High-spatial-resolution array type SERF atom magnetometer based on light beam homogenization

Abstract

The invention relates to a high spatial resolution array SERF atom magnetometer based on light beam homogenization, which provides a new idea for the realization of a miniaturized multi-channel atom magnetometer and lays a foundation for the development of high spatial resolution magnetic field detection, a portable multi-channel atom magnetometer and a biological magnetic imaging technology. Comprising an alkali metal gas chamber located in a magnetic compensation coil, a 3 * 3 photodiode array is arranged on the laser emergent side of the alkali metal gas chamber, the laser incident side of the alkali metal gas chamber is connected with a flat-topped beam shaper through a 1 / 4 wave plate, and the flat-topped beam shaper shapes light spots with incident light intensity in Gaussian distribution into flat-topped light spots with light intensity evenly distributed. The flat-top light spots sequentially pass through the 1 / 4 wave plate and the alkali metal gas chamber along the z axis and then cover the photodiode array located on the xy plane, and nine photodiodes in the photodiode array form nine signal channels for receiving the flat-top light spots from nine positions.

Description

Technical Field

[0001] The present invention relates to the technical field of high-spatial-resolution ultra-weak magnetic field measurement by a multi-channel SERF atomic magnetometer, and in particular to an array-type SERF atomic magnetometer with high spatial resolution based on beam homogenization. Background Art

[0002] The sensitivity of an atomic magnetometer based on the Spin-Exchange Relaxation-Free (SERF) effect has reached the sub-fT / Hz 1 / 2 order of magnitude, enabling ultra-high-sensitivity ultra-weak magnetic field measurement and having great potential for application in magnetocardiogram (MCG) and magnetoencephalogram (MEG) measurement instruments. MCG and MEG applications usually require multi-channel parallel magnetic imaging to effectively improve the efficiency and spatial resolution of magnetic field measurement by synchronously detecting a large area through multiple channels. However, the multi-channel scheme of classical multiple single-channel sensors has a low spatial resolution, usually only on the order of centimeters, with significant performance differences between sensors (or magnetometers), making it difficult to ensure consistency, and there is also a problem of modulated magnetic field crosstalk, seriously affecting the integration of the multi-channel magnetometer system.

[0003] To solve the above problems, the present invention proposes an array-type SERF atomic magnetometer with high spatial resolution based on beam homogenization. By using a single gas cell and a 3×3 photodiode array, a magnetic field measurement resolution of mm level and a sensitivity of fT level are achieved. The alkali metal atoms are polarized by an expanded flat-top laser beam, significantly improving the uniformity of the atomic polarization rate in different regions of the gas cell and enhancing the consistency between the performances of each channel. Further, by filling a high-pressure buffer gas and a quenching gas in the large gas cell, the diffusion of alkali metal atoms is inhibited and the collision relaxation with the gas cell wall is reduced. The channel spacing of the designed magnetometer is greater than the diffusion distance of alkali metal atoms, enabling different regions in the gas cell to be independently used as magnetometers. The optical path structure of this system is simple and easy to implement, having the potential to integrate a miniaturized multi-channel magnetometer. At the same time, this magnetometer only requires a set of magnetic compensation coils, thus avoiding magnetic field crosstalk between different channels. This innovative method provides a new idea for the realization of a miniaturized multi-channel atomic magnetometer and lays a foundation for the development of high-resolution magnetic field detection, portable multi-channel atomic magnetometers, and biomagnetic imaging technology. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a high-spatial-resolution arrayed SERF atomic magnetometer based on beam homogenization, which uses a single gas cell and a 3×3 photodiode array to achieve an mm-level magnetic field measurement resolution and an fT-level sensitivity. The alkali metal atoms are polarized by a flattened-top laser beam after beam expansion, significantly improving the uniformity of the atomic polarization rate in different regions of the gas cell and enhancing the consistency between the performances of each channel. Further, by filling a high-pressure buffer gas and a quenching gas into the large gas cell, the diffusion of alkali metal atoms is inhibited and the collision relaxation with the gas cell wall is reduced. The channel spacing of the designed device is greater than the diffusion distance of alkali metal atoms, enabling different regions in the gas cell to independently act as magnetometers. The optical path structure of this system is simple and easy to implement, having the potential to integrate a miniaturized multi-channel magnetometer. At the same time, this magnetometer only requires a set of magnetic compensation coils, thus avoiding magnetic field crosstalk between different channels. This innovative method provides a new idea for the realization of miniaturized multi-channel atomic magnetometers and lays a foundation for the development of high-resolution magnetic field detection, portable multi-channel atomic magnetometers, and biomagnetic imaging technology.

[0005] The technical solution of the present invention is as follows:

[0006] A high-spatial-resolution arrayed SERF atomic magnetometer based on beam homogenization, characterized in that it includes an alkali metal gas cell located inside a magnetic compensation coil, a 3×3 photodiode array is arranged on the laser output side of the alkali metal gas cell, the laser input side of the alkali metal gas cell is connected to a flattened-top beam shaper through a quarter-wave plate, the flattened-top beam shaper shapes a spot with a Gaussian distribution of incident light intensity into a flattened-top spot with a uniform light intensity distribution, the flattened-top spot sequentially passes through the quarter-wave plate and the alkali metal gas cell along the z-axis and then covers the photodiode array located on the xy plane, and nine photodiodes in the photodiode array form nine signal channels for receiving the flattened-top spot from nine positions.

[0007] The spacing between adjacent signal channels is greater than the diffusion distance of alkali metal atoms, enabling different regions in the gas cell to independently act as magnetometers.

[0008] The photodiode array is connected to a transimpedance amplifier through a transmission cable, and the transimpedance amplifier is connected to a signal acquisition and processing module through a lock-in amplifier.

[0009] The flattened-top beam shaper is sequentially connected to the transmission side of a polarization beam splitter through a mirror group and a beam expander, the input side of the polarization beam splitter is connected to a laser, and the reflection side of the polarization beam splitter is connected to a wavelength meter.

[0010] The magnetic compensation coil is connected to a function source through a transmission cable.

[0011] A magnetic source coil is arranged between the magnetic compensation coil and the alkali metal gas chamber to evaluate the coincidence between the theoretical simulation value and the actual measured value of the gradient magnetic field.

[0012] The outer size of a single photodiode is 3mm×3mm, and the center spacing between adjacent photodiodes is 3.25mm. This number is greater than the diffusion distance of alkali metal atoms calculated theoretically, which is 0.25mm. Therefore, in the nine-channel SERF atomic magnetometer device, the magnitudes of the magnetic fields to be measured at 9 positions can be obtained in one measurement at the same moment, and the resolution of the spatial position of the magnetic field measurement is 3.25mm.

[0013] It includes the following expressions:

[0014]

[0015] where I is the light intensity detected by the photodiode, k1 is the proportionality coefficient, is the z-axis component of the electronic polarizability of alkali metal atoms, P0 is the magnitude of the electronic polarization vector of alkali metal atoms at steady state under the condition of no external magnetic field, J0(u) is the Bessel function of the first kind of order 0, J1(u) is the Bessel function of the first kind of order 1, Γ is the magnetic resonance linewidth, B y is the magnetic field to be measured on the y-axis, B y0 is the residual magnetic field on the y-axis, B x0 is the residual magnetic field on the x-axis, B z0 is the residual magnetic field on the z-axis; the 9-channel optoelectronic signals are calculated in parallel 9 times through the above formula. Finally, at the same moment, the magnitudes of the magnetic fields to be measured at 9 positions can be obtained in one measurement.

[0016] A heating device is attached to the outer wall of the alkali metal gas chamber.

[0017] The technical effects of the present invention are as follows: The high-spatial-resolution array-type SERF atomic magnetometer based on beam homogenization of the present invention realizes mm-level magnetic field measurement resolution and fT-level sensitivity by using a single gas chamber and a photodiode array. The polarization of alkali metal atoms is carried out by the flattened laser beam after beam expansion, which significantly improves the uniformity of the atomic polarizability in different regions of the gas chamber and enhances the consistency between the performances of each channel. Further, by filling high-pressure buffer gas and quenching gas in the large gas chamber, the diffusion of alkali metal atoms is inhibited, and the collision relaxation with the gas chamber wall is reduced. The channel spacing of the designed device is greater than the diffusion distance of alkali metal atoms, so that different regions in the gas chamber can be independently used as magnetometers. The optical path structure of this system is simple and easy to implement, and has the potential of an integrated miniaturized multi-channel magnetometer. At the same time, this magnetometer only needs a group of magnetic compensation coils, thus avoiding the magnetic field crosstalk between different channels. This innovative method provides a new idea for the realization of miniaturized multi-channel atomic magnetometers, and lays a foundation for the development of high-resolution magnetic field detection, portable multi-channel atomic magnetometers and biomagnetic imaging technology. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of a high-spatial-resolution array-type SERF atomic magnetometer based on beam homogenization for implementing the present invention.

[0019] Figure 2 is Figure 1 the magnetic field sensitivity curve graph of 9 channels in Figure 2 where the abscissa in is frequency (Hz, scale values 0, 20, ··· 100), and the ordinate is sensitivity (fT / Hz 1 / 2 , scale values 0, 10 1 , 10 2 , ··· 10 5 ). Figure 2 In, Ch.1 - the first channel, Ch.2 - the second channel, Ch.3 - the third channel, Ch.4 - the fourth channel, Ch.5 - the fifth channel, Ch.6 - the sixth channel, Ch.7 - the seventh channel, Ch.8 - the eighth channel, Ch.9 - the ninth channel. Figure 2 The sensitivity performance of the nine channels in has good consistency, and the average sensitivity of each channel is approximately 10.6 fT / Hz in the range of 10 - 100 Hz 1 / 2 .

[0020] Figure 3 is the measurement Figure 1 the result graph of the gradient magnetic field distribution generated by the magnetic source coil in Figure 3 where the abscissa in is the channel, and the ordinate is the magnetic field (nT, scale values 1.0, 1.2, 1.4, ··· 2.4). Figure 3 In, Ch.1 - the first channel, Ch.2 - the second channel, Ch.3 - the third channel, Ch.4 - the fourth channel, Ch.5 - the fifth channel, Ch.6 - the sixth channel, Ch.7 - the seventh channel, Ch.8 - the eighth channel, Ch.9 - the ninth channel. The solid-line marked squares represent the theoretical calculated values, and the dashed-line marked circles represent the actual measured values. The results show that the theoretical simulation values of the gradient magnetic field are in good agreement with the actual measured values of the gradient magnetic field.

[0021] Explanation of the reference numerals is as follows: 1 - transimpedance amplifier; 2 - lock-in amplifier; 3 - signal acquisition and processing module; 4 - laser; 5 - optical path; 6 - transmission cable; 7 - polarization beam splitter prism; 8 - wavelength meter; 9 - optical beam expander; 10 - mirror; 11 - flat-top beam shaper; 12 - quarter-wave plate; 13 - function generator; 14 - magnetic shielding barrel; 15 - magnetic compensation coil; 16 - heating device; 17 - alkali metal gas cell; 18 - photodiode array; 19 - magnetic source coil; xyz - the three axes of the rectangular coordinate system (i.e., the x-axis, y-axis, and z-axis). Detailed Embodiment

[0022] Below is the attached figure ( Figures 1 - 3 ) and Examples illustrate the present invention.

[0023] Figure 1 The present invention is a schematic diagram of a high spatial resolution array-type SERF atomic magnetometer based on light beam homogenization. Figure 2 yes Figure 1 Magnetic field sensitivity curves of the 9 channels. Figure 3 It is measured Figure 1 The result diagram of the gradient magnetic field distribution generated by the magnetic source coil. Figures 1 to 3 As shown, a high spatial resolution array-type SERF atomic magnetometer based on beam homogenization includes an alkali metal gas chamber 17 located in a magnetic compensation coil 15, a 3×3 photodiode array 18 is arranged on the laser emission side of the alkali metal gas chamber 17, and the laser incident side of the alkali metal gas chamber 17 is connected to a flat-top beam shaper 11 through a 1 / 4 wave plate 12. The flat-top beam shaper 11 shapes a light spot with a Gaussian distribution of incident light intensity into a flat-top light spot with uniform light intensity distribution. The flat-top light spot passes through the 1 / 4 wave plate 12 and the alkali metal gas chamber 17 in sequence along the z-axis and then covers the photodiode array 18 located on the xy plane. The 9 photodiodes in the photodiode array 18 form 9 signal channels for receiving the flat-top light spot from 9 positions.

[0024] The spacing between adjacent signal channels is greater than the diffusion distance of alkali metal atoms, so that different areas in the gas chamber can be independently used as magnetometers. The photodiode array is connected to the transimpedance amplifier 1 through a transmission cable 6, and the transimpedance amplifier 1 is connected to the signal acquisition and processing module 3 through a phase-locked amplifier 2. The flat-top beam shaper 11 is connected to the transmission side of the polarization beam splitter prism 7 through a reflector group (including two reflectors 10) and an optical beam expander 9 in turn, the incident side of the polarization beam splitter prism 7 is connected to the laser 4, and the reflection side of the polarization beam splitter prism 7 is connected to the wavelength meter 8. The magnetic compensation coil 15 is connected to the function source 13 through a transmission cable 6.

[0025] A magnetic source coil 19 is provided between the magnetic compensation coil 15 and the alkali metal gas chamber 17 to evaluate the agreement between the theoretical simulation value of the gradient magnetic field and the actual measured value of the gradient magnetic field. The outer dimensions of a single photodiode are 3 mm × 3 mm, and the center spacing of adjacent photodiodes is 3.25 mm, which is greater than the theoretically calculated diffusion distance of alkali metal atoms of 0.25 mm. Therefore, the nine-channel SERF atomic magnetometer device measures the magnetic field magnitudes of 9 positions at one time at the same time, and the resolution of the magnetic field measurement space position is 3.25 mm.

[0026] Include the following expressions:

[0027]

[0028] where I is the light intensity detected by the photodiode, and k1 is the proportionality coefficient, is the z-axis component of the electronic polarizability of the alkali metal atom, P0 is the magnitude of the electronic polarization vector of the alkali metal atom at steady state under the condition of no external magnetic field, J0(u) is the Bessel function of the first kind of order 0, J1(u) is the Bessel function of the first kind of order 1, Γ is the magnetic resonance linewidth, B y is the magnetic field to be measured on the y-axis, B y0 is the residual magnetic field on the y-axis, B x0 is the residual magnetic field on the x-axis, B z0 is the residual magnetic field on the z-axis; The 9-channel optoelectronic signals are calculated in parallel 9 times by the above formula. Finally, at the same moment, the magnitudes of the magnetic fields to be measured at 9 positions are obtained in one measurement. A heating device 16 is attached to the outer wall of the alkali metal gas cell 17.

[0029] The present invention relates to a high-spatial-resolution array-type SERF atomic magnetometer based on beam homogenization. Using a single gas cell and a 3×3 photodiode array, mm-level magnetic field measurement resolution and fT-level sensitivity are achieved. The alkali metal atoms are polarized by an expanded flat-top laser beam, significantly improving the uniformity of the atomic polarizability in different regions of the gas cell and enhancing the consistency between the performances of each channel. Further, by filling a high-pressure buffer gas and a quenching gas in the large gas cell, the diffusion of the alkali metal atoms is inhibited, and the collision relaxation with the gas cell wall is reduced. The channel spacing of the designed device is greater than the diffusion distance of the alkali metal atoms, enabling different regions in the gas cell to be independently used as magnetometers. The optical path structure of this system is simple and easy to implement, and has the potential to integrate a miniaturized multi-channel magnetometer probe. At the same time, this magnetometer only requires a set of magnetic compensation coils, thus avoiding the magnetic field crosstalk between different channels. This innovative method provides a new idea for the realization of miniaturized multi-channel atomic magnetometers, laying a foundation for the development of high-spatial-resolution magnetic field detection, portable multi-channel atomic magnetometers, and biomagnetic imaging technologies.

[0030] Such as Figure 1As shown in the figure, a high-spatial-resolution array SERF atomic magnetometer based on beam homogenization includes a transimpedance amplifier (1), a lock-in amplifier (2), a signal acquisition and processing module (3), a laser (4), an optical path (5), a transmission cable (6), a polarization beam splitter prism (7), a wavelength meter (8), a beam expander (9), a mirror (10), a flat-top beam shaper (11), a quarter-wave plate (12), a function generator (13), a magnetic shielding barrel (14), a magnetic compensation coil (15), a heating device (16), an alkali metal gas cell (17), a photodiode array (18), and a magnetic source coil (19). Among them, the laser (4) emits laser light, which is split into two beams by the polarization beam splitter prism (7). One beam enters the wavelength meter (8) to detect the laser wavelength, and the other beam is shaped into a flat-top beam with a uniform light intensity distribution by the beam expander (9), the mirror (10), and the flat-top beam shaper (11), and the spot size is large enough to cover the photodiode array (18). The flat-top beam is adjusted to circularly polarized light by the quarter-wave plate (12), passes through the alkali metal gas cell (17), and is detected and collected by the photodiode array (18). The signal passes through the transimpedance amplifier (1) and the lock-in amplifier (2), and is finally processed in the signal acquisition and processing module (3).

[0031] The alkali metal gas cell (17) contains alkali metal atoms (such as potassium, rubidium, or cesium atoms). In addition to alkali metal atoms, the alkali metal gas cell (17) also includes buffer gases (such as nitrogen, etc.) and quenching gases (such as helium, neon, etc.).

[0032] The alkali metal gas cell (17) is placed in a heating device (16) with a heating film attached to its side wall. The gas cell is heated to an alkali metal atomic number density reaching 10 13 ~10 14 cm -3 order of magnitude to ensure that the atoms work in the SERF state. The heating device (16) is placed at the center of the magnetic compensation coil (15). The magnetic compensation coil (15) is located inside the magnetic shielding barrel (14) and their centers coincide.

[0033] The central wavelength of the laser light emitted by the laser (4) is the D1 line resonance wavelength of the alkali metal atoms in the alkali metal gas cell (17).

[0034] The photodiode array (18) is arranged by 9 photodiodes in 3 rows and 3 columns. The outer size of a single photodiode is 3mm×3mm, and the center distance between adjacent photodiodes is 3.25mm. This number is greater than the theoretically calculated alkali metal atomic diffusion distance of 0.25mm. Therefore, the magnetic field measurement spatial resolution of the nine-channel SERF atomic magnetometer device is 3.25mm.

[0035] The incident light beam (5) becomes a flat-top light beam after passing through an optical beam expander (9) and a flat-top beam shaper (11), and is characterized in that the light intensity is uniformly distributed at different positions of the light spot. The diameter of the flat-top light spot is large enough to cover the photodiode array (18). The inner dimensions of the alkali metal gas cell (17) are matched with the dimensions of the incident flat-top light beam and the photodiode array (18).

[0036] The flat-top beam shaper (11) is an optical device that can shape a light spot with a Gaussian-distributed incident light intensity into a flat-top light spot with a uniformly distributed light intensity.

[0037] The magnetic compensation coil (15) and the magnetic source coil (19) are both driven and controlled by a function source (13). The magnetic compensation coil (15) is used to compensate the three-dimensional residual magnetism in the magnetic shielding barrel (14), and is also used to generate the magnetic field to be measured and the modulation magnetic field; the magnetic source coil (19) can generate the magnetic field gradient to be measured, and is used to verify the effectiveness of the constructed nine-channel magnetometer in high-resolution magnetic field measurement.

[0038] Each sensing channel of the arrayed SERF atomic magnetometer adopts the magnetic field measurement principle of the single-beam transverse modulation type SERF atomic magnetometer. The incident light is along the z-axis, and the light intensity I in the z direction collected by the photodiode is proportional to the electronic polarizability of the alkali metal atoms in this direction That is where k1 is the proportionality coefficient. When a modulation magnetic field is applied along the y-axis, where is the amplitude of the modulation magnetic field, ω mod is the angular frequency of the modulation magnetic field, and t is the time. By demodulating the first harmonic component of the nine-channel optoelectronic signals collected by the photodiode array with respect to ω mod using a lock-in amplifier (2), the z-direction component of the electronic polarizability of the alkali metal atoms with respect to the magnetic field B to be measured y can be obtained as follows:

[0039]

[0040] where P0 is the magnitude of the electronic polarization vector of the alkali metal atoms at steady state under the condition of no external magnetic field, J0(u) is the Bessel function of the first kind of order 0, J1(u) is the Bessel function of the first kind of order 1, Γ is the magnetic resonance linewidth, B x0 is the residual magnetic field in the x-axis direction, B y0 is the residual magnetic field in the y-axis direction, B y is the magnetic field to be measured in the y-axis direction, B z0 is the residual magnetic field in the z-axis direction. When the three-dimensional residual magnetic field is compensated to zero and the value of the magnetic field B to be measured y is small, with respect to B yApproximately linear relationship. Therefore, the process of measuring the magnetic field by the nine-channel SERF atomic magnetometer can be briefly described as: the light intensity I in the z direction → the electron polarizability in the z direction → the magnitude B of the magnetic field to be measured y , that is, the magnetic field information is finally obtained from the light intensity information through a series of conversions. The 9 photoelectric signals collected by each sensing channel of the nine-channel SERF atomic magnetometer are calculated in parallel 9 times according to the above formula. Finally, at the same moment, the magnitudes of the magnetic fields to be measured at 9 positions can be obtained in one measurement, and the spatial position resolution is 3.25 mm.

[0041] Figure 2 shows the magnetic field measurement sensitivity curve of a high-spatial-resolution arrayed SERF atomic magnetometer based on beam homogenization according to the present invention. The results show that the sensitivity performances of the 9 sensing channels (the first channel to the ninth channel) of the nine-channel SERF atomic magnetometer constructed by the present invention have good consistency, and the average sensitivity of each channel is about 10.6 fT / Hz in the range of 10 - 100 Hz 1 / 2 .

[0042] Figure 3 In, the solid-line marked squares represent the magnetic field simulation values generated by the magnetic source coil (19) at the positions of the nine sensing channels calculated using the Biot - Savart law, and the dashed-line marked circles represent the actual measurement values of the gradient magnetic field generated by the magnetic source coil (19) by a high-spatial-resolution arrayed SERF atomic magnetometer based on beam homogenization according to the present invention. The results show that the actual measurement values of the gradient magnetic field by the nine-channel SERF atomic magnetometer constructed by the present invention are in good agreement with the theoretical simulation values, indicating that a high-spatial-resolution arrayed SERF atomic magnetometer based on beam homogenization proposed by the present invention is effective in measuring the gradient magnetic field.

[0043] The content not described in detail in the specification of the present invention belongs to the prior art well-known to those skilled in the art. It is hereby pointed out that the above description helps those skilled in the art to understand the present invention, but does not limit the protection scope of the present invention. Any implementation that makes equivalent substitutions, modifications and improvements, and / or simplifies the above description without departing from the essential content of the present invention falls within the protection scope of the present invention.

Claims

1. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization, characterized in that, It includes an alkali metal gas cell located inside a magnetic compensation coil. A 3×3 photodiode array is arranged on the laser output side of the alkali metal gas cell. The laser input side of the alkali metal gas cell is connected to a flat-top beam shaper through a quarter-wave plate. The flat-top beam shaper shapes a spot with a Gaussian distribution of incident light intensity into a flat-top spot with a uniform light intensity distribution. The flat-top spot sequentially passes through the quarter-wave plate and the alkali metal gas cell along the z-axis and then covers the photodiode array located on the xy plane. Nine photodiodes in the photodiode array form nine signal channels for receiving the flat-top spot from nine positions.

2. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, wherein The distance between adjacent signal channels is greater than the diffusion distance of alkali metal atoms, enabling different regions in the gas cell to independently act as magnetometers.

3. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, characterized in that, The photodiode array is connected to a transimpedance amplifier through a transmission cable, and the transimpedance amplifier is connected to a signal acquisition and processing module through a lock-in amplifier.

4. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, characterized in that The flat-top beam shaper is sequentially connected to the transmission side of a polarization beam splitter through a mirror group and a beam expander. The input side of the polarization beam splitter is connected to a laser, and the reflection side of the polarization beam splitter is connected to a wavelength meter.

5. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, characterized in that, The magnetic compensation coil is connected to a function generator through a transmission cable.

6. The high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, wherein A magnetic source coil is arranged between the magnetic compensation coil and the alkali metal gas cell to evaluate the coincidence between the theoretical simulation value and the actual measured value of the gradient magnetic field.

7. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, characterized in that, The outer dimension of a single photodiode is 3mm×3mm, and the center distance between adjacent photodiodes is 3.25mm, which is greater than the diffusion distance of alkali metal atoms calculated theoretically by 0.25mm. Therefore, the nine-channel SERF atomic magnetometer can obtain the magnitudes of the magnetic fields to be measured at nine positions in one measurement at the same time, and the resolution of the spatial position of the magnetic field measurement is 3.25mm.

8. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, characterized in that It includes the following expressions: where I is the light intensity sensed by the photodiode, and k1 is the proportionality coefficient, is the z-axis component of the electronic polarizability of the alkali metal atom, P0 is the magnitude of the electronic polarization vector of the alkali metal atom at steady state without an external magnetic field, J0(u) is the Bessel function of the first kind of order 0, J1(u) is the Bessel function of the first kind of order 1, Γ is the magnetic resonance linewidth, B y is the magnetic field to be measured on the y-axis, B y0 is the residual magnetic field on the y-axis, B x0 is the residual magnetic field on the x-axis, B z0 is the residual magnetic field on the z-axis; the 9-channel optoelectronic signals are calculated in parallel 9 times using the above formula. Finally, at the same moment, the magnitudes of the magnetic fields to be measured at 9 positions are obtained in one measurement.

9. A high-spatial-resolution array SERF atomic magnetometer based on beam homogenization according to claim 1, characterized in that, A heating device is attached to the outer wall of the alkali metal gas cell.

Images