SERF atom magnetometer and pumping laser frequency automatic calibration system and method

Abstract

The invention provides an SERF atom magnetometer and a pumping laser frequency automatic calibration system and method, and the system comprises an atom magnetometer probe which is internally provided with a VCSEL laser, an optical assembly, an alkali metal atom gas chamber, a non-magnetic heating sheet, and a photodiode. The system control circuit comprises a main control module, and a laser current source, a laser heating circuit, a laser thermistor reading circuit, an atomic gas chamber heating circuit and a photodiode transimpedance amplification circuit which are electrically connected with the main control module. According to the invention, a high-precision wavelength meter is not needed, and the pumping laser frequency can be automatically adjusted to be consistent with the resonant frequency of the SERF atom magnetometer D1 only through photodiode transmission light intensity signal feedback; the target value of the heating temperature of the VCSEL laser can be automatically adjusted according to the difference of different SERF atomic magnetic D1 resonant frequencies, and it is guaranteed that the output pump laser frequency of the VCSEL laser is kept consistent with the D1 resonant frequency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of atomic magnetometer, in particular to a SERF atomic magnetometer and a pump laser frequency automatic calibration system and method. BACKGROUND

[0002] In recent years, with the development of photoelectric weak signal detection technology and quantum control technology, the spin-exchange relaxation free (SERF) atomic magnetometer as a new type of ultra-high sensitivity quantum weak magnetic detection technology has been widely used in biological magnetic measurement, ultra-low field magnetic resonance, dark matter search and other fields due to its unique advantages such as no need for liquid helium cryogenic conditions, small size, low price and short detection distance.

[0003] The premise of realizing high-sensitivity detection of the SERF atomic magnetometer is that the pump laser frequency is the same as the D1 resonance frequency of the alkali metal atoms inside the atomic cell. Therefore, the accuracy of the pump laser frequency is extremely important. Generally, the SERF atomic magnetometer uses a semiconductor narrow-line-width laser to output the pump laser, and the pump laser frequency adjustment relies on the temperature adjustment of the laser chip. For different laser chips, the chip temperature corresponding to the pump laser frequency is different. The conventional technology uses a high-precision wavelength meter as a feedback tool and a fixed pump laser frequency preset value to calibrate the temperature of the laser chip. However, the premise of this scheme is that the pump laser frequencies of the SERF atomic magnetometers are consistent. However, in practice, due to the influence of the buffer gas filled in the atomic cell and the manufacturing process of the atomic cell, the actual D1 resonance frequency of the SERF atomic magnetometer will deviate from the theoretical value, and the D1 resonance frequencies corresponding to different SERF atomic magnetometers are different. Therefore, the accurate D1 resonance frequency of the SERF atomic magnetometer cannot be known in advance, and the use of a high-precision wavelength meter and a fixed pump laser frequency preset value will result in a deviation from the actual D1 resonance frequency of the atomic magnetometer, leading to a decrease in the performance of the SERF atomic magnetometer.

[0004] To this end, the present application provides a new SERF atomic magnetometer pump laser frequency automatic calibration system, which does not need to rely on a high-precision wavelength meter, and can automatically calibrate the D1 resonance frequency of different SERF atomic magnetometers according to their characteristics and obtain the corresponding pump laser temperature, so as to finally obtain the accurate pump laser frequency of the SERF atomic magnetometer. SUMMARY

[0005] In order to achieve the above-mentioned purposes and other advantages of the present application, the first object of the present application is to provide a SERF atomic magnetometer pump laser frequency automatic calibration system, comprising: An atomic magnetometer probe, which is internally provided with a VCSEL laser, an optical assembly, an alkali metal atom cell, a non-magnetic heating sheet for heating the atom cell, and a photodiode for detecting transmitted light, the optical assembly being used to guide the laser emitted by the VCSEL laser to sequentially pass through the atom cell and reach the photodiode; a system control circuit, comprising a master control module, and a laser current source, a laser heating circuit, an atom cell heating circuit, and a photodiode trans-impedance amplification circuit, which are electrically connected to the master control module respectively; The atom cell heating circuit is used to drive the non-magnetic heating sheet to make the atom cell reach and maintain at a preset working temperature. The laser current source is used to provide a constant current to the VCSEL laser. The laser heating circuit is used to control the temperature of the VCSEL laser. The photodiode trans-impedance amplification circuit is used to obtain the transmitted light intensity signal detected by the photodiode. The master control module is configured to, when the temperature of the atom cell is constant, change the temperature of the VCSEL laser by adjusting the control parameter of the laser heating circuit based on the transmitted light intensity signal until the transmitted light intensity signal reaches a minimum value, so as to lock the output laser frequency of the VCSEL laser to the D1 resonance frequency of the alkali metal atoms in the atom cell.

[0006] Further, the system control circuit further comprises a laser thermistor reading circuit, which is electrically connected to the master control module and is used to read the resistance value of the thermistor of the VCSEL laser as the temperature feedback of the laser heating circuit.

[0007] Further, the master control module is specifically configured to perform the following steps: controlling the atom cell heating circuit to drive the non-magnetic heating sheet to heat the atom cell, and the heating temperature reaches and maintains at a preset working temperature; controlling the laser current source to output a preset constant current value to the VCSEL laser; controlling the laser heating circuit to heat the VCSEL laser, and taking the resistance value of the thermistor obtained by the laser thermistor reading circuit as the feedback control laser heating temperature; synchronously obtaining the photodiode transmitted light intensity signal detected by the photodiode trans-impedance amplification circuit; The transmission light intensity value obtained by the photodiode cross-group amplification circuit continuously adjusts the target resistance value of the laser heating thermistor, and finally makes the photodiode transmission light intensity reach a minimum value, and records the target resistance value of the laser heating thermistor at this time; The final recorded target resistance value of the laser heating thermistor is used to control the laser heating to reach a preset temperature, at which the pump laser frequency is consistent with the D1 resonance frequency of the SERF atomic magnetometer, and the automatic calibration of the pump laser frequency of the system is completed.

[0008] Further, the preset working temperature is 120 DEG C to 150 DEG C.

[0009] Further, the preset constant current value is 1mA to 2mA.

[0010] Further, the optical assembly comprises a collimating lens, a polarizer, a mirror and a quarter-wave plate arranged in sequence along the light path, so that the pump light forms circularly polarized light to irradiate the alkali metal atom cell.

[0011] Further, the atomic magnetometer probe further comprises a heat insulation cavity, and the alkali metal atom cell and the non-magnetic heating sheet are arranged in the heat insulation cavity.

[0012] The second object of the present application is to provide a SERF atomic magnetometer pump laser frequency automatic calibration method, which is applied to the above-mentioned system and comprises the following steps: Heating and stabilizing the atomic cell to a preset working temperature; Providing a constant driving current to the VCSEL laser; Monitoring the transmission light intensity of the atomic cell in real time during the adjustment of the temperature of the VCSEL laser; According to the real-time monitored transmission light intensity, the temperature of the VCSEL laser is feedback adjusted until the transmission light intensity reaches a minimum value; The temperature of the VCSEL laser is stabilized at a temperature point corresponding to the minimum value of the transmission light intensity, so that the output laser frequency is consistent with the D1 resonance frequency of the alkali metal atom in the atomic cell.

[0013] Further, the adjustment of the temperature of the VCSEL laser is realized by taking the resistance value of the laser thermistor as feedback and controlling the laser heating circuit.

[0014] The third object of the present application is to provide a SERF atomic magnetometer comprising the above-mentioned pump laser frequency automatic calibration system.

[0015] Compared with the prior art, the present application has the following advantages: The SERF atomic magnetometer and the pump laser frequency automatic calibration system and method provided by the application can automatically adjust the target value of the heating temperature of the VCSEL laser according to the difference of the D1 resonance frequencies of different SERF atomic magnetometers, so that the output pump laser frequency of the VCSEL laser is kept consistent with the D1 resonance frequency.

[0016] The SERF atomic magnetometer and the pump laser frequency automatic calibration system and method provided by the application can automatically adjust the target value of the heating temperature of the VCSEL laser according to the difference of the D1 resonance frequencies of different SERF atomic magnetometers, so that the output pump laser frequency of the VCSEL laser is kept consistent with the D1 resonance frequency.

[0017] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, and the content of the specification can be implemented, the following is the preferred embodiment of the application and the detailed description of the drawings. The specific embodiments of the application are described in detail by the following examples and their drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings described herein are used to provide further understanding of the application, and form a part of the application. The schematic embodiments of the application and their descriptions are used to explain the application, and do not constitute an improper limitation on the application. In the drawings: Figure 1 SERF atomic magnetometer pump laser frequency automatic calibration system block diagram; Figure 2 SERF atomic magnetometer pump laser frequency automatic calibration method flow chart.

[0019] In the figure: 1, atomic magnetometer probe; 2, system control circuit; 3, VCSEL laser; 4, collimating lens; 5, polaroid; 6, mirror; 7, quarter wave plate; 8, alkali metal atom gas chamber; 9, non-magnetic heating sheet; 10, heat insulation cavity; 11, photodiode; 12, main control module; 13, laser current source; 14, laser heating circuit; 15, laser thermistor reading circuit; 16, atomic gas chamber heating circuit; 17, photodiode transimpedance amplifier circuit. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the application will be described in detail below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0021] In the drawings, the shapes and sizes of parts can be exaggerated for clarity, and similar reference numerals can be used to refer to similar or identical parts throughout the several views.

[0022] In the following description, terms such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, lower, and the like are defined with respect to the configuration shown in the drawings, and in particular, "height" corresponds to the dimension from top to bottom, "width" corresponds to the dimension from left to right, and "depth" corresponds to the dimension from front to back, which are relative concepts and thus can vary depending on the different positions and different use states, and therefore, these or other orientations should not be construed as limiting terms.

[0023] Terms relating to attachment, coupling, and the like (e.g., "connected" and "attached") refer to a relationship in which structures are directly or indirectly fixed or attached to each other by an intermediate structure, as well as movable or rigid attachment or relationship, unless explicitly stated otherwise.

[0024] Embodiment 1 A SERF atomic magnetometer pump laser frequency automatic calibration system, as shown in Figure 1 comprises: An atomic magnetometer probe 1, which is internally provided with a VCSEL (vertical cavity surface emitting) laser 3, an optical assembly for guiding the laser emitted by the VCSEL laser 3 to pass through the atomic cell 8 in sequence and reach the photodiode 11, a non-magnetic heating sheet 9 for heating the atomic cell 8, and a photodiode 11 for detecting transmitted light; A system control circuit 2, which comprises a main control module 12, and a laser current source 13, a laser heating circuit 14, an atomic cell heating circuit 16, and a photodiode transimpedance amplification circuit 17 electrically connected to the main control module 12, respectively; Among them, the atomic cell heating circuit 16 is used to drive the non-magnetic heating sheet 9 to make the atomic cell 8 reach and maintain at a preset working temperature; preferably, the preset working temperature is 120-150℃.

[0025] Specifically, the preset working temperature of 120-150℃ is the ideal interval designed for alkali metal atom (such as rubidium, cesium) cell. At this temperature, the atomic density and relaxation time in the alkali metal atom cell reach a balance, which not only ensures enough atoms to participate in the magnetic resonance process, but also avoids the broadening of atomic energy level or the aging of cell material caused by high temperature. For example, the rubidium atom has moderate cell pressure at 120℃, and the transmitted light intensity signal is stable, which helps the main control module to accurately identify the D1 resonance frequency.

[0026] The stable gas cell temperature reduces the fluctuation of atomic relaxation time, making the SERF atomic magnetometer more sensitive to weak magnetic fields.

[0027] The laser current source 13 is configured to provide a constant current to the VCSEL laser 3; The laser heating circuit 14 is configured to control the temperature of the VCSEL laser 3; The photodiode transimpedance amplification circuit 17 is configured to obtain the transmitted light intensity signal detected by the photodiode 11; For the SERF atomic magnetometer, when the temperature of the atomic gas cell 8 reaches the working temperature (120-150℃), the transmitted light intensity detected by the photodiode 11 is related to the output pump laser frequency of the VCSEL laser The relationship can be expressed as: wherein, is the D1 resonance frequency of the atomic magnetometer, is the spectral line full width at half maximum, is a constant proportionality coefficient. As can be seen from the above formula, the transmitted light intensity measured by the photodiode 11 is related to the output pump laser frequency of the VCSEL laser There is a specific relationship, when the output pump laser frequency of the VCSEL laser is equal to the D1 resonance frequency of the atomic magnetometer , that is, , the transmitted light intensity measured by the photodiode 11 will reach a minimum value. Therefore, the D1 resonance frequency of the system can be accurately obtained according to the transmitted light intensity value measured by the photodiode 11, and automatic calibration of the pump laser frequency can be completed.

[0028] For this, the system adjusts the pump laser frequency by controlling the temperature of the VCSEL laser, specifically. Specifically, the main control module 12 is configured to, when the temperature of the atomic gas cell 8 is constant, based on the transmitted light intensity signal, change the temperature of the VCSEL laser 3 by adjusting the control parameters of the laser heating circuit 14 until the transmitted light intensity signal reaches a minimum value, thereby locking the output laser frequency of the VCSEL laser 3 to the D1 resonance frequency of the alkali metal atoms in the atomic gas cell 8.

[0029] The system monitors the transmitted light intensity signal in real time through a photodiode. When the temperature of the atomic cell is constant, the main control module automatically adjusts the laser heating circuit to make the transmitted light intensity signal reach a minimum value. This process is essentially locking the output frequency of the VCSEL laser to the D1 resonance frequency of the alkali metal atomic cell. By eliminating frequency drift, the measurement accuracy of the atomic magnetometer is significantly improved, especially in weak magnetic field detection (such as magnetoencephalography and magnetocardiography), which can reduce noise interference and enhance signal-to-noise ratio.

[0030] The synergistic effect of the non-magnetic heating sheet and the atomic cell heating circuit ensures that the cell temperature is constant in the preset working range, avoiding the shift of atomic energy levels caused by temperature fluctuations, thereby maintaining the long-term stability of the magnetometer.

[0031] The system automatically completes the whole process from signal detection to parameter adjustment through the closed-loop control of the main control module. This not only reduces human error, but also significantly shortens the calibration time, making it suitable for applications that require frequent start-up or changes in environmental temperature. The automatic calibration function reduces the dependence on professional operation and reduces maintenance costs, especially suitable for non-laboratory environments such as field or industrial sites.

[0032] The integrated design of optical components (such as lenses and polarizing plates) ensures that the light emitted by the VCSEL laser can efficiently pass through the atomic cell and be received by the photodiode, improving light energy utilization and reducing scattering loss.

[0033] The linkage of the main control module with the laser current source, heating circuit, and transimpedance amplification circuit enables precise control of the laser temperature, current, and cell temperature. For example, the laser current source provides a constant current to maintain the laser output power, and the transimpedance amplification circuit converts the weak photoelectric signal into a processable electrical signal, providing real-time feedback for frequency locking.

[0034] By locking to the D1 resonance frequency, the system can resist the interference of environmental magnetic field or temperature fluctuations on the laser frequency, ensuring that the magnetometer can still maintain high performance in complex environments.

[0035] The system can adapt to different alkali metals (such as rubidium and cesium) and switch to the working frequency of other elements by adjusting the cell parameters and the main control module algorithm, expanding the application range of the system.

[0036] In some embodiments, the system control circuit further includes a laser NTC reading circuit 15 electrically connected to the main control module 12 for reading the resistance value of the NTC of the VCSEL laser 3 as temperature feedback for the laser heating circuit 14.

[0037] The actual temperature of the VCSEL laser is monitored in real time by the thermistor, and the resistance signal is converted into an electrical signal to feed back to the main control module, forming a closed-loop control. The main control module can dynamically adjust the output power of the laser heating circuit according to the deviation of the feedback value from the preset temperature target, realizing precise temperature regulation.

[0038] The traditional open-loop control is easily affected by environmental temperature changes or laser power fluctuations, leading to temperature drift. The closed-loop feedback mechanism can quickly respond to temperature changes, suppress overshoot and oscillation, and ensure that the VCSEL laser works in a constant temperature state, avoiding laser frequency deviation caused by temperature fluctuations.

[0039] Under the premise of constant temperature of the atomic gas chamber, the main control module relies on the minimum transmission light intensity signal to lock the laser frequency. At this time, the stability of the laser temperature directly affects the calibration result. The real-time feedback of the thermistor enables the main control module to more accurately adjust the laser heating circuit, shorten the calibration time (such as from minutes to seconds), and reduce the risk of calibration failure caused by temperature fluctuations.

[0040] In a complex environment (such as sudden temperature change or electromagnetic interference), the thermistor feedback can quickly identify abnormal temperature changes, trigger the compensation mechanism of the main control module, and maintain the stability of the laser frequency, thereby improving the reliability of the atomic magnetometer in the field or industrial scene.

[0041] Since the VCSEL laser is sensitive to temperature, long-term operation in a high-temperature or temperature-fluctuating environment will accelerate device aging. Through real-time monitoring by the thermistor, the main control module can limit the laser temperature within a safe range, avoiding performance degradation or permanent damage caused by overheating.

[0042] Precise temperature control reduces the accumulation of thermal stress on the laser, prolonging its service life and reducing replacement frequency and maintenance costs, especially suitable for scenarios that require long-term continuous operation.

[0043] The thermistor feedback data can be combined with the algorithm of the main control module (such as PID control) to realize dynamic optimization of the laser temperature. For example, automatically adjust the heating power according to the environmental temperature change, reduce energy consumption, and at the same time maintain the frequency locking accuracy.

[0044] In particular, the main control module 12 is specifically configured to perform the following steps: The main control module is specifically configured to perform the following steps: The atomic gas chamber heating circuit 16 is controlled to drive the non-magnetic heating sheet 9 to heat the atomic gas chamber 8, and the heating temperature reaches the preset working temperature (120-150°C) and keeps the temperature constant; The laser current source 13 controls the output of the VCSEL laser to a preset constant current value; preferably, the preset constant current value is 1 mA to 2 mA, which provides stable driving conditions for the VCSEL laser. Too low current may result in insufficient laser power, affecting the detection of the transmitted light intensity signal; too high current may easily cause the laser to heat up, resulting in frequency drift. By precisely controlling the current, the system ensures the long-term stability of the laser output power, providing a reliable light source for frequency locking.

[0045] In combination with the closed-loop feedback of the laser heating circuit, the preset current value and the temperature range work together to avoid frequency jumps caused by sudden changes in current or temperature. For example, when the ambient temperature changes, the main control module can dynamically adjust the heating power to control the laser temperature fluctuation within ±0.002℃, thereby maintaining the stability of the laser frequency.

[0046] The laser heating circuit 14 controls the heating of the VCSEL laser 3, and the resistance value of the thermistor obtained by the laser thermistor reading circuit 15 is used as feedback to control the laser heating temperature; Synchronously, the photodiode transimpedance amplifier circuit 17 detects the photodiode transmitted light intensity and feeds back to the main control module 12; that is, the main control module 12 synchronously acquires the photodiode transmitted light intensity signal detected by the photodiode transimpedance amplifier circuit; According to the transmitted light intensity value obtained by the photodiode transimpedance amplifier circuit 17, the target resistance value of the laser heating thermistor is continuously adjusted, and the photodiode transmitted light intensity is finally minimized, and the target resistance value of the laser heating thermistor at this time is recorded; The final recorded target resistance value of the laser heating thermistor is used to control the laser heating to reach the preset temperature, at which the pump laser frequency is consistent with the SERF atomic magnetometer D1 resonance frequency, completing the automatic calibration of the system pump laser frequency.

[0047] The main control module drives the non-magnetic heating sheet through the atomic chamber heating circuit to quickly raise the chamber temperature to the preset working temperature and keep it constant. This process avoids the temperature fluctuation problem of traditional manual adjustment, ensuring that the alkali metal atomic chamber is always in the best working state, providing a stable atomic energy level environment for subsequent frequency locking.

[0048] In combination with the laser thermistor reading circuit, the main control module monitors the VCSEL laser temperature in real time and dynamically adjusts the laser heating circuit to form a closed-loop control. For example, when the thermistor resistance value deviates due to changes in the ambient temperature, the system can automatically compensate the heating power, significantly improving the long-term stability of the laser frequency.

[0049] The main control module first controls the laser current source to output a preset constant current value, ensuring the initial output power of the VCSEL laser to be stable; then, through the laser heating circuit, temperature adjustment is performed in combination with the feedback of the thermistor, to realize fine control of the temperature of the laser. This "current-temperature" dual-parameter cooperative mechanism avoids the limitations of single-parameter adjustment and shortens the calibration time.

[0050] The main control module synchronously acquires the photoelectric diode transmitted light intensity signal and dynamically adjusts the target resistance value of the laser heating thermistor through an algorithm. When the transmitted light intensity reaches a minimum value, the system automatically records the target resistance value at this time and controls the laser heating to a preset temperature based on the target resistance value. This process does not require manual intervention, the calibration efficiency is improved, and the frequency deviation caused by operation errors is avoided.

[0051] Through the minimization locking of the transmitted light intensity, the main control module ensures that the pump laser frequency is completely consistent with the D1 resonance frequency of the SERF atomic magnetometer. This mechanism eliminates the influence of frequency drift on the measurement accuracy of the magnetometer, improves the signal-to-noise ratio of the weak magnetic field detection, and significantly improves the detection sensitivity of the weak biomagnetic field, especially in biomedical applications such as magnetoencephalography and magnetocardiography.

[0052] In a complex environment (such as electromagnetic interference or sudden temperature change), the main control module quickly responds to abnormalities through a closed-loop feedback mechanism to maintain the stability of the laser frequency. For example, when the external magnetic field causes the transmitted light intensity to fluctuate, the system can automatically adjust the heating parameters to ensure that the frequency locking is not affected, thereby improving the reliability of the atomic magnetometer in industrial fields or field operations.

[0053] In some embodiments, the optical assembly includes a collimating lens 4, a polarizer 5, a mirror 6, and a quarter-wave plate 7 arranged in sequence along the optical path, so that the pump light forms circularly polarized light to irradiate the alkali metal atom cell 8.

[0054] The collimating lens ensures that the laser beam enters the subsequent optical elements as parallel light, avoiding energy loss caused by beam divergence; the polarizer filters non-polarized light and only retains linearly polarized light in a specific direction, providing pure input for subsequent circular polarization conversion. The folding effect of the mirror makes the optical path perpendicular to the cell axis, in combination with the circular polarization conversion of the quarter-wave plate, ensuring uniform distribution of the pump light in the cell cross-section. This uniformity reduces the light intensity gradient in the atom cell, avoiding uneven atomic relaxation time caused by local over-strength or over-weakness, and improving the measurement consistency of the magnetometer.

[0055] In some embodiments, the atomic magnetometer probe 1 further includes a heat-insulating cavity 10, and the alkali metal atom cell 8 and the non-magnetic heating sheet 9 are arranged in the heat-insulating cavity 10.

[0056] The heat insulation cavity is constructed by using a low-thermal-conductivity material (such as ceramic or a composite heat insulation layer), and effectively blocks the influence of external environmental temperature changes on the internal gas chamber. Through the heat preservation effect of the heat insulation cavity, the non-magnetic heating sheet only needs to maintain the gas chamber at a preset working temperature (such as 120 DEG C), and does not need to continuously compensate for external heat loss.

[0057] In the SERF atomic magnetometer, the pumping laser frequency needs to be locked to the D1 resonance frequency through the minimum transmission light intensity. The heat insulation cavity can ensure that the atomic gas chamber is always in the best working state by suppressing the temperature fluctuation of the gas chamber, so that the transmission light intensity signal converges faster and fluctuates less.

[0058] In a complex electromagnetic environment (such as near a high-voltage transformer substation or medical equipment), the heat insulation cavity can reduce the direct radiation of external heat sources to the gas chamber, avoid laser frequency jumping caused by local overheating, and improve the measurement accuracy of the magnetometer in a strong interference scene.

[0059] The SERF atomic magnetometer pumping laser frequency automatic calibration system provided by the application can automatically adjust the pumping laser frequency to be consistent with the D1 resonance frequency of the SERF atomic magnetometer only through the feedback of the photodiode transmission light intensity signal without the aid of a high-precision wavemeter.

[0060] The SERF atomic magnetometer pumping laser frequency automatic calibration system provided by the application can automatically adjust the VCSEL laser heater temperature target value according to the difference of the D1 resonance frequency of different SERF atomic magnetometers, so as to ensure that the output pumping laser frequency is consistent with the D1 resonance frequency.

[0061] Embodiment 2 A SERF atomic magnetometer pumping laser frequency automatic calibration method is applied to the above-mentioned system, and the detailed description of the system can be referred to the system embodiment, which will not be repeated here. As shown in the figure, the method comprises the following steps: Figure 2 S100, heating and stabilizing the atomic gas chamber to a preset working temperature; Specifically, the system main control module 12 controls the atomic gas chamber heating circuit 16 to drive the non-magnetic heating sheet 9 to heat the atomic gas chamber 8, and the heating temperature reaches a preset value (120-150 DEG C) and keeps constant; S200, providing a constant driving current to the VCSEL laser; Specifically, the system main control module 12 controls the laser current source 13 to output a preset constant current value (1-2 mA) to the VCSEL laser; S300, in the process of adjusting the temperature of the VCSEL laser, the transmission light intensity of the atomic gas chamber is monitored in real time; ​Specifically, the system main control module 12 controls the laser heating circuit 14 to heat the VCSEL laser 3, and uses the NTC resistance value obtained by the laser NTC reading circuit 15 as feedback to control the laser heating temperature. Synchronously, the photodiode cross-group amplifier circuit 17 detects the intensity of the transmitted light from the photodiode and feeds it back to the main control module 12; S400. Based on the real-time monitored transmitted light intensity, adjust the temperature of the VCSEL laser until the transmitted light intensity reaches its minimum value. Furthermore, the temperature of the VCSEL laser is adjusted by controlling the laser heating circuit based on feedback from the resistance value of the laser thermistor.

[0062] S500. Stabilize the temperature of the VCSEL laser at the temperature point corresponding to the minimum transmitted light intensity, so that its output laser frequency is consistent with the D1 resonance frequency of the alkali metal atoms in the atomic gas cell.

[0063] Specifically, the main control module 12 continuously adjusts the target resistance of the laser-heated NTC based on the transmitted light intensity value obtained by the photodiode cross-group amplifier circuit 17, and finally makes the transmitted light intensity of the photodiode reach the minimum value, and records the target resistance of the laser-heated NTC at this time. The laser heating is controlled to reach the preset temperature by using the final recorded target resistance value of the laser heating NTC. At this time, the pump laser frequency is consistent with the resonance frequency of SERF atomic magnetometer D1, and the automatic calibration of the system pump laser frequency is completed.

[0064] Example 3 A SERF atomic magnetometer includes the aforementioned automatic pump laser frequency calibration system. For a detailed description of the system, please refer to the above-described system embodiment, which will not be repeated here.

[0065] Among them, the pump laser frequency automatic calibration system locks the laser frequency to the D1 resonance frequency of alkali metal atoms (such as rubidium and cesium) through closed-loop feedback adjustment, thereby eliminating the influence of frequency drift on the measurement accuracy of the magnetometer.

[0066] In complex electromagnetic environments (such as industrial sites or near medical equipment), the closed-loop feedback mechanism can quickly respond to frequency shifts caused by changes in temperature or magnetic field, maintaining laser frequency stability.

[0067] With the integration of an automatic pump laser frequency calibration system, the SERF atomic magnetometer can perform atomic chamber heating, laser temperature adjustment, and frequency locking without manual intervention. Calibration time is reduced from several minutes using traditional methods to tens of seconds, making it particularly suitable for scenarios requiring rapid deployment.

[0068] Traditional frequency calibration requires professional technicians to adjust laser parameters, while this design enables non-professionals to quickly complete the calibration through preset parameters and closed-loop feedback, expanding the application range of the equipment in non-professional environments such as industrial sites and scientific research laboratories.

[0069] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0070] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

[0071] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0072] The above description is merely an embodiment of this specification and is not intended to limit the scope of one or more embodiments of this specification. Various modifications and variations can be made to one or more embodiments of this specification by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of one or more embodiments of this specification should be included within the scope of the claims of one or more embodiments of this specification.

Claims

1. An automatic calibration system for the pump laser frequency of a SERF atomic magnetometer, characterized in that, include: An atomic magnetometer probe contains a VCSEL laser, optical components, an alkali metal atom gas cell, a non-magnetic heating element for heating the atom gas cell, and a photodiode for detecting transmitted light. The optical components guide the laser emitted by the VCSEL laser through the atom gas cell and to the photodiode. The system control circuit includes a main control module, and a laser current source, a laser heating circuit, an atomic gas chamber heating circuit, and a photodiode transimpedance amplifier circuit, all electrically connected to the main control module. The atomic gas chamber heating circuit is used to drive the non-magnetic heating element so that the atomic gas chamber reaches and is maintained at a preset working temperature. The laser current source is used to provide a constant current to the VCSEL laser; The laser heating circuit is used for temperature control of the VCSEL laser. The photodiode transimpedance amplifier circuit is used to acquire the transmitted light intensity signal detected by the photodiode. The main control module is configured to, when the temperature of the atomic gas chamber is constant, adjust the control parameters of the laser heating circuit to change the temperature of the VCSEL laser based on the transmitted light intensity signal until the transmitted light intensity signal reaches a minimum value, thereby locking the output laser frequency of the VCSEL laser to the D1 resonance frequency of the alkali metal atoms in the atomic gas chamber.

2. The SERF atomic magnetometer pump laser frequency automatic calibration system as described in claim 1, characterized in that, The system control circuit also includes a laser thermistor reading circuit, which is electrically connected to the main control module and is used to read the resistance value of the VCSEL laser as temperature feedback for the laser heating circuit.

3. The SERF atomic magnetometer pump laser frequency automatic calibration system as described in claim 2, characterized in that, The main control module is specifically configured to perform the following steps: The heating circuit of the atomic gas chamber is controlled to drive the non-magnetic heating element to heat the atomic gas chamber, and the heating temperature reaches the preset working temperature and is kept constant. The laser current source is controlled to output a preset constant current value to the VCSEL laser; The laser heating circuit is controlled to heat the VCSEL laser, and the thermistor resistance value obtained by the laser thermistor reading circuit is used as feedback to control the laser heating temperature. The transmitted light intensity signal of the photodiode detected and fed back by the transimpedance amplifier circuit of the photodiode is simultaneously acquired. Based on the transmitted light intensity value obtained from the cross-group amplification circuit of the photodiode, the target resistance value of the laser heating thermistor is continuously adjusted, and the transmitted light intensity of the photodiode is finally reduced to the minimum value. The target resistance value of the laser heating thermistor at this time is recorded. The laser heating temperature is controlled by the target resistance value of the laser heating thermistor obtained by the final recording. At this time, the pump laser frequency is consistent with the resonance frequency of SERF atomic magnetometer D1, and the automatic calibration of the system pump laser frequency is completed.

4. The SERF atomic magnetometer pump laser frequency automatic calibration system as described in claim 1 or 2, characterized in that, The preset operating temperature is 120℃ to 150℃.

5. The SERF atomic magnetometer pump laser frequency automatic calibration system as described in claim 3, characterized in that, The preset constant current value is 1mA to 2mA.

6. The SERF atomic magnetometer pump laser frequency automatic calibration system as described in claim 1, characterized in that, The optical components include a collimating lens, a polarizer, a reflector, and a quarter-wave plate arranged sequentially along the optical path, so that the pump light forms circularly polarized light to irradiate the alkali metal atom gas cell.

7. The SERF atomic magnetometer pump laser frequency automatic calibration system as described in claim 1, characterized in that, The atomic magnetometer probe also includes a heat insulation cavity, in which the alkali metal atom gas chamber and the non-magnetic heating element are disposed.

8. An automatic calibration method for the pump laser frequency of a SERF atomic magnetometer, applied to the system described in any one of claims 1 to 7, characterized in that, Includes the following steps: Heat and stabilize the atomic gas chamber to the preset operating temperature; Provide a constant drive current to the VCSEL laser; During the adjustment of the VCSEL laser temperature, the transmitted light intensity of the atomic gas cell is monitored in real time. Based on the real-time monitored transmitted light intensity, the temperature of the VCSEL laser is adjusted according to feedback until the transmitted light intensity reaches its minimum value. The temperature of the VCSEL laser is stabilized at the temperature point corresponding to the minimum transmitted light intensity, so that its output laser frequency is consistent with the D1 resonance frequency of the alkali metal atoms in the atomic gas cell.

9. The automatic calibration method for the pump laser frequency of a SERF atomic magnetometer as described in claim 8, characterized in that, The temperature of the VCSEL laser is adjusted by controlling the laser heating circuit based on feedback from the resistance value of the laser thermistor.

10. A SERF atomic magnetometer, characterized in that, Includes an automatic pump laser frequency calibration system as described in any one of claims 1 to 7.

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