CN116224180A - Ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop - Google Patents
Ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop Download PDFInfo
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Abstract
The invention provides an ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop, which provides a feasible closed loop scheme for the ellipsometric SERF atomic magnetometer, thereby locking the magnetic field sensed by alkali metal atoms in the ellipsometric SERF atomic magnetometer at zero field, remarkably increasing the dynamic range and bandwidth of magnetic field measurement and improving the stability of magnetic field measurement. According to the invention, a dimensionless operation signal obtained by the quotient of the first harmonic component and the second harmonic component of the zero-order resonance signal is used as an input signal of the closed-loop feedback system, so that the interference of factors such as ovality, optical power density, optical frequency fluctuation, atomic air chamber temperature fluctuation and the like of pumping laser on the input signal of the closed-loop feedback system is weakened, and the accuracy and the robustness of a closed loop are improved.
Description
Technical Field
The invention relates to a magnetic field closed loop-based ellipsometric SERF (Spin-Exchange-Relaxation-Free) atomic magnetometer device and method, and belongs to the technical field of atomic magnetometers.
Background
The SERF atomic magnetometer is an ultra-high sensitivity quantum precision measuring instrument for measuring an extremely weak magnetic field, and has been widely used in the fields of leading edge physics research, biological magnetic measurement and the like in recent years. The ellipsometric SERF atomic magnetometer uses a beam of ellipsometric light to pump alkali metal atoms, and simultaneously utilizes a polarization differential detection technology to detect the rotation angle, thereby having the advantages of small volume and high sensitivity. However, the existing ellipsometric SERF atomic magnetometer works in an open loop state, and the magnetic field to be measured in the z direction is directly measured through the first harmonic component of the zero-order resonance signal output by the ellipsometric SERF atomic magnetometer, so that the dynamic range and bandwidth of the atomic magnetometer are limited, the atomic magnetometer is easily disturbed by fluctuation of the temperature of an atomic air chamber, laser parameters and the like, the magnetic field measurement signal is caused to drift, and the measurement effect of the ellipsometric SERF atomic magnetometer is limited.
Disclosure of Invention
The invention provides an ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop, which provides a feasible closed loop scheme for the ellipsometric SERF atomic magnetometer, and locks the magnetic field sensed by a sensitive medium-alkali metal atomic spin ensemble in the ellipsometric SERF atomic magnetometer at zero field in real time, thereby remarkably improving the dynamic range and bandwidth of the ellipsometric SERF atomic magnetometer. The first harmonic component and the second harmonic component of the zero-order resonance signal output by the atomic magnetometer are input to the closed-loop feedback system after being calculated, so that the interference of factors such as ellipticity, optical power density, optical frequency, atomic air chamber temperature and the like fluctuation of pumping laser on the input signal of the closed-loop feedback system is weakened, the closed-loop stability is improved, and the stability and accuracy of magnetic field measurement are further improved.
The technical scheme of the invention is as follows:
the ellipsometric SERF atomic magnetometer device based on the magnetic field closed loop is characterized by comprising a triaxial magnetic field coil and a polarization differential detection module, wherein the triaxial magnetic field coil and the polarization differential detection module are arranged in an atomic magnetometer head shell, a laser input end of the polarization differential detection module is connected with a laser emitting end of an atomic air chamber in the triaxial magnetic field coil, a laser incident end of the atomic air chamber is sequentially connected with a narrow linewidth semiconductor laser through an elliptical polarizer and a polarization maintaining fiber, an output end of the polarization differential detection module is sequentially connected with the triaxial magnetic field coil through a lock-in amplifier, a division circuit, a subtraction circuit, a PID module and a z-axis function generator, the triaxial magnetic field coil is connected with an xy-axis function generator, the z-axis function generator outputs direct current voltage to drive the triaxial magnetic field coil to generate a magnetic field in the z direction, and the xy-axis function generator outputs direct current voltage to drive the triaxial magnetic field coil to generate a magnetic field in the x direction and the y direction.
The polarization differential detection module comprises a lateral displacement polarization beam splitter prism, wherein the input end of the lateral displacement polarization beam splitter prism is connected with the laser emitting end of the atomic gas chamber through a half wave plate, and the output end of the lateral displacement polarization beam splitter prism is connected with the lock-in amplifier through a photoelectric detector and a differential amplifying circuit in sequence.
The elliptical polarizer comprises a linear polarizer and a quarter wave plate, the included angle of the optical axis direction of the linear polarizer and the included angle of the optical axis direction of the quarter wave plate are alpha, the polarization direction of linearly polarized light emitted by the narrow linewidth semiconductor laser coincides with the optical axis direction of the linear polarizer, a linearly polarized light source is converted into elliptical polarized light with ellipticity alpha through the elliptical polarizer, and the elliptical polarized light is pumping laser of an elliptical polarized light SERF atomic magnetometer.
An oven is arranged between the atomic air chamber and the triaxial magnetic field coil, the lock-in amplifier inputs a first harmonic component and a second harmonic component to the dividing circuit respectively, the subtracting circuit makes a difference between a dimensionless operation signal from the dividing circuit and a set value, the obtained difference is used as an error signal to be input to a PID (Proportional Integral Derivative, proportion, integral and derivative) module, the dimensionless operation signal is a quotient obtained by dividing the first harmonic component by the second harmonic component, and the first harmonic component and the second harmonic component are harmonic components in an ellipsometric SERF atomic magnetometer zero-order resonance signal.
The z-axis function generator outputs a feedback control signal, and the feedback control signal and a coil constant of the triaxial magnetic field coil in the z direction are calculated to obtain an output signal of the atomic magnetometer, namely a magnetic field to be detected in the z-axis forward direction.
Wherein θ is w Is a first harmonic component, θ 2w Is the second harmonic component, K is the amplification factor, I 0 For pumping optical power density, OD (v) is optical depth, n is atomic number density, c is light velocity, r is classical electron radius, f is alkali metal atom D1 line resonance intensity, l is atom air chamber length, v 0 Is the resonance frequency of the D1 line of the alkali metal atom, v is the frequency of laser, and gamma is the pressure broadening of an atomic air chamber, R op For pumping rate, R rel Is the transverse atomic spin relaxation rate, s is the spin angular momentum of pumping light, gamma e Is gyromagnetic ratio of electrons, J 0 And J 1 And J 2 Bessel functions of 0 order, 1 order and 2 order respectively, u is a magnetic field modulation coefficient, B 0 Is the z-axis positive magnetic field to be measured.
Wherein S is input Is a dimensionless operation signal S ctrl Is a feedback control signal, R op For pumping rate, R rel For transverse relaxation rate, J 1 And J 2 Bessel functions of 1 order and 2 order respectively, u is a magnetic field modulation parameter, B 0 Is a magnetic field to be measured in the positive direction of the z axis, kz is a coil constant in the z direction of the triaxial magnetic field coil, and R is a resistance in the z direction of the triaxial magnetic field coil.
The application method of the ellipsometric SERF atomic magnetometer based on the magnetic field closed loop is characterized by comprising the following steps of:
step 1, adjusting the frequency of laser emitted by a narrow linewidth semiconductor laser to deviate from the linear resonance frequency of an alkali metal atom D1, wherein the polarization state is linear polarization, coupling the laser as a light source into a polarization maintaining fiber, converting linear polarized light emitted by the polarization maintaining fiber into elliptical polarized light with ellipticity alpha through an elliptical polarizer, and irradiating the light as pumping laser to an atomic air chamber;
The three-dimensional magnetic compensation technology in the step 2 is a technology for realizing the return-to-zero of the environmental magnetic field sensed by the atomic air chamber by controlling the triaxial magnetic field coils around the atomic air chamber to generate the magnetic field with the same size and opposite direction as the environmental magnetic field.
The invention has the following technical effects: the ellipsometric SERF atomic magnetometer device and the method based on magnetic field closed loop provide a feasible closed loop scheme for the ellipsometric SERF atomic magnetometer, lock the magnetic field sensed by alkali metal atoms in the ellipsometric SERF atomic magnetometer at zero field, remarkably increase the dynamic range and bandwidth of the ellipsometric SERF atomic magnetometer and improve the stability of magnetic field measurement. According to the invention, a dimensionless operation signal obtained by the quotient of the first harmonic component and the second harmonic component of the zero-order resonance signal is used as an input signal of the closed-loop feedback system, so that the interference of factors such as ovality, optical power density, optical frequency, atomic air chamber temperature fluctuation and the like of pumping laser on the closed-loop feedback system is weakened, and the accuracy and the robustness of closed loop are improved.
Compared with the prior art, the invention has the advantages that:
(1) The conventional ellipsometric SERF atomic magnetometer works in an open loop state, so that the atomic magnetometer has small measurement bandwidth and dynamic range, large measurement signal fluctuation and easy interference; the invention provides a closed-loop method, so that an ellipsometric SERF atomic magnetometer can work in a closed-loop state, and the environmental magnetic field sensed by an atomic air chamber is compensated to zero field by a triaxial magnetic field coil in real time, so that the dynamic range and bandwidth of the ellipsometric SERF atomic magnetometer are increased, and meanwhile, the stability of signal measurement is improved due to the closed-loop control method;
(2) Conventional ellipsometric SERF atomic magnetometers use the first harmonic component of the zero order resonance signal as the atomic magnetometer output signal. The first harmonic component is directly used as an input signal of closed loop feedback, so that the feedback control signal is interfered by parameters of pumping laser and temperature fluctuation of an atomic air chamber, and the like, so that an environmental magnetic field sensed by the atomic air chamber fluctuates near a zero field, and the closed loop effect is reduced. The method uses dimensionless operation signals obtained by the first harmonic component and the second harmonic component as input signals of a closed loop feedback system, so that the items related to pumping laser and atomic gas chamber temperature in the two components are reduced, thereby weakening the influence of laser power density, frequency, ovality fluctuation and atomic gas chamber temperature fluctuation of the pumping laser on feedback control signals and improving the accuracy and robustness of the closed loop method.
(3) The invention does not change the original ellipsometric SERF atomic magnetometer probe structure, realizes the acquisition of feedback control signals by extracting the second harmonic component, and retains the advantages of compact structure and high sensitivity.
Drawings
Fig. 1 is a schematic structural diagram of an ellipsometric SERF atomic magnetometer device based on magnetic field closed loop embodying the invention. SERF (Spin-Exchange Relaxation Free) is Spin-free relaxation.
The reference numerals are explained as follows: 1-a narrow linewidth semiconductor laser; a 2-xy axis function generator; 3-polarization maintaining optical fiber; a 4-elliptical polarizer; a 5-atom gas cell; 6-half wave plate; 7-a lateral displacement polarization beam splitter prism; 8-a photodetector; a 9-differential amplifying circuit; 10-an oven; 11-differentially amplifying the signal; 12-triaxial magnetic field coil; 13-atomic magnetometer gauge outfit housing; a 14-lock-in amplifier; 15-first harmonic component; 16-second harmonic component; 17-dividing circuit; an 18-subtracting circuit; 19-PID module (PID, proportion Integration Differentiation, proportional-integral-derivative); a 20-z axis function generator; 21-a feedback control signal; 22-a closed loop feedback system; and a 23-polarization differential detection module.
Detailed Description
The invention is described below with reference to the accompanying drawings (fig. 1) and examples.
Fig. 1 is a schematic structural diagram of an ellipsometric SERF atomic magnetometer device based on magnetic field closed loop embodying the invention. Referring to fig. 1, an ellipsometric SERF atomic magnetometer device based on magnetic field closed loop comprises a triaxial magnetic field coil 12 and a polarization differential detection module 23, wherein the triaxial magnetic field coil 12 and the polarization differential detection module 23 are positioned in an atomic magnetometer head shell 13, a laser input end of the polarization differential detection module 23 is connected with a laser emitting end of an atomic air chamber 5 in the triaxial magnetic field coil 12, a laser incident end of the atomic air chamber 5 is sequentially connected with a narrow linewidth semiconductor laser 1 through an elliptical polarizer 4 and a polarization maintaining fiber 3, an output end of the polarization differential detection module 23 is sequentially connected with the triaxial magnetic field coil 12 through a phase-locked amplifier 14, a division circuit 17, a subtracting circuit 18, a PID module 19 and a z-axis function generator 20, the triaxial magnetic field coil 12 is connected with an xy-axis function generator 2, the z-axis function generator 20 is used for controlling the triaxial magnetic field coil 12 to compensate the environmental magnetic field in the z-direction to zero, and the xy-axis function generator 2 is used for controlling the triaxial magnetic field coil 12 to compensate the environmental magnetic field in the x-direction and the y-direction to zero.
The polarization differential detection module 23 comprises a lateral displacement polarization splitting prism 7, the input end of the lateral displacement polarization splitting prism 7 is connected with the laser emitting end of the atomic gas chamber 5 through a half wave plate 6, and the output end of the lateral displacement polarization splitting prism 7 is connected with the lock-in amplifier 14 sequentially through a photoelectric detector 8 and a differential amplifying circuit 9. The linearly polarized light source emitted by the narrow linewidth semiconductor laser 1 is transmitted to the elliptical polarizer 4 through the polarization maintaining fiber 3. The elliptical polarizer 4 comprises a linear polarizer and a quarter wave plate, the included angle between the optical axis directions of the linear polarizer and the quarter wave plate is alpha, the polarization direction of a linear polarized light source coincides with the optical axis direction of the linear polarizer, the linear polarized light source is converted into elliptical polarized light with ellipticity alpha through the elliptical polarizer 4, and the elliptical polarized light is pumping laser of an elliptical polarized light SERF atomic magnetometer.
An oven 10 is arranged between the atomic air chamber 5 and the triaxial magnetic field coil 12, a first harmonic component 15 and a second harmonic component 16 are respectively input to the dividing circuit 17 by the lock-in amplifier 14, a dimensionless operation signal from the dividing circuit 17 is differenced from a set value 0 by the subtracting circuit 18, the obtained difference is input to the PID module 19 as an error signal, the dimensionless operation signal is a quotient (a/b) obtained by dividing a first harmonic component 15 (a) by a second harmonic component 16 (b), and the first harmonic component 15 and the second harmonic component 16 are harmonic components in an ellipsometric SERF atomic magnetometer zero-order resonance signal. The z-axis function generator 20 outputs a feedback control signal 21, and the feedback control signal 21 and a coil constant in the z direction of the triaxial magnetic field coil 12 are calculated to obtain an atomic magnetometer output signal, that is, a magnetic field measurement value in the z direction.
The invention provides an ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop, which uses dimensionless operation signals obtained by the quotient of a first harmonic component and a second harmonic component as input signals of a closed loop feedback system, and controls a three-dimensional magnetic field coil to make the environmental magnetic field sensed by an atomic air chamber be compensated to zero field in real time, thereby working in a closed loop state. The present invention will be described in detail below with reference to the attached drawings and specific embodiments, it being understood that these embodiments are only for illustrating the invention and not for limiting the scope of the invention, and that modifications of the invention in its various equivalent forms will fall within the scope of the appended claims to the present application after reading the present invention.
Referring to fig. 1, the invention provides an ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop. As shown in fig. 1, an ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop comprises: the device comprises a narrow linewidth semiconductor laser 1, an xy-axis function generator 2, a polarization maintaining fiber 3, an elliptical polarizer 4, an atomic gas chamber 5, a half wave plate 6, a lateral displacement polarization beam splitter prism 7, a photoelectric detector 8, a differential amplifying circuit 9, an oven 10, a differential amplifying signal 11, a triaxial magnetic field coil 12, an atomic magnetometer gauge head shell 13, a lock-in amplifier 14, a first harmonic component 15, a second harmonic component 16, a dividing circuit 17, a subtracting circuit 18, a PID module 19, a z-axis function generator 20, a feedback control signal 21, a closed loop feedback system 22 and a polarization differential detection module 23;
as shown in fig. 1, the specific implementation steps of the present invention are as follows:
(1) The frequency of the linear polarized laser emitted by the narrow linewidth semiconductor laser 1 deviates from the linear resonance frequency of the alkali metal atom D1 by 50GHz, the laser is used as a light source to be coupled into the polarization maintaining fiber 3, the linear polarized light emitted by the polarization maintaining fiber 3 is converted into elliptical polarized light with ellipticity of 22.5 degrees through the elliptical polarizer 4, and the light is used as pumping laser to irradiate the atomic air chamber 5;
(2) After the step (1) is completed, the output voltages of the xy-axis function generator 2 and the z-axis function generator 20 are regulated, and the surrounding magnetic field sensed by the atomic gas chamber 5 is zeroed by utilizing a three-dimensional magnetic compensation technology; controlling the z-axis function generator 20 to apply a high-frequency modulation magnetic field in the z direction, wherein the frequency is 1kHz and the amplitude is 80nT;
(3) After step (2) is completed, the differential amplified signal 11 output by the polarization differential detection module 23 is led into a phase-locked amplifier 14, and the differential amplified signal 11 is demodulated at 1kHz and 2kHz respectively by using a phase-locked amplification technology in the phase-locked amplifier to obtain a first harmonic component 15 which is marked as theta w The second harmonic component 16, denoted θ 2w ；
Wherein K is an amplification factor, I 0 For pumping optical power density, OD (v) is optical depth, n is atomic number density, c is light velocity, r is classical electron radius, f is alkali metal atom D1 line resonance intensity, l is atom air chamber length, v 0 Is the resonance frequency of the D1 line of the alkali metal atom, v is the frequency of laser, and gamma is the pressure broadening of an atomic air chamber, R op For pumping rate, R rel S is spin angular momentum of pumping light, gamma is the transverse relaxation rate e Gyromagnetic ratio of single electron, J 0 And J 1 And J 2 Bessel functions of 0 order, 1 order and 2 order respectively, u is a magnetic field modulation parameter, B 0 Is the magnetic field to be measured in the positive direction of the z axis;
(4) The first harmonic component 15 theta obtained in the step (3) is processed w Second harmonic component 16 theta 2w Through a division circuit 17, a dimensionless operation signal S is obtained input ＝θ w /θ 2w Will S input The subtraction circuit 18 is connected to make difference with the set value 0, the obtained difference is input as an error signal to the PID module 19, the output signal of the PID module 19 controls the z-axis function generator 20 to generate a feedback control signal 21, which is marked as S ctrl ；
Wherein S is input Is a dimensionless operation signal S ctrl Is a feedback control signal, R op For pumping rate, R rel For transverse relaxation rate, J 1 And J 2 Bessel functions of 1 order and 2 order respectively, u is a magnetic field modulation parameter, B 0 Is the magnetic field to be measured in the positive direction of the z axis;
(5) S obtained in step (4) ctrl Acts on the z direction of the triaxial magnetic field coil 12 to make the magnetic field generated by the coil equal to the magnetic field to be measured in the positive direction of the z axis and opposite to the magnetic field to be measured in the positive direction of the z axis, thereby locking the perceived magnetic field of the ellipsometric SERF atomic magnetometer to zero field, kz and S ctrl Calculating to obtain a z-axis positive magnetic field B to be measured 0 ；
％ 0 ＝-KzS ctrl/ R
Where Kz is the coil constant in the z direction of the triaxial magnetic field coil 12, R is the resistance in the z direction of the triaxial magnetic field coil, and B 0 Is the z-axis positive magnetic field to be measured.
In a word, the invention provides an ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop, which uses dimensionless operation signals obtained by the quotient of a first harmonic component and a second harmonic component as input signals of a closed loop feedback system, weakens the influence of parameter fluctuation of pumping laser and atomic air chamber temperature fluctuation on feedback control signals, and improves the accuracy and robustness of the closed loop method. The three-dimensional magnetic field coil is controlled by a closed loop method, so that the environmental magnetic field sensed by the atomic air chamber is compensated to zero field in real time, and the dynamic range and the bandwidth of measurement are improved.
An ellipsometric SERF atomic magnetometer device and method based on magnetic field closed loop, characterized in that: the device comprises a narrow-linewidth semiconductor laser (1), an xy-axis function generator (2), a polarization maintaining optical fiber (3), an elliptical polarizer (4), an atomic gas chamber (5), a half wave plate (6), a lateral displacement polarization beam splitter prism (7), a photoelectric detector (8), a differential amplifying circuit (9), an oven (10), a differential amplifying signal (11), a triaxial magnetic field coil (12), an atomic magnetometer gauge outfit shell (13), a lock-in amplifier (14), a first harmonic component (15), a second harmonic component (16), a division circuit (17), a subtracting circuit (18), a PID module (19), a z-axis function generator (20), a feedback control signal (21), a closed loop feedback system (22) and a polarization differential detection module (23). Adjusting the frequency of laser emitted by a narrow linewidth semiconductor laser (1) to deviate from the D1 line resonance frequency of an alkali metal atom, coupling the laser as a light source into a polarization maintaining optical fiber (3), converting the laser into elliptical polarized light through an elliptical polarizer (4), and irradiating the light as pumping laser to an atomic gas chamber (5); controlling the xy-axis function generator (2) and the z-axis function generator (20), zeroing the magnetic field sensed by the atomic air chamber (5) by utilizing a three-dimensional magnetic compensation technology, and controlling the z-axis function generator (20) to apply a high-frequency modulation magnetic field in the z direction; demodulating the differential amplified signal (11) in a phase-locked amplifier by using a phase-locked amplification technology at a frequency multiplication frequency and a frequency doubling frequency respectively to obtain a first harmonic component (15) and a second harmonic component (16); the two-component quotient is subjected to dimensionless operation signals and is subjected to difference with 0, the obtained difference is used as an error signal and is input into a PID module (19), a z-axis function generator (20) is controlled by an output signal of the PID module (19) to generate a feedback control signal (21) and act on the z direction of a triaxial magnetic field coil (12), and the coil generates a magnetic field with the same magnitude and opposite direction to a magnetic field to be detected in the positive direction of the z axis, so that the magnetic field sensed by an ellipsometric SERF atomic magnetometer is locked at a zero field.
The device also comprises a narrow linewidth semiconductor laser (1), a polarization maintaining fiber (3) and an elliptical polarizer (4); the narrow linewidth semiconductor laser (1) is used for providing a linearly polarized laser light source; the polarization maintaining optical fiber (3) is used for transmitting a laser light source; an elliptical polarizer (4) is used to convert linearly polarized light into elliptical polarized light of a specific ellipticity, which serves as a pump laser to polarize alkali metal atoms.
The device also comprises an xy-axis function generator (2), a z-axis function generator (20) and a triaxial magnetic field coil (12); the xy-axis function generator (2) is used for controlling the triaxial magnetic field coil (12) to compensate the ambient magnetic field in the x-direction and the y-direction to zero; the z-axis function generator (20) is used to control the triaxial magnetic field coil (12) to compensate for the ambient magnetic field in the z-direction to zero.
The device also comprises an atomic air chamber (5) and an oven (10); an atomic gas chamber (5) is used as a sensing element, filled with alkali metal atoms and in a weak magnetic environment; the oven (10) is wrapped around the atomic air chamber (5),for heating the atomic gas chamber (5) to a density of 10 of the number of alkali metal atoms 13 ～10 14 Individual/cm 3 。
The device also comprises a half wave plate (6), a lateral displacement polarization beam splitter prism (7), a photoelectric detector (8), a differential amplifying circuit (9) and a polarization differential detection module (23); before the alkali metal atoms are heated, the half wave plate (6) adjusts the splitting ratio of two orthogonal components of the lateral displacement polarization splitting prism (7) to 50 percent and 50 percent; the lateral displacement polarization beam splitter prism (7) is used for splitting pumping laser into two linearly polarized lights with orthogonal polarization directions; the photoelectric detector (8) is used for converting light intensity information of two linearly polarized lights transmitted through the lateral displacement polarization beam splitter prism (7) into a current signal; the differential amplifying circuit (9) is used for carrying out difference and amplification on two current signals output by the photoelectric detector (8); the polarization differential detection module (23) comprises a half wave plate (6), a lateral displacement polarization beam splitter prism (7), a photoelectric detector (8) and a differential amplifying circuit (9) and is used for realizing a polarization differential detection technology.
The device also comprises a differential amplified signal (11), a phase-locked amplifier (14), a first harmonic component (15), a second harmonic component (16) and a division circuit (17); the phase-locked amplifier (14) is used for realizing phase-locked amplification technology to obtain harmonic components; the first harmonic component (15) and the second harmonic component (16) are harmonic components in the zero-order resonance signal of the ellipsometric SERF atomic magnetometer, and the two harmonic components are used for obtaining dimensionless operation signals through a division circuit (17).
The system also comprises a subtracting circuit (18), a PID module (19), a z-axis function generator (20), a feedback control signal (21) and a closed-loop feedback system (22); the closed loop feedback system (22) comprises a subtracting circuit (18), a PID module (19), a z-axis function generator (20) and a feedback control signal (21), wherein the subtracting circuit (18) is used for making a difference between a dimensionless operation signal and a set value 0, the obtained difference value is input into the PID module (19) as an error signal, an output signal of the PID module (19) is connected to the z-axis function generator (20), and the z-axis function generator (20) is used for generating the feedback control signal (21) for controlling a z-direction magnetic field of the triaxial magnetic field coil (12).
The atomic magnetometer is characterized in that the tail end of the polarization maintaining optical fiber (3), the elliptical polarizer (4), the atomic air chamber (5), the oven (10), the triaxial magnetic field coil (12) and the polarization difference detection module (23) are placed in the atomic magnetometer gauge outfit shell (13) to form the atomic magnetometer gauge outfit together with the atomic magnetometer gauge outfit shell (13).
The optical axis direction of the lateral displacement polarization beam splitter prism (7) is aligned with the fast axis direction of the polarization maintaining fiber (3).
The emitting frequency of the narrow linewidth semiconductor laser (1) deviates from the linear polarized light source of the linear resonance frequency of the alkali metal atom D1, and the light source is coupled into the polarization maintaining fiber (3) by aligning the polarization direction of the linear polarized light with the fast axis direction of the polarization maintaining fiber (3).
The elliptical polarizer (4) comprises a linear polarizer and a quarter wave plate, the included angle between the optical axis directions of the linear polarizer and the quarter wave plate is alpha, the polarization direction of a linear polarized light source is coincident with the optical axis direction of the linear polarizer, the linear polarized light source is converted into elliptical polarized light with ellipticity alpha through the elliptical polarizer (4), and the light is pumping laser of an elliptical polarized light SERF atomic magnetometer.
And the feedback control signal (21) and the coil constant of the triaxial magnetic field coil (12) in the z direction are calculated to obtain an atomic magnetometer output signal, namely a magnetic field measurement value in the z direction.
What is not described in detail in the present specification belongs to the prior art known to those skilled in the art. It is noted that the above description is helpful for a person skilled in the art to understand the present invention, but does not limit the scope of the present invention. Any and all such equivalent substitutions, modifications and/or deletions as may be made without departing from the spirit and scope of the invention.
Claims (9)
1. The ellipsometric SERF atomic magnetometer device based on the magnetic field closed loop is characterized by comprising a triaxial magnetic field coil and a polarization differential detection module, wherein the triaxial magnetic field coil and the polarization differential detection module are arranged in an atomic magnetometer head shell, a laser input end of the polarization differential detection module is connected with a laser emitting end of an atomic air chamber in the triaxial magnetic field coil, a laser incident end of the atomic air chamber is sequentially connected with a narrow linewidth semiconductor laser through an elliptical polarizer and a polarization maintaining fiber, an output end of the polarization differential detection module is sequentially connected with the triaxial magnetic field coil through a lock-in amplifier, a division circuit, a subtraction circuit, a PID module and a z-axis function generator, the triaxial magnetic field coil is connected with an xy-axis function generator, the z-axis function generator outputs direct current voltage to drive the triaxial magnetic field coil to generate a magnetic field in the z direction, and the xy-axis function generator outputs direct current voltage to drive the triaxial magnetic field coil to generate a magnetic field in the x direction and the y direction.
2. The ellipsometric SERF atomic magnetometer device based on magnetic field closed loop according to claim 1, wherein the polarization differential detection module comprises a lateral displacement polarization beam splitter prism, the input end of the lateral displacement polarization beam splitter prism is connected with the laser emitting end of the atomic gas chamber through a half wave plate, and the output end of the lateral displacement polarization beam splitter prism is connected with the lock-in amplifier sequentially through a photoelectric detector and a differential amplifying circuit.
3. The ellipsometric SERF atomic magnetometer device based on closed loop of magnetic field according to claim 1, wherein the ellipsometer comprises a linear polarizer and a quarter wave plate, the included angle between the optical axis directions of the two is α, the polarization direction of the linear polarized light source coincides with the optical axis direction of the linear polarizer, the linear polarized light source is converted into ellipsometric light with ellipticity α by the ellipsometer, and the ellipsometric light is pumping laser of the ellipsometric SERF atomic magnetometer.
4. The ellipsometric SERF atomic magnetometer device based on a closed loop of a magnetic field according to claim 1, characterized in that an oven is arranged between the atomic air chamber and the triaxial magnetic field coil, the lock-in amplifier inputs a first harmonic component and a second harmonic component to the dividing circuit, respectively, the subtracting circuit inputs a difference between a dimensionless operation signal from the dividing circuit, which is a quotient of the first harmonic component divided by the second harmonic component, and a set value 0, as an error signal, to the PID module, and the first harmonic component and the second harmonic component are harmonic components in the ellipsometric SERF atomic magnetometer zero-order resonance signal.
5. The ellipsometric SERF atomic magnetometer device based on magnetic field closed loop according to claim 1, wherein the z-axis function generator outputs a feedback control signal, and the feedback control signal is calculated with a coil constant in the z-direction of the triaxial magnetic field coil to obtain an atomic magnetometer output signal, namely a magnetic field to be measured in the z-axis forward direction.
6. The ellipsometric SERF atomic magnetometer device based on magnetic field closed loop according to claim 1, characterized in that it comprises:
wherein θ is w Is a first harmonic component, θ 2w Is the second harmonic component, K is the amplification factor, I 0 For pumping optical power density, OD (v) is optical depth, n is atomic number density, c is light velocity, r is classical electron radius, f is alkali metal atom D1 line resonance intensity, l is atom air chamber length, v 0 Is the resonance frequency of the D1 line of the alkali metal atom, v is the frequency of laser, and gamma is the pressure broadening of an atomic air chamber, R op For pumping rate, R rel S is spin angular momentum of pumping light, gamma is the transverse relaxation rate e Gyromagnetic ratio of single electron, J 0 And J 1 And J 2 Bessel functions of 0 order, 1 order and 2 order respectively, u is a magnetic field modulation parameter, B 0 Is the z-axis positive magnetic field to be measured.
7. The ellipsometric SERF atomic magnetometer device based on magnetic field closed loop according to claim 1, characterized in that it comprises:
wherein S is input Is a dimensionless operation signal S ctrl Is a feedback control signal, R op For pumping rate, R rel For transverse relaxation rate, J 1 And J 2 Bessel functions of 1 order and 2 order respectively, u is a magnetic field modulation parameter, B 0 Is a magnetic field to be measured in the positive direction of the z axis, kz is a coil constant in the z direction of the triaxial magnetic field coil, and R is a resistance in the z direction of the triaxial magnetic field coil.
8. A method for operating a magnetic field closed loop based ellipsometric SERF atomic magnetometer, comprising the steps of using a magnetic field closed loop based ellipsometric SERF atomic magnetometer according to any of the preceding claims 1-7, and:
step 1, adjusting the frequency of laser emitted by a narrow linewidth semiconductor laser to deviate from the linear resonance frequency of an alkali metal atom D1, wherein the polarization state is linear polarization, coupling the laser as a light source into a polarization maintaining fiber, converting linear polarized light emitted by the polarization maintaining fiber into elliptical polarized light with ellipticity alpha through an elliptical polarizer, and irradiating the light as pumping laser to an atomic air chamber;
step 2, controlling an xy-axis function generator and a z-axis function generator, zeroing the magnetic field sensed by the atomic air chamber by utilizing a three-dimensional magnetic compensation technology, and controlling the z-axis function generator to apply a high-frequency modulation magnetic field in the z direction, wherein the frequency is w m ；
Step 3, leading the differential amplified signals output by the polarization differential detection module into phase-locked amplifiers, and using phase-locked amplification technology in the phase-locked amplifiers to respectively multiply the frequency by one w m Frequency doubling 2w m Demodulating the differential amplified signal to obtain a first harmonic component theta w Second harmonic component θ 2w ；
Step 4, θ w And theta 2w Obtaining a dimensionless operation signal S through a division circuit input ＝θ w /θ 2wt Will S input Accessing a subtracting circuit to make S input Difference from the set value 0, the obtained difference is used as an error signal to be input into a PID module, and the output signal of the PID module controls a z-axis function generator to generate a feedback control signal S ctrl ；
Step 5,S ctrl Acts on the z direction of the triaxial magnetic field coil to lead the magnetic field generated by the coil to be opposite to the z-axis positive magnetic field B to be measured 0 Equal and opposite in magnitude, thereby locking the perceived magnetic field of the ellipsometric SERF atomic magnetometer to zero field.
9. The method according to claim 8, wherein the three-dimensional magnetic compensation technique in step 2 is a technique of controlling the triaxial magnetic field coil around the atomic gas chamber to generate a magnetic field having the same magnitude and opposite directions as the ambient magnetic field, thereby realizing the zeroing of the ambient magnetic field sensed by the atomic gas chamber.
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| CN116879813A (en) * | 2023-06-20 | 2023-10-13 | 北京自动化控制设备研究所 | Signal detection method and system based on in-situ magnetic compensation very low frequency atomic magnetometer |
| CN116879812A (en) * | 2023-06-20 | 2023-10-13 | 北京自动化控制设备研究所 | Frequency closed-loop control detection method and system for electronic resonance magnetometer |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116879813A (en) * | 2023-06-20 | 2023-10-13 | 北京自动化控制设备研究所 | Signal detection method and system based on in-situ magnetic compensation very low frequency atomic magnetometer |
| CN116879812A (en) * | 2023-06-20 | 2023-10-13 | 北京自动化控制设备研究所 | Frequency closed-loop control detection method and system for electronic resonance magnetometer |
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