Atomic magnetometer optical coupling in-situ inhibition device and method

Abstract

The invention discloses an atomic magnetometer optical coupling in-situ suppression device and method. The method comprises the steps that S1, the atomic magnetometer optical coupling in-situ suppression device is deployed; s2, magnetic field modulation in the y-axis direction is carried out; s3, adjusting the direct current value of the precise current source until a frequency multiplication component is eliminated; s4, magnetic field modulation in the x-axis direction is carried out; s5, adjusting the direct current value of the precise current source until a frequency multiplication component is eliminated; s6, repeating the steps S2 to S5 for three times to obtain three groups of direct-current magnetic field compensation values, and calculating to obtain ax and ay; and step 7, according to ax and ay, adjusting the propagation direction of the pumping light by using a reflector so as to inhibit optical coupling caused by non-orthogonality of the pumping light and the detection light. According to the scheme, optical coupling caused by poor orthogonality and polarization of pumping and detection light in the atomic magnetometer due to the installation process and the light beam quality can be measured and inhibited, so that the measurement error in the sensitive direction of the atomic magnetometer is reduced, and the magnetic field measurement sensitivity is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetically sensitive atomic sensors, and in particular relates to an optically coupled in-situ suppression device and method for an atomic magnetometer. Background Art

[0002] In the field of space remote sensing, atomic magnetometers have extremely high sensitivity in measuring magnetic fields and can be used for magnetic anomaly detection, geomagnetic detection, deep space detection, and planetary soil magnetic analysis, and have broad development prospects. Atomic magnetometers usually use a dual-beam configuration in which circularly polarized pump light and linearly polarized detection light are orthogonal. The pump light is used to polarize the alkali metal atoms in the sensitive core of the atomic magnetometer so that the spins of the alkali metal atoms point in the same direction. When there is an external magnetic field, the spin polarization direction deviates from the original direction, and the detection light is used to detect the deflection of the atomic spin, thereby obtaining magnetic field information.

[0003] During the deployment and installation of the atomic magnetometer, due to the poor orthogonality and polarization caused by the installation process and beam quality, the atomic magnetometer has optical coupling, mainly including the non-orthogonal projection component of the pumping light in the detection light direction, and the pumping effect caused by the ellipticity of the detection light. These optical couplings cause measurement errors in the sensitive direction of the atomic magnetometer, reduce sensitivity, and need to be suppressed in situ. Summary of the invention

[0004] The technology of the present invention solves the problem: overcomes the shortcomings of the prior art, provides an in-situ suppression scheme for optical coupling of an atomic magnetometer, suppresses optical coupling caused by poor orthogonality and polarization caused by installation process and beam quality, and improves the measurement sensitivity and measurement accuracy of the atomic magnetometer by reducing the non-orthogonal projection component of the pumping light in the detection light direction and the pumping effect caused by the ellipticity of the detection light.

[0005] In order to solve the above technical problems, the present invention discloses an atomic magnetometer optical coupling in-situ suppression device, comprising: a magnetic shielding device and an atomic magnetometer; the atomic magnetometer comprises: a three-dimensional coil, an atomic magnetometer sensitive core, a precision current source, an oscilloscope, a photodetector, a pumping light source, a detection light source, a reflector and a polarizer;

[0006] A precision current source, an oscilloscope, a pumping light source and a detection light source are arranged outside the magnetic shielding device; wherein the pumping light source is arranged in the z-axis direction of the magnetic shielding device, and the detection light source is arranged in the x-axis direction of the magnetic shielding device; the oscilloscope is connected to the precision current source and the photodetector respectively; the precision current source is connected to the three-dimensional coil;

[0007] The three-dimensional coil, the sensitive core of the atomic magnetometer, the photodetector, the reflector and the polarizer are arranged in the magnetic shielding device; wherein the three-dimensional coil is located at the center of the magnetic shielding device; the sensitive core of the atomic magnetometer is located at the center of the three-dimensional coil; the reflector is arranged in the z-axis direction of the magnetic shielding device and between the pumping light source and the sensitive core of the atomic magnetometer; the polarizer is arranged in the x-axis direction of the magnetic shielding device and between the detection light source and the sensitive core of the atomic magnetometer; the photodetector is arranged in the x-axis direction of the magnetic shielding device and on the side of the sensitive core of the atomic magnetometer away from the polarizer.

[0008] In the above-mentioned atomic magnetometer optical coupling in-situ suppression device,

[0009] The magnetic shielding device is used to suppress the influence of external magnetic field disturbance on the working performance of the atomic magnetometer. It cooperates with the three-dimensional coil driven by the precision current source to provide the weak magnetic field environment required for the atomic magnetometer to maintain the spin-free exchange relaxation state for the sensitive core of the atomic magnetometer.

[0010] A precision current source is used to generate three control currents to drive the three-dimensional coil to actively apply a uniform magnetic field with known amplitude and frequency in the three directions of the x-axis, y-axis and z-axis to actively compensate for the DC magnetic field;

[0011] A pumping light source, used for providing pumping light in the z-axis direction;

[0012] A reflector, used to adjust the propagation direction of the pump light;

[0013] A detection light source, used for providing detection light in the x-axis direction;

[0014] Polarizer, used to adjust the ellipticity of the detection light;

[0015] The sensitive core of the atomic magnetometer is used for highly sensitively measuring the magnetic field components in three orthogonal directions of x, y and z; wherein the sensitive core of the atomic magnetometer is made of an alkali metal atom gas chamber, and the alkali metal atom gas chamber contains alkali metal atoms; the alkali metal atoms are polarized by the pumping light along the z-axis direction, and the spin angular momentum is detected by the detection light along the x-axis direction;

[0016] A photodetector, used for converting the received detection light into an output signal of the atomic magnetometer and outputting the signal to an oscilloscope;

[0017] An oscilloscope is used to perform waveform or spectrum analysis on the output signal of the received atomic magnetometer.

[0018] In the above-mentioned atomic magnetometer optically coupled in-situ suppression device, the atomic magnetometer output signal is proportional to the component of the spin angular momentum of the alkali metal atoms in the sensitive core of the atomic magnetometer in the x-axis direction.

[0019] In the above-mentioned atomic magnetometer optical coupling in-situ suppression device, the magnetic shielding device is made of magnetic shielding material, and the residual magnetism at the center is ≤5nT after demagnetization treatment.

[0020] In the above-mentioned atomic magnetometer optical coupling in-situ suppression device, the three-dimensional coil includes: an x-axis uniform field coil, a y-axis uniform field coil and a z-axis uniform field coil; wherein the x-axis uniform field coil, the y-axis uniform field coil and the z-axis uniform field coil are respectively connected to a precision current source.

[0021] Correspondingly, the present invention also discloses an atomic magnetometer optical coupling in-situ suppression method based on the above device, comprising:

[0022] Step 1, deploying the atomic magnetometer optically coupled in-situ suppression device;

[0023] Step 2, perform magnetic field modulation in the y-axis direction: use a precision current source to drive the three-dimensional coil to apply a low-frequency AC magnetic field in the y-axis direction, and maintain a DC magnetic field in the x-axis and z-axis directions; measure the output signal A of the atomic magnetometer in the current state through a photodetector, and output the output signal A of the atomic magnetometer to an oscilloscope for waveform or spectrum analysis;

[0024] Step 3, adjusting the DC current value of the precision current source, driving the three-dimensional coil to actively compensate the DC magnetic field, and observing the output signal A of the atomic magnetometer when the magnetic field is modulated in the y-axis direction, until the one-fold frequency component in the output signal A of the atomic magnetometer in the oscilloscope is eliminated;

[0025] Step 4, perform magnetic field modulation in the x-axis direction: use a precision current source to drive the three-dimensional coil to apply a low-frequency AC magnetic field in the x-axis direction, and maintain a DC magnetic field in the y-axis and z-axis directions; measure the output signal B of the atomic magnetometer in the current state through a photodetector, and output the output signal B of the atomic magnetometer to an oscilloscope for waveform or spectrum analysis;

[0026] Step 5, adjusting the DC current value of the precision current source, driving the three-dimensional coil to actively compensate the DC magnetic field, and observing the output signal B of the atomic magnetometer when the magnetic field is modulated in the x-axis direction, until the one-fold frequency component in the output signal B of the atomic magnetometer in the oscilloscope is eliminated;

[0027] Step 6, repeat steps 2 to 5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the components a of the pumping light in the x-axis and y-axis directions. x and a y ;

[0028] Step 7, calculate a x and a y , a reflector is used to adjust the propagation direction of the pumping light, thereby suppressing the optical coupling caused by the non-orthogonality between the pumping light and the detection light.

[0029] In the above method, the amplitude and frequency of the low-frequency AC magnetic field applied in the y-axis direction in step 2 are the same as those of the low-frequency AC magnetic field applied in the x-axis direction in step 4; wherein the amplitude of the low-frequency AC magnetic field is less than 5nT, and the corresponding dimensionless parameter is β m ;The frequency of the low-frequency AC magnetic field ω is less than 5Hz.

[0030] In the above method, in step 2, the dimensionless parameters corresponding to the DC magnetic field in the x-axis and z-axis directions are β x0 and β z0 ; Considering the DC magnetic field in the y-axis direction, the modulation β y =β y0 +β m sin(ωt); where β y represents the dimensionless parameter corresponding to the resultant magnetic field in the y-axis direction, β y0 It represents the dimensionless parameter corresponding to the DC magnetic field in the y-axis direction, and t represents the modulation time.

[0031] In the above method, in step 4, the dimensionless parameters corresponding to the DC magnetic field in the y-axis and z-axis directions are β y0 and β z0 ; Considering the DC magnetic field in the x-axis direction, the modulation β x =β x0 +β m sin(ωt); where β x represents the dimensionless parameter corresponding to the resultant magnetic field in the x-axis direction, β x0 It represents the dimensionless parameter corresponding to the DC magnetic field in the x-axis direction, and t represents the modulation time.

[0032] In the above method, steps 2 to 5 are repeated three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, the components a of the pumping light in the x-axis and y-axis directions are calculated. x and a y ,include:

[0033] In the process of repeating steps 2 to 5 three times, a set of DC magnetic field compensation values ​​in three directions is obtained in each repetition process, and the corresponding dimensionless parameters are: and Among them, a set of DC magnetic field compensation values ​​in three directions obtained in each repetition process can achieve the elimination of the one-fold frequency component;

[0034] and satisfy:

[0035]

[0036] To simplify the calculation, in step 3 and step 5, when adjusting the DC current value of the precision current source to drive the three-dimensional coil to actively compensate the DC magnetic field, the parameters of the precision current source are set so that Then we have:

[0037]

[0038] Where, ΔB x0 express and The difference, ΔB y0 express and The difference.

[0039] The present invention has the following advantages:

[0040] (1) The present invention discloses an in-situ suppression scheme for optical coupling of an atomic magnetometer, which can measure and suppress the optical coupling caused by poor orthogonality and polarization of pumping and detection light in the atomic magnetometer due to the installation process and beam quality, thereby reducing the measurement error in the sensitive direction of the atomic magnetometer and improving the sensitivity of magnetic field measurement.

[0041] (2) The present invention discloses an in-situ suppression scheme for optical coupling of an atomic magnetometer. All components required in the implementation of the scheme are components of the atomic magnetometer itself, and no additional components are required. In-situ suppression of optical coupling can be achieved, which is conducive to miniaturized applications.

[0042] (3) The present invention discloses an optically coupled in-situ suppression scheme for an atomic magnetometer. Although the atomic magnetometer needs to work in a spin-exchange relaxation-free state, its device and configuration are applicable to a variety of atomic magnetometers. After optical suppression, the magnetometer parameters can be adjusted in-situ to switch to other working states. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of an optically coupled in-situ suppression device for an atomic magnetometer according to an embodiment of the present invention;

[0044] Figure 2 It is a flow chart of an in-situ suppression method of optical coupling of an atomic magnetometer in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0046] Reference Figure 1In this embodiment, the atomic magnetometer optical coupling in-situ suppression device includes: a magnetic shielding device 1 and an atomic magnetometer; further, the atomic magnetometer includes: a three-dimensional coil 2, an atomic magnetometer sensitive core 3, a precision current source 4, an oscilloscope 5, a photodetector 6, a pumping light source 7, a detection light source 8, a reflector 9 and a polarizer 10. Among them, the precision current source 4, the oscilloscope 5, the pumping light source 7 and the detection light source 8 are arranged outside the magnetic shielding device 1; the pumping light source 7 is arranged in the z-axis direction of the magnetic shielding device 1, and the detection light source 8 is arranged in the x-axis direction of the magnetic shielding device 1; the oscilloscope 5 is connected to the precision current source 4 and the photodetector 6 respectively; the precision current source 4 is connected to the three-dimensional coil 2. The three-dimensional coil 2, the atomic magnetometer sensitive core 3, the photodetector 6, the reflector 9 and the polarizer 10 are arranged in the magnetic shielding device 1; the three-dimensional coil 2 is located at the center of the magnetic shielding device 1; the atomic magnetometer sensitive core 3 is located at the center of the three-dimensional coil 2; the reflector 9 is arranged in the z-axis direction of the magnetic shielding device 1, between the pumping light source 7 and the atomic magnetometer sensitive core 3; the polarizer 10 is arranged in the x-axis direction of the magnetic shielding device 1, between the detection light source 8 and the atomic magnetometer sensitive core 3; the photodetector 6 is arranged in the x-axis direction of the magnetic shielding device 1, and on the side of the atomic magnetometer sensitive core 3 away from the polarizer 10.

[0047] In this embodiment, the magnetic shielding device 1 is used to suppress the influence of external magnetic field disturbance on the working performance of the atomic magnetometer, and cooperates with the three-dimensional coil 2 driven by the precision current source 4 to provide the atomic magnetometer sensitive core 3 with the weak magnetic field environment required for the atomic magnetometer to maintain a spin-exchange relaxation state. The precision current source 4 is used to generate three control currents to drive the three-dimensional coil 2 to actively apply a uniform magnetic field with known amplitude and frequency in the three directions of the x-axis, y-axis and z-axis, respectively, to actively compensate for the DC magnetic field. The pumping light source 7 is used to provide pumping light 71 in the z-axis direction. The reflector 9 is used to adjust the propagation direction of the pumping light 71. The detection light source 8 is used to provide detection light 81 in the x-axis direction. The polarizer 10 is used to adjust the ellipticity of the detection light 81. The sensitive core 3 of the atomic magnetometer is used for highly sensitively measuring the magnetic field components in three orthogonal directions of x, y and z; the sensitive core 3 of the atomic magnetometer is made of an alkali metal atom gas chamber, and the alkali metal atom gas chamber contains alkali metal atoms; the alkali metal atoms are polarized by the pumping light 71 along the z-axis direction, and the spin angular momentum is detected by the detection light 81 along the x-axis direction. The photodetector 6 is used to convert the received detection light 81 into an atomic magnetometer output signal, and output it to the oscilloscope 5. The oscilloscope 5 is used to perform waveform or spectrum analysis on the received atomic magnetometer output signal.

[0048] In this embodiment, the output signal of the atomic magnetometer is proportional to the component of the spin angular momentum of the alkali metal atoms in the sensitive core 3 of the atomic magnetometer in the x-axis direction. The magnetic shielding device 1 is made of magnetic shielding material, and the residual magnetism at the center after demagnetization is ≤5nT. The three-dimensional coil 2 mainly includes: an x-axis uniform field coil, a y-axis uniform field coil and a z-axis uniform field coil; the x-axis uniform field coil, the y-axis uniform field coil and the z-axis uniform field coil are respectively connected to a precision current source 4.

[0049] In this embodiment, based on the above-mentioned atomic magnetometer optical coupling in-situ suppression device, the present invention further discloses an atomic magnetometer optical coupling in-situ suppression method.

[0050] like Figure 2 As shown, the atomic magnetometer optical coupling in-situ suppression method comprises:

[0051] Step 1: Deploy the atomic magnetometer optically coupled in-situ suppression device.

[0052] In this embodiment, the optically coupled in-situ suppression device for an atomic magnetometer can refer to the description of the above embodiment, which will not be described in detail here.

[0053] With the atomic magnetometer sensitive core 3 as the origin, the detection light is set in the x-axis direction, and the atomic magnetometer is kept in a spin-exchange relaxation-free state through active and passive magnetic compensation. When working, the atomic magnetometer output signal is proportional to the atomic spin angular momentum component in the x-axis direction where the detection light is located. The evolution of the atomic spin angular momentum in the atomic magnetometer is:

[0054]

[0055] Where S represents the spin angular momentum vector of the atomic spin ensemble, B represents the magnetic field vector; γ represents the gyromagnetic ratio of the atomic ensemble, γ = γ e / Q(P), Q(P) represents the slowing factor, γ e represents the gyromagnetic ratio of the electron, γ e ≈2π×28Hz / nT, Q(P) and γ e are all considered as constants; R represents the pumping vector, which is used to characterize the laser pumping effect. The components of R in the x-axis, y-axis, and z-axis directions are represented by R x , R y and R z Indicates; Δω indicates the magnetic resonance line width, Δω=R tot / Q(P),R tot represents the total relaxation rate of atomic spins.

[0056] The steady-state response S0 of the atomic ensemble spin angular momentum is mainly determined by the static magnetic field B0 and the pumping vector R. Considering the static or slowly varying magnetic field response, the dimensionless magnetic field parameter β = γ eB / R tot Simplify the operation, β x , β y and β z are the components of β in the x-axis, y-axis, and z-axis directions.

[0057] The ideal pumping light should be set in the z-axis direction. Considering the factors such as installation error, poor detection beam quality and ellipticity, the actual pumping light is mainly along the z-axis direction, but there are projection components in the x-axis and y-axis directions, which cause the equivalent small-angle pumping components in the detection light direction, and the corresponding angles are a and x and a y , then: sina x ≈a x , sina y ≈a y , cosa x ≈1, cosa y ≈1, that is, the pumping vector is R=R z [a x ,a y ,1] T , the steady-state response in the direction of the detected light is actually:

[0058]

[0059] Among them, S 0z It represents the initial angular momentum in the z-axis direction of the steady-state response under no magnetic field conditions. The steady-state response includes the response error term of optical coupling. Need to eliminate a x and a y Suppress optical coupling.

[0060] Step 2: Modulate the magnetic field in the y-axis direction: Use the precision current source 4 to drive the three-dimensional coil 2 to apply a low-frequency AC magnetic field in the y-axis direction (amplitude < 5nT, the corresponding dimensionless parameter is β m , frequency ω<5Hz), the x-axis and z-axis directions maintain a DC magnetic field, and the corresponding dimensionless parameters are β x0 and β z0 Considering the DC magnetic field in the y-axis direction, when modulating β y =β y0 +β m sin(ωt),β y represents the dimensionless parameter corresponding to the resultant magnetic field in the y-axis direction, β y0 represents the dimensionless parameter corresponding to the DC magnetic field in the y-axis direction, and t represents the modulation time. The atomic magnetometer output signal A in the current state is measured by the photodetector 6, and the atomic magnetometer output signal A is output to the oscilloscope 5 for waveform or spectrum analysis.

[0061] In this embodiment, the output signal A of the atomic magnetometer is proportional to the steady-state response of the detection light direction. The steady-state response at this time is:

[0062] S x ≈S 0z [β y0 +β x0 β z0 +a x (1+β x0 2 )+a y (-β z0 +β x0 β y0 )

[0063] +β m (1+a y β x0 )sin(ωt)]

[0064] Step 3, adjust the DC current value of the precision current source 4, drive the three-dimensional coil 2 to actively compensate the DC magnetic field, and observe the atomic magnetometer output signal A when the magnetic field is modulated in the y-axis direction until the one-fold frequency component in the atomic magnetometer output signal A in the oscilloscope 5 is eliminated.

[0065] Step 4, perform magnetic field modulation in the x-axis direction: use the precision current source 4 to drive the three-dimensional coil 2 to apply a low-frequency AC magnetic field in the x-axis direction (amplitude < 5nT, the corresponding dimensionless parameter is β m , frequency ω<5Hz), the y-axis and z-axis directions maintain a DC magnetic field, and the corresponding dimensionless parameters are β y0 and β z0 Considering the DC magnetic field in the x-axis direction, when modulating β x =β x0 +β m sin(ωt),β x represents the dimensionless parameter corresponding to the resultant magnetic field in the x-axis direction, β x0 The dimensionless parameter corresponding to the DC magnetic field in the x-axis direction is represented by the photoelectric detector 6 to measure the output signal B of the atomic magnetometer in the current state, and the output signal B of the atomic magnetometer is output to the oscilloscope 5 for waveform or spectrum analysis.

[0066] In this embodiment, the low-frequency AC magnetic field applied in the x-axis direction in this step is the same as the low-frequency AC magnetic field applied in the y-axis direction in step 2. The output signal B of the atomic magnetometer is proportional to the steady-state response in the direction of the detection light, and the steady-state response at this time is:

[0067] S x ≈S 0z [β y0 +β x0 βz0 +a x (1+β x0 2 +β m 2 / 2)+a y (-β z0 +β x0 β y0 )

[0068] +(β z0 +2a x β x0 +a y β y0 )β m sin(ωt)

[0069] -a x β m 2 / 2cos(2ωt)]

[0070] From the above formula, we can know that in the process of magnetic field modulation in the x-axis direction, the double frequency component of the atomic magnetometer output signal contains a small angle component a x By using an oscilloscope to perform waveform or frequency domain analysis on the output signal of the atomic magnetometer, the double frequency component information can be observed.

[0071] Step 5, adjust the DC current value of the precision current source 4, drive the three-dimensional coil 2 to actively compensate the DC magnetic field, and observe the atomic magnetometer output signal B when the magnetic field is modulated in the x-axis direction until the one-fold frequency component in the atomic magnetometer output signal B in the oscilloscope 5 is eliminated.

[0072] Step 6, repeat steps 2 to 5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the components a of the pumping light in the x-axis and y-axis directions. x and a y .

[0073] In this embodiment, the dimensionless parameter β corresponding to the DC magnetic field (static magnetic field) x0 , β y0 , β z0 The residual magnetism and compensated DC magnetic field in the three directions of x-axis, y-axis and z-axis are included respectively. The compensated DC magnetic field can make β z0 +2a x β x0 +a y β y0 =0, that is, the first-harmonic frequency component in the output signal of the atomic magnetometer is zero, and the DC compensation magnetic field values ​​in the three directions are not unique.

[0074] In the process of repeating steps 2 to 5 three times, a set of DC magnetic field compensation values ​​in three directions are obtained in each repetition process (all of which can achieve the elimination of the first-harmonic frequency component), and the corresponding dimensionless parameters are: and

[0075] and satisfy:

[0076]

[0077] To simplify the calculation, in step 2 and step 4, when adjusting the DC current value of the precision current source 4 to drive the three-dimensional coil 2 to actively compensate the DC magnetic field, the parameters of the precision current source 4 are set so that Then we have:

[0078]

[0079] Where, ΔB x0 express and The difference, ΔB y0 express and The difference.

[0080] At this time, although the residual magnetism in the x-axis, y-axis and z-axis directions is unknown, the magnetic field compensation amplitude difference ΔB adjusted by the known precision current source is x0 , ΔB y0 , So we can find a x and a y .

[0081] Step 7, calculate a x and a y , the propagation direction of the pumping light 7 is adjusted by using the reflector 9, thereby suppressing the optical coupling caused by the non-orthogonality between the pumping light and the detection light.

[0082] In this embodiment, due to a x The projection component of the pumping light in the direction of the detection light and the ellipticity of the detection light are jointly affected. Then, the polarization degree of the detection light is adjusted by the polarizer until the difference of the DC term when the x-axis and y-axis directions are modulated respectively is a x β m 2 / 2 is zero (the difference is equal to the amplitude of the double frequency of the response signal). At this time, the detection steady-state response signal no longer contains the double frequency component, and the suppression of the optical coupling of the atomic magnetometer is completed. That is, after suppressing the optical coupling, the DC component of the steady-state response output signal should be the same when the x-axis and y-axis directions are modulated respectively. Through the above method of the present invention, the optical coupling of the dual-beam atomic magnetometer based on the pump-detection orthogonal configuration can be conveniently suppressed in situ.

[0083] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0084] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. An atomic magnetometer optical coupling in-situ suppression device, characterized in that: include: A magnetic shielding device (1) and an atomic magnetometer; An atomic magnetometer, comprising: a three-dimensional coil (2), an atomic magnetometer sensitive core (3), a precision current source (4), an oscilloscope (5), a photodetector (6), a pumping light source (7), a detection light source (8), a reflector (9) and a polarizer (10); A precision current source (4), an oscilloscope (5), a pumping light source (7) and a detection light source (8) are arranged outside the magnetic shielding device (1); wherein the pumping light source (7) is arranged in the z-axis direction of the magnetic shielding device (1), and the detection light source (8) is arranged in the x-axis direction of the magnetic shielding device (1); the oscilloscope (5) is connected to the precision current source (4) and the photodetector (6) respectively; and the precision current source (4) is connected to the three-dimensional coil (2); A three-dimensional coil (2), an atomic magnetometer sensitive core (3), a photodetector (6), a reflector (9) and a polarizer (10) are arranged in a magnetic shielding device (1); wherein the three-dimensional coil (2) is located at the center of the magnetic shielding device (1); the atomic magnetometer sensitive core (3) is located at the center of the three-dimensional coil (2); the reflector (9) is arranged in the z-axis direction of the magnetic shielding device (1) and between a pumping light source (7) and the atomic magnetometer sensitive core (3); the polarizer (10) is arranged in the x-axis direction of the magnetic shielding device (1) and between a detection light source (8) and the atomic magnetometer sensitive core (3); and the photodetector (6) is arranged in the x-axis direction of the magnetic shielding device (1) and on a side of the atomic magnetometer sensitive core (3) away from the polarizer (10).

2. The atomic magnetometer optical coupling in-situ suppression device according to claim 1, characterized in that: The magnetic shielding device (1) is used to suppress the influence of external magnetic field disturbance on the working performance of the atomic magnetometer, and cooperates with the three-dimensional coil (2) driven by the precision current source (4) to provide the atomic magnetometer sensitive core (3) with a weak magnetic field environment required for the atomic magnetometer to maintain a spin-exchange relaxation-free state; A precision current source (4) is used to generate three-way control current to drive the three-dimensional coil (2) to actively apply a uniform magnetic field with known amplitude and frequency in the three directions of the x-axis, y-axis and z-axis respectively, so as to actively compensate for the DC magnetic field; A pumping light source (7), used for providing pumping light (71) in the z-axis direction; A reflector (9) for adjusting the propagation direction of the pumping light (71); A detection light source (8), used for providing detection light (81) in the x-axis direction; A polarizing plate (10) for adjusting the ellipticity of the detection light (81); An atomic magnetometer sensitive core (3) is used for highly sensitively measuring magnetic field components in three orthogonal directions of x, y and z; wherein the atomic magnetometer sensitive core (3) is made of an alkali metal atom gas chamber, wherein the alkali metal atom gas chamber contains alkali metal atoms; the alkali metal atoms are polarized by pumping light (71) along the z-axis direction, and the spin angular momentum is detected by detection light (81) along the x-axis direction; A photodetector (6) for converting the received detection light (81) into an atomic magnetometer output signal and outputting the signal to an oscilloscope (5); The oscilloscope (5) is used for performing waveform or spectrum analysis on the received output signal of the atomic magnetometer.

3. The atomic magnetometer optical coupling in-situ suppression device according to claim 2, characterized in that: The output signal of the atomic magnetometer is proportional to the component of the spin angular momentum of the alkali metal atoms in the sensitive core (3) of the atomic magnetometer in the x-axis direction.

4. The atomic magnetometer optical coupling in-situ suppression device according to claim 1, characterized in that: The magnetic shielding device (1) is made of magnetic shielding material, and after demagnetization, the residual magnetism at the center is ≤5nT.

5. The atomic magnetometer optical coupling in-situ suppression device according to claim 1, characterized in that: The three-dimensional coil (2) comprises: an x-axis uniform field coil, a y-axis uniform field coil and a z-axis uniform field coil; wherein the x-axis uniform field coil, the y-axis uniform field coil and the z-axis uniform field coil are respectively connected to a precision current source (4).

6. An in-situ suppression method for optical coupling of an atomic magnetometer based on the device of claim 1, characterized in that: include: Step 1, deploying the atomic magnetometer optically coupled in-situ suppression device; Step 2, performing magnetic field modulation in the y-axis direction: using a precision current source (4) to drive the three-dimensional coil (2) to apply a low-frequency AC magnetic field in the y-axis direction, and maintaining a DC magnetic field in the x-axis and z-axis directions; measuring the output signal A of the atomic magnetometer in the current state through a photodetector (6), and outputting the output signal A of the atomic magnetometer to an oscilloscope (5) for waveform or spectrum analysis; Step 3, adjusting the DC current value of the precision current source (4), driving the three-dimensional coil (2) to actively compensate for the DC magnetic field, and observing the output signal A of the atomic magnetometer when the magnetic field is modulated in the y-axis direction, until the one-fold frequency component in the output signal A of the atomic magnetometer in the oscilloscope (5) is eliminated; Step 4, performing magnetic field modulation in the x-axis direction: using a precision current source (4) to drive the three-dimensional coil (2) to apply a low-frequency AC magnetic field in the x-axis direction, and maintaining a DC magnetic field in the y-axis and z-axis directions; measuring the output signal B of the atomic magnetometer in the current state through a photodetector (6), and outputting the output signal B of the atomic magnetometer to an oscilloscope (5) for waveform or spectrum analysis; Step 5, adjusting the DC current value of the precision current source (4), driving the three-dimensional coil (2) to actively compensate for the DC magnetic field, and observing the output signal B of the atomic magnetometer when the magnetic field is modulated in the x-axis direction, until the one-fold frequency component in the output signal B of the atomic magnetometer in the oscilloscope (5) is eliminated; Step 6, repeat steps 2 to 5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the components a of the pumping light in the x-axis and y-axis directions. x and a y ; Step 7, calculate a x and a y The propagation direction of the pumping light (7) is adjusted by using a reflector (9), thereby suppressing the optical coupling caused by the non-orthogonality between the pumping light and the detection light.

7. The method according to claim 6, characterized in that The amplitude and frequency of the low-frequency AC magnetic field applied in the y-axis direction in step 2 are the same as those of the low-frequency AC magnetic field applied in the x-axis direction in step 4; wherein the amplitude of the low-frequency AC magnetic field is less than 5nT, and the corresponding dimensionless parameter is β m ;The frequency of the low-frequency AC magnetic field ω is less than 5Hz.

8. The method according to claim 7, characterized in that In step 2, the dimensionless parameters corresponding to the DC magnetic field in the x-axis and z-axis directions are β x0 and β z0 ; Considering the DC magnetic field in the y-axis direction, the modulation β y =β y0 +β m sin(ωt); where β y represents the dimensionless parameter corresponding to the resultant magnetic field in the y-axis direction, β y0 It represents the dimensionless parameter corresponding to the DC magnetic field in the y-axis direction, and t represents the modulation time.

9. The method according to claim 8, characterized in that In step 4, the dimensionless parameters corresponding to the DC magnetic field in the y-axis and z-axis directions are β y0 and β z0 ; Considering the DC magnetic field in the x-axis direction, the modulation β x =β x0 +β m sin(ωt); where β x represents the dimensionless parameter corresponding to the resultant magnetic field in the x-axis direction, β x0 It represents the dimensionless parameter corresponding to the DC magnetic field in the x-axis direction, and t represents the modulation time.

10. The method according to claim 9, characterized in that Repeat steps 2 to 5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the components a of the pumping light in the x-axis and y-axis directions x and a y ,include: In the process of repeating steps 2 to 5 three times, a set of DC magnetic field compensation values ​​in three directions is obtained in each repetition process, and the corresponding dimensionless parameters are: and Among them, a set of DC magnetic field compensation values ​​in three directions obtained in each repetition process can achieve the elimination of the one-fold frequency component; and satisfy: To simplify the calculation, in step 3 and step 5, when adjusting the DC current value of the precision current source (4) to drive the three-dimensional coil (2) to actively compensate for the DC magnetic field, the parameters of the precision current source (4) are set so that Then we have: Where, ΔB x0 express and The difference, ΔB y0 express and The difference.

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