Miniaturized omnidirectional wide-temperature-range geomagnetic field atom magnetometer device

Abstract

The invention relates to the technical field of geomagnetic field measurement, and provides a miniaturized omnidirectional wide-temperature-range geomagnetic field atom magnetometer device. The magnetometer mainly solves the problem that in the prior art, a magnetometer is limited in the aspects of sensitivity, measuring range, working temperature range, omni-directivity and the like. According to the main scheme, accurate temperature control is achieved through a VCSEL laser and a TEC controller, and it is ensured that the laser works stably; the atomic gas chamber is heated to a preset temperature through the DIP controller, and ideal conditions are created for magnetic field measurement; a laser frequency modulation lock-in amplifier is adopted to control the wavelength of a VCSEL laser, and the transition of a fine structure of an alkali metal atom D1 line is tracked, so that the measurement precision is improved; drifting of the microwave generator is reduced by using a digital phase-locked loop and a microwave modulation technology, and long-term stability is improved; the magnetic field intensity is measured through the Zeeman frequency generator and the phase modulation technology, and high sensitivity and accuracy are achieved. The method is suitable for accurate measurement of the geomagnetic field and can be widely applied to the fields of geological exploration, space exploration and the like.

Description

Technical Field

[0001] The invention relates to the field of quantum precision sensing and measurement, and provides a miniaturized omnidirectional geomagnetic field atomic magnetometer device with a wide temperature range. Background Art

[0002] Frequency measurement is one of the most precise and intensively studied measurement methods in the field of quantum sensing and precision measurement technology. The measurement principle of quantum magnetic field meters is based on the determination of the difference frequency between two atoms or molecules. Therefore, by using precisely known quantum mechanical relationships, the measured frequency can be related to the external magnetic field acting on the quantum system.

[0003] The CDSM (Coupled Dark State Magnetometer) coupled dark state atomic magnetometer is an absolute scalar magnetometer based on the two-photon spectrum of free alkali atoms. In an external magnetic field, multiple coherent dark resonance peaks related to the magnetic field will be generated. Each resonance peak reaches its maximum intensity at different angles between the magnetic field direction and the sensor reference axis defined by the laser excitation optical path. The strongest available resonance is selected according to this angle, which allows omnidirectional measurement without dead zones, without the need for complex sensor design and additional moving parts or RF coils.

[0004] A single CPT (coherent population trapping) atomic magnetometer based on the two-photon spectrum of free alkali atoms can be chip-based to achieve high sensitivity, but the measurement error is restricted by factors such as the type of buffer gas in the atomic gas chamber, the buffer gas pressure and the ambient temperature. It requires high temperature control accuracy and a narrow operating temperature range. However, the widely used optical pump magnetometer has a dead zone, the sensor design is complex, and the probe has a radio frequency coil. Some applications require multiple optical pump sensor probes to be used together to compensate for the measurement dead zone. The temperature adaptation range is narrow, and the temperature environment adaptation range for drone applications and space magnetic field detection is insufficient. The design of the quantum system is crucial in the system, which determines the main performance indicators and wide temperature adaptation range that the magnetometer can meet. The innovative design of the quantum system also determines the miniaturization of the sensor probe. The use of embedded coupling mirrors instead of commercial coupling mirrors in optical design further reduces the size and weight of the sensor probe. The miniaturization of the electronic system must also be solved for drone airborne applications. Based on this device, the size and power consumption of the electronic system can be reduced. In summary, realizing a miniaturized, omnidirectional atomic magnetometer with a wide temperature range is of great significance for geophysical detection applications and accelerating localization and independent control.

[0005] The present invention aims to propose a device and sensor probe design of a miniaturized atomic magnetometer for measuring the earth's magnetic field and magnetic anomalies (10 -4T or less). The method is to measure the magnetic field by using multiple dark resonances based on the Zeeman effect. In this method, the quantum system of the working atoms of the sensor is irradiated by electromagnetic radiation of different frequencies in the atomic gas chamber and frequency-tuned and excited, thereby causing frequency splitting and frequency shift due to the Zeeman effect. This frequency splitting leads to a decrease in fluorescence radiation, a decrease in absorption, or an increase in transmission at a certain resonance frequency (i.e., dark resonance). The resonance frequency depends on the magnetic field and is determined by frequency tuning to measure the magnetic field. The characteristic of this method is that multiple dark resonances are coupled by using polychromatic electromagnetic radiation, and thus frequency detection that depends only on the frequency shift caused by the magnetic field is performed to measure the magnetic field.

[0006] This design can eliminate the ground state frequency ν HFS The systematic errors in (p,T) make the magnetic field measurement independent of factors such as the atomic chamber buffer gas, temperature and pressure. A clear advantage of optical dark resonance compared to radio frequency excitation is that optical fibers can be used to transmit the excitation radiation into the sample. This is particularly beneficial for sensitive magnetometers, as all magnetic and electronic components can be kept away from the measurement volume. In addition, in principle, spatial resolutions in the micrometer range are possible with optical excitation, rather than the centimeter-sized excitation areas in radio frequency experiments, so such designs can achieve miniaturization and micro-miniaturization of sensors and even the development of chip-based atomic magnetometers.

[0007] The sensor adopts multiple coherently trapped atomic resonance peak detection schemes and triple frequency modulation spectroscopy technology. It is an all-optical design without RF coils and motor drive mechanisms. It has omnidirectional measurement capabilities without dead zones within a wide temperature range (2060°C), and can meet the needs of various geomagnetic range scalar magnetic field detection application scenarios such as satellite-borne space magnetic fields, UAV magnetic measurements, and offshore magnetic field detection.

[0008] 133 The coherent dark resonance excited by the D1 line laser of Cs has a narrower line width than the D2 line and thus has better sensitivity. When the same saturated vapor pressure is reached in the atomic gas chamber, 133 The heating temperature of Cs is lower, which is beneficial to reduce the power consumption of the whole machine. At room temperature, the vapor pressure of cesium atoms is about 1.6×10 -4 Pa, experiments and tests can be carried out at room temperature without temperature control. 133 Cs is purified from natural cesium salts by reduction. 87 Rb price is dozens of times lower, based on 133 Cs atomic magnetometer is conducive to reducing costs and is more suitable for productization and industrialization. Summary of the invention

[0009] The present invention proposes a miniaturized, omnidirectional, wide temperature range geomagnetic field atomic magnetometer device and sensor probe design, which mainly solves the limitations of magnetometers in the prior art in terms of sensitivity, range, operating temperature range, omnidirectionality, etc. 133 The coupled dark state magnetic field measurement scheme of Cs D1 line excitation adopts all-optical triple frequency modulation spectroscopy technology, which can achieve omnidirectional measurement without dead zone in a wide temperature range of 2060℃. The sensor probe adopts non-magnetic housing material and optical fiber coupling to achieve miniaturization design. In addition, the electronic system is also miniaturized and low-power designed, which overall meets the needs of applications such as drone aeromagnetic detection, satellite-borne space magnetic field measurement and unmanned vehicle magnetic navigation.

[0010] In order to achieve the above purpose, the following technical solutions cannot be invented:

[0011] The present invention provides a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device, comprising:

[0012] Sensor probe: connected to the multimode optical fiber, used to receive and transmit optical signals;

[0013] Multimode optical fiber: connected to the sensor probe, coupling mirror and photodetector to transmit optical signals;

[0014] Coupling mirror and photodetector: connected to multimode optical fiber to detect optical signals;

[0015] Preamplifier: connected to the photodetector to amplify the optical signal;

[0016] Laser frequency modulation lock-in amplifier: connected to the preamplifier, used to demodulate the laser frequency modulation signal;

[0017] Microwave FM lock-in amplifier: connected to the preamplifier, used to demodulate microwave FM signals;

[0018] Zeeman frequency FM lock-in amplifier: connected to the preamplifier, used to demodulate the Zeeman frequency FM signal;

[0019] Controller: connected with laser frequency modulation lock-in amplifier, microwave frequency modulation lock-in amplifier, Zeeman frequency frequency modulation lock-in amplifier, used to control signal processing and equipment operation;

[0020] Zeeman frequency generator: connected to the controller, used to generate a Zeeman frequency signal;

[0021] Microwave modulation frequency generator: connected to the controller, used to generate microwave modulation frequency signal;

[0022] Coupling mirror and gradient refractive index optical fiber: connected to the microwave modulation frequency generator to couple microwave signals;

[0023] TEC temperature controller: connected to the VCSEL laser to control the laser temperature;

[0024] Static constant current source: connected to the VCSEL laser to provide the laser working current;

[0025] VCSEL laser: connected with static constant current source, TEC temperature controller, coupling mirror and gradient refractive index fiber to generate laser signal;

[0026] DC bias device: connected to the VCSEL laser to provide laser bias voltage;

[0027] The first signal adder is connected to the preamplifier and is used for signal addition processing;

[0028] 50 ohm impedance matching: connected to the first signal adder for impedance matching;

[0029] Electrically adjustable attenuator: connected to the dielectric oscillator to adjust the amplitude of the microwave signal;

[0030] Dielectric oscillator (VCO): connected with the electronically adjustable attenuator and digital phase-locked loop to generate microwave signals;

[0031] The second signal adder is connected to the digital phase-locked loop and is used for signal addition processing;

[0032] Digital phase-locked loop: connected with the second signal adder, dielectric oscillator, constant temperature voltage-controlled crystal oscillator (OCXO), used to lock the microwave signal frequency;

[0033] Constant temperature voltage controlled crystal oscillator: connected to the digital phase-locked loop to provide a stable reference frequency;

[0034] Laser current modulation frequency generator: connected to the controller, used to generate laser current modulation signal;

[0035] Host computer: connected to the controller for data processing and equipment control;

[0036] Sensor probe PID temperature controller: connected to the sensor probe, used to control the temperature of the sensor probe;

[0037] Zeeman tracking modulation frequency generator: connected to the controller, used to generate Zeeman tracking modulation frequency signal.

[0038] In the above scheme, the sensor probe includes:

[0039] A non-magnetic shell is provided, a thin film heater is arranged at the bottom of the non-magnetic shell, and an embedded micro-coupling mirror, a neutral light blocking film, a polarizing film, a 1 / 4 glass slide, an alkali metal atom gas chamber, and an embedded micro-coupling mirror are arranged in sequence inside the non-magnetic shell according to the direction of the light path.

[0040] In the above solution, the sensor probe includes: an embedded micro-coupling mirror is arranged in a non-magnetic housing through a coupling mirror adjustment support.

[0041] In the above scheme, VCSEL laser adopts 133 Cs D1 line laser.

[0042] The present invention also provides a control method for a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device, comprising the following steps:

[0043] Step 1, the temperature of the VCSEL laser is controlled by PID mode by setting the temperature control point through the TEC controller, and the static constant current source sets the static working current of the VCSEL laser;

[0044] Step 2, according to a given set temperature, start the DIP controller to heat the atomic gas chamber to a predetermined temperature range;

[0045] Step 3: The controller controls the laser current modulation frequency generator to generate a laser frequency modulation signal f refL , generate a first frequency modulation spectrum, obtain the frequency modulation spectrum absorption spectrum through the photodetector, amplify it through the preamplifier, demodulate it by the laser frequency modulation phase-locked amplifier, collect the demodulation value through the controller and adjust the static constant current source output to control the wavelength of the VCSEL laser, so that the wavelength of the VCSEL laser tracks the fine structure transition of the alkali metal atom D1 line, and suppress the frequency modulation spectrum drift;

[0046] Step 4: The controller controls a digital phase-locked loop that uses a constant temperature voltage-controlled crystal oscillator as a reference source to lock a dielectric oscillator to generate a microwave signal f HFS , the controller controls the microwave modulation frequency generator to generate the microwave modulation frequency f refM , input into the digital phase-locked loop through the second signal adder, and then generate modulation sidebands in the output microwave signal of the dielectric oscillator, the microwave signal is input into the DC bias device after being adjusted by the electrically adjustable attenuator, thereby driving the VCSEL laser to generate a second frequency modulation spectrum, and obtaining the transmitted light coherent layout trapped signal through the photodetector, amplified by the preamplifier, demodulated by the microwave lock-in amplifier, and locked to the constant temperature voltage-controlled crystal oscillator, thereby reducing the drift of the microwave generator and improving the long-term stability of the atomic magnetometer;

[0047] Step 5: The controller drives the Zeeman frequency generator to synthesize the scanning frequency, and generates the Zeeman tracking modulation frequency f through the Zeeman tracking modulation frequency generator. refZThe Zeeman scanning frequency signal is modulated and sent to the phase modulation input terminal of the digital phase-locked loop through the second signal adder. The frequency value corresponding to the zero-crossing point of the orthogonal phase output of the Zeeman frequency modulation phase-locked amplifier is measured to track the Zeeman energy level change induced by the magnetic field. The controller sends the obtained frequency data to the host computer and uses the Briet-Rabi formula to calculate the magnetic field B value.

[0048] In the above scheme, the light projected by the VCSEL laser through the embedded coupling mirror is converted into linearly polarized light, and then converted into σ+ circularly polarized light through a 1 / 4 glass slide at an angle of 45° to the optical axis. The circularly polarized light is projected into the cylindrical alkali metal atom gas chamber, and the transmitted light is coupled to the coupling mirror and the photodetector through a multimode optical fiber.

[0049] In the above scheme, the calculation formula for obtaining the magnetic field B value is as follows:

[0050]

[0051] Among them, v B is the Zeeman frequency of the magnetic field B, μ B for 133 Bohr magneton of Cs, g J is the fine structure Lande factor, g I is the nuclear Lande factor, the number of CPT dark resonance n = m F1 +m F2 , Δm=m F2 -m F1 , I k express 133 Cs nuclear spin quantum number, m F1 express 133 The magnetic quantum number of the ground state F=3 of Cs, m F2 express 133 The magnetic quantum number of the ground state of Cs is F=4, where h is Planck's constant.

[0052] Because the present invention adopts the above technical means, it has the following beneficial effects:

[0053] 1. High sensitivity measurement solution: Based on 133 The coupled dark state magnetic field measurement scheme of the D1 line excitation of Cs is compared with 87 Rb has a narrower dark resonance line width, which can achieve higher sensitivity. 133 The heating temperature of Cs is lower, which is beneficial to reducing the power consumption of the whole machine.

[0054] 2. Omnidirectional measurement without dead zone in a wide temperature range: Through all-optical triple frequency modulation spectroscopy technology, omnidirectional measurement capability without dead zone is achieved in a wide temperature range of 20-60°C. This design can process multiple dark resonance signals generated by magnetic fields at different angles, and select the strongest available resonance peak according to the direction of the magnetic field and the optical axis, and perform dead zone-free measurement in all directions without the need for additional motor adjustment or RF coils.

[0055] 3. Miniaturization design of sensor probe: Using non-magnetic housing materials and fiber coupling, an embedded micro-coupling mirror is designed to further reduce the volume and weight of the sensor probe. At the same time, by using an optical platform to adjust the height and lateral position of the coupling mirror adjustment support to adjust the optical path alignment, the dark resonance spectrum line width is optimized.

[0056] 4. Miniaturized low-power electronics system: The phase control end of the digital phase-locked loop is used to achieve the mixing of two modulation frequencies, thereby miniaturizing the mixing circuit. The phase-locked amplifier uses a synchronous integration based on an integrated operational amplifier and a phase-sensitive detection circuit based on an electronic switch, which realizes the miniaturization of the phase-locked amplifier and reduces the volume, weight and power consumption.

[0057] These innovations together solve the shortcomings of single CPT resonant atomic magnetometers and optically pumped magnetometers in terms of performance, sensor probes and electronic systems, making the device particularly suitable for applications such as UAV aeromagnetic measurement, satellite-borne space magnetic field measurement and unmanned vehicle magnetic navigation. It has important practical value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is the overall structure diagram of a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device;

[0059] Figure 2 Schematic diagram of the sensor probe structure.

[0060] Figure 1 The present invention is a general structural diagram of a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device. Figure 2 yes Figure 1 Schematic diagram of the sensor probe structure involved.

[0061] Attached photos( Figure 1) The labels are listed as follows: 1-sensor probe; 2-multimode optical fiber; 3-coupling mirror and photodetector; 4-preamplifier; 5-laser frequency modulation phase-locked amplifier; 6-microwave frequency modulation phase-locked amplifier; 7-Zeeman frequency frequency modulation phase-locked amplifier; 8-controller (); 9-Zeeman frequency generator; 10-microwave modulation frequency generator; 11-coupling mirror and gradient refractive index optical fiber; 12-TEC temperature controller; 13-static constant current source; 14-VCSEL laser; 15-DC bias device (); 16-signal adder; 17-50 ohm impedance matching; 18-electrically adjustable attenuator; 19-dielectric oscillator (); 20-signal adder; 21-digital phase-locked loop; 22-constant temperature voltage-controlled crystal oscillator (); 23-laser current modulation frequency generator; 24-host computer (); 25-sensor probe PID temperature controller; 26-Zeeman tracking modulation frequency generator.

[0062] Attached photos( Figure 2 ) The markings are listed as follows: 27-embedded micro coupling mirror; 28-neutral light shielding film; 29-polarizing film; 30-1 / 4 glass slide; 31-alkali metal atom gas chamber; 32-thin film heater; 33-coupling mirror adjustment support; 34-non-magnetic shell. DETAILED DESCRIPTION

[0063] The following is a detailed description of the embodiments of the present invention. Although the present invention will be described and illustrated in conjunction with some specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, modifications or equivalent substitutions made to the present invention should all be included in the scope of the claims of the present invention.

[0064] In addition, in order to better illustrate the present invention, numerous specific details are given in the following specific embodiments. It will be understood by those skilled in the art that the present invention can also be implemented without these specific details.

[0065] Figure 1 The present invention is a general structural diagram of a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device. Figure 2 yes Figure 1 Schematic diagram of the sensor probe structure involved. Referring to the attached figure, a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device and sensor probe design specific implementation method includes the following steps: Step 1, the VCSEL laser 14 is temperature-controlled in a PID manner through the TEC temperature controller 12 setting the temperature control point, and the static constant current source 13 sets the static working current of the VCSEL laser 14; Step 2, according to the given set temperature, start the DIP controller 25 to heat the atomic gas chamber to a predetermined temperature range; Step 3, the controller 8 controls the laser current modulation frequency generator 23 to generate a laser frequency modulation signal f refL, generate a first frequency modulation spectrum, obtain the frequency modulation spectrum absorption spectrum through the photodetector 3, amplify it through the preamplifier 4, demodulate it by the laser frequency modulation phase-locked amplifier 5, collect the demodulation value through the controller 8 and adjust the static constant current source output to control the wavelength of the VCSEL laser 14, so that the wavelength of the VCSEL laser 14 tracks the fine structure transition of the alkali metal atom D1 line, and suppress the drift of the frequency modulation spectrum; step 4, the controller 8 controls the digital phase-locked loop 21 with a constant temperature voltage-controlled crystal oscillator 22 as a reference source to lock the dielectric oscillator 19, and generate a microwave signal f HFS , the controller 8 controls the microwave modulation frequency generator 10 to generate the microwave modulation frequency f refM , is input into the digital phase-locked loop 21 through the second signal adder 20, and then generates a modulation sideband in the output microwave signal of the dielectric oscillator 19. The microwave signal is input into the DC bias device 15 after being adjusted by the electrically adjustable attenuator 18, thereby driving the VCSEL laser 14 to generate a second frequency modulation spectrum, and obtaining the transmitted light coherent placement trapped (CPT) signal through the photodetector 3, amplified by the preamplifier 4, and demodulated by the microwave phase-locked amplifier 6, and then locking the OCXO, reducing the drift of the microwave generator and thus improving the long-term stability of the atomic magnetometer; step 5, the controller 8 drives the Zeeman frequency generator 9 to synthesize the scanning frequency, and generates the Zeeman tracking modulation frequency f through the Zeeman tracking modulation frequency generator 26 refZ The Zeeman scanning frequency signal is modulated and sent to the phase modulation input terminal of the digital phase-locked loop 21 through the second signal adder 20. The frequency value corresponding to the zero-crossing point of the orthogonal phase output of the Zeeman frequency modulation phase-locked amplifier 7 is measured to track the Zeeman energy level change induced by the magnetic field. The controller MCU8 sends the obtained frequency data to the host computer 24, and the Briet-Rabi formula is used to calculate the B value.

[0066] exist Figure 2 In the process, the optical path alignment is adjusted by adjusting the height and lateral position of the support 33 by using the optical platform to adjust the coupling mirror; the polarizer 29 is Figure 1 The light projected by the VCSEL laser 14 through the embedded coupling mirror is converted into linearly polarized light, and then converted into σ+ circularly polarized light through a 1 / 4 glass plate at an angle of 45° to the optical axis. The circularly polarized light is projected into the cylindrical alkali metal atom gas chamber 31, and the transmitted light passes through Figure 1 The multimode optical fiber 2 is coupled to a coupling mirror and a photodetector 3 .

[0067] Specifically, the present invention is used to achieve 133The coupled dark state atomic magnetometer device and sensor probe excited by the D1 line laser of Cs are designed, and the implementation steps are as follows: Step 1, the temperature control point of VCSEL laser 14 is set to 75°C through TEC controller 12, and the temperature is controlled in PID mode, and the static constant current source 13 sets the static working current of VCSEL laser 14 to 1-1.2mA, and the wavelength of VCSEL laser 14 is measured to be about 894.59nm; Step 2, the temperature of sensor probe 1 is set to 50°C, and the DIP controller 25 is started to heat the atomic gas chamber to a predetermined temperature range, and the heating temperature is monitored by the negative coefficient thermistor (NTC) attached to the outside of the sensor probe 1; Step 3, the controller 8 controls the laser current modulation frequency generator 23 to generate a laser frequency modulation signal f refL , a 5kHz square wave frequency modulation can be used to generate a first frequency modulation spectrum, and the Doppler absorption spectrum after frequency modulation is obtained through the photodetector 3, and amplified by the preamplifier 4. The preamplifier is a transimpedance amplifier that outputs an AC signal with a certain amplification factor and signal-to-noise ratio. After the signal is demodulated by the laser frequency modulation phase-locked amplifier 5, the controller 8 collects the demodulation value and adjusts the static constant current source output to control the wavelength of the VCSEL laser 14, so that the wavelength of the VCSEL laser 14 tracks 133 The fine structure transition of the D1 line of Cs atoms suppresses the drift of the frequency modulation spectrum; Step 4, the controller 8 controls the ∑-Δ digital phase-locked loop 21 with a 10MHz constant temperature voltage-controlled crystal oscillator (OCXO) 22 as a reference source to lock the 4596MHz dielectric oscillator 19 to generate a microwave signal f HFS , 9192.63MHz, the controller 8 controls the microwave modulation frequency generator 10 to generate the microwave modulation frequency f refM , 300kHz, is input into the digital phase-locked loop 21 through the second signal adder 20, and then a modulation sideband is generated in the output microwave signal of the dielectric oscillator 19, and the frequency difference between the two primary sidebands is 9192.63MHz. The microwave signal is input into the DC bias device 15 after being adjusted by the electrically adjustable attenuator 18, thereby driving the VCSEL laser 14 to generate a second frequency modulation spectrum, and a transmitted light coherent placement trapping (CPT) signal is obtained through the photodetector 3, amplified by the preamplifier 4, and demodulated by the microwave phase-locked amplifier 6, and then locked to the 10MHz constant temperature voltage-controlled crystal oscillator (OCXO) 22, so as to reduce the drift of the microwave generator and thus improve the long-term stability of the atomic magnetometer; Step 5, the controller 8 drives the Zeeman frequency generator 9 to synthesize the scanning frequency (<1.2MHz, step 0.3mHz), and generates the Zeeman tracking modulation frequency f through the Zeeman tracking modulation frequency generator 26 refZ The Zeeman scanning frequency signal (3kHz) is modulated, and the signal is sent to the phase modulation input terminal of the digital phase-locked loop 21 through the second signal adder 20 to measure the frequency value v corresponding to the zero-crossing point of the orthogonal phase output of the Zeeman frequency frequency modulation phase-locked amplifier 7. B, tracking the Zeeman energy level changes induced by the magnetic field, the controller MCU8 sends the obtained frequency data to the host computer 24, and uses the Briet-Rabi formula to calculate the B value. The Briet-Rabi formula is shown as follows:

[0068]

[0069] Among them, v B is the Zeeman frequency of the magnetic field B, μ B for 133 Bohr magneton of Cs, g J is the fine structure Lande factor, g I is the nuclear Lande factor, the number of CPT dark resonance n = m F1 +m F2 , Δm=m F2 -m F1 , I k express 133 Cs nuclear spin quantum number, m F1 express 133 The magnetic quantum number of the ground state F=3 of Cs, m F2 express 133 The magnetic quantum number of the ground state of Cs is F=4, where h is Planck's constant.

[0070] The mixing of two modulation frequencies is realized by using the phase control end of the digital phase-locked loop 21, instead of using the mixing scheme of the ring mixer and the circulator, so that the miniaturization of the mixing circuit can be realized. The laser frequency modulation phase-locked amplifier 5, the microwave frequency modulation phase-locked amplifier 6, and the Zeeman frequency frequency modulation phase-locked amplifier 7 adopt the synchronous integration based on the integrated operational amplifier and the phase-sensitive detection circuit based on the electronic switch, and the surface-mounted integrated operational amplifier IC is used to realize the miniaturization of the laser frequency modulation phase-locked amplifier 5, the microwave frequency modulation phase-locked amplifier 6, and the Zeeman frequency frequency modulation phase-locked amplifier 7.

[0071] exist Figure 2 In the process, the optical path alignment is adjusted by adjusting the height and lateral position of the support 33 by using the optical platform to adjust the coupling mirror; the polarizer 29 is Figure 1 The light projected by the VCSEL laser 14 through the embedded coupling mirror is converted into linear polarized light, and the polarization angle of the 1 / 4 glass slide is obtained by polarization measurement, which is then loaded into the sensor probe non-magnetic housing 34 and then converted into σ+ circularly polarized light through the 1 / 4 glass slide at an angle of 45° to the optical axis. The circularly polarized light is projected into the cylindrical alkali metal atom gas chamber 31, and the transmitted light passes through Figure 1 The multimode optical fiber 2 is coupled to the coupling mirror and the photodetector 3. The neutral light shielding sheet 28 is adjusted and replaced in the device, and the short-term stability change of the 10MHz output is measured and optimized.

[0072] Except for the sensor probe and the coupler, the rest of the device can be designed as a miniaturized, low-power digital-analog hybrid electronics system implemented on a circuit board. In particular, multiple phase-locked amplifiers are implemented using synchronous integration and switching phase-sensitive detection circuits based on integrated operational amplifiers, which reduces the size, weight, and power consumption and eliminates the risk of autonomous control.

[0073] The miniaturized atomic magnetometer developed by the method of this patent has high sensitivity, wide range, wide operating temperature range, and omnidirectionality without dead zones. It can be used for UAV aeromagnetic measurement or satellite-borne space magnetic field measurement, and can be used in geophysical surveying and mapping, port or offshore salvage detection, seismic station geomagnetic monitoring, military unexploded ordnance detection, concealed tactical target detection and other fields within the range of the earth's magnetic field. Its miniaturization and wide temperature range are particularly suitable for UAV mounting applications, and can also be used for portable field magnetic detection.

Claims

1. A miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device, characterized in that: include: A sensor probe (1) connected to the multimode optical fiber (2) for receiving and transmitting optical signals; Multimode optical fiber (2): connected to the sensor probe (1), the coupling mirror and the photodetector (3), and used for transmitting optical signals; A coupling mirror and a photodetector (3) are connected to the multimode optical fiber (2) and are used to detect optical signals; Preamplifier (4): connected to the photodetector (3) and used to amplify the optical signal; Laser frequency modulation lock-in amplifier (5): connected to the preamplifier (4) and used for demodulating the laser frequency modulation signal; Microwave frequency modulation lock-in amplifier (6): connected to the preamplifier (4) and used for demodulating the microwave frequency modulation signal; Zeeman frequency modulation lock-in amplifier (7): connected to the preamplifier (4), used for demodulating the Zeeman frequency modulation signal; Controller (8): connected to the laser frequency modulation lock-in amplifier (5), the microwave frequency modulation lock-in amplifier (6), and the Zeeman frequency frequency modulation lock-in amplifier (7), and used for controlling signal processing and equipment operation; A Zeeman frequency generator (9) is connected to the controller (8) and is used to generate a Zeeman frequency signal; A microwave modulation frequency generator (10) is connected to the controller (8) and is used to generate a microwave modulation frequency signal; A coupling mirror and a gradient refractive index optical fiber (11) are connected to a microwave modulation frequency generator (10) and are used to couple microwave signals; TEC temperature controller (12): connected to the VCSEL laser (14) and used to control the laser temperature; Static constant current source (13): connected to the VCSEL laser (14) and used to provide laser operating current; VCSEL laser (14): connected to a static constant current source (13), a TEC temperature controller (12), a coupling mirror and a gradient refractive index optical fiber (11), for generating a laser signal; A DC bias device (15) is connected to the VCSEL laser (14) and is used to provide a laser bias voltage; A first signal adder (16) connected to the preamplifier (4) and used for signal addition processing; 50 ohm impedance matching (17): connected to the first signal adder (16) for impedance matching; An electrically adjustable attenuator (18) connected to the dielectric oscillator (19) and used to adjust the amplitude of the microwave signal; A dielectric oscillator (19) is connected to the electrically adjustable attenuator (18) and the digital phase-locked loop (21) and is used to generate a microwave signal; A second signal adder (20) connected to the digital phase-locked loop (21) for signal addition processing; A digital phase-locked loop (21) is connected to the second signal adder (20), the dielectric oscillator (19), and the constant temperature voltage-controlled crystal oscillator (22) and is used to lock the frequency of the microwave signal; A constant temperature voltage controlled crystal oscillator (22) is connected to the digital phase locked loop (21) to provide a stable reference frequency; A laser current modulation frequency generator (23) is connected to the controller (8) and is used to generate a laser current modulation signal; Host computer (24): connected to the controller (8) for data processing and equipment control; Sensor probe PID temperature controller (25): connected to the sensor probe (1) and used to control the temperature of the sensor probe; Zeeman tracking modulation frequency generator (26): connected to the controller (8), used to generate a Zeeman tracking modulation frequency signal.

2. According to the miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device of claim 1, the sensor probe (1) comprises: A non-magnetic shell (34) is provided with a thin film heater (32) at the bottom of the non-magnetic shell (34), and an embedded micro-coupling mirror (27), a neutral light blocking film (28), a polarizing film (29), a quarter glass slide (30), an alkali metal atom gas chamber (31), and an embedded micro-coupling mirror (27) are sequentially arranged inside the non-magnetic shell (34) according to the direction of the light path.

3. According to the miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device of claim 1, the sensor probe (1) comprises: The embedded micro-coupling mirror (27) is arranged in a non-magnetic housing (34) via a coupling mirror adjustment support (33).

4. According to the miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device of claim 1, the VCSEL laser adopts 133 Cs D1 line laser.

5. A control method for a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, the temperature of the VCSEL laser (14) is controlled by PID method via a temperature control point set by a TEC controller (12), and a static constant current source (13) sets a static working current of the VCSEL laser (14); Step 2, according to a given set temperature, start the DIP controller (25) to heat the atomic gas chamber to a predetermined temperature range; Step 3: The controller (8) controls the laser current modulation frequency generator (23) to generate a laser frequency modulation signal f refL , generating a first frequency modulation spectrum, obtaining a frequency modulation spectrum absorption spectrum through a photodetector (3), amplifying it through a preamplifier (4), demodulating it through a laser frequency modulation phase-locked amplifier (5), collecting the demodulation value through a controller (8) and adjusting the output of a static constant current source to control the wavelength of a VCSEL laser (14), so that the wavelength of the VCSEL laser (14) tracks the fine structure transition of the alkali metal atom D1 line, and suppressing the frequency modulation spectrum drift; Step 4: The controller (8) controls the digital phase-locked loop (21) using the constant temperature voltage-controlled crystal oscillator (22) as a reference source to lock the dielectric oscillator (19) to generate a microwave signal f HFS The controller (8) controls the microwave modulation frequency generator (10) to generate a microwave modulation frequency f refM , input into a digital phase-locked loop (21) through a second signal adder (20), thereby generating a modulation sideband in the output microwave signal of the dielectric oscillator (19), the microwave signal is input into a DC bias device (15) after being adjusted by an electrically adjustable attenuator (18), thereby driving a VCSEL laser (14) to generate a second frequency modulation spectrum, obtaining a transmitted light coherent layout trapped signal through a photodetector (3), amplifying it through a preamplifier (4), demodulating it through a microwave lock-in amplifier (6), and locking a constant temperature voltage-controlled crystal oscillator (22), thereby reducing the drift of the microwave generator and improving the long-term stability of the atomic magnetometer; Step 5: The controller (8) drives the Zeeman frequency generator (9) to synthesize the scanning frequency, and generates the Zeeman tracking modulation frequency f through the Zeeman tracking modulation frequency generator (26). refZ The Zeeman scanning frequency signal is modulated and sent to the phase modulation input terminal of the digital phase-locked loop (21) through the second signal adder (20). The frequency value corresponding to the zero-crossing point of the orthogonal phase output of the Zeeman frequency modulation phase-locked amplifier (7) is measured to track the Zeeman energy level change induced by the magnetic field. The controller (8) sends the obtained frequency data to the host computer (24) and uses the Briet-Rabi formula to calculate the magnetic field B value.

6. The control method of a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device according to claim 4, characterized in that: The light projected by the VCSEL laser (14) through the embedded coupling mirror (27) is converted into linearly polarized light (1), and then the linearly polarized light is converted into σ+ circularly polarized light through a 1 / 4 glass slide (30) at an angle of 45° to the optical axis. The circularly polarized light is projected into a cylindrical alkali metal atom gas chamber (31), and the transmitted light is coupled to the coupling mirror and the photodetector (3) through a multimode optical fiber (2).

7. The control method of a miniaturized omnidirectional wide temperature range geomagnetic field atomic magnetometer device according to claim 4, characterized in that: The calculation formula for obtaining the magnetic field B value is as follows: where v B is the Zeeman frequency of the magnetic field B, μ B is 1 33 Bohr magneton of Cs, g J is the fine structure Lande factor, g I is the nuclear Lande factor, the number of CPT dark resonance n = m F1 +m F2 , Δm=m F2 -m F1 , I k express 133 Cs nuclear spin quantum number, m F1 express 133 The magnetic quantum number of the ground state F=3 of Cs, m F2 express 133 The magnetic quantum number of the ground state of Cs is F=4, where h is Planck's constant.

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