SERF atom magnetometer measuring device integrated with magnetic flux guiding-gathering device

Abstract

According to the SERF atom magnetometer measuring device integrated with the magnetic flux guiding-gathering device, the magnetic flux guiding-gathering device is placed at the front end of an SERF atom magnetometer, the amplification effect on a far-end low-intensity magnetic field can be achieved, the amplified magnetic field is guided to pass through an air chamber of the SERF atom magnetometer, the response signal of the atom magnetometer can be improved, and the measurement accuracy of the SERF atom magnetometer can be improved. The signal-to-noise ratio of the magnetic measurement device is improved; on the other hand, by designing the shape of the surface of the contact magnetic field, the magnetic field to be measured in a specific range can be amplified by magnetic flux gathering magnetism, so that the spatial resolution is improved, and the magnetometer probe is characterized by comprising a magnetic flux guiding-gathering device arranged on a magnetic field input interface of the magnetometer probe, the magnetic flux guiding-gathering device and the magnetometer probe are combined to form a magnetometer head with submillimeter spatial resolution, and the magnetometer head is connected with a three-dimensional displacement table through a connecting rod.

Description

Technical Field

[0001] The invention relates to the technical field of quantum precision measuring instruments, in particular to a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator. Background Art

[0002] SERF (Spin-Exchange-Relaxation-Free) atomic magnetometers measure magnetic fields by polarizing atoms and are the most sensitive atomic magnetometers. Miniaturized SERF atomic magnetometers have the advantages of compact structure and high measurement sensitivity, and have great application potential in the fields of cardio-cerebral magnetometry, muscle magnetometry, and magnetic imaging. The size of conventional miniaturized SERF atomic magnetometer probes is at the centimeter level, which limits the spatial resolution of the magnetometer to the centimeter level. In addition, the atomic gas chamber, the sensitive element of the magnetometer, is generally located in the center of the detection head and is at a certain distance from the magnetic source to be measured. This causes the magnetic field generated by the magnetic source to decay rapidly as the square of the distance during the process of being transmitted to the atomic gas chamber, weakening the signal to be measured. This limits the application of conventional miniaturized SERF atomic magnetometers in the fields of cardio-cerebral magnetometry, magnetic imaging, etc. At present, magnetic flux guides or magnetic flux concentrators can be used to solve the above problems. However, due to the geometric characteristics of the two, they can only achieve the amplification of the magnetic field to be measured or improve the spatial resolution of the SERF atomic magnetometer, resulting in the inability to achieve both spatial resolution and signal strength, thus limiting the application of SERF atomic magnetometers in the fields of rock measurement, material magnetic testing, etc. The structural design of the present invention comprehensively considers the geometric characteristics of spatial resolution improvement and magnetic field signal amplification, and achieves simultaneous amplification of spatial resolution and signal strength. Summary of the invention

[0003] The problem solved by the present invention is: to provide a SERF atomic magnetometer measuring device with an integrated magnetic flux guide-concentrator, to design a magnetic flux guide-concentrator which can converge a magnetic field to be measured, to place the magnetic flux guide-concentrator at the front end of the SERF atomic magnetometer, to achieve an amplification effect on a remote weak magnetic field, to guide the amplified magnetic field through an air chamber of the SERF atomic magnetometer, to improve a response signal of the atomic magnetometer, thereby improving a signal-to-noise ratio of the magnetic measuring device; on the other hand, by designing the shape of a contact magnetic field surface, the magnetic flux concentrator can amplify the magnetic field to be measured within a specific range, thereby achieving an improvement in spatial resolution.

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

[0005] A SERF atomic magnetometer measurement device with integrated magnetic flux guide-concentrator, characterized in that a magnetic flux guide-concentrator is arranged on the magnetic field input interface of a magnetometer probe, the combination of the magnetic flux guide-concentrator and the magnetometer probe constitutes a magnetometer head with sub-millimeter spatial resolution, and the magnetometer head is connected to a three-dimensional displacement stage through a connecting rod.

[0006] The magnetic flux guide-concentrator includes a magnetic field collector whose thin end is used to abut against a magnetic sample to be measured, a magnetic field transmitter axially extending from the thick end of the magnetic field collector, and a magnetic field amplifier axially extending from the end face of the magnetic field transmitter while radially contracting. The thin end of the magnetic field amplifier is bonded to the magnetic field input interface of the magnetometer probe, and the end face dimensions of the thin end of the magnetic field amplifier match the end face dimensions of the alkali metal atom gas chamber in the magnetometer probe.

[0007] The magnetic flux guide-concentrator is an integrated structure formed by soft ferrite. The end face scale of the thin end of the magnetic field collector is sub-millimeter. The magnetic field convergence and amplification effect of the magnetic flux guide-concentrator is expressed as follows:

[0008]

[0009] Where A is the magnification factor, N is the demagnetization factor, which is related to the length L 1 , L 2 and L 3 Related physical quantities, L 1 is the length of the magnetic field amplifier, L 2 is the length of the magnetic field transmitter, L 3 is the length of the magnetic field collector, μ r is the relative magnetic permeability of the soft ferrite material, Φ 1 is the diameter of the thin end of the magnetic field amplifier; Φ 3 is the diameter of the thin end of the magnetic field collector.

[0010] The magnetometer probe comprises a shell, a gas chamber electric heating module is arranged in the shell, and the alkali metal atom gas chamber is located in the gas chamber electric heating module.

[0011] The magnetometer head is located in the magnetic shielding device, the magnetometer probe is respectively connected to the pumping laser module and the detection laser module in the optoelectronic measurement and control system through respective polarization-maintaining optical fibers, the magnetometer probe is connected to the signal acquisition and processing module in the optoelectronic measurement and control system through a data transmission line, and the magnetometer probe is connected to a host computer.

[0012] Includes the following formulas:

[0013]

[0014] Where VB is the magnetometer output signal output by the signal acquisition and processing module, A is the amplification factor, G is the conversion coefficient of the photodetector, e is the natural constant, OD is the optical depth, c is the speed of light, r is the classical electron radius, f is the alkali metal D1 line resonance intensity, n is the atomic number density, l is the atomic gas chamber length, I pr is the intensity of the detection light incident on the gas chamber, η represents the attenuation coefficient of the gas chamber glass to the detection light intensity, γ e represents the gyromagnetic ratio, v is the frequency of the laser, and v 0 is the resonance frequency of the alkali metal D1 line, Г is the pressure broadening of the atomic gas cell, R op is the pumping rate, R rel is the transverse relaxation rate, B z is the magnitude of the magnetic field to be measured.

[0015] The thin end of the magnetic field amplifier is tightly attached to the magnetic field input interface of the magnetometer probe through ultraviolet glue.

[0016] The distance between the thin end surface of the magnetic field collector and the surface of the magnetic sample to be measured is maintained at 1 mm to 1.5 mm.

[0017] The gas chamber electric heating module heats the alkali metal atom gas chamber so that the atomic density of the alkali metal vapor reaches 10 13 ~10 14 Pieces / cm 3 Magnitude.

[0018] The advantages of the present invention compared with the prior art are:

[0019] (1) Conventional SERF atomic magnetometers are limited by the volume of the atomic gas chamber itself, and usually have a spatial resolution of millimeters to centimeters. The present invention designs a structure of a magnetic flux guide-concentrator to converge the magnetic field to be measured, thereby improving the spatial resolution of the entire SERF atomic magnetometer magnetic measurement device to sub-millimeter level.

[0020] (2) Conventional SERF atomic magnetometers have high sensitivity, but because the magnetic field decays quadratically with distance, the information loss of the remote weak magnetic field is relatively large. The present invention guides the magnetic field to be measured to the vicinity of the SERF atomic magnetometer sensitive device through a magnetic flux guide-concentrator, and amplifies the magnetic field to be measured during the guiding process.

[0021] (3) Conventional flux guide-concentrators can only achieve the effect of guiding and amplifying the magnetic field or improving the spatial resolution. The present invention achieves amplification of the remote magnetic field and improvement of the spatial resolution through the design of the flux guide-concentrator structure. The cross-sectional area of ​​the part of the flux guide-concentrator that contacts the magnetic field to be measured is relatively small, which limits the range of the amplified magnetic field, thereby improving the spatial resolution; combined with the size of the gas chamber in the SERF atomic magnetometer, the magnetic field to be measured is amplified by designing the size of the magnetic field output cross-section, thereby achieving an improvement in the signal-to-noise ratio of the remote magnetic field measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a schematic diagram of the structure of a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator.

[0023] Figure 2 The present invention is a schematic diagram of the overall structure of a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator.

[0024] Figure 3 yes Figure 2 Schematic diagram of the connection structure between the three-dimensional translation stage and the magnetometer probe.

[0025] Figure 4 yes Figure 1 Medium or Figure 2 Schematic diagram of the magnetic flux guide-concentrator structure.

[0026] The reference numerals are as follows: 1-magnetic flux guide-concentrator; 2-magnetic sample to be measured; 3-magnetometer probe; 4-gas chamber electric heating module; 5-alkali metal atom gas chamber; 6-polarization-maintaining optical fiber; 7-data transmission line; 8-photoelectric measurement and control system; 9-host computer (receives magnetometer output signal); 10-three-dimensional displacement stage; 11-connecting rod; 12-magnetic shielding device; 13-magnetic field amplifier; 14-magnetic field transmitter; 15-magnetic field collector; Φ 1 is the diameter of the thin end of the magnetic field amplifier; Φ 2 is the diameter of the thick end of the magnetic field amplifier or the diameter of the magnetic field transmitter or the thick end diameter of the magnetic field collector; Φ 3 is the diameter of the thin end of the magnetic field collector; L 1 is the length of the magnetic field amplifier; L 2 is the length of the magnetic field transmitter; L 3 is the length of the magnetic field collector. DETAILED DESCRIPTION

[0027] Below is the attached figure ( Figure 1-Figure 4 ) and Examples illustrate the present invention.

[0028] Figure 1The present invention is a schematic diagram of the structure of a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator. Figure 2 The present invention is a schematic diagram of the overall structure of a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator. Figure 3 yes Figure 2 Schematic diagram of the connection structure between the three-dimensional translation stage and the magnetometer probe. Figure 4 yes Figure 1 Medium or Figure 2 Schematic diagram of the magnetic flux guide-concentrator structure. Figures 1 to 4 As shown, a SERF atomic magnetometer measurement device with integrated flux guide-concentrator includes a flux guide-concentrator 1 arranged on the magnetic field input interface of the magnetometer probe 3, the combination of the flux guide-concentrator 1 and the magnetometer probe 3 constitutes a magnetometer head with sub-millimeter spatial resolution, and the magnetometer head is connected to a three-dimensional displacement stage 10 via a connecting rod 11.

[0029] The magnetic flux guide-concentrator 1 includes a magnetic field collector 15 whose thin end is used to abut against the magnetic sample 2 to be measured, a magnetic field transmitter 14 axially extending from the thick end of the magnetic field collector 15, and a magnetic field amplifier 13 axially extending from the end face of the magnetic field transmitter 14 while radially contracting. The thin end of the magnetic field amplifier 13 is bonded to the magnetic field input interface of the magnetometer probe 3, and the end face scale of the thin end of the magnetic field amplifier 3 matches the end face scale of the alkali metal atom gas chamber 5 in the magnetometer probe 3. The magnetic flux guide-concentrator 1 is an integrated structure formed by soft ferrite, and the end face scale of the thin end of the magnetic field collector 15 is sub-millimeter. The magnetic field convergence and amplification effect of the magnetic flux guide-concentrator 1 is expressed as follows:

[0030]

[0031] Where A is the magnification factor, N is the demagnetization factor, which is related to the length L 1 , L 2 and L 3 Related physical quantities, L 1 is the length of the magnetic field amplifier, L 2 is the length of the magnetic field transmitter, L 3 is the length of the magnetic field collector, μ r is the relative magnetic permeability of the soft ferrite material, Φ 1 is the diameter of the thin end of the magnetic field amplifier; Φ 3 is the diameter of the thin end of the magnetic field collector.

[0032] The magnetometer probe 3 includes a shell, and a gas chamber electric heating module 4 is arranged in the shell, and the alkali metal atom gas chamber 5 is located in the gas chamber electric heating module 4. The magnetometer head is located in the magnetic shielding device 12, and the magnetometer probe 3 is respectively connected to the pumping laser module and the detection laser module in the photoelectric measurement and control system 8 through respective polarization-maintaining optical fibers 6, and the magnetometer probe 3 is connected to the signal acquisition and processing module in the photoelectric measurement and control system 8 through the data transmission line 7, and the magnetometer probe 3 is connected to the host computer 9.

[0033] Includes the following formulas:

[0034]

[0035] Where V B is the magnetometer output signal output by the signal acquisition and processing module, A is the amplification factor, G is the conversion coefficient of the photodetector, e is the natural constant, OD is the optical depth, c is the speed of light, r is the classical electron radius, f is the alkali metal D1 line resonance intensity, n is the atomic number density, l is the atomic gas chamber length, I pr is the intensity of the detection light incident on the gas chamber, η represents the attenuation coefficient of the gas chamber glass to the detection light intensity, γ e represents the gyromagnetic ratio, v is the frequency of the laser, and v 0 is the resonance frequency of the alkali metal D1 line, Г is the pressure broadening of the atomic gas cell, R op is the pumping rate, R rel is the transverse relaxation rate, B z is the magnitude of the magnetic field to be measured.

[0036] The thin end of the magnetic field amplifier 13 is attached to the magnetic field input interface of the magnetometer probe 3 by ultraviolet glue. The thin end surface of the magnetic field collector 15 is kept at a distance of 1 mm to 1.5 mm from the surface of the magnetic sample 2 to be measured. The gas chamber electric heating module 4 heats the alkali metal atom gas chamber 5 to make the atomic density of the alkali metal vapor reach 10 13 ~10 14 Pieces / cm 3 Magnitude.

[0037] The present invention proposes a SERF atomic magnetometer measurement device with an integrated magnetic flux guide-concentrator. The present invention designs a magnetic flux guide-concentrator structure, and uses the properties of soft ferrites and the geometric characteristics of the designed structure to achieve ultra-high sensitivity fT-level high-resolution submillimeter-level weak magnetic source magnetic field measurement. The instrument designed by the present invention uses a high-permeability soft ferrite with a specially designed geometric structure to change the distribution of the magnetic field in space, guide and amplify the weak magnetic field signal far away from the sensitive part of the SERF atomic magnetometer to the near end of the atomic source of the atomic magnetometer, thereby realizing the detection of the far-end weak magnetic field; at the same time, through the design of the cross section of the contact magnetic field to be measured, the spatial resolution of the SERF atomic magnetometer is improved. Compared with the conventional SERF atomic magnetometer, the present invention uses a magnetic flux guide-concentrator to improve the spatial resolution of the SERF atomic magnetometer from the centimeter level to the submillimeter level, and can simultaneously achieve the amplification of the magnetic field signal to be measured, and can achieve ultra-high sensitivity fT-level high-resolution submillimeter-level magnetic imaging.

[0038] Provided is a SERF atomic magnetometer measuring device with an integrated magnetic flux guide-concentrator, the components of which mainly include: a magnetic flux guide-concentrator (1), a magnetic sample to be measured (2), a magnetometer probe (3), an air chamber electric heating module (4), an alkali metal atom air chamber (5), a polarization-maintaining optical fiber (6), a data transmission line (7), an optoelectronic measurement and control system (8), a host computer (9), a three-dimensional displacement stage (10), a connecting rod (11), a magnetic shielding device (12), a magnetic field amplifier (13), a magnetic field transmitter (14), and a magnetic field collector (15). The magnetic flux guide-concentrator (1) is placed on the outside of the magnetometer probe (3), and the two are bonded by high-temperature ultraviolet glue, and the central axis of the magnetic flux guide-concentrator (1) and the central symmetry axis of the alkali metal atom air chamber (5) are on the same straight line; the magnetic flux guide-concentrator (1) and the magnetometer probe (3) containing the air chamber electric heating module (4) and the alkali metal atom air chamber (5) together form an atomic magnetometer probe with a sub-millimeter spatial resolution. Two laser beams generated by a narrow linewidth laser in an optoelectronic measurement and control system (8) are respectively introduced into a magnetometer probe (3) through polarization-maintaining optical fibers (6), wherein the pumping light incident from the polarization-maintaining optical fibers (6) is converted into circularly polarized light in the magnetometer probe (3) through polarization state conversion, and the alkali metal atoms in the gas chamber are pumped and polarized; the detection light incident from the polarization-maintaining optical fibers (6) is incident on the alkali metal atom gas chamber (5), and the emitted linearly polarized light generates an optical rotation angle, which is detected by using a differential detection technology and transmitted to the optoelectronic measurement and control system (8) by a data transmission line (7), and the data is preliminarily processed by a data acquisition and processing module, and the obtained magnetometer signal is transmitted to a host computer (9).

[0039] The magnetic flux guide-concentrator (1) is integrally processed from a soft magnetic material with high magnetic permeability, and its structure can be divided into: a magnetic field amplifier (13), a magnetic field transmitter (14), and a magnetic field collector (15). The geometric features of the magnetic field amplifier (13), the magnetic field transmitter (14), and the magnetic field collector (15) are respectively a truncated cone, a cylinder, and a cone, and the corresponding diameters are respectively: Φ 1 , Φ 2 , Φ 3 , the lengths are L 1 , L 2 , L 3 , and satisfy Φ 3 <Φ 1 <Φ 2 and Φ 1 and the side length of the alkali metal gas chamber (10), and in addition, Φ 3 The size is sub-millimeter, Φ 1 and Φ 2 The size condition is in the order of millimeters. The top of the magnetic field collector (15) determines the range in which the magnetic field to be measured is amplified, and the cross-sectional diameter of the top contacting the magnetic field to be measured is designed to be in the order of sub-millimeter; the magnetic field transmitter (14) plays the role of converging and guiding the magnetic field, and the size of its end face is respectively equal to the bottom surface of the magnetic field collector (15) and the magnetic field amplifier (13); the surface with a small cross-sectional area of ​​the magnetic field amplifier (13) faces the magnetometer probe (3), so that the magnetic field is converged and amplified before being emitted, and the diameter of the emission surface of the magnetic field amplifier (13) is similar to the size of the alkali metal gas chamber (5), so that the amplified magnetic field can be completely detected.

[0040] The photoelectric measurement and control system (8) is composed of a pumping narrow line width laser, a detection narrow line width laser and a signal acquisition preprocessing module. The pumping narrow line width laser and the detection narrow line width laser generate two laser beams for pumping atoms and detecting magnetic fields. The two laser beams enter the magnetometer probe (3) after passing through two polarization-maintaining optical fibers (6). The photoelectric measurement and control system (8) collects magnetic field information through a data transmission line (7), processes the signal using a data acquisition and processing module, and transmits the magnetometer output signal to a host computer (9) after processing.

[0041] The magnetometer probe (3) contains an air chamber electric heating module (4) and an alkali metal atom air chamber (5). The laser light incident through one of the polarization-maintaining optical fibers (6) is a pumping light whose polarization state is circularly polarized light, and performs pumping polarization on the alkali metal atoms in the alkali metal atom air chamber (10); and the laser light incident through another polarization-maintaining optical fiber (6) is a detection light whose polarization state is linearly polarized light.

[0042] The alkali metal atom gas chamber (5) is in a weak magnetic environment and is placed inside the gas chamber electric heating module (4). It is filled with alkali metal atoms and the atomic number density reaches 1013 ~10 14 Pieces / cm 3 The alkali metal atom gas chamber (5) is placed at the center of the gas chamber electric heating module (4), and the alkali metal atom gas chamber (5) is heated by the gas chamber electric heating module (4).

[0043] The magnetometer probe (3) and the magnetic flux guide-concentrator (1) form a magnetometer probe with sub-millimeter spatial resolution, and together with the photoelectric measurement and control system (8) form a magnetic measurement device.

[0044] The magnetometer probe (3) and the magnetic flux guide-concentrator (1) constitute a magnetometer probe with sub-millimeter spatial resolution. The magnetometer probe with sub-millimeter spatial resolution is placed in a magnetic shielding device (12) so that the working environment of the magnetometer probe (3) is a near-zero magnetic environment. The magnetic flux guide-concentrator (1) and the magnetometer probe (3) containing the gas chamber electric heating module (4) and the alkali metal atom gas chamber (5) together constitute an atomic magnetometer probe with sub-millimeter spatial resolution. The magnetic flux guide-concentrator (1) and the magnetometer probe (3) constitute an atomic magnetometer probe with sub-millimeter spatial resolution and are placed in a magnetic shielding device (12). The photoelectric measurement and control system (8), the three-dimensional displacement stage (10), and the connecting rod (11) are placed outside the magnetic shielding device (12).

[0045] One end of the connecting rod (11) is fixed on the three-dimensional displacement stage (10), and the other end is connected to the magnetometer probe (3). The platform of the three-dimensional displacement stage (10) is moved, and the magnetometer probe (3) can be moved in the xy plane through synchronous movement, thereby realizing two-dimensional spatial magnetic field distribution measurement. Movement in the z direction can realize the distance adjustment between the magnetometer probe (3) and the sample array (2) to be measured. The three-dimensional displacement stage (11) can move in the x direction and the y direction. One end of the connecting rod (11) is fixed on the platform of the three-dimensional displacement stage (10), and the magnetometer probe (3) is fixed on the other end of the connecting rod (11). When the platform of the three-dimensional displacement stage (10) is moved, the magnetometer probe (3) is synchronously moved, thereby realizing two-dimensional movement in the xy plane. The central axis of the magnetic flux guide-concentrator (1) is perpendicular to the plane where the magnetic sample to be measured (2) is located, and the position between the magnetic flux guide-concentrator (1) and the magnetic sample to be measured (2) is adjusted by a three-dimensional displacement stage (10) so that the distance between the two meets the range of 1 mm to 1.5 mm.

[0046] See also Figure 1 The present invention provides a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator. Figure 1As shown, a SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator comprises: a magnetic flux guide-concentrator 1, a magnetic sample to be measured 2, a magnetometer probe 3, an air chamber electric heating module 4, an alkali metal atom air chamber 5, a polarization-maintaining optical fiber 6, a data transmission line 7, an optoelectronic measurement and control system 8, and a host computer 9 for receiving the output signal of the magnetometer; the central axis of the magnetic flux guide-concentrator 1 is perpendicular to the horizontal plane where the magnetic sample to be measured 2 is located.

[0047] See also Figure 2 The present invention provides a SERF atomic magnetometer measuring device with an integrated magnetic flux guide-concentrator, wherein a three-dimensional displacement stage 10 can realize two-dimensional movement in an xy plane, one end of a connecting rod 11 is fixed to one end of the three-dimensional displacement stage 10, a magnetometer probe 3 is fixed to the other end of the connecting rod 11, and a magnetic flux guide-concentrator 1 is fixed to the outer shell of the magnetometer probe 3 by using a high-temperature ultraviolet glue, so that the central axis of the magnetic flux guide-concentrator 1 and the central symmetry axis of the alkali metal atom gas chamber 5 are in the same straight line; a magnetometer probe with a sub-millimeter spatial resolution formed by the magnetic flux guide-concentrator 1 and the magnetometer probe 3 is placed in a magnetic shielding device 12, and an optoelectronic measurement and control system 8, a connecting rod 11, and a three-dimensional displacement stage 10 are placed outside the magnetic shielding device 12;

[0048] See also Figure 3 The present invention provides a motion structure for realizing three-dimensional motion. Figure 3 As shown, one end of the connecting rod 11 is fixed to the motion platform of the three-dimensional translation stage 10, and the other end is connected to the magnetometer probe 3, so as to realize the synchronous movement between the magnetometer probe 3 and the three-dimensional translation stage 10;

[0049] See also Figure 4 The present invention provides a magnetic flux guide-concentrator structure. Figure 3 As shown, the structure with improved spatial resolution and magnetic field guidance amplification effect includes: a magnetic field amplifier 12, a magnetic field transmitter 13, and a magnetic field collector 14. The cross-sectional diameter of the magnetic field amplifier 12 is Φ 1 , length L 1 ; The cross-sectional diameter of the magnetic field transmitter 13 is Φ 2 , length L 2 ; The magnetic field collector 14 is the magnification range of the magnetic field to be measured by the cross-sectional diameter Φ 3 Determine that its length is L 3 ; and the diameter parameter satisfies: Φ 3 <Φ 1 <Φ 2 , where Φ 3 The size is sub-millimeter, Φ 1 and Φ 2 The size is in the order of millimeters.

[0050] like Figure 1, Figure 2 , Figure 3 and Figure 4 As shown, the specific implementation steps of the present invention are as follows:

[0051] (1) First, the preparation of the magnetic flux guide-concentrator is completed. A soft ferrite with high magnetic permeability and high Curie temperature is processed. The cross-sectional diameter of the magnetic field collector 15 is Φ 3 0.1mm, length L 3 1mm; the cross-sectional diameter of the magnetic field transmitter 14 is Φ 2 3mm, length L 2 1mm; the cross-sectional diameter of the magnetic field amplifier 13 is Φ 1 1mm, length L 1 2mm; the magnetic field convergence and magnification effect of the flux guide-concentrator is related to the above-mentioned structural geometric dimensions, and the magnification A can be expressed as:

[0052]

[0053] Where N is the demagnetization factor, which is related to the length L 1 , L 2 , L 3 Related physical quantities, μ r is the relative magnetic permeability of the soft ferrite material;

[0054] (2) The magnetic flux guide-concentrator 1 is placed outside the magnetometer probe 3, and the two are tightly attached with ultraviolet glue to form a magnetometer head with sub-millimeter spatial resolution; the alkali metal atom gas chamber 5 is heated by the gas chamber electric heating module 4 to make the atomic number density of the alkali metal vapor reach 10 13 ~10 14 Pieces / cm 3 Magnitude;

[0055] (3) Adjust the narrow line width semiconductor laser in the optoelectronic measurement and control system 8 so that the laser frequency of the pump light entering the magnetometer probe 3 through the polarization-maintaining optical fiber 6 is alkali metal D 1 The linear resonance frequency is converted into circularly polarized light through polarization state conversion in the detection head, polarizing the alkali metal atoms in the alkali metal atom gas chamber 5; the narrow line width semiconductor laser in the photoelectric measurement and control system 8 is adjusted to make the detection light laser frequency entering the magnetometer probe 3 through the polarization-maintaining optical fiber 6 detuned to the alkali metal D 1 The linear resonance frequency is 5GHz. The detection light is introduced into the alkali metal atom gas chamber 5. At this time, the linear polarized light will rotate in the polarization direction. The rotation angle is called the optical rotation angle θ. The optical information containing the magnetic field information is converted into electrical information by using the differential amplification technology. It is collected by the photoelectric measurement and control system 8 through the output transmission line 7. After being processed by the data acquisition and processing module, the magnetometer output signal V is output. B, expressed as:

[0056]

[0057] In the formula, G is the conversion coefficient of the photodetector, e is the natural constant, I pr is the intensity of the detection light incident on the gas cell, c is the speed of light, r is the classical electron radius, n is the atomic number density, f is the resonance intensity of the alkali metal D1 line, l is the length of the atomic gas cell, η represents the attenuation coefficient of the gas cell glass to the intensity of the detection light, and v 0 is the resonance frequency of the alkali metal D1 line, v is the frequency of the laser, Г is the pressure broadening of the atomic gas chamber, OD is the optical depth, γ e represents the gyromagnetic ratio, R op is the pumping rate, R rel is the transverse relaxation rate, G is the measurement magnification factor, B z is the magnitude of the magnetic field to be measured. Compared with the SERF atomic magnetometer magnetic measurement device without the magnetic flux guide-concentrator 1, the present invention increases the output response signal by A times, and realizes high-sensitivity measurement of the remote weak magnetic field;

[0058] (7) placing the magnetic sample 2 to be measured in the xy plane, using the three-dimensional translation stage 10 to adjust the position of the atomic magnetometer probe with sub-millimeter spatial resolution, so that the central axis of the magnetic flux guide-concentrator 1 is perpendicular to the xy plane, and adjusting the distance between the probe head and the plane where the magnetic sample 2 to be measured is located, so that the distance between the two is maintained within 1 mm to 1.5 mm;

[0059] (8) The magnetometer probe 3 is moved at a constant speed in the xy plane by using the three-dimensional displacement stage 10, so that it moves from one end of the magnetic sample 2 to the other end along the x direction, and the magnetometer output signal displayed by the host computer 9 is recorded, and then the magnetometer probe 3 is moved 0.3 mm along the y direction, and the above process is repeated at a constant speed again. The relationship between the magnetic field and the spatial position is plotted using the collected magnetometer output signal, so as to achieve the resolution of sub-millimeter remote weak magnetic sources.

[0060] In summary, the present invention provides a SERF atomic magnetometer measuring device with an integrated magnetic flux guide-concentrator, constructs a magnetic flux guide-concentrator that can increase the size of the magnetic field to be measured, and uses it to improve the spatial resolution and response signal of the SERF atomic magnetometer, and then uses the optical pumping principle and differential detection technology in the SERF atomic magnetometer to complete the measurement of the magnetic field. The present invention uses high-permeability soft ferrite to design a magnetic flux guide-concentrator, improves the spatial resolution of the SERF atomic magnetometer magnetic measurement device, and amplifies the magnetic field to be measured, and can perform high-sensitivity and accurate measurement of small-volume remote weak magnetic fields.

[0061] 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 SERF atomic magnetometer measuring device with integrated flux guide-concentrator, characterized in that: The invention comprises arranging a magnetic flux guide-concentrator on the magnetic field input interface of a magnetometer probe, wherein the combination of the magnetic flux guide-concentrator and the magnetometer probe constitutes a magnetometer head with sub-millimeter spatial resolution, and the magnetometer head is connected to a three-dimensional displacement stage through a connecting rod.

2. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 1, characterized in that: The magnetic flux guide-concentrator includes a magnetic field collector whose thin end is used to abut against a magnetic sample to be measured, a magnetic field transmitter axially extending from the thick end of the magnetic field collector, and a magnetic field amplifier axially extending from the end face of the magnetic field transmitter while radially contracting. The thin end of the magnetic field amplifier is bonded to the magnetic field input interface of the magnetometer probe, and the end face dimensions of the thin end of the magnetic field amplifier match the end face dimensions of the alkali metal atom gas chamber in the magnetometer probe.

3. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 2, characterized in that: The magnetic flux guide-concentrator is an integrated structure formed by soft ferrite. The end face scale of the thin end of the magnetic field collector is sub-millimeter. The magnetic field convergence and amplification effect of the magnetic flux guide-concentrator is expressed as follows: Where A is the magnification factor, N is the demagnetization factor, which is a physical quantity related to the lengths L1, L2 and L3. L1 is the length of the magnetic field amplifier, L2 is the length of the magnetic field transmitter, L3 is the length of the magnetic field collector, and μ r is the relative magnetic permeability of the soft ferrite material, Φ1 is the diameter of the thin end of the magnetic field amplifier; Φ3 is the diameter of the thin end of the magnetic field collector.

4. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 2, characterized in that: The magnetometer probe comprises a shell, a gas chamber electric heating module is arranged in the shell, and the alkali metal atom gas chamber is located in the gas chamber electric heating module.

5. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 1, characterized in that: The magnetometer head is located in the magnetic shielding device, the magnetometer probe is respectively connected to the pumping laser module and the detection laser module in the optoelectronic measurement and control system through respective polarization-maintaining optical fibers, the magnetometer probe is connected to the signal acquisition and processing module in the optoelectronic measurement and control system through a data transmission line, and the magnetometer probe is connected to a host computer.

6. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 3, characterized in that: Includes the following formulas: Where V B is the magnetometer output signal output by the signal acquisition and processing module, A is the amplification factor, G is the conversion coefficient of the photodetector, e is the natural constant, OD is the optical depth, c is the speed of light, r is the classical electron radius, f is the alkali metal D1 line resonance intensity, n is the atomic number density, l is the atomic gas chamber length, I pr is the intensity of the detection light incident on the gas chamber, η represents the attenuation coefficient of the gas chamber glass to the detection light intensity, γ e represents the gyromagnetic ratio, v is the frequency of the laser, v0 is the resonance frequency of the alkali metal D1 line, Г is the pressure broadening of the atomic gas chamber, and R op is the pumping rate, R rel is the transverse relaxation rate, B z is the magnitude of the magnetic field to be measured.

7. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 2, characterized in that: The thin end of the magnetic field amplifier is tightly attached to the magnetic field input interface of the magnetometer probe through ultraviolet glue.

8. The SERF atomic magnetometer measuring device with integrated magnetic flux guide-concentrator according to claim 2, characterized in that: The distance between the thin end surface of the magnetic field collector and the surface of the magnetic sample to be measured is maintained at 1 mm to 1.5 mm.

9. The SERF atomic magnetometer measuring device with integrated magnetic flux guider-concentrator according to claim 4, characterized in that: The gas chamber electric heating module heats the alkali metal atom gas chamber so that the atomic density of the alkali metal vapor reaches 10 13 ~10 14 Pieces / cm 3 Magnitude.

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