A pump-probe nonorthogonal angle calibration method for atomic spin inertial measurement

Abstract

A pump-probe non-orthogonal angle calibration method for atomic spin inertial measurement is used to accurately evaluate the pump-probe laser non-orthogonal angle, characterized in that it comprises the following steps: step 1, place the atomic spin inertial measurement device in the working state, adjust the z-axis magnetic field bias to the compensation point, and record the initial value of the longitudinal electron spin polarization at this time step 2, apply a magnetic field B of 0.075 nT in the y-axis direction y ; step 3, change the pump laser power, record the pump laser power value I in , the corresponding inertial output signal steady-state value S x and the longitudinal electron spin polarization value; step 4, use the particle swarm algorithm to fit the parameters in step 3 to obtain the value of the pump-probe laser non-orthogonal angle α.

Description

TECHNICAL FIELD

[0001] The present application relates to a pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement, aiming to accurately calibrate the pumping-detection laser non-orthogonal angle of the atomic spin inertial measurement device online, and is suitable for the field of high-precision active compensation of the residual magnetic field of the atomic inertial measurement device. BACKGROUND

[0002] In recent years, atomic spin inertial measurement devices have attracted widespread attention due to their important role in high-precision sensing and navigation systems. Their high sensitivity and excellent stability in rotational motion detection have been widely recognized and widely applied in aerospace, deep sea exploration and other fields.

[0003] The pumping-detection laser non-orthogonal angle is limited by the assembly precision of the prototype, etc., and it is difficult to be adjusted to 0. The influence of longitudinal polarization on the inertial measurement signal always exists, so the pumping-detection laser non-orthogonal angle can be regarded as an inherent property of the atomic spin inertial measurement system, and software compensation can be used to reduce the influence. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement, which can accurately evaluate the pumping-detection laser non-orthogonal angle.

[0005] The technical solution of the present application is as follows:

[0006] A pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement, characterized in that it comprises the following steps:

[0007] Step 1, place the atomic spin inertial measurement device in a working state, adjust the z-axis magnetic field bias to the compensation point, and record the initial value of the longitudinal electron spin polarization at this time

[0008] Step 2, apply a magnetic field B of 0.075nT in the y-axis direction y ;

[0009] Step 3, change the pumping laser power, record the pumping laser power value I in , the corresponding inertial output signal steady-state value S x and the longitudinal electron spin polarization value

[0010] Step 4, use the particle swarm algorithm to fit the parameters in step 3 to obtain the value of the pumping-detection laser non-orthogonal angle a.

[0011] The step 1 comprises the following steps: the atomic gas chamber is in a high-temperature state by a non-magnetic heating device, and the atoms in the alkali metal gas chamber are polarized by pumping light to reach a working state, and the residual magnetic field in the device is compensated to close to zero by a magnetic field coil, so that the residual magnetism in the barrel does not affect the subsequent measurement.

[0012] The step 2 comprises the following steps: a signal generator is used to apply a constant current to the y-axis magnetic field coil, so as to generate a magnetic field with a constant size of 0.075 nT.

[0013] The step 3 comprises the following steps: the pumping laser controller is adjusted to change the current size, so as to change the pumping laser power, and I in , S x and

[0014] The step 4 comprises the following expression:

[0015]

[0016] Wherein k and b are to-be-fitted parameters, is an intermediate quantity, is a transverse electron spin polarization value, γ e is a known constant, B z is a z-axis magnetic field, B e , B n are to-be-fitted parameters, B y = 0.075, is a total electron relaxation rate, and a is a to-be-fitted parameter.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] (1) The pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement provided by the present application can measure and calibrate the pumping-detection laser non-orthogonal angle online, greatly improving the operation convenience and efficiency of the system.

[0019] (2) The intelligent optimization algorithm fitting calculation adopted by the present application improves the precision and reliability of the non-orthogonal angle calibration, and overcomes the errors caused by signal noise or instability in the traditional method. DETAILED DESCRIPTION

[0020] Figure 1 is a parameter coordinate diagram related to the pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement. Figure 1 1 indicates pumping laser, 2 is the pumping-detection laser non-orthogonal angle to be calibrated, 3 is a longitudinal electron spin polarization value 4 is a transverse electron spin polarization value

[0021] Figure 2 is a flowchart of a pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement according to the present application. Figure 2 The method comprises the following steps: step 1, polarizing atoms and compensating residual magnetic field, and recording the initial value of longitudinal electron spin polarization; step 2, applying a constant magnetic field to the Y axis; step 3, changing the pumping light power, and recording the longitudinal electron spin polarization value and output signal; and step 4, fitting by using a particle swarm algorithm. DETAILED DESCRIPTION

[0022] The present application will be described below in conjunction with the accompanying drawings Figures 1-2 and examples.

[0023] Figure 1 is a parameter coordinate diagram related to a pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement according to the present application. Figure 2 is a flowchart of a pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement according to the present application. Referring to Figures 1-2 , a pumping-detection non-orthogonal angle calibration method for atomic spin inertial measurement comprises the following steps: step 1, placing an atomic spin inertial measurement device in a working state, adjusting a z-axis magnetic field bias to a compensation point, and recording the initial value of longitudinal electron spin polarization at this time Step 2, applying a magnetic field B y of 0.075 nT to the y-axis direction Figure 1 Step 3, changing the pumping laser power (pumping laser, see in 1 in the figure), recording the pumping laser power value I x , the corresponding inertial output signal steady-state value S in , and the longitudinal electron spin polarization value (see Figure 1 3 in the figure) each time; step 4, fitting the parameters in step 3 by using a particle swarm algorithm to obtain the value of the pumping-detection laser non-orthogonal angle α (see Figure 1 2 in the figure).

[0024] In step 1, the atomic cell is in a high-temperature state by using a non-magnetic heating device, and the atoms in the alkali metal cell are polarized by using pumping light to achieve a working state. The residual magnetic field inside the device is compensated to close to zero value by using a magnetic field coil, so that the residual magnetism in the barrel does not affect the subsequent measurement. In step 2, a signal generator is used to apply a constant current to the y-axis magnetic field coil to generate a constant magnetic field of 0.075 nT. In step 3, the pumping laser controller is adjusted to change the current size, thereby changing the pumping laser power. I in is obtained by an optical power detector, and S x and

[0025] The step 4 includes the following expressions:

[0026]

[0027]

[0028]

[0029]

[0030] Among them, k and b are parameters to be fitted. is the intermediate quantity, is the transverse electron spin polarization value (see Figure 1 Mark 4), γ e is a known constant, B z is the z-axis magnetic field, B e ,B n are all parameters to be fitted, B y =0.075, is the total electron relaxation rate, and a is the parameter to be fitted.

[0031] This invention discloses a method for calibrating the pump-detection non-orthogonality angle for atomic spin inertial measurement. This method studies the pump-detection laser non-orthogonality angle in atomic spin inertial measurement systems and proposes an innovative solution for online measurement of this non-orthogonality angle. This method obtains different inertial output signals by varying the pump laser power and calculates the non-orthogonality angle using an intelligent optimization algorithm. This method can calibrate the pump-detection laser non-orthogonality angle without disrupting the atomic spin polarization state.

[0032] like Figure 1 As shown, the angle formed by the pumping laser (1) and the z-axis direction is the non-orthogonal angle (2) of the pumping-detection laser.

[0033] like Figure 2 As shown in FIG, the specific calibration process for calibrating the non-orthogonal angle of the pump-detection laser is shown.

[0034] Specifically include the following:

[0035] A pump-detection non-orthogonal angle calibration method for atomic spin inertial measurement, comprising the following steps:

[0036] Step 1: Put the atomic spin inertial measurement device into working state, adjust the z-axis magnetic field bias to the compensation point, and record the initial value of the longitudinal electron spin polarization at this time.

[0037] Step 2, a magnetic field B of 0.075 nT is applied to the y-axis direction y .

[0038] Step 3, the pumping laser power is changed, and the pumping laser power value I of each time is recorded in , the corresponding inertial output signal steady-state value S x , and the longitudinal electron spin polarization value

[0039] Step 4, the particle swarm algorithm is used to fit the parameters in step 3 to obtain the value of the non-orthogonal angle of the pumping-detection laser.

[0040] The step 1 puts the atomic spin inertia measurement device into a working state, adjusts the z-axis magnetic field bias to the compensation point, and records the longitudinal electron spin polarization value at this time The specific process is that the atomic cell is in a high temperature state by a non-magnetic heating device, and the atoms in the alkali metal cell are polarized by the pumping light to reach the working state. The residual magnetic field in the device is compensated to near zero value by using a magnetic field coil, so that the residual magnetism in the barrel does not affect the subsequent measurement.

[0041] The step 2 applies a magnetic field of 0.075 nT to the y-axis direction. The specific process is that a signal generator is used to apply a constant current to the y-axis magnetic field coil, thereby generating a constant magnetic field.

[0042] The step 3 changes the pumping laser power, and the pumping laser power value I of each time is recorded in , the corresponding inertial output signal steady-state value S x , and the longitudinal electron spin polarization value The specific process is to adjust the pumping laser controller to change the current size, thereby changing the pumping laser power. The pumping laser power value I in can be obtained by an optical power detector, the inertial output signal steady-state value S x , and the longitudinal electron spin polarization value

[0043] The step 4 uses the particle swarm algorithm to fit the parameters in step 3 to obtain the value of the non-orthogonal angle of the pumping-detection laser. The specific process is to set the initial parameters of the particle swarm algorithm, and determine the function to be fitted as follows:

[0044]

[0045] Wherein

[0046]

[0047] Wherein k, b, B e , B na, a are fitting parameters, y e is a known constant, B y is the value of the magnetic field applied in step 2, 0.075 nT, is the value of the transverse electron spin polarization, is the value of the longitudinal electron spin polarization recorded in step 3, is the initial value of the longitudinal electron spin polarization in step 1, I in is the value of the pump laser power recorded in step 3. Finally, the value of the pump-probe laser non-orthogonal angle a can be derived.

[0048] The contents not described in detail in the specification of the present application are the prior art known to the person skilled in the art. It is hereby pointed out that the above description is helpful for the person skilled in the art to understand the present application, but does not limit the protection scope of the present application. Any implementation of equivalent replacement, modification, improvement and / or deletion of the above description without departing from the essential content of the present application falls within the protection scope of the present application.

Claims

1. A pump-probe nonorthogonal angle calibration method for atomic spin inertial measurement, characterized in that, The method comprises the following steps: Step 1, put the atomic spin inertial measurement device into working state, adjust the z-axis magnetic field bias to the compensation point, and record the initial value of longitudinal electron spin polarization at this time Step 2, a magnetic field B of 0.075 nT is applied in the y-axis direction y ; Step 3, change the pump laser power, record the value of the pump laser power I each time in , the corresponding inertial output signal steady-state value S x and longitudinal electron spin polarization value Step 4, fitting the parameters in step 3 by using a particle swarm algorithm to obtain the value of the pump-probe laser non-orthogonal angle alpha; The step 4 comprises the following expression: where k, b are both fitting parameters, is an intermediate quantity, is the transverse electron spin polarization value, γ e is a known constant, B z is the z-axis magnetic field, B e ,B n are both fitting parameters, B y = 0.075, is the total electron relaxation rate, a is a fitting parameter.

2. The pump-probe nonorthogonal angle calibration method for atomic spin inertial measurement of claim 1, wherein, The step 1 comprises: heating the atomic gas chamber by a non-magnetic heating device, polarizing the atoms in the alkali metal gas chamber by using pump light to reach a working state, and compensating the residual magnetic field in the device by using a magnetic field coil so that the residual magnetism in the bucket does not affect the subsequent measurement.

3. The pump-probe nonorthogonal angle calibration method for atomic spin inertial measurement of claim 1, wherein, The step 2 comprises: applying a constant current to the y-axis magnetic field coil by using a signal generator to generate a constant magnetic field of 0.075 nT.

4. The pump-probe nonorthogonal angle calibration method for atomic spin inertial measurement of claim 1, wherein, The step 3 includes: adjusting the pumping laser controller to change the current size, thereby changing the pumping laser power, obtaining I in by the host computer software S x and

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