Dual-optical-path atom magnetometer based on polarization metasurface and measurement method

Abstract

The invention provides a polarization metasurface-based dual-optical-path atom magnetometer and a measurement method. The polarization metasurface-based dual-optical-path atom magnetometer comprises a laser unit, a collimator, a polarization metasurface, a magnetic probe unit, a first reflector and a signal processing unit, the laser sequentially passes through the collimator and the polarization metasurface, is converted by the polarization metasurface and emits circular polarization pump light at a fixed inclination angle, due to the interaction of the detection light and polarization atoms, the polarization plane of the detection light rotates, and the detection light is detected by the signal processing unit after being transmitted out of the atom gas chamber; through the characteristics of ultra-thinness, planarization and function integration of the polarization metasurface structure, regulation and control of electromagnetic waves are realized through the sub-wavelength structure, and a dual-optical-path small magnetometer structure constructed by a single laser source is realized, so that the overall structure meets the design requirements of small size, high integration level, convenience in operation, high sensitivity and adaptation to miniaturization, and is suitable for popularization.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic measurement technology, and in particular to a dual-optical path atomic magnetometer based on polarization metasurface and a measurement method. Background Art

[0002] There is a magnetic field around magnets. The magnetic field is an important physical quantity that is inherent in the object itself or generated when it interacts with other objects. The interaction between magnets is mediated by the magnetic field. Atomic magnetic measurement is one of the most sensitive field measurement technologies for biological, geographical surveys and navigation applications.

[0003] Common weak magnetic sensors include: atomic magnetometer, induction magnetometer, fluxgate magnetometer, proton magnetometer, superconducting quantum interference device, anisotropic magnetoresistive magnetometer, planar Hall effect magnetometer and giant magnetic impedance magnetometer, etc.

[0004] Among them: Optically pumped atomic magnetometers have shown broad application potential in the fields of magnetic anomaly measurement, mineral resource exploration, and biomagnetic field measurement due to their advantages of low power consumption, low cost, high sensitivity, medium size, vibration resistance, and non-refrigeration working conditions, especially in the development of portable devices.

[0005] The application trend represented by wearable health monitoring devices requires atomic magnetometers to develop towards chip-based and integrated development; however, existing technologies cannot meet the above requirements and have the following insurmountable technical defects:

[0006] ① Existing atomic magnetometers mainly rely on bulky discrete optical components, which hinders the development of miniaturized applications;

[0007] ② The single-beam atomic magnetometer based on a single laser source has limitations in improving sensitivity;

[0008] ③Although the dual-beam magnetometer built using two laser sources has higher sensitivity, it occupies too much space and is not conducive to reducing the overall volume of the system.

[0009] Therefore, based on the above-mentioned deficiencies, technical personnel in this field urgently need to explore a new path that is miniaturized, highly sensitive, and safe and reliable in operation. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a dual-path atomic magnetometer and measurement method based on polarization metasurface. By taking advantage of the ultra-thin, planar and functionally integrated characteristics of the polarization metasurface structure, the electromagnetic waves are regulated through a subwavelength structure, and a single laser source is used to construct a dual-path small magnetometer structure, so that the overall structure meets the design requirements of small size, high integration, easy operation, high sensitivity, and adaptability to miniaturization.

[0011] To achieve the above object, the present invention provides the following technical solution, a dual-optical path atomic magnetometer based on polarization metasurface and a measurement method, wherein:

[0012] A dual-optical path atomic magnetometer based on polarization metasurface, comprising: a laser unit, a collimator, a polarization metasurface, a magnetic probe unit, a first reflector, and a signal processing unit;

[0013] The laser unit emits laser light, and a collimator and a polarization metasurface are sequentially arranged along the optical path direction of the laser light;

[0014] The polarization metasurface divides the laser into two paths: a first outgoing light path and a second outgoing light path;

[0015] After being reflected by the first reflector, the second outgoing light path intersects the first outgoing light path perpendicularly at the magnetic probe unit; and is incident on the magnetic probe unit through the first outgoing light path and the second outgoing light path;

[0016] The detection light after passing through the magnetic probe unit enters the signal processing unit, the signal processing unit receives and processes the optical signal of the detection light, and outputs a signal to the magnetic probe unit to generate a radio frequency magnetic field, and processes and solves to obtain the Larmor precession frequency corresponding to the magnetic field strength;

[0017] As an example, the laser unit includes: a laser control system and a laser, and the laser control system is used to control the laser to emit laser light that meets the conditions.

[0018] As a preferred example, the conditions refer to: the operating temperature and operating current of the laser.

[0019] As an example, the magnetic probe unit includes: an atomic gas chamber, a gas chamber frame, an oven, an oven temperature control system, and a radio frequency coil;

[0020] The atomic gas chamber is filled with alkali metal atomic gas and buffer gas;

[0021] The oven is used to wrap the atomic gas chamber;

[0022] The oven temperature control system is used to monitor and control the temperature of the oven;

[0023] The air chamber skeleton is used to provide support and external covering for the atomic air chamber and the oven;

[0024] The radio frequency coil is fixed on the air chamber frame and connected to the phase-locked amplifier to provide the radio frequency magnetic field required for detecting the magnetic field strength.

[0025] As an application example, the oven temperature control system uses a heating film and a thermistor configured in the heating structure of the oven.

[0026] As an example, the collimator is used to collimate the divergent light of the laser emitted by the laser unit.

[0027] As an example, the laser light collimated by the collimator is directly projected onto the polarization metasurface, and a part of the laser light is converted into circularly polarized light, and is emitted at a fixed tilt angle, passing through the atomic gas chamber in the magnetic probe unit, and serving as the pump light of the heated atomic vapor. The optical path trajectory of the circularly polarized light is the first emission optical path.

[0028] The linearly polarized light projected onto the polarization metasurface but not converted is emitted perpendicular to the polarization metasurface, and the transmission direction is adjusted by the first reflector to be perpendicular to the direction of the first emission light path, and is emitted into the atomic gas chamber as detection light. The detection light after transmitting through the atomic gas chamber enters the signal processing unit, and the light path trajectory is the second emission light path.

[0029] As an example of the effect, a single device of the polarization metasurface can convert the collimated laser into circularly polarized light, and make the circularly polarized light emit at a fixed angle relative to the unconverted linearly polarized light, so as to separate the converted circularly polarized light from the unconverted linearly polarized light; the periodic nanostructure distribution of the polarization metasurface can shape the laser into a more symmetrical and smooth distribution after incidence.

[0030] As an example, the signal processing unit includes: a second reflector, a polarization beam splitter, a balanced detector and a lock-in amplifier;

[0031] The polarization beam splitter splits the detection light into two mutually perpendicular light beams, wherein the first light beam is consistent with the detection light path; the second light beam is directed downward, and after being reflected by the second reflector, the first light beam and the second light beam are made parallel, and are emitted into the balanced detector together to detect the light intensity signal and process it, and the generated optical power data is transmitted to the phase-locked amplifier, which excites the radio frequency coil to generate a radio frequency magnetic field.

[0032] Also included is a measurement method of a dual-optical path atomic magnetometer based on a polarization metasurface, comprising:

[0033] Step 1: Lock the laser input frequency;

[0034] The laser wavelength is tuned to the resonance wavelength based on the alkali metal electron transition frequency to control the absorption of the laser by the alkali metal vapor so that the atoms in the atomic gas chamber are uniformly pumped;

[0035] Step 2: Atomic gas chamber temperature monitoring and control;

[0036] After setting the desired heating temperature and the corresponding PID parameters, the oven temperature control system calculates the actual temperature in the oven through the resistance value of the thermistor configured in the oven;

[0037] Based on the difference between the expected heating temperature and the actual temperature, the oven temperature control system controls the power output amplitude of the heating film through PID regulation, so that the temperature in the oven rises to the expected value and reaches stability, and the alkali metal atoms filled in the atomic gas chamber embedded in the oven reach a vaporized state;

[0038] Step 3: Dual-beam pumping and detection;

[0039] The laser light emitted by the laser passes through the collimator and polarization metasurface in sequence, and is converted by the polarization metasurface and emitted as circularly polarized light at a fixed tilt angle, and then enters the atomic gas chamber along the first outgoing light path, so that the alkali metal atoms inside the atomic gas chamber are fully spin polarized;

[0040] The linearly polarized light that is not converted by the polarization metasurface goes along the second outgoing light path, is adjusted in angle by the first reflector, and then enters the atomic gas chamber perpendicular to the first outgoing light path as detection light;

[0041] Due to the interaction between the detection light and the polarized atoms, the polarization plane of the detection light rotates, and is detected by the signal processing unit after being transmitted out of the atomic gas chamber;

[0042] Step 4: Use of magnetic field detection;

[0043] A dual-optical path atomic magnetometer based on polarization metasurface of the present invention is placed in a geomagnetic environment, and a phase-locked amplifier scans the radio frequency magnetic field frequency within a certain frequency range to obtain the difference of the light intensity power signal and the radio frequency frequency corresponding to the extreme value, and then automatically calculates the magnetic field strength.

[0044] Beneficial effects of the present invention:

[0045] The magnetometer of the present invention adopts a polarization metasurface based on the principle of phase mutation to realize the conversion of linearly polarized laser into circularly polarized light. The polarization metasurface has the characteristics of ultra-thinness, planarization and functional integration, and is more streamlined in structure than the traditional bulky optical device that relies on the medium thickness to accumulate phase to realize polarization conversion; at the same time, the polarization metasurface can emit the converted circularly polarized light at a fixed angle to avoid mixing with the unconverted part of the laser, thereby ensuring the purity of the emitted circularly polarized light; the magnetometer utilizes the unconverted linearly polarized light transmitted by the metasurface, and uses a reflector to adjust its transmission direction to be perpendicular to the direction of the pump light to enter the atomic gas chamber as the detection light of the magnetometer, thereby improving the energy utilization rate and realizing the splitting of the pump light and the detection light based on a single device of the polarization metasurface on a subwavelength scale. Based on this, the magnetometer constructs a dual-beam structure with a small optical path volume, which is adapted to the technical requirements of chipization and integration.

[0046] The magnetometer of the present invention only needs a single laser source to realize dual-path pumping and detection. Compared with a dual-beam magnetometer using dual laser sources, the system volume is reduced and the structural integration is improved. Compared with a single-beam magnetometer using a single laser source, the magnetometer has a higher upper limit of sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is an overall structural design diagram of a dual-optical path atomic magnetometer based on polarization metasurface of the present invention.

[0048] Description of reference numerals:

[0049] 1. Laser unit; 2. Laser; 3. Laser control system 4. Collimator; 5. Polarization metasurface; 6. Magnetic probe unit; 7. First reflector; 8. Atomic gas chamber; 9. Oven; 10. Oven temperature control system; 11. Gas chamber skeleton; 12. RF coil; 13. Signal processing unit; 14. Second reflector; 15. Polarization beam splitter; 16. Balanced detector; 17. Phase-locked amplifier. DETAILED DESCRIPTION

[0050] Below, reference Figure 1 As shown, a dual-path atomic magnetometer and measurement method based on polarization metasurface, wherein:

[0051] A dual-optical path atomic magnetometer based on polarization metasurface, comprising: a laser unit 1, a collimator 4, a polarization metasurface 5, a magnetic probe unit 6, a first reflector 7 and a signal processing unit 13;

[0052] The laser unit 1 emits laser light, and a collimator 4 and a polarization metasurface 5 are sequentially arranged along the optical path direction of the laser light;

[0053] The polarization metasurface 5 divides the laser into two paths: a first outgoing light path and a second outgoing light path;

[0054] After being reflected by the first reflector 7, the second outgoing light path intersects the first outgoing light path perpendicularly at the magnetic probe unit 6; that is, the second outgoing light path enters the magnetic probe unit 6 through both the first outgoing light path and the second outgoing light path;

[0055] The detection light after passing through the magnetic probe unit 6 enters the signal processing unit 13, and the signal processing unit 13 receives and processes the optical signal of the detection light, and outputs a signal to the magnetic probe unit 6 to generate a radio frequency magnetic field, and processes and solves to obtain the Larmor precession frequency corresponding to the magnetic field strength.

[0056] As an example, the laser unit 1 includes: a laser control system 3 and a laser 2, and the laser control system 3 is used to control the laser 2 to emit laser light that meets the conditions.

[0057] As a preferred example, the conditions refer to: the operating temperature and the operating current of the laser 2 .

[0058] As an example, the magnetic probe unit 6 includes: an atomic gas chamber 8, a gas chamber frame 11, an oven 9, an oven temperature control system 10 and a radio frequency coil 12;

[0059] The atomic gas chamber 8 is filled with alkali metal atomic gas and buffer gas;

[0060] The oven 9 is used to wrap the atomic gas chamber 8;

[0061] The oven temperature control system 10 is used to monitor and control the temperature of the oven 9;

[0062] The air chamber skeleton 11 is used to provide support and external covering for the atomic air chamber 8 and the oven 9;

[0063] The radio frequency coil 12 is fixed on the air chamber frame 11 and connected to the phase-locked amplifier 17 to provide a radio frequency magnetic field required for detecting the magnetic field strength.

[0064] As an application example, the oven temperature control system 10 uses a heating film and a thermistor configured in the heating structure of the oven.

[0065] As an example, the collimator 4 is used to collimate the divergent light of the laser emitted by the laser unit 1 .

[0066] As an example, the laser light collimated by the collimator 4 is directly projected onto the polarization metasurface 5, and a part of the laser light is converted into circularly polarized light, and is emitted at a fixed tilt angle, passing through the atomic gas chamber 8 in the magnetic probe unit 6, and serving as the pump light of the heated atomic vapor. The optical path trajectory of the circularly polarized light is the first emission optical path;

[0067] The linearly polarized light projected onto the polarization metasurface 5 but not converted is emitted perpendicular to the polarization metasurface 5, and the transmission direction is adjusted by the first reflector to be perpendicular to the direction of the first emission light path, and is emitted into the atomic gas chamber 8 as detection light. The detection light after transmitting through the atomic gas chamber 8 enters the signal processing unit 13, and the light path trajectory is the second emission light path.

[0068] As an example of the effect, the polarization metasurface 5, as a single device, can convert the collimated laser into circularly polarized light, and make the circularly polarized light emit at a fixed angle relative to the unconverted linearly polarized light, so as to separate the converted circularly polarized light from the unconverted linearly polarized light; the periodic nanostructure distribution of the polarization metasurface can shape the laser into a more symmetrical and smooth distribution after incidence.

[0069] As an example, the signal processing unit 13 includes: a second reflector 14, a polarization beam splitter 15, a balanced detector 16 and a lock-in amplifier 17;

[0070] The polarization beam splitter 15 splits the detection light into two mutually perpendicular light beams, wherein the first light beam is consistent with the detection light path; the second light beam is directed downward, and after being reflected by the second reflector, the first light beam and the second light beam are made parallel, and are emitted into the balanced detector 16 together to detect the light intensity signal and process it, and the generated optical power data is transmitted to the phase-locked amplifier 17, which excites the radio frequency coil 12 to generate a radio frequency magnetic field.

[0071] Also included is a measurement method of a dual-optical path atomic magnetometer based on a polarization metasurface, comprising:

[0072] Step 1: Lock the input frequency of laser 2;

[0073] The laser wavelength is tuned to the resonance wavelength based on the alkali metal electron transition frequency to control the absorption of the laser by the alkali metal vapor so that the atoms in the atomic gas chamber 8 are uniformly pumped;

[0074] Step 2: monitoring and controlling the temperature of the atomic gas chamber 8;

[0075] After setting the desired heating temperature and the corresponding PID parameters, the oven temperature control system 10 calculates the actual temperature in the oven 9 through the resistance value of the thermistor configured in the oven 9;

[0076] Based on the difference between the desired heating temperature and the actual temperature, the oven temperature control system 10 controls the power output amplitude of the heating film through PID regulation, so that the temperature in the oven 9 rises to the desired value and reaches stability, and the alkali metal atoms filled in the atomic gas chamber 8 embedded in the oven 9 reach a gasified state;

[0077] Step 3: Dual-beam pumping and detection;

[0078] The laser light emitted by the laser 2 passes through the collimator 4 and the polarization metasurface 5 in sequence, and is converted by the polarization metasurface 5 and emitted as circularly polarized light at a fixed tilt angle, and then enters the atomic gas chamber 8 along the first outgoing light path, so that the alkali metal atoms inside the atomic gas chamber are fully spin polarized;

[0079] The linearly polarized light that is not converted by the polarization metasurface 5 goes along the second outgoing light path, is adjusted by the first reflector 7, and is perpendicular to the first outgoing light path, and enters the atomic gas chamber 8 as detection light;

[0080] Due to the interaction between the detection light and the polarized atoms, the detection light polarization plane rotates, and is detected by the signal processing unit 13 after being transmitted out of the atomic gas chamber 8;

[0081] Step 4: Use of magnetic field detection;

[0082] A dual-path atomic magnetometer based on polarization metasurface of the present invention is placed in a geomagnetic environment, and a phase-locked amplifier 17 scans the radio frequency magnetic field frequency within a certain frequency range to obtain the difference of the light intensity power signal and the radio frequency corresponding to the extreme value, and then automatically calculates the magnetic field strength.

[0083] In order to better illustrate the design principle of the present invention, specific embodiments are now described as follows:

[0084] Example 1: Reference Figure 1 As shown;

[0085] The laser diode operating temperature and current are set by the laser control system to ensure that the wavelengths of the pump light and detection light incident on the atomic gas chamber 8 are near the D1 transition line (795nm) of the 87Rb atom, and the beam power is sufficient to achieve normal pumping and detection functions;

[0086] In the laboratory coordinate system, the direction of the pump light is defined as the z-axis, the direction of the detection light is defined as the x-axis, and the direction of the RF magnetic field is defined as the y-axis;

[0087] The oven 9 surrounding the atomic gas chamber 8 is heated to a temperature of 90-110° C. by the oven temperature control system 10 to vaporize the alkali metal atoms in the atomic gas chamber 8;

[0088] The magnetometer of the present invention is placed in the geomagnetic field or simulated geomagnetic field, and the phase-locked amplifier 17 outputs a continuous frequency sinusoidal signal within a certain frequency range to the radio frequency coil 12 according to the upper computer software setting, and scans the light intensity difference and sum signal received from the balanced detector 16. The radio frequency frequency ω corresponding to the peak value of the magnetic resonance signal amplitude curve corresponds to the Larmor precession frequency ω=γB0 of the 87Rb atom in the magnetic field to be measured, and γ=7Hz / nT is the gyromagnetic ratio of the rubidium atom. The size of the external magnetic field is preliminarily calculated based on the radio frequency field frequency corresponding to the peak value.

[0089] Through the description of the above implementation methods, technicians in this field can clearly understand that the above-mentioned implementation methods can be implemented by means of software plus a necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method; based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium (such as ROM / RAM, disk, CD), including a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0090] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0091] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0092] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0093] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways; for example, the device embodiments described above are only schematic, and the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0094] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0095] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks, or optical disks.

[0096] The above are only preferred embodiments of the present invention. It should be understood that the description of the above embodiments is only used to help understand the method and core ideas of the present invention, and is not used to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, etc. made within the ideas and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-path atomic magnetometer based on polarization metasurface, characterized in that: include: A laser unit, a collimator, a polarization metasurface, a magnetic probe unit, a first reflector, and a signal processing unit; The laser unit emits laser light, and a collimator and a polarization metasurface are sequentially arranged along the optical path direction of the laser light; The polarization metasurface divides the laser into two paths: a first outgoing light path and a second outgoing light path; After being reflected by the first reflector, the second outgoing light path intersects the first outgoing light path perpendicularly at the magnetic probe unit; and is incident on the magnetic probe unit through the first outgoing light path and the second outgoing light path; The detection light after passing through the magnetic probe unit enters the signal processing unit, and the signal processing unit receives and processes the optical signal of the detection light, and outputs a signal to the magnetic probe unit to generate a radio frequency magnetic field, and processes and solves to obtain the Larmor precession frequency corresponding to the magnetic field strength.

2. The dual-path atomic magnetometer based on polarization metasurface according to claim 1, characterized in that: The laser unit comprises: a laser control system and a laser, wherein the laser control system is used to control the laser to emit laser light that meets the conditions.

3. The dual-path atomic magnetometer based on polarization metasurface according to claim 2, characterized in that: The conditions refer to: the operating temperature and operating current of the laser.

4. The dual-path atomic magnetometer based on polarization metasurface according to claim 1, characterized in that: The magnetic probe unit includes: an atomic gas chamber, a gas chamber frame, an oven, an oven temperature control system and a radio frequency coil; The atomic gas chamber is filled with alkali metal atomic gas and buffer gas; The oven is used to wrap the atomic gas chamber; The oven temperature control system is used to monitor and control the temperature of the oven; The air chamber skeleton is used to provide support and external covering for the atomic air chamber and the oven; The radio frequency coil is fixed on the air chamber frame and connected to the phase-locked amplifier to provide the radio frequency magnetic field required for detecting the magnetic field strength.

5. The dual-path atomic magnetometer based on polarization metasurface according to claim 4, characterized in that: The oven temperature control system adopts a heating film and a thermistor configured in the heating structure of the oven.

6. The dual-path atomic magnetometer based on polarization metasurface according to claim 1, characterized in that: The collimator is used to collimate the divergent light of the laser emitted by the laser unit.

7. The dual-path atomic magnetometer based on polarization metasurface according to claim 1, characterized in that: The laser light collimated by the collimator is directly projected onto the polarization metasurface, and a part of the laser light is converted into circularly polarized light, which is emitted at a fixed tilt angle and passes through the atomic gas chamber in the magnetic probe unit as pump light for the heated atomic vapor. The optical path of the circularly polarized light is the first emission optical path. The linearly polarized light projected onto the polarization metasurface but not converted is emitted perpendicular to the polarization metasurface, and the transmission direction is adjusted by the first reflector to be perpendicular to the direction of the first emission light path, and is emitted into the atomic gas chamber as detection light. The detection light after transmitting through the atomic gas chamber enters the signal processing unit, and the light path trajectory is the second emission light path.

8. The dual-path atomic magnetometer based on polarization metasurface according to claim 1, characterized in that: The signal processing unit includes: a second reflector, a polarization beam splitter, a balanced detector and a lock-in amplifier; The polarization beam splitter splits the detection light into two mutually perpendicular light beams, wherein the first light beam is consistent with the detection light path; the second light beam is directed downward, and after being reflected by the second reflector, the first light beam and the second light beam are made parallel, and are emitted into the balanced detector together to detect the light intensity signal and process it, and the generated optical power data is transmitted to the phase-locked amplifier, which excites the radio frequency coil to generate a radio frequency magnetic field.

9. A measurement method of a dual-path atomic magnetometer based on polarization metasurface according to any one of claims 1 to 8, characterized in that: include: Step 1: Lock the laser input frequency; The laser wavelength is tuned to the resonance wavelength based on the alkali metal electron transition frequency to control the absorption of the laser by the alkali metal vapor so that the atoms in the atomic gas chamber are uniformly pumped; Step 2: Atomic gas chamber temperature monitoring and control; After setting the desired heating temperature and the corresponding PID parameters, the oven temperature control system calculates the actual temperature in the oven through the resistance value of the thermistor configured in the oven; Based on the difference between the expected heating temperature and the actual temperature, the oven temperature control system controls the power output amplitude of the heating film through PID regulation, so that the temperature in the oven rises to the expected value and reaches stability, and the alkali metal atoms filled in the atomic gas chamber embedded in the oven reach a vaporized state; Step 3: Dual-beam pumping and detection; The laser light emitted by the laser passes through the collimator and polarization metasurface in sequence, and is converted by the polarization metasurface and emitted as circularly polarized light at a fixed tilt angle, and then enters the atomic gas chamber along the first outgoing light path, so that the alkali metal atoms inside the atomic gas chamber are fully spin polarized; The linearly polarized light that is not converted by the polarization metasurface goes along the second outgoing light path, is adjusted in angle by the first reflector, and then enters the atomic gas chamber perpendicular to the first outgoing light path as detection light; Due to the interaction between the detection light and the polarized atoms, the polarization plane of the detection light rotates, and is detected by the signal processing unit after being transmitted out of the atomic gas chamber; Step 4: Use of magnetic field detection; A dual-optical path atomic magnetometer based on polarization metasurface of the present invention is placed in a geomagnetic environment, and a phase-locked amplifier scans the radio frequency magnetic field frequency within a certain frequency range to obtain the difference of the light intensity power signal and the radio frequency frequency corresponding to the extreme value, and then automatically calculates the magnetic field strength.

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