CN111983526B

CN111983526B - Atomic magnetometer and magnetic field imaging system

Info

Publication number: CN111983526B
Application number: CN202010856052.4A
Authority: CN
Inventors: 冯焱颖; 李晓杰
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2020-08-24
Filing date: 2020-08-24
Publication date: 2021-11-23
Anticipated expiration: 2040-08-24
Also published as: WO2022041701A1; CN111983526A

Abstract

The present application relates to an atomic magnetometer and a magnetic field imaging system. The laser with the first wavelength and the laser with the second wavelength are formed through a laser light source and a frequency doubling module. The optical power of the first wavelength laser is adjusted through the optical attenuation module, the non-magnetic light heating of the atomic gas chamber is achieved, and the attenuation is adjusted to control the temperature. And laser with a second wavelength enters the atomic gas chamber to realize magnetic field detection. Therefore, the atomic magnetometer can realize nonmagnetic heating and atomic pumping detection without coupling the heating laser and the pumping laser, and the complexity of a light path is reduced. A laser light source in the magnetic field imaging system is connected with a plurality of atomic magnetometer probes. Through the position information of a plurality of atomic magnetometer probes and the detected magnetic field information, the accurate positioning of the magnetic field position can be realized, so that the multi-dimensional magnetic field space reconstruction is realized.

Description

Atomic magnetometer and magnetic field imaging system

Technical Field

The application relates to the technical field of precision measurement equipment, in particular to an atomic magnetometer and a magnetic field imaging system.

Background

An atomic magnetometer is a sensor that precisely measures a weak magnetic field. Because the working condition of the atomic magnetometer does not require an ultralow temperature environment and has extremely high magnetic detection sensitivity, the atomic magnetometer gradually becomes an extremely low magnetic detection mode which can be compared with a superconducting quantum interference device in the field of low magnetic detection. The atomic magnetometer has advantages in aspects of system volume, distance between the atomic magnetometer and a measured body, power consumption and the like, and can be used in the field of cardio-cerebral magnetic imaging, and extremely-weak magnetic field detection caused by cardio-cerebral nerve current has important application value in detection of diseases such as coronary heart disease, epilepsy and the like, evaluation of cardio-cerebral health of newborns and the like.

The atomic magnetometer has many working modes, and the basic principle is that polarized alkali metal atoms are prepared by light through the interaction of light and atoms, and larmor (laror) precession of atomic electron spin under the action of an external magnetic field is detected, so that the sensing of the magnetic field is realized. In order to achieve sensitivity of the atomic magnetometer, the atomic magnetometer is generally operated under a Spin-exchange-relaxation-free (SERF) condition. At the moment, the gas chamber of the alkali metal atoms is heated to a certain high-temperature state to improve the atom number density of the alkali metal in the gas chamber, and the ambient magnetic field is reduced to be close to a zero magnetic field, finally, the Larmor precession frequency is far less than that of spin exchange relaxation, and the spin exchange relaxation is effectively inhibited. Therefore, the atomic magnetometer requires heating at a relatively high temperature, and it is ensured that the heating process does not generate excessive magnetic noise to reduce the sensitivity of the magnetometer.

However, the heating method of the conventional atomic magnetometer mainly includes a hot air heating method and an electric heating method. The heating of hot gas flow needs to be added with a gas flow source, and the gas flow source can generate certain hot gas flow fluctuation to influence the stability of the system. The electric heating method inevitably introduces certain magnetic field noise due to the heating current and the residual magnetism of the metal material. Therefore, interference factors are still introduced into the heating mode of the traditional atomic magnetometer to interfere the magnetic field, so that the detection accuracy of the atomic magnetometer is low.

Disclosure of Invention

Based on this, there is a need for an atomic magnetometer and magnetic field imaging system.

An atomic magnetometer is provided. The atomic magnetometer comprises a laser light source, a frequency doubling module, an atomic gas chamber and a light absorption module. The laser light source is used for emitting laser with a first wavelength. The frequency doubling module is arranged on a light path of the first wavelength laser and used for converting part of the first wavelength laser into second wavelength laser. The atomic gas chamber is arranged on the light path of the first wavelength laser. The light absorption module is arranged on a light path of the first wavelength laser. And the light absorption module is arranged on the surface of the atomic gas chamber and used for absorbing the first wavelength laser and converting the first wavelength laser into heat energy to heat the atomic gas chamber. The second wavelength laser is used for entering the atomic gas chamber and interacting with atomic gas in the atomic gas chamber to realize detection of magnetic field signals.

According to the atomic magnetometer and the magnetic field imaging system, after frequency multiplication is carried out by the frequency multiplication module, a part of laser is frequency multiplied to form frequency multiplication laser with the wavelength being half of the original wavelength. The other part of laser keeps the original wavelength, and the two parts of laser are transmitted on the same optical path. That is, the wavelength of the first wavelength laser light is twice the wavelength of the second wavelength laser light. And the first wavelength laser and the second wavelength laser share the same optical path for transmission. And the frequency doubling module is used for doubling the frequency of the original first wavelength laser to form the second wavelength laser. At this time, the second wavelength laser formed after the frequency doubling by the frequency doubling module corresponds to a resonance transition spectral line of the energy level of the sensitive gas.

The light absorption module is arranged on the surface of the atomic gas chamber and has strong absorption on the first wavelength laser. It is understood that the light absorption module absorbs laser light of a specific wavelength. The first wavelength laser can be strongly absorbed after passing through the light absorption module and is converted into heat for heating the atomic gas chamber.

And the second wavelength laser enters the gas chamber of the atom gas chamber, interacts with sensitive gas atoms in the gas chamber, and then outputs light to irradiate the photoelectric detection module through the focusing lens for detection so as to realize detection of the magnetic field signal. When the magnetic field changes, the optical power detected by the photoelectric detection module changes, so that a signal for measuring the magnetic field is obtained.

Therefore, the laser light source and the frequency doubling module with fixed wavelength can realize frequency doubling of the laser and output the first wavelength laser (original wavelength laser) and the second wavelength laser (frequency-doubled wavelength laser). The first wavelength laser (primary wavelength laser) is used for heating the atomic gas chamber. And the second wavelength laser (the wavelength laser after frequency doubling) is used for entering the atomic gas chamber to realize pumping and detection of the atomic magnetometer.

Therefore, the atomic magnetometer can meet the requirements of optical heating and optical pumping detection through one laser light source and one frequency doubling module. Compared with the traditional atomic magnetometer, the atomic magnetometer does not introduce an electric part which interferes with a magnetic field around the atomic gas chamber, so that the introduction of magnetic field noise is avoided. Meanwhile, the atomic magnetometer has a simple structure, reduces the number of devices, and is favorable for reducing the cost. In addition, the first wavelength laser and the second wavelength laser share the same path in the atomic magnetometer, so that the complexity of an optical system is reduced, and the system integration is facilitated.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an atomic magnetometer in an embodiment provided in the present application.

Fig. 2 is a schematic structural diagram of an atomic magnetometer in an embodiment provided in the present application.

Fig. 3 is a schematic diagram of a physical package structure of an atomic gas cell in an embodiment provided in the present application.

Fig. 4 is a schematic structural diagram of an atomic magnetometer in an embodiment provided in the present application.

Fig. 5 is a schematic diagram of a connection structure of the magnetic field control phase-locked amplifying module and the magnetic field modulation coil according to an embodiment of the disclosure.

Fig. 6 is a schematic structural diagram of an atomic magnetometer according to an embodiment of the present disclosure.

Fig. 7 is a schematic structural diagram of an atomic magnetometer in an embodiment provided in the present application.

Fig. 8 is a schematic diagram of a physical package structure of an atomic gas cell in an embodiment provided in the present application.

Fig. 9 is a schematic structural diagram of a magnetic field imaging system in an embodiment provided in the present application.

Fig. 10 is a schematic structural diagram of a position measurement control array and an atomic magnetometer probe in a magnetic field imaging system according to an embodiment of the present disclosure.

Description of reference numerals:

the atomic magnetometer 100, the laser light source 10, the frequency doubling module 20, the light attenuation module 30, the atomic gas cell 510, the light absorption module 520, the first light absorption structure 521, the second light absorption structure 522, the temperature detection module 530, the temperature control module 40, the photodetection module 60, the heating chamber 540, the magnetic field modulation coil 550, the first modulation coil 551, the second modulation coil 552, the bias magnetic field coil 560, the first bias coil 561, the second bias coil 562, the third bias coil 563, the magnetic field control phase-locked amplification module 80, the signal generation module 810, the phase shift module 820, the low-pass filter module 830, the light amplification module 710, the collimation module 720, the polarization module 730, the first quarter wave plate 740, the first light splitting module 910, the half wave plate 920, the second quarter wave plate 930, the magnetic field imaging system 200, the second light splitting module 201, the temperature control array 202, the magnetic field coil driving array 203, the polarization module 730, the second light absorption structure 522, the temperature detection module 530, the temperature control module 40, the photodetection module 60, the electromagnetic field control module 80, the electromagnetic field control module 810, the electromagnetic field modulation coil driving array, and the electromagnetic field module, The system comprises a signal acquisition processing array 204, a micro control module 205, an atomic magnetometer probe 206, a position measurement control array 207, a position sensing module 2071 and a displacement control module 2072.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. The first resistance and the second resistance are both resistances, but they are not the same resistance.

It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.

As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, as used in this specification, the term "and/or" includes any and all combinations of the associated listed items.

Referring to fig. 1, the present application provides an atomic magnetometer 100. The atomic magnetometer 100 comprises a laser light source 10, a frequency doubling module 20, an atomic gas cell 510 and a light absorption module 520. The laser light source 10 is used for emitting laser light with a first wavelength. The frequency doubling module 20 is disposed on an optical path of the first wavelength laser, and is configured to convert a part of the first wavelength laser into a second wavelength laser. The atomic gas cell 510 is disposed on the optical path of the first wavelength laser. The light absorption module 520 is disposed on the optical path of the first wavelength laser. And the light absorption module 520 is disposed on the surface of the atomic gas cell 510, and is configured to absorb the laser with the first wavelength and convert the laser into heat energy to heat the atomic gas cell 510. The second wavelength laser is used for entering the atomic gas cell 510 and interacting with atomic gas in the atomic gas cell 510 to detect a magnetic field signal.

In this embodiment, after the frequency doubling by the frequency doubling module 20, a part of the laser is frequency doubled to form a frequency doubled laser with a wavelength half of the original wavelength. The other part of laser keeps the original wavelength, and the two parts of laser are transmitted on the same optical path. That is, the wavelength of the first wavelength laser light is twice the wavelength of the second wavelength laser light. And the first wavelength laser and the second wavelength laser share the same optical path for transmission.

The atomic gas cell 510 contains a sensitive gas (e.g., alkali metal atoms) and a buffer gas (e.g., nitrogen). The original first wavelength laser light (such as the laser light with the 1590nm wavelength) is frequency-doubled by the frequency doubling module 20 to form the second wavelength laser light (such as the laser light with the 795nm wavelength). At this time, the second wavelength laser (for example, the wavelength is 795nm) formed after the frequency doubling by the frequency doubling module 20 corresponds to a resonance transition spectral line of the energy level of the sensitive gas (for example, rubidium atoms).

The light absorption module 520 is disposed on the surface of the atomic gas cell 510, and has strong absorption to the first wavelength laser. It is understood that the light absorption module 520 absorbs laser light of a specific wavelength. The laser light with the first wavelength is strongly absorbed after passing through the light absorption module 520, and is converted into heat for heating the atomic gas cell 510.

The second wavelength laser enters the gas chamber of the atom gas chamber 510, and after interaction with the sensitive gas atoms in the gas chamber, output light irradiates the photoelectric detection module through the focusing lens for detection. When the magnetic field changes, the optical power detected by the photoelectric detection module changes, so that a signal for measuring the magnetic field is obtained.

Therefore, the laser light source 10 and the frequency doubling module 20 with a fixed wavelength can double the frequency of the laser light and output the first wavelength laser (original wavelength laser) and the second wavelength laser (frequency-doubled wavelength laser). The first wavelength laser (primary wavelength laser) is used to heat the atomic gas cell 510. The second wavelength laser (wavelength laser after frequency doubling) is used to enter the atomic gas cell 510, so as to realize pumping and detection of the atomic magnetometer.

Therefore, the atomic magnetometer 100 of the present application can meet the requirements of optical heating and optical pumping detection through one of the laser light sources 10 and one of the frequency doubling modules 20. Compared with the traditional atomic magnetometer, the atomic magnetometer 100 does not introduce an electrical part which interferes with the magnetic field around the atomic gas chamber, and the introduction of magnetic field noise is avoided. Meanwhile, the atomic magnetometer 100 has a simple structure, reduces the number of devices, and is beneficial to reducing the cost. In addition, in the atomic magnetometer 100, the first wavelength laser and the second wavelength laser share a common path, so that the complexity of an optical system is reduced, and system integration is facilitated.

In one embodiment, the atomic cell 510 is a closed glass chamber or other closed chamber with a light-transmissive window that contains a sensitive gas (e.g., alkali metal atoms) and a buffer gas (e.g., nitrogen).

In one embodiment, the frequency doubling module 20 is a Periodically Poled Lithium Niobate (PPLN) crystal. The light-passing wavelength range of the Periodically Poled Lithium Niobate (PPLN) crystal is 0.4 μm-5 μm. At this time, the Periodically Poled Lithium Niobate (PPLN) crystal has low scattering and absorption in the visible and infrared band range, and can better realize laser frequency doubling.

In one embodiment, the light absorption module 520 includes a first light absorption structure 521 and a second light absorption structure 522. The first light absorbing structure 521 and the second light absorbing structure 522 are disposed on two opposite surfaces of the atomic gas cell 510. The first wavelength laser passes through the first light absorption structure 521, the atomic gas cell 510, and the second light absorption structure 522 in sequence.

In this embodiment, the first light absorbing structure 521 and the second light absorbing structure 522 can be used to heat the atomic gas cell 510 from two sides. The first light absorbing structure 521 and the second light absorbing structure 522 have strong absorption for the first wavelength laser light. When the laser light with the first wavelength passes through the first light absorption structure 521 and the second light absorption structure 522 in sequence, the laser light with the first wavelength is absorbed by the first light absorption structure 521 and the second light absorption structure 522 in sequence. Meanwhile, the sensitive gas in the atomic gas cell 510 interacts with the laser with the second wavelength, and the laser with the first wavelength does not interfere with the sensitive gas.

In one embodiment, the outer wall of the chamber (the surface away from the sensitive gas) of the atomic gas cell 510 is provided with the first light absorbing structure 521 and the second light absorbing structure 522. The first light absorption structure 521 and the second light absorption structure 522 are arranged on the outer walls of the two side chambers of the atomic gas cell 510 by means of bonding.

In one embodiment, the first light absorbing structure 521 and the second light absorbing structure 522 are heated glass. The heating glass is bonded to the surface of the atomic gas cell 510. The heating glass has strong absorption to the first wavelength laser (1590nm laser), and the second wavelength laser can penetrate through the heating glass with higher efficiency.

In one embodiment, the thickness of the second light absorbing structure 522 is greater than the thickness of the first light absorbing structure 521.

In this embodiment, the first wavelength laser passes through the first light absorption structure 521, the atomic gas cell 510, and the second light absorption structure 522 in sequence. The second light absorption structure 522 is disposed at the rear side of the atomic gas cell 510, and is thicker than the first light absorption structure 521, so that the laser efficiency of absorption and heating at the front side and the rear side can be the same, and the absorbed laser energy is converted into heat energy to directly heat the atomic gas cell uniformly.

Referring to fig. 2, in one embodiment, the atomic magnetometer 100 further comprises a light attenuation module 30, a temperature detection module 530 and a temperature control module 40. The light attenuation module 30 is disposed in an optical path of the first wavelength laser, and is configured to adjust power of the first wavelength laser. The temperature detection module 530 is disposed on the surface of the atomic gas cell 510, and is configured to monitor the real-time measured temperature of the atomic gas cell 510. The monitoring end of the temperature control module 40 is connected to the temperature detection module 530 for obtaining the real-time measured temperature. The control end of the temperature control module 40 is connected to the optical attenuation module 30, and is configured to regulate and control the optical attenuation module 30 to change the power of the first wavelength laser according to the real-time measured temperature.

In this embodiment, the optical attenuation module 30 is configured to adjust the optical power of the laser light with the first wavelength, and it can be understood that the optical attenuation module 30 attenuates the laser light with a specific wavelength. The optical power of the first wavelength laser injected into the optical absorption module 520 can be adjusted by the optical attenuation module 30, so as to adjust the temperature of the atomic gas cell 510.

The first wavelength laser and the second wavelength laser after passing through the frequency doubling module 20 pass through the optical attenuation module 30 with wavelength selectivity to adjust the power of the un-doubled wavelength laser. The temperature detection module 530 can monitor the temperature of the atomic gas cell 510 in real time and convert the real-time measured temperature into an electrical signal to be transmitted to the temperature control module 40. The temperature control module 40 compares the real-time measured temperature with a target temperature to obtain a temperature difference. Meanwhile, the temperature control module 40 regulates and controls the light attenuation module 30 through a PID controller to change the power of the first wavelength laser, thereby realizing the temperature control of the atomic gas cell 510.

In one embodiment, the temperature control module 40 includes a feedback control module (not shown). The feedback control module is configured to compare the real-time measured temperature with a target temperature, and adjust and control the optical attenuation module 30 by using a feedback control method to change the power of the first wavelength laser. The feedback control module includes, but is not limited to, a Micro Controller Unit (MCU), a Central Processing Unit (CPU), an embedded Microcontroller (MCU), an embedded Microprocessor (MPU), and an embedded System On Chip (SOC).

In one embodiment, the temperature control module 40 controls the angle of a 1590nm filter (variable light attenuation panel) with a linearly variable filter efficiency. Alternatively, the temperature control module 40 controls the polarization angle of the linearly polarized light before the beam splitter of the Polarization Beam Splitter (PBS), so as to regulate the optical power (heating laser optical power) of the first wavelength laser injected onto the surface of the atomic gas cell 510, thereby achieving the temperature control of the atomic gas cell 510.

In one embodiment, the temperature detection module 530 may be a temperature sensor, such as a nonmagnetic platinum resistor.

In one embodiment, the atomic magnetometer 100 further comprises a photodetection module 60. The photodetection module 60 is disposed on the light path of the second wavelength laser, and is configured to receive the second wavelength laser after passing through the atomic gas cell 510.

In this embodiment, the second wavelength laser enters the gas chamber of the atom gas chamber 510, and after interaction with the sensitive gas atoms in the gas chamber, the output light irradiates the photoelectric detection module 60 through the focusing lens for detection. When the magnetic field changes, the optical power detected by the photodetection module 60 changes, so as to obtain a signal of magnetic field measurement.

Referring to FIG. 3, in one embodiment, the atomic magnetometer 100 further comprises a heating chamber 540, a magnetic field modulating coil 550, and a bias magnetic field coil 560. The heating chamber 540 surrounds and forms a heating space. The light absorption module 520, the atomic gas cell 510, and the temperature detection module 530 are disposed in the heating space. The magnetic field modulation coil 550 is disposed around the heating chamber 540 for modulating a magnetic field in a certain direction. The bias magnetic field coil 560 is disposed around the heating chamber 540 for nulling the magnetic field of the atomic gas cell 510 in the absence of a magnetic signal.

In this embodiment, the heating chamber 540 forms a heat shielding layer to ensure the temperature of the heating space to be stable. The temperature detection module 530 is disposed in the heating chamber 540 and on the outer sidewall of the atom gas cell 510, and can monitor the temperature of the atom gas cell 510 in real time. The magnetic field modulation coil 550 may be a two-dimensional magnetic field modulation coil, which is disposed around the heating chamber 540 for modulating a magnetic field in a certain direction. The bias magnetic field coil 560, which may be a three-dimensional bias magnetic field coil, is disposed around the heating chamber 540 for compensating the influence of residual magnetic field (e.g., geomagnetic field) in the atomic gas cell 510, so that the magnetic field of the atomic gas cell 510 is set to zero when there is no magnetic signal.

Referring to fig. 3, 4 and 5, in one embodiment, the magnetic field modulation coil 550 includes a first modulation coil 551 and a second modulation coil 552.

In this embodiment, the first modulation coil 551 and the second modulation coil 552 are both disposed in a direction perpendicular to the optical path direction of the second wavelength laser light, and perform modulation from two directions, as shown in fig. 4.

In one embodiment, the atomic magnetometer 100 further comprises a physically encapsulated outer cavity (not shown), which is selected from non-metallic materials having low thermal conductivity. The atomic gas cell 510, the heating chamber 540, the magnetic field modulation coil 550, and the bias magnetic field coil 560 are held in place by physically enclosing external cavities. Meanwhile, a high-temperature working environment is provided for the atomic gas chamber 510 through a physical encapsulation external cavity, so that the atomic magnetometer 100 meets the SERF working condition. Wherein the magnetic field modulation coil 550 and the bias magnetic field coil 560 are fixed to the physically enclosed external cavity surface containing the atomic gas cell 510. The magnetic field modulation coil 550 and the bias magnetic field coil 560 are of a helmholtz coil structure.

The atomic magnetometer 100 needs to work near a zero magnetic field, and the bias magnetic field coil 560 is fixed on the surface of the physically-encapsulated external cavity of the atomic gas chamber 510, so as to compensate the influence of the residual magnetic field (such as the geomagnetism) in the atomic gas chamber 510, and to set the magnetic field of the atomic gas chamber 510 to zero when there is no magnetic signal.

At this time, in the atomic magnetometer 100, the atomic gas cell 510, the first light absorption structure 521 (heated glass), the second light absorption structure 522 (heated glass), the temperature detection module 530 (temperature sensor), the magnetic field modulation coil 550 (two-dimensional magnetic field modulation coil), and the bias magnetic field coil 560 (three-dimensional compensation coil) form a sensitive component for realizing magnetic field measurement.

Referring to FIG. 5, in one embodiment, the atomic magnetometer 100 further comprises a signal generating module 810. The signal generating module 810 is configured to generate two paths of modulation signals with the same frequency. The signal generating module 810 is connected to the magnetic field modulation coil 550, and is configured to modulate a magnetic field in a certain direction by using a path of modulation signal.

In this embodiment, the signal generating module 810 outputs two paths of sine waves or square waves with the same frequency to form two paths of modulation signals with the same frequency. One path of modulation signal is output to one of the magnetic field modulation coils 550 (two-dimensional magnetic field modulation coil) for realizing modulation of a magnetic field in a certain direction.

In one embodiment, the signal generating module 810 is a signal generator for outputting a sine wave or square wave signal.

In one embodiment, the atomic magnetometer 100 further comprises a phase shifting module 820 and a low pass filtering module 830. A first input terminal of the phase shift module 820 is connected to the signal generating module 810. A second input end of the phase shift module 820 is connected to the output end of the photodetection module 60, and is configured to modulate the magnetic field detection signal by another modulation signal. The low-pass filtering module 830 is connected to the output end of the phase shifting module 820, and is configured to perform phase-locked amplification on the modulated magnetic field detection signal and output the phase-locked amplified magnetic field detection signal.

In this embodiment, the magnetic field detection signal received by the photodetection module 60 includes magnetic field information. The other path of modulation signal output by the signal generation module 810 is multiplied by the magnetic field detection signal through the phase shift module 820, so as to modulate the magnetic field detection signal. The modulated magnetic field detection signal passes through the low-pass filtering module 830, and then the phase-locked amplified output of the magnetic field signal is realized. Therefore, the signal-to-noise ratio of the magnetic field detection signal is improved through phase-locked amplification output.

In one embodiment, the phase shifting module 820 is a phase shifter. The low pass filtering module 830 is a low pass filter.

Referring to fig. 4, in one embodiment, the atomic magnetometer 100 further comprises a light amplifying module 710, a collimating module 720, a polarizing module 730, and a first quarter wave plate 740. The optical amplification module 710 is disposed on an optical path of the first wavelength laser light, and configured to amplify the first wavelength laser light. The collimating module 720 is disposed on a light path of the first wavelength laser, and is configured to collimate the first wavelength laser and the second wavelength laser formed after passing through the frequency doubling module 20. The polarization module 730 is disposed on the optical path of the first wavelength laser light, and is configured to polarize the second wavelength laser light passing through the optical attenuation module 30. The first quarter wave plate 740 is disposed on a light path of the first wavelength laser, and is configured to convert the second wavelength laser after passing through the polarization module 730 to form circularly polarized light.

In this embodiment, the first wavelength laser light (e.g., 1590nm laser light) output by the laser light source 10 generally has a small output optical power. Amplified by the optical amplification module 710, thereby increasing the laser power of the first wavelength laser (e.g., 1590nm laser). The amplified first wavelength laser light (e.g., 1590nm laser light) is input into the frequency doubling module 20. The second wavelength laser (795nm laser) is formed by the frequency doubling module 20 doubling the wavelength of the first wavelength laser (e.g., 1590nm laser). At this time, the frequency-doubled second wavelength laser (795nm laser) corresponds to a resonance transition line of the energy level of the sensitive gas (e.g., rubidium atoms) in the atomic gas cell 510.

The first wavelength laser and the second wavelength laser after passing through the frequency doubling module 20 are collimated into parallel beams by the collimating module 720, so that the parallel beams irradiate the atomic gas cell 510.

The first wavelength laser and the second wavelength laser after passing through the collimating module 720 regulate and control the optical power of the first wavelength laser through the optical attenuation module 30. After the first wavelength laser and the second wavelength laser which pass through the light attenuation module 30 are coupled by an optical fiber, sequentially pass through the polarization module 730 (polarizer of the second wavelength laser) and the first quarter wave plate 740, pass through the window of the atomic gas chamber 510, are injected into the atomic gas chamber 510, and interact with the sensitive gas.

The second wavelength laser sequentially passes through the polarization module 730 and the first quarter wave plate 740 to enter the atomic gas cell 510, so that a light path structure of a common path of the detection light and the pump light is formed.

For the optical path structure of the common path of the probe light and the pump light, the laser light with the second wavelength (for example, laser light with 795nm) passing through the optical attenuation module 30 passes through the polarization module 730 and the first quarter wave plate 740 with corresponding wavelengths, and is converted into circularly polarized light. At this time, the spin polarization direction of the circularly polarized light is the same as the direction of light beam propagation. The laser with the second wavelength (such as 795nm laser) passes through the first light absorption structure 521 (heating glass) and the glass gas chamber window of the atomic gas chamber 510 in sequence with high efficiency and enters the atomic gas chamber 510. The second wavelength laser (e.g., 795nm laser) interacts with the rubidium atom gas within the atomic gas cell 510.

Under the action of the magnetic field, the atomic spin and the detection light interact to change the polarization characteristic of the atomic gas, so that the polarization direction of the light is deflected, and the light power is changed. Thus, the circularly polarized light passing through the atomic gas cell 510 (i.e., the output light of the atomic gas cell 510) is received by the photodetection module 60 through the focusing lens. Or, the output light of the atomic gas cell 510 is coupled into an optical fiber through a fiber coupling head. At the other end of the fiber is detected by the photodetection module 60. The photo detection module 60 converts the optical signal into an electrical signal for analyzing and calculating to obtain a signal for measuring the magnetic field.

Therefore, the atomic magnetometer 100 in this application can output a laser component including a primary wavelength and a frequency-doubled laser component through one of the laser light sources 10 and one of the frequency doubling modules 20. The laser component of the primary wavelength is used to heat the atomic gas cell. And the laser component with the wavelength after frequency doubling is used for realizing pumping and detection of the atomic magnetometer.

In one embodiment, the laser light source 10 is a laser. The polarization module 730 is a polarizer. The optical amplification module 710 is an optical amplifier, and may be an erbium-doped fiber amplifier. The collimating module 720 is a nonmagnetic fiber collimator.

In one embodiment, the laser, the optical amplifier and the frequency doubling crystal can be all in a crystal-optical fiber integrated structure. And the laser and other amplification frequency doubling components are connected through the optical fiber adapter. The broadband high-power single-mode polarization maintaining fiber can simultaneously meet the transmission requirements of the first wavelength laser (1590nm laser) and the second wavelength laser (795nm laser), and is simple in structure and convenient to integrate and package.

Referring to fig. 6, in one embodiment, the atomic magnetometer 100 further comprises a first light splitting module 910, a half waveplate 920 and a second quarter waveplate 930. The first light splitting module 910 is disposed on an optical path of the second wavelength laser light, and is configured to split the second wavelength laser light passing through the light attenuation module 30 into pump light and probe light that are perpendicular to each other. The half wave plate 920 is disposed on the optical path of the detection light, and is used for adjusting the polarization angle of the detection light. The probe light after passing through the half wave plate 920 enters the atomic gas cell 510. The second quarter wave plate 930 is disposed on the optical path of the pump light, and is configured to convert the pump light into pump circularly polarized light. The pump light after passing through the second quarter wave plate 930 enters the atomic gas cell 510.

In this embodiment, the second wavelength laser beam forms two mutually perpendicular optical paths through the first light splitting module 910. One path is the detection light, and the detection light enters the atomic gas cell 510 through the half wave plate 920. The other path is the pumping light, which enters the atomic gas cell 510 through the second quarter-wave plate 930. Thus, an optical path structure in which the probe light and the pump light are perpendicular is formed by the first light-splitting module 910, the half-wave plate 920, and the second quarter-wave plate 930.

For the optical path structure where the probe light and the pump light are perpendicular to each other, the second wavelength laser light (e.g. 795nm laser light) passing through the optical attenuation module 30 is split into two paths by the first light splitting module 910 with corresponding wavelengths. Wherein, one path of pumping light is converted into circularly polarized light by the second quarter-wave plate 930 and irradiated into the atomic gas cell 510 for optical pumping. And the other path of probe light perpendicular to the pump light is used for adjusting the polarization angle of the linearly polarized light before entering the atomic gas cell 510 through the half-wave plate 920. The detection light passing through the half-wave plate 920 irradiates onto the atomic gas polarized by the pump light pump, and is detected and received by the photoelectric detection module 60.

When the magnetic field changes, the optical power detected by the photodetection module 60 changes, so as to obtain a signal of magnetic field measurement. The atomic magnetometer 100 adopts a light path structure in which the detection light and the pump light are perpendicular, and enters the atomic gas chamber 510 from two directions, so that the magnetic field detection precision is improved.

In one embodiment, the first light splitting module 910 is a light splitting prism with wavelength selectivity, and is used for splitting the second wavelength laser light (such as 795nm laser light).

Referring to fig. 7, in an embodiment, for an optical path structure where the detection light and the pump light are perpendicular, a relative position relationship between the laser light source 10, the light amplification module 710, the frequency doubling module 20, the collimation module 720, the light attenuation module 30, the temperature control module 40, the magnetic field control phase-locked amplification module 80, and the photoelectric detection module 60 is the same as an optical path structure where the detection light and the pump light are in a common path, which can be referred to in the above embodiments.

In one embodiment, for the optical path structure where the probe light and the pump light are perpendicular, the magnetic field modulation coil 550 is disposed perpendicular to the probe light direction, and performs modulation from one direction, as shown in fig. 7 and 8. The signal generating module 810 is connected to the magnetic field modulation coil 550, and is configured to modulate a magnetic field in a certain direction by a path of modulation signal.

In one embodiment, the bias magnetic field coil 560 includes a first bias coil 561, a second bias coil 562, and a third bias coil 563 respectively disposed perpendicular to the optical path and distributed in different directions. The bias field coil 560 is connected to a constant current source. And is output to the bias magnetic field coil 560 (three-dimensional bias magnetic field coil) through a constant current source for magnetic field zero clearing.

The spin polarization direction of the pump light is coincident with the light transmission direction. The scanning magnetic field scans around a zero magnetic field, which affects the polarization properties of light according to the Hanle effect. After the photodetection module 60 receives the output light from the atomic gas cell 510, it detects the absorption peak at the zero magnetic field position. The signal generating module 810 modulates the magnitude of the magnetic field, and then the signal is demodulated by the phase-locked amplifying loop, and PID feedback control is performed to the zero field position. Thus, the calibration magnetic field and the feedback signal are used for accurate magnetic field measurement.

Referring to FIG. 9, in one embodiment, the present application provides a magnetic field imaging system 200. The magnetic field imaging system 200 includes a laser light source 10, a frequency doubling module 20, a second light splitting module 201, and a plurality of atomic magnetometer probes 206. The laser light source 10 is used for emitting laser light with a first wavelength. The frequency doubling module 20 is disposed on an optical path of the first wavelength laser, and is configured to convert a part of the first wavelength laser into a second wavelength laser. The second light splitting module 201 is disposed on an optical path of the first wavelength laser light, and is configured to split the first wavelength laser light into a plurality of first wavelength sub-beams and split the second wavelength laser light into a plurality of second wavelength sub-beams. Wherein one of said first wavelength sub-beams is co-optically coupled with one of said second wavelength sub-beams.

Each of the atomic magnetometer probes 206 includes a light attenuation module 30, an atomic gas cell 510, and a light absorption module 520. The atomic gas cell 510 is disposed on the optical path of the first wavelength sub-beam. Each of the light attenuation modules 30 is disposed on the light path of the first wavelength sub-beam, and is configured to adjust the power of the first wavelength sub-beam. The light absorption module 520 is disposed on the light path of the first wavelength sub-beam. And the light absorption module 520 is disposed on the surface of the atomic gas cell 510, and is configured to absorb the first wavelength sub-beam and convert the first wavelength sub-beam into heat energy to heat the atomic gas cell 510. The second wavelength sub-beams are configured to enter the atomic gas cell 510 and interact with the atomic gas in the atomic gas cell 510.

In this embodiment, one of the laser light sources 10 outputs the laser light of the first wavelength. The first wavelength laser and the second wavelength laser are formed after passing through the frequency doubling module 20. And the second wavelength laser corresponds to atomic energy level resonance transition and is one half of the wavelength of the first wavelength laser. The first wavelength laser and the second wavelength laser share a light path and are transmitted on the same light path. A plurality of light paths are formed by the second light splitting module 201, and the plurality of light paths are connected to a plurality of the atomic magnetometer probes 206. Therefore, a plurality of the atomic magnetometer probes 206 share the same laser as a light source.

The laser light source 10 outputs the first wavelength laser light (1590nm laser light). The first wavelength laser (1590nm laser) passes through the frequency doubling module 20 to form a laser component containing both the first wavelength laser (1590nm) and the second wavelength laser (795nm laser). Laser light of two different wavelengths is split by the second light splitting module 201 to form multiple light channels, and is connected to the plurality of atomic magnetometer probes 206. The laser with the second wavelength (795nm laser) enters the atom gas chamber 510 in the atomic magnetometer probe 206 to interact with atoms, so that the measurement of a magnetic field signal is realized.

When performing magnetic brain imaging by the magnetic field imaging system 200, a helmet to be worn on the head to fix the plurality of atomic magnetometer probes 206 can be prepared according to the shape of the brain. A plurality of the atomic magnetometer probes 206 are mechanically clamped at the locations where magnetic field measurements are to be taken. At this time, an atomic magnetometer probe array is formed on the surface of the brain to measure the magnitude of the magnetic field at the position of the probe.

Therefore, the magnetic field imaging system 200 forms an atomic magnetometer array by a single laser light source, the frequency doubling module 20, the second light splitting module 201, and the atomic magnetometer probe 206, and can simultaneously realize optical heating and magnetic field detection. Meanwhile, since the lasers in the atomic magnetometer probes 206 all come from the same laser light source, the magnetic field imaging system 200 has good common-mode noise rejection, and can obtain a magnetic field image with lower noise. Moreover, the plurality of atomic magnetometer probes 206 share one laser light source 10 and one frequency doubling module 20, so that the preparation cost can be reduced.

In one embodiment, the second light splitting module 201 is a fiber optic splitter. After the second wavelength laser (795nm laser) enters the atom gas chamber 510 in the atomic magnetometer probe 206 and interacts with atoms, the output laser is received by the photoelectric detection module 60.

In one embodiment, the photodetection module 60 may be integrated within the atomic magnetometer probe 206. Alternatively, the laser output from the atomic gas cell 510 in the plurality of atomic magnetometer probes 206 is coupled out of the probe by a fiber coupling head, and is connected to the plurality of photoelectric detection modules 60.

Referring to FIG. 9, in one embodiment, the magnetic field imaging system 200 further includes a temperature control array 202. The temperature control array 202 is respectively connected to the plurality of atomic magnetometer probes 206, and is configured to regulate and control the atomic magnetometer probes 206 so as to change the power of the first wavelength sub-beam.

In this embodiment, a plurality of the temperature control modules 40 form the temperature control array 202. Each of the temperature control modules 40 is connected to each of the atomic magnetometer probes 206 in a one-to-one correspondence manner, and is configured to regulate and control the atomic magnetometer probes 206 so as to change the power of the first wavelength sub-beam. The power of the first wavelength sub-beam is the optical power of the heating laser that heats the atomic gas cell 510.

In one embodiment, each of the atomic magnetometer probes 206 also includes at least the polarization module 730, the first quarter wave plate 740, the temperature detection module 530, the heating chamber 540, the magnetic field modulation coil 550, the bias magnetic field coil 560, and the like, as discussed in the previous embodiments.

Alternatively, each atomic magnetometer probe 206 further comprises at least the first light splitting module 910, the half wave plate 920, the second quarter wave plate 930, the temperature detecting module 530, the heating chamber 540, the magnetic field modulating coil 550, the bias magnetic field coil 560, and the like, which are involved in the above embodiments.

The monitoring end of each temperature control module 40 is connected to the temperature detection module 530 for obtaining the real-time measured temperature. The control end of each temperature control module 40 is connected to the light attenuation module 30, and is configured to compare the real-time measured temperature with the target temperature, and regulate and control the light attenuation module 30 by using feedback control to change the power of the first wavelength sub-beam, so as to achieve temperature regulation.

Thus, each of the atomic magnetometer probes 206 is positioned in one-to-one correspondence with each of the temperature control modules 40. The plurality of temperature control modules 40 form the temperature control array 202 to actively regulate the temperature of the plurality of atomic magnetometer probes 206 as a whole, that is, actively regulate the temperature of the atomic gas cell 510 to be stable within a certain range.

Referring to FIG. 10, in one embodiment, the magnetic field imaging system 200 further includes a position measurement control array 207. The position measurement control array 207 includes a plurality of position sensing modules 2071 and a plurality of displacement control modules 2072. Each of the position sensing modules 2071 is disposed on each of the atomic magnetometer probes 206 and is used for measuring the spatial position of the atomic magnetometer probe 206. Each displacement control module 2072 is disposed on each atomic magnetometer probe 206 and is configured to control the displacement of the atomic magnetometer probe 206.

In this embodiment, during magnetic field measurement and imaging, the plurality of atomic magnetometer probes 206 are fixed and arranged to form a probe array according to the magnetic field spatial structure of the object to be measured. Meanwhile, the spatial position of the magnetic field measured by the atomic magnetometer probe 206 is measured by the position sensing module 2071. The atomic magnetometer probe 206 is subjected to a small displacement adjustment by the displacement control module 2072.

Each of the atomic magnetometer probes 206 is provided with the position sensing module 2071 and the displacement control module 2072, and measures and adjusts the spatial position of the magnetic field measured by the atomic magnetometer probe 206. Therefore, the space in the magnetic field imaging process can be positioned through the spatial position of the measured magnetic field.

In one embodiment, the position sensing module 2071 is a position sensor, such as an optoelectronic position sensor. The displacement control module 2072 is a displacement controller.

Referring to fig. 9, in one embodiment, the magnetic field imaging system 200 further includes a signal acquisition processing array 204. The signal acquisition processing array 204 includes a plurality of signal acquisition processing modules (not shown). Each signal acquisition processing module is connected to each position sensing module 2071, and is configured to acquire a spatial position of the atomic magnetometer probe 206. Each signal acquisition processing module is connected to each displacement control module 2072, and is configured to regulate and control the displacement of the atomic magnetometer probe 206. Each signal acquisition processing module is connected with the output end of each atomic magnetometer probe 206 and is used for acquiring the magnetic field signal detected by the atomic magnetometer probe 206.

In this embodiment, the magnetic field signal detected by each atomic magnetometer probe 206 and the spatial position information of each atomic magnetometer probe 206 are transmitted to each signal acquisition and processing module. The signal acquisition processing module includes, but is not limited to, a Micro Control Unit (MCU), a Central Processing Unit (CPU), an embedded Microcontroller (MCU), an embedded Microprocessor (MPU), and an embedded System On Chip (SOC).

Referring to fig. 9, in one embodiment, the magnetic field imaging system 200 further includes a magnetic field coil driver array 203. The magnetic field coil drive array 203 includes a plurality of magnetic field controlled lock-in amplification modules 80. Each magnetic field control phase-locking amplification module 80 is arranged corresponding to each atomic magnetometer probe 206, and is used for regulating and controlling the surrounding magnetic field and performing phase-locking amplification on the magnetic field signal detected by the atomic magnetometer probe 206.

In this embodiment, each of the magnetic field control lock-phase amplifying modules 80 includes the signal generating module 810, the phase shifting module 820 and the low-pass filtering module 830. The magnetic field in a certain direction is modulated by the signal generation module 810. The phase shift module 820 and the low-pass filter module 830 are used to perform phase-locked amplification on the magnetic field signal detected by the photodetection module 60 and output the amplified magnetic field signal. The specific regulation and control process can refer to the above embodiments.

Thus, a series of specific output waveforms can be generated by the magnetic field coil drive array 203, input to the magnetic field modulation coils 550 and the bias magnetic field coils 560 in the atomic magnetometer probe 206. Thus, the two-dimensional magnetic field modulation coil and the three-dimensional compensation coil required for driving by the magnetic field coil driving array 203 generate a specific magnetic field to compensate the influence of the residual magnetic field of the atomic gas cell 510. Meanwhile, the detected magnetic field signal is phase-locked, amplified and output by the magnetic field coil driving array 203.

Referring to fig. 9, in one embodiment, the magnetic field imaging system 200 further comprises a micro-control module 205. The micro control module 205 is connected to the position measurement control array 207, the signal acquisition processing array 204, the magnetic field coil driving array 203, and the temperature control array 202, respectively, and is configured to control and reconstruct a magnetic field image.

In this embodiment, the Micro control module 205 includes, but is not limited to, a Micro Control Unit (MCU), a Central Processing Unit (CPU), an embedded Microcontroller (MCU), an embedded Microprocessor (MPU), an embedded System On Chip (SOC), a computer, and the like.

The micro control module 205 outputs a regulation timing sequence to control the position measurement control array 207, the signal acquisition processing array 204, the magnetic field coil driving array 203, and the temperature control array 202, respectively. Thus, the control of the entire magnetic field imaging system is achieved by the micro control module 205. When the micro control module 205 outputs the regulation timing sequence, a control program based on the FPGA may be used to implement unified control of the processes of temperature control, magnetic field modulation, position control, signal acquisition and processing, and the like.

In one embodiment, the output end of the signal acquisition processing array 204 is connected to the micro control module 205, and is configured to transmit the magnetic field signal detected by each atomic magnetometer probe 206 and the spatial position information of each atomic magnetometer probe 206 to the micro control module 205. The micro-control module 205 presents a reconstructed magnetic field image to be measured through a display according to the magnetic field signal detected by each atomic magnetometer probe 206.

Therefore, the magnetic field imaging system 200 only uses one laser light source 10 to drive the plurality of atomic magnetometer probes 206, which is beneficial to common mode of noise of each probe and differential processing of magnetic field signals. Therefore, the suppression of the common-mode noise is obtained through differential processing, the common-mode noise of each probe can be effectively eliminated, and the noise of a magnetic field image is reduced. Meanwhile, the magnetic field imaging system 200 can reconstruct a magnetic field image with high resolution according to the corresponding relationship between the magnetic field signal and the position signal, and the system cost is reduced.

It is to be understood that the modules mentioned in the above embodiments may also take other forms, not limited to the forms mentioned in the above embodiments, as long as they can achieve the corresponding functions.

In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An atomic magnetometer, comprising:

a laser light source (10) for emitting laser light of a first wavelength;

the frequency doubling module (20) is arranged on the optical path of the first wavelength laser and is used for converting part of the first wavelength laser into second wavelength laser, and the optical path of the second wavelength laser and the optical path of the first wavelength laser share the optical path;

the light attenuation module (30) is arranged on the optical path of the first wavelength laser and is used for adjusting the power of the first wavelength laser;

an atomic gas cell (510) provided in an optical path of the first wavelength laser light;

a light absorption module (520) comprising a first light absorption structure (521) and a second light absorption structure (522), the first light absorption structure (521) and the second light absorption structure (522) being disposed on two surfaces of the atomic gas cell (510) opposite to each other;

the first wavelength laser sequentially passes through the first light absorption structure (521), the atomic gas cell (510) and the second light absorption structure (522);

the first light absorption structure (521) and the second light absorption structure (522) are used for absorbing the laser with the first wavelength and converting the laser into heat energy to heat the atomic gas cell (510);

the laser with the second wavelength enters the atomic gas chamber (510) and interacts with atomic gas in the atomic gas chamber (510) to realize detection of a magnetic field signal;

the temperature detection module (530) is arranged on the surface of the atomic gas chamber (510) and is used for monitoring the real-time measurement temperature of the atomic gas chamber (510);

the monitoring end of the temperature control module (40) is connected with the temperature detection module (530) and is used for acquiring the real-time measured temperature;

and the control end of the temperature control module (40) is connected with the light attenuation module (30) and is used for regulating and controlling the light attenuation module (30) according to the real-time measured temperature so as to change the power of the first wavelength laser.

2. An atomic magnetometer according to claim 1, wherein the thickness of the second light absorbing structure (522) is greater than the thickness of the first light absorbing structure (521).

3. An atomic magnetometer according to claim 1, characterized in that said temperature control module (40) comprises a feedback control module;

the feedback control module is used for comparing the real-time measured temperature with a target temperature and regulating and controlling the light attenuation module (30) by adopting a feedback control method so as to change the power of the first wavelength laser.

4. The atomic magnetometer of claim 3, wherein the atomic magnetometer further comprises:

and the photoelectric detection module (60) is arranged on the light path of the second wavelength laser and is used for receiving the second wavelength laser after passing through the atomic gas chamber (510).

5. The atomic magnetometer of claim 4, wherein the atomic magnetometer further comprises:

a heating chamber (540) enclosing a heating space, the light absorption module (520), the atomic gas cell (510), and the temperature detection module (530) being disposed in the heating space;

a magnetic field modulation coil (550) disposed around the heating chamber (540) for modulating a magnetic field in a direction;

a bias magnetic field coil (560) disposed around the heating chamber (540) for nulling a magnetic field of the atomic gas cell (510) in the absence of a magnetic signal.

6. The atomic magnetometer of claim 5, wherein the atomic magnetometer further comprises:

the signal generating module (810) is used for generating two paths of modulation signals with the same frequency;

the signal generation module (810) is connected with the magnetic field modulation coil (550) and is used for modulating the magnetic field in a certain direction through one path of modulation signal.

7. The atomic magnetometer of claim 6, wherein the atomic magnetometer further comprises:

a phase shift module (820), a first input end of the phase shift module (820) is connected with the signal generation module (810), and a second input end of the phase shift module (820) is connected with an output end of the photoelectric detection module (60) and is used for modulating the magnetic field detection signal by another modulation signal;

and the low-pass filtering module (830) is connected with the output end of the phase shifting module (820) and is used for performing phase-locked amplification output on the modulated magnetic field detection signal.

8. The atomic magnetometer of claim 1, wherein the atomic magnetometer further comprises:

the optical amplification module (710) is arranged on an optical path of the first wavelength laser and is used for amplifying the first wavelength laser;

the collimation module (720) is arranged on a light path of the first wavelength laser and is used for collimating the first wavelength laser and the second wavelength laser which are formed after passing through the frequency doubling module (20);

a polarization module (730) disposed on an optical path of the first wavelength laser light for polarizing the second wavelength laser light after passing through the optical attenuation module (30);

the first quarter wave plate (740) is arranged on a light path of the first wavelength laser and used for converting the second wavelength laser after passing through the polarization module (730) to form circularly polarized light.

9. The atomic magnetometer of claim 1, wherein the atomic magnetometer further comprises:

a first light splitting module (910) disposed on an optical path of the second wavelength laser light, for splitting the second wavelength laser light after passing through the light attenuation module (30) into pump light and probe light perpendicular to each other;

a half wave plate (920) arranged on the optical path of the detection light and used for adjusting the polarization angle of the detection light;

the detection light after passing through the half wave plate (920) enters the atomic gas chamber (510);

a second quarter wave plate (930) disposed on an optical path of the pumping light, for converting the pumping light into pumping circularly polarized light;

the pump light after the second quarter wave plate (930) enters the atomic gas cell (510).

10. A magnetic field imaging system, comprising:

a laser light source (10) for emitting laser light of a first wavelength;

the frequency doubling module (20) is arranged on an optical path of the first wavelength laser and is used for converting part of the first wavelength laser into second wavelength laser;

the second light splitting module (201) is arranged on an optical path of the first wavelength laser and is used for splitting the first wavelength laser into a plurality of first wavelength sub-beams and splitting the second wavelength laser into a plurality of second wavelength sub-beams; wherein one of said first wavelength sub-beams is co-optically coupled with one of said second wavelength sub-beams;

a plurality of atomic magnetometer probes (206), each atomic magnetometer probe (206) comprising a light attenuation module (30), an atomic gas cell (510), a light absorption module (520), and;

each light attenuation module (30) is arranged on the light path of the first wavelength sub-beam and is used for adjusting the power of the first wavelength sub-beam;

the atomic gas chamber (510) is arranged on the light path of the first wavelength sub-beam;

the light absorption module (520) comprises a first light absorption structure (521) and a second light absorption structure (522), and the first light absorption structure (521) and the second light absorption structure (522) are arranged on two opposite surfaces of the atomic gas cell (510);

the first wavelength sub-beam sequentially passes through the first light absorption structure (521), the atomic gas cell (510) and the second light absorption structure (522);

the first light absorption structure (521) and the second light absorption structure (522) are used for absorbing the first wavelength sub-beam and converting the first wavelength sub-beam into heat energy to heat the atomic gas cell (510);

the second wavelength sub-beams are used for entering the atomic gas chamber (510) and interacting with atomic gas in the atomic gas chamber (510);

and the temperature control array (202) is respectively connected with the plurality of atomic magnetometer probes (206) and is used for regulating and controlling the atomic magnetometer probes (206) so as to change the power of the first wavelength sub-beam.

11. The magnetic field imaging system of claim 10, further comprising:

a position measurement control array (207) comprising a plurality of position sensing modules (2071) and a plurality of displacement control modules (2072);

each position sensing module (2071) is arranged on each atomic magnetometer probe (206) and is used for measuring the spatial position of the atomic magnetometer probe (206);

each displacement control module (2072) is arranged on each atomic magnetometer probe (206) and is used for controlling the displacement of the atomic magnetometer probe (206) to move.

12. The magnetic field imaging system of claim 11, further comprising:

the signal acquisition processing array (204) is respectively connected with the position sensing modules (2071) and is used for acquiring the spatial positions of the atomic magnetometer probes (206);

the signal acquisition processing array (204) is respectively connected with the displacement control modules (2072) and is used for regulating and controlling the displacement of the atomic magnetometer probes (206);

the signal acquisition processing array (204) is respectively connected with the output ends of the plurality of atomic magnetometer probes (206) and is used for acquiring the magnetic field signals detected by the plurality of atomic magnetometer probes (206).

13. The magnetic field imaging system of claim 12, further comprising:

and the magnetic field coil driving array (203) is respectively connected with the plurality of atomic magnetometer probes (206) and used for regulating and controlling the surrounding magnetic field and performing phase-locked amplification on the magnetic field signals detected by the atomic magnetometer probes (206).

14. The magnetic field imaging system of claim 13, further comprising:

and the micro-control module (205) is respectively connected with the position measurement control array (207), the signal acquisition processing array (204), the magnetic field coil driving array (203) and the temperature control array (202) and is used for controlling and reconstructing magnetic field images.