Closed-loop magnetic compensation method for SERF magnetic field measurement device based on double-beam detection

Abstract

The closed-loop magnetic compensation method of the SERF magnetic field measurement device based on double-beam detection can realize the decoupling of three-axis magnetic field signals by adding Y-axis direction detection light for decoupling on the basis of X-axis direction detection light, thereby realizing independent measurement and closed-loop control of three-axis magnetic field real-time magnetic compensation, and providing support for further improving compensation accuracy, including setting Y-axis direction detection light passing through the alkali metal gas chamber along the Y-axis direction, X-axis direction detection light passing through the alkali metal gas chamber along the X-axis direction, and pumping light passing through the alkali metal gas chamber along the Z-axis direction in the SERF magnetic field measurement device, the X-axis direction detection light is used for detecting the optical rotation angle, the Y-axis direction detection light is used for three-axis magnetic field decoupling, and the pumping light is used for polarizing atoms in the alkali metal gas chamber; adding a Y-axis calibration signal; according to P y controlling the Z-axis coil current to compensate the Z-axis magnetic field; according to P y controlling the X-axis coil current to compensate the X-axis magnetic field; according to P x controlling the Y-axis coil current to compensate the Y-axis magnetic field.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic compensation of SERF ultra-high-sensitivity magnetic field measurement or inertial measurement devices, and in particular to a closed-loop magnetic compensation method of a SERF magnetic field measurement device based on dual-beam detection. Background Art

[0002] Ultra-high-sensitivity spin-exchange-relaxation-free (SERF) measurement devices measure magnetic fields by measuring the Larmor precession angle of atomic spins under a magnetic field. Passive magnetic shielding and active magnetic compensation techniques are typically used to create a space with minimal magnetic field and gradient, keeping the atoms in the SERF state and improving the measurement device's sensitivity. Passive magnetic shielding utilizes the high permeability of a soft magnetic material shielding barrel to confine the magnetic field and shield it from external magnetic interference. Even after passive magnetic shielding, the internal space still retains a remanent magnetization on the order of nanotons, which still significantly affects the sensitivity of the magnetic device. Active magnetic compensation can further reduce this remanent magnetization, which is crucial for improving the sensitivity of SERF magnetic field measurement devices. Traditional methods use a three-axis coil cross-modulation to compensate for the magnetic field. By adjusting a waveform generator, a sinusoidal magnetic field is repeatedly applied across the X and Z axes. After three-axis compensation is completed, the current is stabilized, and the device begins sensitivity testing. This method cannot achieve decoupling of the X-axis and Z-axis magnetic fields, has low accuracy, and is difficult to perform closed-loop control and real-time magnetic field compensation. When testing after the compensation current stabilizes, it cannot respond to real-time changes in the external magnetic field environment, which greatly affects the accuracy of magnetic field compensation and further affects the sensitivity of the magnetic field measurement device. Summary of the Invention

[0003] In response to the defects or shortcomings in the prior art, the present invention provides a closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection. By adding Y-axis detection light for decoupling on the basis of X-axis detection light, the decoupling of three-axis magnetic field signals can be achieved, thereby realizing independent measurement of the three-axis magnetic field and closed-loop control of real-time magnetic compensation. It has strong anti-interference ability and provides support for further improving the compensation accuracy.

[0004] The technical solutions of the present invention are as follows:

[0005] A closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection is characterized by comprising the following steps:

[0006] Step 1, in the SERF magnetic field measuring device, set Y-axis direction detection light passing through the alkali metal cell along the Y-axis direction, X-axis direction detection light passing through the alkali metal cell along the X-axis direction, and pumping light passing through the alkali metal cell along the Z-axis direction, the X-axis direction detection light is used for detecting the optical rotation angle, the Y-axis direction detection light is used for three-axis magnetic field decoupling, and the pumping light is used for polarizing atoms in the alkali metal cell;

[0007] Step 2, add a Y-axis calibration signal;

[0008] Step 3, according to P y control the Z-axis coil current to compensate the Z-axis magnetic field, P y is the Y-axis direction detection light signal;

[0009] Step 4, judge whether P y is extremely small, if not, return to step 3, if yes, go to step 5;

[0010] Step 5, according to P y control the X-axis coil current to compensate the X-axis magnetic field;

[0011] Step 6, judge whether P y is extremely small, if not, return to step 5, if yes, go to step 7;

[0012] Step 7, according to P x control the Y-axis coil current to compensate the Y-axis magnetic field, P x is the X-axis direction detection light signal;

[0013] Step 8, judge whether P x is extremely small, if not, return to step 7, if yes, go to step 9;

[0014] Step 9, end the three-axis decoupling magnetic compensation or return to step 3 to continue real-time magnetic compensation.

[0015] The Y-axis calibration signal in step 2 is , A is the amplitude of the calibration signal, ω y is the frequency of the calibration magnetic field, and t is time, and the Y-axis calibration signal is used as a calibration signal in the whole sensitivity test and as a modulation signal in the three-axis decoupling magnetic compensation.

[0016] In step 2, the following expression is included:

[0017] ,

[0018] Where β y is the Y-axis magnetic field information, is the Y-axis to-be-compensated environmental magnetic field information.

[0019] Steps 3 and 7 include the following expressions:

[0020] ,

[0021] Where k is the proportional coefficient, S0 is the intermediate quantity, β x is the X-axis magnetic field information, β z is the Z-axis magnetic field information, s is the photon polarizability, R OP is the pumping rate of the pump light, R rel is the total relaxation rate.

[0022] Step 4 includes the following expression:

[0023] .

[0024] Step 8 includes the following expression:

[0025] .

[0026] In step 1, the SERF magnetic field measuring device includes a detection light laser for detecting a double beam, the detection light laser is connected to the input side of a beam splitter through a 1 / 2 wave plate, the transmission side of the beam splitter is connected to a data acquisition and control system in sequence through a first reflector, a second reflector, an X-direction detection light polarizer, an alkali metal gas chamber, an X-direction detection light analyzer, and an X-direction detection photoelectric converter, the reflection side of the beam splitter is connected to a data acquisition and control system in sequence through a Y-direction detection light polarizer, an alkali metal gas chamber, a Y-direction detection light analyzer, and a Y-direction detection photoelectric converter, the data acquisition and control system is connected to a three-axis magnetic field compensation coil through a magnetic field compensation waveform generator, and the three-axis magnetic field compensation coil is connected to a magnetic field calibration waveform generator.

[0027] The three-axis magnetic field compensation coil is located in the high magnetic permeability shielding layer, the alkali metal gas chamber is located in the heating chamber, and the heating chamber is located in the three-axis magnetic field compensation coil.

[0028] The technical effects of the present invention are as follows: The present invention is based on a closed-loop magnetic compensation method for a SERF magnetic field measurement device with dual-beam detection. By constructing an optical path structure in which X-axis detection light, Y-axis detection light for decoupling, and pumping light are injected into the gas chamber along the Z direction for polarization, the decoupling of three-axis magnetic field signals can be effectively realized in the three-axis magnetic compensation technology, thereby realizing independent measurement of the three-axis magnetic field and closed-loop control of real-time magnetic compensation, providing support for further improving the compensation accuracy.

[0029] The characteristics of the present invention are as follows:

[0030] (1) This method does not need to repeatedly apply cross modulation signal to X-axis and Z-axis compensation coils, only uses the original magnetic field calibration signal of the sensitive axis Y-axis of the magnetic field measuring device for sensitivity measurement as the modulation signal, does not increase other interference signals, and greatly simplifies the control process.

[0031] (2) The X-direction and Y-direction photoelectric detector signals can be used to realize decoupling of three-axis magnetic field signals, so as to realize independent measurement and closed-loop control of three-axis magnetic field real-time magnetic compensation, and the anti-interference ability is strong, which provides support for further improving the compensation accuracy.

[0032] (3) Another beam of light separated by the beam splitter prism for adjusting the X-direction detection light into the barrel power is used, without adding a laser. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a SERF magnetic field measuring device structure schematic diagram involved in the closed-loop magnetic compensation method of the SERF magnetic field measuring device based on the double-beam detection of the present application.

[0034] Figure 2 is a top view structure schematic diagram of Figure 1 .

[0035] Figure 3 is a flowchart of the closed-loop magnetic compensation method of the SERF magnetic field measuring device based on the double-beam detection of the present application. Figure 3 includes step 1, adding a Y-axis calibration signal (also as a modulation signal for three-axis decoupling magnetic compensation); step 2, according to P y , control the Z-axis coil current to compensate the Z-axis magnetic field, P y is the Y-axis direction detection light signal or represents the X-axis in-situ magnetic field signal (when P y reaches a minimum value) or represents the Y-axis in-situ magnetic field signal (when P y bias reaches a minimum value); step 3, judge whether P y amplitude is minimum, if not, return to step 2, if yes (indicating that the Z-axis magnetic field has been compensated), then enter step 4; step 4, according to P y , control the X-axis coil current to compensate the X-axis magnetic field; step 5, judge whether P y bias is minimum, if not, return to step 4, if yes (indicating that the X-axis magnetic field has been compensated), then enter step 6; step 6, according to P x , control the Y-axis coil current to compensate the Y-axis magnetic field, P x is the X-axis direction detection light signal; step 7, judge whether P xIs the bias extremely small? If not, return to step 6. If yes (indicating that the Y-axis magnetic field has been compensated), proceed to step 8. In step 8, end the three-axis decoupling magnetic compensation or return to step 2 to continue real-time magnetic compensation.

[0036] The accompanying drawings are marked as follows: 1-pumping light; 2-alkali metal gas chamber; 3-heating chamber; 4-three-axis magnetic field compensation coil; 5-high magnetic permeability shielding layer; 6-data acquisition and control system; 7-magnetic field compensation waveform generator; 8-magnetic field calibration waveform generator; 9-detection light laser; 10-1 / 2 wave plate; 11-beam splitter; 12-first reflector; 13-second reflector; 14-X-direction detection light polarizer (X direction, i.e., X-axis direction); 15-X-direction detection light analyzer; 16-X-direction detection photoelectric converter; 17-Y-direction detection light polarizer (Y direction, i.e., Y-axis direction); 18-Y-direction detection light analyzer; 19-Y-direction detection photoelectric converter. DETAILED DESCRIPTION

[0037] Below is the attached figure ( Figures 1-3 ) and Examples illustrate the present invention.

[0038] Figure 1 It is a structural schematic diagram of a SERF magnetic field measuring device involved in implementing the closed-loop magnetic compensation method of the SERF magnetic field measuring device based on dual-beam detection of the present invention. Figure 2 yes Figure 1 Schematic diagram of the structure from the top view. Figure 3 This is a flow chart of the closed-loop magnetic compensation method for SERF magnetic field measurement device based on dual-beam detection according to the present invention. Figures 1 to 3 As shown, a closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection includes the following steps: Step 1, setting a Y-axis detection light passing through the alkali metal gas cell along the Y-axis direction, an X-axis detection light passing through the alkali metal gas cell along the X-axis direction, and a pumping light 1 passing through the alkali metal gas cell along the Z-axis direction in the SERF magnetic field measurement device, wherein the X-axis detection light is used to detect the optical rotation angle, the Y-axis detection light is used for three-axis magnetic field decoupling, and the pumping light is used to polarize the atoms in the alkali metal gas cell; Step 2, adding a Y-axis calibration signal; Step 3, according to P y Control the Z-axis coil current to compensate the Z-axis magnetic field, P y It is the light signal detected in the Y-axis direction; Step 4, judge P y Is the amplitude extremely small? If not, return to step 3. If yes, go to step 5. Step 5, according to P y Control the X-axis coil current to compensate the X-axis magnetic field; Step 6, determine P y Is the bias extremely small? If not, return to step 5. If yes, go to step 7. Step 7, according to P xControl the Y-axis coil current to compensate the Y-axis magnetic field, P x Is the X-axis direction detection light signal; Step 8, determine P x Is the bias extremely small? If not, return to step 7; if yes, proceed to step 9; in step 9, end the three-axis decoupling magnetic compensation or return to step 3 to continue real-time magnetic compensation.

[0039] The Y-axis calibration signal in step 2 is , A is the calibration signal amplitude, ω y is the frequency of the calibration magnetic field, t is the time, and the Y-axis calibration signal is used as a calibration signal throughout the sensitivity test and as a modulation signal in the three-axis decoupling magnetic compensation.

[0040] Step 2 includes the following expression:

[0041] ,

[0042] where β y is the Y-axis magnetic field information, It is the Y-axis environmental magnetic field information to be compensated.

[0043] Steps 3 and 7 include the following expressions:

[0044] ,

[0045] Where k is the proportional coefficient, S0 is the intermediate quantity, β x is the X-axis magnetic field information, β z is the Z-axis magnetic field information, s is the photon polarizability, R OP is the pumping rate of the pump light, R rel is the total relaxation rate.

[0046] Step 4 includes the following expression:

[0047] .

[0048] Step 8 includes the following expression:

[0049] .

[0050] In step 1, the SERF magnetic field measurement device includes a detection light laser 9 for detecting a dual-beam. The detection light laser 9 is connected to the input side of a beam splitter 11 via a half-wave plate 10. The transmission side of the beam splitter 11 is connected to a data acquisition and control system 6 via a first reflector 12, a second reflector 13, an X-direction detection light polarizer 14, an alkali metal gas cell 2, an X-direction detection light analyzer 15, and an X-direction detection photoelectric converter 16. The reflection side of the beam splitter 11 is connected to the data acquisition and control system 6 via a Y-direction detection light polarizer 17, an alkali metal gas cell 2, a Y-direction detection light analyzer 18, and a Y-direction detection photoelectric converter 19. The data acquisition and control system 6 is connected to a three-axis magnetic field compensation coil 4 via a magnetic field compensation waveform generator 7. The three-axis magnetic field compensation coil 4 is connected to a magnetic field calibration waveform generator 8. The three-axis magnetic field compensation coil 4 is located within a high-permeability shielding layer 5. The alkali metal gas cell 2 is located within a heating chamber 3, which is located within the three-axis magnetic field compensation coil 4.

[0051] The invention discloses a closed-loop magnetic compensation method for a SERF magnetic field measuring device based on double-beam detection, comprising: a pumping light (1), an alkali metal gas chamber (2), a heating chamber (3), a three-axis magnetic field compensation coil (4), a high-permeability shielding layer (5), a data acquisition and control system (6), a magnetic field compensation waveform generator (7), a magnetic field calibration waveform generator (8), a detection light laser (9), a 1 / 2 wave plate (10), a beam splitter (11), a first reflector (12), a second reflector (13), an X-direction detection light polarizer (14), an X-direction detection light analyzer (15), an X-direction detection photoelectric converter (16), a Y-direction detection light polarizer (17), a Y-direction detection light analyzer (18), and a Y-direction detection photoelectric converter (19).

[0052] A closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection comprises: a pumping light (1), an alkali metal gas chamber (2), a heating chamber (3), a three-axis magnetic field compensation coil (4), a high magnetic permeability shielding layer (5), a data acquisition and control system (6), a magnetic field compensation waveform generator (7), a magnetic field calibration waveform generator (8), a detection light laser (9), a 1 / 2 wave plate (10), a beam splitter (11), a first reflector (12), a second reflector (13), an X-direction detection light polarizer (14), an X-direction detection light analyzer (15), an X-direction detection photoelectric converter (16), a Y-direction detection light polarizer (17), a Y-direction detection light analyzer (18), and a Y-direction detection photoelectric converter (19). The high magnetic permeability shielding layer (5) shields external interference. The pumping light (1) is injected into the alkali metal gas chamber (2) along the Z direction for pumping. The magnetic field calibration waveform generator (8) is connected to the three-axis magnetic field compensation coil (4) and applies a sinusoidal calibration signal to the Y-axis coil. The laser light generated by the detection light laser (9) is divided into two beams along the X direction and the Y direction by the beam splitter prism (11). The X-direction detection light passes through the first reflector (12), the second reflector (13) and the X-direction detection light polarizer (14) and is injected into the alkali metal gas chamber (2) in the heating chamber (3). After passing through the gas chamber, the The X-direction detection light is input into the data acquisition and control system (6) through the X-direction detection light polarizer (15) and the X-direction detection photoelectric converter (16); the Y-direction detection light is struck into the alkali metal gas chamber (2) in the heating chamber (3) through the Y-direction detection light polarizer (17); after passing through the gas chamber, the light is input into the data acquisition and control system (6) through the Y-direction detection light polarizer (18) and the Y-direction detection photoelectric converter (19); and the data acquisition and control system (6) controls the magnetic field compensation waveform generator (7) according to the signal to apply direct current to the three-axis magnetic field compensation coil (4) to generate a compensation magnetic field.

[0053] The high magnetic permeability shielding layer (5) is arranged outside the three-axis magnetic field compensation coil (4) to shield external static magnetic fields and magnetic field interference. After passing through the shielding layer, the residual magnetism decays to the nT level.

[0054] The alkali metal gas chamber (2) is located in the center and is filled with alkali metal atomic gas, such as potassium, rubidium, etc. The heating chamber (3) heats the atomic gas chamber to make the alkali metal atomic vapor in a saturated state. The pumping light (1) is injected into the gas chamber from the Z direction to pump the atoms.

[0055] The magnetic field calibration waveform generator (8) is connected to the three-axis magnetic field compensation coil (4) and applies a sinusoidal calibration signal with a constant frequency, constant amplitude and no bias to the Y-axis coil. Then, the Y-axis magnetic field information is:

[0056] ,

[0057] Among them, β yis the Y-axis magnetic field information, and the Y-axis magnetic field component B y Proportional, is the Y-axis component of the ambient magnetic field information to be compensated, A is the amplitude of the calibration signal, ω y is the frequency of the calibration magnetic field, and t is the time.

[0058] The detection light laser (9) generates laser light, which is split into two beams by the beam splitter (11). The splitting power can be controlled by the 1 / 2 wave plate (10) and the beam splitter (11). The X-direction detection light passes through the first reflector (12), the second reflector (13) and the X-direction detection light polarizer (14) and enters the alkali metal gas chamber (2) in the heating chamber (3). After passing through the gas chamber, it is input to the data acquisition and control system (6) through the X-direction detection light polarizer (15) and the X-direction detection photoelectric converter (16); the Y-direction detection light passes through the Y-direction detection light polarizer (17) and enters the alkali metal gas chamber (2) in the heating chamber (3). After passing through the gas chamber, it is input to the data acquisition and control system (6) through the Y-direction detection light polarizer (18) and the Y-direction detection photoelectric converter (19). At this time, the X-axis and Y-axis voltage signals of the input system are

[0059] ,

[0060] Among them, P x is the light signal detected in the X direction, P y is the light signal detected in the Y direction, k is the proportional coefficient, , R OP is the pumping rate of the pump light, s is the photon polarizability, R rel is the total relaxation rate, β x is the X-axis magnetic field information, and the X-axis magnetic field component B x Proportional, β z is the Z-axis magnetic field information, and the Z-axis magnetic field component B z Directly proportional.

[0061] The data acquisition and control system (6) controls the magnetic field compensation waveform generator (7) to output direct current to generate a compensation magnetic field with the same magnitude and opposite direction to the residual magnetic field according to the signals of the X-direction detection photoelectric converter (16) and the Y-direction detection photoelectric converter (19): y , the output DC adopts feedback control to compensate the Z-axis residual magnetism, so that β z ≈0, then:

[0062] ,

[0063] Then compensate the X-axis residual magnetism, β x ≈0, then:

[0064] ,

[0065] Finally, according to the X direction detection light signal P x Compensate for the Y-axis residual magnetism, so ≈0.

[0066] refer to Figure 3 , the complete steps of magnetic compensation are as follows:

[0067] ① Optical path construction: construct the X-axis detection light and the Y-axis detection light for decoupling, and the pumping light (1) is injected into the alkali metal gas chamber (2) heated by the heating chamber (3) along the Z direction for pumping;

[0068] ② Signal modulation: Apply a sinusoidal modulation signal to the Y-axis coil through the magnetic field calibration waveform generator (8);

[0069] ③Z-axis residual magnetism compensation: Data acquisition and control system (6) according to P y Feedback control is performed, and the magnetic field compensation waveform generator (7) outputs current to the Z-axis coil to compensate the Z-axis magnetic field until P y The signal amplitude reaches its minimum value, at which point P y It can be regarded as the X-axis in-situ magnetic field signal;

[0070] ④X-axis residual magnetism compensation: Data acquisition and control system (6) is based on the in-situ magnetic field signal P y Feedback control is performed, and the magnetic field compensation waveform generator (7) outputs current to the X-axis coil to compensate the X-axis magnetic field until P y The signal bias reaches its minimum value, at which point P x It can be regarded as the Y-axis in-situ magnetic field signal;

[0071] ⑤Y-axis residual magnetism compensation: Data acquisition and control system (6) according to the in-situ magnetic field signal P x Feedback control is performed, and the magnetic field compensation waveform generator (7) outputs current to the Y-axis coil to compensate the Y-axis magnetic field until P x The signal bias reaches a minimum value;

[0072] ⑥ Determine whether to end real-time magnetic compensation. If so, end real-time magnetic compensation. Otherwise, go to step ③.

[0073] like Figure 1As shown, a closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection is provided. The external magnetic field is shielded by a high-magnetic permeability shielding layer (5) and attenuated to the nT level. The alkali metal gas chamber (2) is filled with alkali metal atomic gas. The heating chamber (3) heats the gas chamber to saturate the alkali metal atoms. Pumping light pumps the atoms in the gas chamber. The Y axis is the measurement sensitive axis. The X-direction detection light and the Y-direction detection light pass through the gas chamber. The sensitivity signal is obtained by calculating the optical rotation angle signal of the X-axis detection light. The three-axis magnetic field compensation coil (4) is set outside the heating chamber (3) to compensate for the magnetic field in the gas chamber area. In the SERF system, the Bloch equation describing the dynamic equation of the ground state electron spin is:

[0074] (1),

[0075] Where S is the atomic spin polarization vector, q is the slowing factor, and γ e is the gyromagnetic ratio of the electron, B is the magnetic field vector, B=(B x ,B y ,B z ) T , B x is the X-axis magnetic field component, B y is the Y-axis magnetic field component, B z is the Z-axis magnetic field component, is the pump light direction vector.

[0076] ,

[0077] Among them, β x is the X-axis magnetic field information, and B x Proportional, β y is the Y-axis magnetic field information, and B y Proportional, β z is the Z-axis magnetic field information, and B z Directly proportional. When , the steady-state solution of the Bloch equation is:

[0078] ,

[0079] Among them, S x is the X-axis component of the atomic spin polarization, S y is the Y-axis component of the atomic spin polarization, S z is the Z-axis component of the atomic spin polarization, .

[0080] like Figure 2As shown, the two beams of light of X-axis and Y-axis are input into the air chamber through the polarizer, the polarization state is changed under the influence of the magnetic field, and then the signal is input into the data acquisition and control system through the polarizer and the photoelectric converter. The signal intensity is proportional to the spin polarization component, and the proportional coefficient is k. The magnitude of the residual magnetic field after shielding by the high magnetic permeability shielding body is very small, so that The signal containing magnetic field information output by the X-axis photodetector and the Y-axis photodetector is:

[0081] ,

[0082] Where, P x is the X-direction detection light signal, and P y is the Y-direction detection light signal, which contains three-axis magnetic field information. For the X-direction detection light signal P x alone, the magnetic fields of X-axis and Z-axis are coupled to each other, and three-axis magnetic field in-situ measurement cannot be realized. By adding the Y-direction detection light signal P y , a sinusoidal calibration signal with a certain frequency and amplitude and without bias is applied to the Y-axis magnetic field compensation coil. This signal serves as a calibration signal during the whole sensitivity test, and also as a modulation signal for three-axis decoupling magnetic compensation. Therefore, for the Y-axis magnetic field, there is:

[0083] ,

[0084] The Y-direction detection light signal of formula (5) becomes:

[0085] ,

[0086] According to P y , the output current is fed back to the Z-axis coil to compensate for the Z-axis magnetic field, so that , and

[0087] ,

[0088] In formula (8), P y can be regarded as the in-situ information of X-axis magnetic field. According to the in-situ magnetic field information P y at this time, the output current is fed back to the X-axis coil to make β x ≈0. For the X-direction detection light signal P x , the decoupling of X-axis and Z-axis magnetic fields has been realized. At the same time, β x β z ≈0, and formula (4) becomes:

[0089] ,

[0090] According to P x , the output current is fed back to the Y-axis coil to compensate for the Y-axis residual magnetic field bias Direct compensation, ≈0, thereby realizing real-time magnetic compensation of the three-axis magnetic field. Combining the coil constant to solve the compensation current can also realize real-time magnetic field measurement.

[0091] Any content not described in detail in this specification is prior art known to those skilled in the art. It should be noted that the above description is intended to help those skilled in the art understand the present invention, but does not limit the scope of protection of the present invention. Any equivalent substitution, modification, improvement, and / or simplification of the above description that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection, characterized in that: The following steps are involved: Step 1: In a SERF magnetic field measurement device, a Y-axis detection light is provided that passes through the alkali metal gas cell along the Y-axis direction, an X-axis detection light is provided that passes through the alkali metal gas cell along the X-axis direction, and a pumping light is provided that passes through the alkali metal gas cell along the Z-axis direction. The X-axis detection light is used to detect the optical rotation angle, the Y-axis detection light is used for three-axis magnetic field decoupling, and the pumping light is used to polarize atoms in the alkali metal gas cell. Step 2: Add Y-axis calibration signal; Step 3: According to P y Control the Z-axis coil current to compensate the Z-axis magnetic field, P y It is the detection light signal in the Y-axis direction; Step 4: Determine P y Is the amplitude extremely small? If not, return to step 3; if yes, go to step 5; Step 5: According to P y Control the X-axis coil current to compensate the X-axis magnetic field; Step 6: Determine P y Is the bias extremely small? If not, return to step 5; if yes, go to step 7; Step 7, according to P x Control the Y-axis coil current to compensate the Y-axis magnetic field, P x It is the detection light signal in the X-axis direction; Step 8: Determine P x Is the bias extremely small? If not, return to step 7; if yes, go to step 9; Step 9, end the three-axis decoupling magnetic compensation or return to step 3 to continue real-time magnetic compensation; The Y-axis calibration signal in step 2 is , A is the calibration signal amplitude, ω y is the frequency of the calibration magnetic field, t is the time, and the Y-axis calibration signal is used as the calibration signal throughout the sensitivity test and as the modulation signal in the three-axis decoupling magnetic compensation; Step 2 includes the following expression: ， where β y is the Y-axis magnetic field information, It is the Y-axis environmental magnetic field information to be compensated.

2. The closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection according to claim 1 is characterized in that: Steps 3 and 7 include the following expressions: ， Where k is the proportional coefficient, S0 is the intermediate quantity, β x is the X-axis magnetic field information, β z is the Z-axis magnetic field information, s is the photon polarizability, R OP is the pumping rate of the pump light, R rel is the total relaxation rate.

3. The closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection according to claim 2, characterized in that: Step 4 includes the following expression: 。 4. The closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection according to claim 2, characterized in that: Step 8 includes the following expression: 。 5. The closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection according to claim 1, characterized in that: In step 1, the SERF magnetic field measuring device includes a detection light laser for detecting a double beam, the detection light laser is connected to the input side of a beam splitter through a 1 / 2 wave plate, the transmission side of the beam splitter is connected to a data acquisition and control system in sequence through a first reflector, a second reflector, an X-direction detection light polarizer, an alkali metal gas chamber, an X-direction detection light analyzer, and an X-direction detection photoelectric converter, the reflection side of the beam splitter is connected to a data acquisition and control system in sequence through a Y-direction detection light polarizer, an alkali metal gas chamber, a Y-direction detection light analyzer, and a Y-direction detection photoelectric converter, the data acquisition and control system is connected to a three-axis magnetic field compensation coil through a magnetic field compensation waveform generator, and the three-axis magnetic field compensation coil is connected to a magnetic field calibration waveform generator.

6. The closed-loop magnetic compensation method for a SERF magnetic field measurement device based on dual-beam detection according to claim 5, characterized in that: The three-axis magnetic field compensation coil is located in the high magnetic permeability shielding layer, the alkali metal gas chamber is located in the heating chamber, and the heating chamber is located in the three-axis magnetic field compensation coil.

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