5; the outer wall of the atomic cell 6 is wound with high-resistance twisted pair wires for uniform heating, and a thermocouple is provided for real-time detection of the cell temperature.

[0041] The optical imaging detection part includes a charge-coupled device sensing chip 11 and a photodetector chip 12. A high-precision charge-coupled device sensing chip 11 is used to capture the transverse light intensity distribution of the radially polarized light 4 passing through the atomic cell 6, and three-dimensional magnetic field vector information is obtained by detecting the spatial light intensity absorption response of the polarized atoms to the radially polarized light 4; a high-sensitivity photodetector chip 12 is used to collect the optical magnetic resonance signal to achieve accurate detection of the magnetic field strength by utilizing the interaction process between the radially polarized light 4 and the polarized atoms.

[0042] For the atom Cs, the following operations are performed during measurement:

[0043] The first step: Lock the laser frequency of the VCSEL laser 1 at the 6 2 S 1 / 2 , F = 4 → 6 2 P 1 / 2 , F = 3 transition, and the wavelength is controlled at 894 nm.

[0044] Step 2: Set the optical power of the VCSEL laser 1 at 60 μW, and generate a radially polarized light 4 with a topological charge number L = 1 through a half-wave plate 2 and a micro S-waveplate polarization conversion plate 3.

[0045] Step 3: Place the atomic gas cell 6 into a micro three-layer μ-metal magnetic shielding barrel, input high-frequency alternating current into the high-resistance twisted pair wire, and uniformly heat the atomic gas cell 6. Real-time detect the gas cell temperature through a T-type thermocouple, so that the gas cell temperature is maintained at 75 degrees Celsius.

[0046] Step 4: Apply direct current to two sets of orthogonal Helmholtz coils 5 and a set of solenoid coils 7, so that the two sets of orthogonal Helmholtz coils 5 respectively generate transverse uniform magnetic fields along the X and Y axes, and a set of solenoid coils 7 generates a longitudinal uniform magnetic field along the optical propagation direction Z axis. By adjusting the current ratio of these coils, a static magnetic field of about 50 mG along any direction can be easily established. Figure 2 (a) in shows the schematic diagram of the present invention and the magnetic field angle coordinate system.

[0047] When the magnetic field is along the Y axis, the parallel polarization component of the radially polarized light 4 will be transmitted with low loss after passing through the atoms, while a part of the light of the perpendicular polarization component will be significantly absorbed, thus forming two completely separated light spots, as shown in Figure 2 (b) in. When the magnetic field is along the Z axis, the radially polarized light 4 will be completely absorbed after passing through the atoms, but the light intensity distribution pattern will not change, as shown in Figure 2 (c) in.

[0048] Step 5: Take the case where the magnetic field direction is on the XOY plane as an example. Change the currents of the Helmholtz coils 5 and the solenoid coils 7, keep the magnitude of the static magnetic field at 50 mG unchanged, adjust the static magnetic field direction to the XOY plane, and continuously change the orientation of the magnetic field on the XOY plane. Turn on the charge-coupled device sensing chip 11 to capture different transmitted light spot patterns. According to the azimuth angle of the transmitted light spot, the azimuth angle φ of the magnetic field on the XOY plane can be determined B . Figure 3 Shows the transmitted light spot pattern when the magnetic field on the XOY plane changes the angle φ B When, φ B Are successively set to 0°, 30°, 90°, 120°, 150° and 180°.

[0049] Step 6: Take the plane with the magnetic field inclination angle θ B = 80° as an example. Change the currents of the Helmholtz coils 5 and the solenoid coils 7, keep the magnitude of the static magnetic field at 50 mG unchanged, adjust the static magnetic field direction to the plane where θ B = 80°, repeat the operation of Step 5 to obtain Figure 4 . Figure 4shows the magnetic field change angle φ B in the plane of θ B = 80°. When the magnetic field is not in the coordinate axis plane, the present invention can still clearly display the azimuth angle of the transmitted light intensity distribution where the light spot is separated, so as to obtain the azimuth angle φ B of the magnetic field.

[0050] Step 7: Identify the transmitted light spot pattern to infer the inclination angle θ B and azimuth angle φ B of the magnetic field. Under any magnetic field direction, turn on the charge-coupled device sensing chip 11 to capture the transmitted light spot, extract the light intensity in a region with a side length of 250 pixels, and calculate the absorption ratio R of the vertical polarization component and the parallel polarization component of the transmitted light spot, as shown in Figure 5 (a). Combining the curve relationship formula (1) of the absorption ratio R with respect to the magnetic field inclination angle θ B , the corresponding magnetic field inclination angle θ B can be determined. Figure 5 (b) shows the relationship diagram of the magnetic field angle in the XOZ plane and the normalized absorption ratio of the transmitted light spot.

[0051] Step 8: After obtaining the transmitted light spot pattern by shooting, apply an alternating frequency-swept signal in the radio frequency coil 8 to generate a radio frequency magnetic field along the Y-axis. The scanning period of the frequency-swept signal is about 100 ms, the initial center frequency is set to 5 kHz, the initial frequency-swept range is set to 10 kHz, and the driving power is limited to 400 mV.

[0052] Step 9: Gradually increase the center frequency in steps of 1 kHz until the photoelectric detector chip 12 collects the optical magnetic resonance signal, and then gradually reduce the frequency-swept range to obtain a clear optical magnetic resonance signal; according to the center frequency of the optical magnetic resonance signal, the magnitude B0 of the applied magnetic field can be determined. Figure 6 shows the optical magnetic resonance signal diagram of a 50 mG magnetic field located on the X-axis.

[0053] The present invention adopts the above technical solution, demonstrates a miniaturized thermal atomic vector magnetometer based on an S-wave plate, demonstrates a new method for simultaneously detecting the magnetic field strength and orientation based on a thermal atomic ensemble, enables the three-dimensional information of the magnetic field to be inferred from the transverse light intensity distribution after a radially polarized light beam passes through polarized atoms, and the magnitude of the magnetic field strength can be reflected from the optical magnetic resonance signal.

[0054] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "an implementation manner", "specific implementation manner", "other implementation manners", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment, implementation manner, or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described above can also be combined in a suitable manner in any one or more embodiments, implementation manners, or examples. The technical solutions described in the present invention also include the technical solutions formed by any one or more of the above-described specific features, structures, materials, or characteristics alone or in combination.

[0055] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Without departing from the principles and purposes of the present invention, those of ordinary skill in the art can make changes, modifications, substitutions, variations, delete some features, add features, or re-combine features to form technical solutions within the scope of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the innovative principles of the present invention still fall within the scope of the technical solutions of the present invention.

Claims

1. A miniaturized thermal atomic vector magnetometer based on an S-wave plate, characterized in that, It includes a light source part, an optical path part, an atomic gas cell part, a magnetic field part, and an optical imaging detection part; The laser frequency of the VCSEL laser (1) selected for the light source part is tuned to the transition frequency of the atomic medium; The optical path part passes the light emitted by the VCSEL laser (1) through the micro S-waveplate polarization conversion sheet (3) to generate radially polarized light (4) and incident on the atomic gas cell (6), pumping and polarizing the atoms in the atomic gas cell (6) and performing magnetic field detection; The magnetic field part includes two sets of orthogonal Helmholtz coils (5), a set of solenoid coils (7), and a set of RF coils (8); the two sets of orthogonal Helmholtz coils (5) are used to generate transverse magnetic fields along the X and Y axes respectively, a set of solenoid coils (7) is used to generate a longitudinal magnetic field along the light propagation direction Z axis, and a set of RF coils (8) is used to generate an RF magnetic field along the Y axis; The atomic gas cell part includes an atomic gas cell (6) located at the center of the Helmholtz coils (5); The optical imaging detection part uses a charge-coupled device sensing chip (11) to capture the transverse light intensity distribution of the radially polarized light (4) transmitted through the atomic gas cell (6), and obtains the three-dimensional magnetic field vector information by detecting the spatial light intensity absorption response of the polarized atoms to the radially polarized light (4); uses a photodetector chip (12) to collect the optical magnetic resonance signal to achieve magnetic field strength detection by utilizing the interaction process between the radially polarized light (4) and the polarized atoms.

2. The miniaturized thermal atomic vector magnetometer based on a S-wave plate according to claim 1, characterized in that, The light source part includes a VCSEL laser (1); the frequency of the VCSEL laser (1) is locked at the 6 of the D1 line of Cs 2 S 1 / 2 , F = 4 → 6 2 P 1 / 2 , on the F = 3 transition, with a wavelength of 894 nm and the optical power set at 60 μW.

3. A miniaturized thermal atomic vector magnetometer based on a S-wave plate according to claim 1, characterized in that, The optical path part includes a half-wave plate (2), a micro S-waveplate polarization conversion sheet (3), a beam splitter prism (9), and a mirror (10); the laser passes through the half-wave plate (2) and the micro S-waveplate polarization conversion sheet (3) to generate radially polarized light (4) with a topological charge number L = 1; the radially polarized light (4) is split into two beams by the beam splitter prism (9) after passing through the atomic gas cell (6), one beam of light is incident on the charge-coupled device sensing chip (11), and the other beam of light is reflected by the mirror (10) and enters the photodetector chip (12).

4. A miniaturized thermal atomic vector magnetometer based on an S-wave plate according to claim 1, characterized in that, The atomic gas cell (6) in the atomic gas cell part is filled with Cs atomic vapor, and the outer wall of the atomic gas cell (6) is wound with high-resistance twisted pairs to uniformly heat the atomic gas cell (6), and a thermocouple for real-time detection of the gas cell temperature is provided.

5. A miniaturized thermal atomic vector magnetometer based on a S-wave plate according to claim 1, characterized in that, The charge-coupled device sensing chip (11) captures the light spot of the radially polarized light (4) transmitted through the atomic gas cell (6) and outputs it to a computer to display the transmitted light spot pattern; the photodetector chip (12) collects the optical magnetic resonance signal and outputs it.

6. A miniaturized thermal atomic vector magnetometer based on an S-wave plate according to claim 1, characterized in that, Assume that the distribution of the external vector magnetic field is B = B xoy + B z = B0(sinθ B cosφ B e x + sinθ B sinφ B e y + cosθ B e z ); where, B xoy = B0(sinθ B cosφ B e x + sinθ B sinφ B e y ) is the transverse component of the magnetic field, B z = B0cosθ B e z is the longitudinal component of the magnetic field, B0 is the magnitude of the magnetic field modulus, θ B and φ B are the inclination angle and azimuth angle of the magnetic field respectively, e x , e y and e z are the unit vectors of the coordinate axes; due to the polarization selective absorption effect of polarized atoms, the polarization component of the radially polarized light (4) parallel to B xoy will be transmitted after passing through the polarized atoms, while the polarization component perpendicular to B xoy will be absorbed, forming two separated light spots; at this time, turn on the charge-coupled device sensing chip (11) to capture the transmitted light spots, and identify the azimuth angles of the two separated light spots in the transmitted light spot pattern, then the azimuth angle φ B of the magnetic field can be determined; if the azimuth angle φ B of the magnetic field changes, that is, the vector direction of B xoy changes, then the transmitted light spot will rotate at the same angle as B xoy ; by identifying and calculating the absorption ratio R of the perpendicular polarization component and parallel polarization component of the transmitted light spot, and combining with the curve relationship formula (1) of the absorption ratio R with respect to the magnetic field inclination angle θ B , the corresponding magnetic field inclination angle θ B can be determined; Among them, Ω L = g F μ B B0 represents the Larmor precession frequency of the atom, g F represents the Landé factor, μ B represents the Bohr magneton; introducing the parameter Γ represents the spontaneous relaxation rate from the excited state to the ground state, γ represents the coherent relaxation rate of the atomic ground state, Ω R is the Rabi frequency of the radially polarized light.

7. A miniaturized thermal atomic vector magnetometer based on a S-wave plate according to any one of claims 1-6, characterized in that, After obtaining the transmitted light spot pattern by photographing with the charge-coupled device sensing chip (11), an AC sweep signal is applied in the RF coil (8) to generate an RF magnetic field along the Y axis; the center frequency is gradually increased in fixed steps until the photodetector chip (12) collects the optical magnetic resonance signal, and then the sweep range is gradually reduced to obtain an optical magnetic resonance signal with a clear spectrum line; according to the center frequency of the optical magnetic resonance signal, the magnitude of the applied magnetic field can be determined.

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