A dual optical path atomic magnetometer based on polarization super surface and a measuring method thereof

Abstract

The application provides a kind of double optical path atomic magnetometer based on polarization super surface and measuring method, comprising: laser unit, collimator, polarization super surface, magnetic probe unit, first mirror and signal processing unit;Laser passes collimator and polarization super surface in turn, circularly polarized pump light is converted and emitted by polarization super surface with fixed tilt angle, due to the interaction of the detection light and polarized atom, the polarization plane of detection light is rotated, and the signal processing unit detects after transmitting out of the atomic cell;Through the characteristics of super thin, planarization and function integration of polarization super surface structure, the regulation of electromagnetic wave is realized through subwavelength structure, the structure of double optical path small magnetometer is realized by single laser source, so that the overall structure meets the design requirements of small volume, high integration, easy operation, high sensitivity, small size adaptation, and is suitable for promotion.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetic measurement, and particularly relates to a dual-optical-path atomic magnetometer based on a polarization super surface and a measuring method. BACKGROUND

[0002] A magnetic field exists around a magnet, and the magnetic field is an important physical quantity generated by an object itself or interaction, and the interaction between magnets is mediated by the magnetic field; atomic magnetic measurement is one of the most sensitive field measurement technologies in biological, geographical investigation and navigation applications.

[0003] Common weak magnetic sensors include an atomic magnetometer, an induction magnetometer, a fluxgate magnetometer, a proton magnetometer, a superconducting quantum interference device, an anisotropic magnetoresistance magnetometer, a planar Hall effect magnetometer and a giant magnetoimpedance magnetometer.

[0004] Among them, the optical pumping atomic magnetometer has the advantages of low power consumption, low cost, high sensitivity, medium volume, anti-vibration ability and non-refrigeration working conditions, and has wide application potential in magnetic anomaly measurement, mineral resource exploration and biological magnetic field measurement, and has significant advantages in the development of portable devices.

[0005] The application trend represented by wearable health monitoring devices requires atomic magnetometers to be developed towards chip and integration; however, the existing technology cannot meet the above requirements and has the following technical defects that cannot be overcome:

[0006] ①In the existing atomic magnetometer, heavy discrete optical elements are mainly relied on, which hinders the development of miniaturized applications.

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

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

[0009] Therefore, based on the above deficiencies, the technical personnel in the field urgently need to develop a new path of miniaturization, high sensitivity and safe and reliable operation. SUMMARY

[0010] In order to solve the above technical problems, the application provides a dual-optical-path atomic magnetometer based on a polarization super surface and a measuring method, which realizes the regulation of electromagnetic waves through the sub-wavelength structure by the characteristics of the polarization super surface structure, such as ultra-thin, planarization and functional integration, realizes the construction of a dual-optical-path small magnetometer structure by a single laser source, and makes the overall structure meet the design requirements of small volume, high integration, easy operation, high sensitivity and small size.

[0011] To achieve the above object, the application provides the following technical scheme, a dual optical path atomic magnetometer based on a polarization super surface and a measuring method, wherein:

[0012] A dual optical path atomic magnetometer based on a polarization super surface, comprising a laser unit, a collimator, a polarization super surface, a magnetic probe unit, a first mirror and a signal processing unit.

[0013] The laser unit emits laser light, and the collimator and the polarization super surface are sequentially arranged along the optical path direction of the laser light.

[0014] The polarization super surface divides the laser light into two paths: a first exit light path and a second exit light path.

[0015] The second exit light path is reflected by the first mirror and perpendicularly intersects the first exit light path at the magnetic probe unit; the magnetic probe unit is incident to the magnetic probe unit through the first exit light path and the second exit light path.

[0016] The detection light after 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 calculates the Larmor precession frequency corresponding to the magnetic field strength.

[0017] As an example, the laser unit comprises a laser control system and a laser, and the laser control system is used to control the laser to emit laser light meeting the conditions.

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

[0019] As an example, the magnetic probe unit comprises an atomic gas chamber, a gas chamber skeleton, an oven, an oven temperature control system and a radio frequency coil.

[0020] The atomic gas chamber is filled with alkali metal atom 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 gas chamber skeleton is used to provide support and external coverage for the atomic gas chamber and the oven.

[0024] The radio frequency coil is fixed on the gas chamber skeleton and connected with a lock-in amplifier, and is used to provide a radio frequency magnetic field required for detecting the magnetic field strength.

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

[0026] As an example, the collimator is used for collimating the laser emitted by the laser unit.

[0027] As an example, the laser collimated by the collimator is directly projected to the polarization super surface, a part of the laser is converted into circularly polarized light, and is emitted at a fixed tilt angle, and the circularly polarized light transmits through an atomic cell in the magnetic probe unit as pump light of the heated atomic vapor, and the light path trajectory of the circularly polarized light is a first emission light path.

[0028] The linearly polarized light projected to the polarization super surface but not converted is emitted perpendicularly to the polarization super surface, the transmission direction is adjusted by the first mirror to be perpendicular to the direction of the first emission light path, the detection light is projected into the atomic cell as detection light, and the detection light after transmitting through the atomic cell enters the signal processing unit, and the light path trajectory is a second emission light path.

[0029] As an example, the polarization super surface can convert the collimated laser into circularly polarized light, and make the circularly polarized light be emitted at a fixed angle relative to the linearly polarized light, so as to separate the converted circularly polarized light from the linearly polarized light; the periodic nanostructure distribution of the polarization super surface makes the laser incident to be shaped into a more symmetrical and smooth distribution.

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

[0031] The polarization beam splitter divides the detection light into two mutually perpendicular beams, wherein the first beam is consistent with the light path of the detection light; the second beam is downward, and after being reflected by the second mirror, the first beam and the second beam are parallel, and are projected into the balanced detector to detect the light intensity signal and are processed, and the formed optical power data is transmitted to the lock-in amplifier, and the lock-in amplifier excites the radio frequency coil to generate a radio frequency magnetic field.

[0032] Further, a measurement method of a polarization super surface-based double light path atomic magnetometer is provided, and the method comprises the following steps.

[0033] Step 1, locking the input frequency of the laser;

[0034] On the basis of ensuring that the wavelength of the laser is at the frequency of the electronic transition of the alkali metal, the wavelength of the laser is tuned to the resonance wavelength, so as to control the absorption of the laser by the alkali metal vapor, and make the atoms in the atomic cell be uniformly pumped;

[0035] Step 2, atomic cell 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 arranged in the oven;

[0037] Based on the difference between the desired heating temperature and the actual temperature, the oven temperature control system controls the power output amplitude of the heating film through PID adjustment, so that the temperature in the oven rises to the desired value and stabilizes, and the alkali metal atoms filled in the atomic cell embedded in the oven reach the gasification state;

[0038] Step three, double-beam pumping and detection;

[0039] The laser emitted by the laser passes through the collimator and the polarization super surface in turn, and the polarization super surface converts and emits circularly polarized light at a fixed tilt angle, which enters the atomic cell along the first exit light path, so that the internal alkali metal atoms are fully spin polarized;

[0040] The linearly polarized light emitted without conversion by the polarization super surface follows the second exit light path, and after adjusting the angle by the first mirror, it is perpendicular to the first exit light path and enters the atomic cell 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 after being transmitted out of the atomic cell, it is detected by the signal processing unit;

[0042] Step four, use of magnetic field detection;

[0043] Place the double-light-path atomic magnetometer based on the polarization super surface of the application in the geomagnetic environment, and the lock-in amplifier scans the frequency of the radio frequency magnetic field within a certain frequency range to obtain the corresponding radio frequency when the difference and sum of the light intensity power signals reach the extreme value, and then automatically calculate the magnetic field strength.

[0044] The application has the following advantages:

[0045] The magnetometer of the application realizes the conversion of linearly polarized laser to circularly polarized light based on the phase jump principle of the polarization super surface. The polarization super surface has the characteristics of ultra-thinness, planarization and functional integration, and the structure is more compact compared to traditional bulky optical devices that rely on medium thickness to accumulate phase to realize polarization conversion. At the same time, the polarization super surface can emit the converted circularly polarized light at a fixed angle to avoid mixing with the unconverted part of the laser and ensure the purity of the emitted circularly polarized light. The magnetometer utilizes the unconverted linearly polarized light transmitted by the super surface, adjusts its transmission direction with a mirror to enter the atomic cell perpendicular to the pumping light direction as detection light, improves the energy utilization rate, and realizes beam splitting of the pumping light and the detection light based on the subwavelength scale polarization super surface single device. The magnetometer is based on this to build a double-beam structure with small optical path volume, which is suitable for chip and integration technology requirements.

[0046] The magnetometer of the present application only needs a single laser source to realize double optical path pumping and detection, which reduces the system volume and improves the structural integration compared with the double-beam magnetometer using double laser sources, and has a higher sensitivity upper limit compared with the single-beam magnetometer using a single laser source. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 It is an overall structure design diagram of the present application, a double optical path atomic magnetometer based on a polarization super surface.

[0048] BRIEF DESCRIPTION OF DRAWINGS

[0049] 1, laser unit; 2, laser; 3, laser control system 4, collimator; 5, polarization super surface; 6, magnetic probe unit; 7, first mirror; 8, atomic gas chamber; 9, oven; 10, oven temperature control system; 11, gas chamber skeleton; 12, radio frequency coil; 13, signal processing unit; 14, second mirror; 15, polarization beam splitter; 16, balanced detector; 17, lock-in amplifier. DETAILED DESCRIPTION

[0050] Below, referring to Figure 1 the figure, a double optical path atomic magnetometer based on a polarization super surface and a measuring method, wherein:

[0051] A double optical path atomic magnetometer based on a polarization super surface, comprising: a laser unit 1, a collimator 4, a polarization super surface 5, a magnetic probe unit 6, a first mirror 7 and a signal processing unit 13;

[0052] The laser unit 1 emits laser light, and the collimator 4 and the polarization super surface 5 are arranged in sequence along the direction of the laser light path;

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

[0054] The second exit light path is reflected by the first mirror 7 and intersects perpendicularly with the first exit light path at the magnetic probe unit 6; that is, the magnetic probe unit 6 is incident to the magnetic probe unit 6 through the first exit light path and the second exit light path;

[0055] The detection light after the magnetic probe unit 6 enters the signal processing unit 13, which 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 calculates 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 operating current of the laser 2.

[0058] As an example, the magnetic probe unit 6 includes an atomic cell 8, a cell skeleton 11, an oven 9, an oven temperature control system 10, and a radio frequency coil 12.

[0059] The atomic cell 8 is filled with alkali metal atomic gas and buffer gas.

[0060] The oven 9 is used to wrap the atomic cell 8.

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

[0062] The cell skeleton 11 is used to provide support and external cover for the atomic cell 8 and the oven 9.

[0063] The radio frequency coil 12 is fixed on the cell skeleton 11 and connected to a lock-in amplifier 17, which is used to provide the 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 arranged in the heating structure of the oven.

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

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

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

[0068] As an example, the polarization metasurface 5 can convert the collimated laser light into circularly polarized light with a single device, and make the circularly polarized light exit 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 makes the laser light incident to be reshaped into a more symmetrical and smooth distribution.

[0069] As an example, the signal processing unit 13 includes: a second mirror 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 beams, wherein the first beam is consistent with the detection light path; the second beam is downward, after being reflected by the second mirror, the first beam and the second beam are parallel, and the detection light intensity signal is detected by the balanced detector 16, and the light power data is transmitted to the lock-in amplifier 17, and the lock-in amplifier 17 excites the radio frequency coil 12 to generate a radio frequency magnetic field.

[0071] Also includes a kind of measurement method based on polarization metasurface double optical path atomic magnetometer, comprising:

[0072] Step one, lock laser 2 input frequency;

[0073] Ensure that the wavelength of laser is based on alkali metal electron transition frequency, tune the wavelength of laser to resonance wavelength, to control the absorption of alkali metal vapor to laser, so that the atoms in the atomic cell 8 are uniformly pumped;

[0074] Step two, atomic cell 8 temperature monitoring and control;

[0075] After setting the desired heating temperature and corresponding PID parameters, the oven temperature control system 10 calculates the actual temperature in the oven 9 by configuring the resistance value of the thermistor 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 heating film power output amplitude by PID adjustment, 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 cell 8 embedded in the oven 9 reach the gasification state;

[0077] Step three, double-beam pumping and detection;

[0078] The laser emitted by the laser 2 passes through the collimator 4 and the polarization metasurface 5 in turn, and the circularly polarized light is converted by the polarization metasurface 5 and emitted at a fixed tilt angle, and enters the atomic cell 8 along the first exit light path, so that the internal alkali metal atoms are fully spin-polarized;

[0079] The linearly polarized light emitted without conversion by the polarization metasurface 5 enters the atomic cell 8 as detection light after adjusting the angle by the first mirror 7, which is perpendicular to the first exit light path;

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

[0081] Step four, the use of magnetic field detection;

[0082] The polarized super surface-based dual optical path atomic magnetometer of the application is placed in a geomagnetic environment, the phase-locked amplifier 17 scans the frequency of the radio frequency magnetic field within a certain frequency range, the corresponding radio frequency frequency when the difference and of the light intensity power signal reaches an extreme value is obtained, and then the magnetic field strength is automatically calculated.

[0083] In order to better illustrate the design principle of the application, the following is illustrated by means of specific embodiments:

[0084] Embodiment 1: refer to Figure 1 as shown;

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

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

[0087] The oven 9 surrounding the atomic cell 8 is heated to 90-110 DEG C by the oven temperature control system 10, so that the alkali metal atoms in the atomic cell 8 are vaporized;

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

[0089] Through the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment method can be realized by means of software and the necessary general hardware platform, of course, it can also be realized by hardware, but in many cases, the former is a better embodiment; based on such understanding, the technical solutions of the application can be embodied in the form of a software product, the computer software product is stored in a storage medium (such as ROM / RAM, magnetic disc, optical disc), and includes a plurality of instructions for making a terminal (which can be a mobile phone, computer, server, air conditioner, or network equipment) execute the method described in each embodiment of the application.

[0090] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the specific embodiments described above, and the specific embodiments described above are merely illustrative, but not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection of the present application.

[0091] Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in the embodiments of the present application can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software manner depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0092] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0093] In the embodiments provided by the present application, it should be understood that the disclosed device and method can be implemented by other ways; for example, the device embodiments described above are only schematic, the division of the units is only a logical function division, and other division manners can be used in actual implementation, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection between each other can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

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

[0095] If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a ROM, a RAM, a magnetic disk or an optical disk, and various program code storage media.

[0096] The above only describes the preferred embodiments of the present application, and it should be understood that the above description of the embodiments is only used to help understand the method of the present application and its core idea, and does not limit the protection scope of the present application. Any modification, equivalent replacement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A dual optical path atomic magnetometer based on polarization supersurfaces, characterized in that, include: Laser unit, collimator, polarization metasurface, magnetic probe unit, first reflecting mirror, and signal processing unit; The laser unit emits a laser beam, and a collimator and a polarizing metasurface are sequentially arranged along the optical path of the laser beam. The polarization metasurface splits the laser into two paths: a first outgoing light path and a second outgoing light path. The second outgoing light path, after being reflected by the first reflector, intersects the magnetic probe unit perpendicularly with the first outgoing light path; it is incident on the magnetic probe unit through both the first and second outgoing light paths. 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. The signal processing unit processes and calculates the Larmor precession frequency corresponding to the magnetic field strength. 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 enclose the atomic gas chamber. The oven temperature control system is used for monitoring and regulating the temperature of the oven. The gas chamber frame serves to provide support and external coverage for the atomic gas chamber and the oven. The radio frequency coil is fixed on the air chamber frame and connected to the lock-in amplifier to provide the radio frequency magnetic field required for detecting the magnetic field strength. The laser, after being collimated by the collimator, is directly projected onto the polarization metasurface. A portion of the laser is converted into circularly polarized light and emitted at a fixed tilt angle. It passes through the atomic gas cell in the magnetic probe unit and serves as the pump light for the heated atomic vapor. The optical path of the circularly polarized light is the first outgoing optical path. Linearly polarized light projected onto the polarization metasurface but not converted is emitted perpendicular to the polarization metasurface. The transmission direction is adjusted by the first reflector to be perpendicular to the first outgoing light path direction. It is then used as detection light and enters the atomic gas cell. The detection light after passing through the atomic gas cell enters the signal processing unit, and the light path trajectory is the second outgoing light path. 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 beams. The first beam is aligned with the detection light path, while the second beam points downwards and is reflected by the second mirror, making the first beam parallel to the second beam. Both beams are then injected into the balanced detector to detect and process the light intensity signal. The resulting optical power data is transmitted to the lock-in amplifier, which in turn excites the radio frequency coil to generate a radio frequency magnetic field.

2. The polarization super-structured surface-based dual-optical-path atomic magnetometer according to claim 1, characterized in that, The laser unit includes a laser control system and a laser, wherein the laser control system is used to control the laser to emit laser light that meets certain conditions.

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

4. The dual-optical-path atomic magnetometer based on a polarization metasurface according to claim 3, characterized in that, The oven temperature control system uses a heating film and a thermistor configured in the oven's heating structure.

5. A dual-optical-path atomic magnetometer based on a polarization metasurface according to claim 1, characterized in that, The collimator is used to collimate the diverging light emitted from the laser unit.

6. A measurement method using a dual-optical-path atomic magnetometer based on a polarization metasurface as described in any one of claims 1-5, characterized in that, include: Step 1: Lock the laser input frequency; To ensure that the laser wavelength is at the alkali metal electronic transition frequency, the laser wavelength is tuned to the resonant wavelength in order to control the absorption of the laser by the alkali metal vapor, so that the atoms in the atomic gas cell are uniformly pumped. Step 2: Temperature monitoring and control of the atomic gas chamber; After setting the desired heating temperature and corresponding PID parameters, the oven temperature control system calculates the actual temperature inside the oven by the resistance value of the thermistor configured inside the oven. Based on the difference between the desired heating temperature and the actual temperature, the oven temperature control system uses PID regulation to control the power output amplitude of the heating film, so that the temperature inside the oven rises to the desired value and stabilizes, and the alkali metal atoms filled inside the atomic gas chamber embedded in the oven reach a vaporized state. Step 3: Dual-beam pumping and detection; The laser emitted from the laser passes sequentially through a collimator and a polarizing metasurface. The polarizing metasurface converts the laser light into circularly polarized light, which is then emitted at a fixed tilt angle. The light then enters the atomic gas cell along the first outgoing light path, causing the alkali metal atoms inside the cell to be fully spin-polarized. Linearly polarized light emitted without polarization metasurface conversion travels along the second outgoing light path. After the angle is adjusted by the first reflecting mirror, it becomes perpendicular to the first outgoing light path and enters the atomic gas cell as detection light. Due to the interaction between the detection light and the polarized atoms, the polarization plane of the detection light rotates, and after being transmitted out of the atomic gas cell, it is detected by the signal processing unit. Step 4: Using the magnetic field detector; A dual-path atomic magnetometer based on a polarization metasurface is placed in a geomagnetic environment. A lock-in amplifier scans the radio frequency magnetic field frequency within a certain frequency range to obtain the difference between the optical intensity power signal and the radio frequency corresponding to the extreme value. Then, the magnetic field strength is automatically calculated.

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