SERF inertial measurement multi-error synchronous suppression method based on air chamber parameter adjustment

Abstract

The invention discloses a gas chamber parameter adjustment-based SERF inertial measurement multi-error synchronous suppression method, which comprises the following steps of: establishing a coupling spin Bloch model under a mixed light pumping condition, and calculating the change rule of a temperature sensitivity coefficient and a total light frequency shift along with the diameter, the pressure intensity and the density ratio of a gas chamber; a common temperature working point with insensitive temperature fluctuation and zero total optical frequency shift is theoretically determined, and a parameter combination corresponding to a relatively low temperature is preferably selected, so that the influence of a low-frequency magnetic field disturbance error is effectively inhibited. According to the scheme, the temperature fluctuation error, the optical frequency shift error and the low-frequency magnetic field disturbance error can be synchronously suppressed only by adjusting parameters of the alkali metal air chamber and the glass air chamber without other hardware changes. The method disclosed by the invention can be modified on the basis of an original device, and is simple in structure and easy to implement, so that the requirements of experimental test and future engineering of the SERF inertial measurement device are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of atomic inertial sensing, and particularly relates to a SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment. BACKGROUND

[0002] Compared with traditional inertial measurement instruments, the atomic spin inertial measurement system based on the spin-exchange relaxation-free (SERF) effect has the potential of higher accuracy, smaller size and lower cost in theory, and can be widely applied to the fields of long-time navigation, high-precision inertial navigation, marine resource exploration, aerospace, and CPT symmetry breaking. The SERF atomic spin inertial measurement device has important application potential in the fields of navigation, geological exploration and basic scientific research due to its high measurement sensitivity. However, the high sensitivity of the device also makes it extremely sensitive to changes in environmental parameters, such as temperature fluctuations, fluctuations in optical frequency or intensity, and disturbances in the environmental magnetic field. Specifically, a slight fluctuation in the temperature of the gas chamber will cause a change in the density of alkali metal atoms, thereby affecting the system scale factor and the atomic spin polarization state, causing the zero drift of the measurement signal. A slight fluctuation in the pumping light frequency or intensity will produce an optical frequency shift (AC Stark shift), forming a virtual magnetic field bias, which directly interferes with the output signal of the system. A slight disturbance in the low-frequency magnetic field will also destroy the low-magnetic-field environment required to maintain the SERF state, further reducing the measurement accuracy and stability of the system.

[0003] In the prior art, the suppression of these error sources is usually carried out separately for a single error source, for example, a high-precision temperature control system is used to reduce the influence of temperature fluctuations, or a frequency locking device is used to reduce the optical frequency shift. However, these single-error-source suppression strategies are often independent of each other, making it difficult to effectively achieve synchronous suppression of all error sources, and increasing the complexity and cost of the system. Therefore, there is an urgent need to develop a method that can effectively suppress multiple errors from the root cause, thereby simultaneously improving the accuracy and long-term stability of the system. SUMMARY

[0004] In view of the prior art deficiency, the present application provides a SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment, a common temperature working point is determined through theoretical calculation, so that the SERF system simultaneously satisfies the conditions of gas chamber temperature fluctuation insensitivity and total optical frequency shift being zero, and further, a parameter combination corresponding to a lower temperature working point is selected, so that the sensitivity to low-frequency magnetic field disturbance is effectively reduced, and the synchronous optimization of multiple errors is realized.

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

[0006] The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment has the characteristics that it comprises the following steps:

[0007] Step 1: the following gas chamber parameters are used as optimization variables: gas chamber diameter, buffer gas pressure, and two alkali metal atom density ratios;

[0008] Step 2: a mathematical model of a coupled spin system is established based on Bloch equations and atomic polarization theory, and the temperature sensitive coefficient K T and the total optical frequency shift S tot with the change of temperature are calculated, so as to determine a common temperature working point T that makes K T ≈0 and S tot ≈0;

[0009] Step 3: a theoretical gas chamber parameter combination of a lower common temperature working point is optimized, so as to reduce the sensitivity to low-frequency magnetic field disturbance by reducing the working temperature of the gas chamber;

[0010] Step 4: a hybrid pumping SERF atomic spin inertial measurement system is built according to the theoretical gas chamber parameter combination, and the synchronous suppression effect of multiple errors is verified through experiments, wherein the multiple errors include temperature fluctuation error, optical frequency shift error and low-frequency magnetic field disturbance error.

[0011] In step 4, the temperature sensitive coefficient K T and the low-frequency magnetic field sensitive coefficient K m are obtained through linear fitting by applying ±0.05℃ temperature disturbance and ±10nT magnetic field disturbance and measuring the steady-state response, and the total optical frequency shift S tot is extracted by using the "S curve" method, so as to verify the synchronous suppression effect of the temperature fluctuation error, the optical frequency shift error and the low-frequency magnetic field disturbance error.

[0012] The gas chamber in step 1 is a high borosilicate glass gas chamber, the optimization range of the gas chamber diameter starts from 2mm, the optimization range of the buffer gas pressure starts from 0atm, and the buffer gas is neon Ne 21 , and the two alkali metal atoms are potassium K and rubidium Rb.

[0013] In step 2, the mathematical model is K-Rb- 21Response model of a Ne ternary coupled spin system to rotation.

[0014] Step 2 includes obtaining the operating temperature point at which the steady-state output is insensitive to fluctuations in the gas chamber temperature by differentiating the temperature of the gas chamber; adjusting the atomic density ratio of the two alkali metals in the gas chamber and the pressure of the buffer gas to change the optical frequency shift of the two alkali metal atoms, thereby achieving the cancellation of optical frequency shifts of equal magnitude and opposite direction at a certain operating temperature point, which is manifested as a total optical frequency shift of 0; and obtaining the state where the steady-state output of the SERF inertial measurement device is insensitive to fluctuations in the gas chamber temperature by adjusting the gas chamber diameter, the pressure of the buffer gas, and the atomic density ratio of the two alkali metals, thereby achieving synchronous suppression of gas chamber temperature fluctuation errors and optical frequency shift errors.

[0015] Step 4 includes the following expression:

[0016]

[0017] Where V i It is the i-th data set {V i B zi The voltage difference in the magnetic field response, where A is an intermediate quantity, and B is an intermediate quantity. zi It is the i-th data set {V i B zi The z-axis bias magnetic field in the middle, It is the z-axis magnetic field self-compensation point. It is the total optical frequency shift along the z-axis, B is an intermediate quantity, and k is the total optical frequency shift along the z- c It is the conversion coefficient between the system output voltage and the polarization vector. It is polarizability. It is the relaxation rate, γ e It is the electron gyromagnetic ratio.

[0018] In step 4, the hybrid pump SERF atomic spin inertial measurement system includes a pump optical path, a detection optical path, and a main structure housed within a casing. The gas chamber is located inside an oven, which is located inside an oven support. The oven support is located inside a magnetic field coil, which is located inside a ferrite magnetic shielding cylinder. The ferrite magnetic shielding cylinder is located inside a permalloy magnetic shielding cylinder, which is located inside the main structure.

[0019] The pump optical path includes a pump laser, a first half-wave plate, a first beam splitter, a first liquid crystal, a second beam splitter, a beam expander group, a reflector, a second half-wave plate, a third beam splitter, a first quarter-wave plate, and a gas cell connected in sequence. The third beam splitter is connected to the first liquid crystal through a first photodetector.

[0020] The detection light path comprises a detection laser, a third 1 / 2 wave plate, a fourth light splitting prism, a second liquid crystal, a fifth light splitting prism, a fourth 1 / 2 wave plate, a sixth light splitting prism, a second 1 / 4 wave plate, a gas chamber, a fifth 1 / 2 wave plate, a seventh light splitting prism, a second photodetector and a differential circuit connected in sequence, and the sixth light splitting prism is connected with the second liquid crystal through a third photodetector.

[0021] The technical effect of the present application is as follows: the SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment of the present application, by establishing a coupled spin Bloch model under mixed optical pumping conditions, calculating the variation law of temperature sensitivity coefficient and total optical frequency shift with gas chamber diameter, pressure and density ratio, theoretically determining the common temperature working point of temperature fluctuation insensitivity and zero total optical frequency shift, and optimizing the parameter combination corresponding to lower temperature, thereby effectively suppressing the influence of low-frequency magnetic field disturbance error. This scheme only adjusts the alkali metal gas chamber glass chamber parameters, without involving other hardware changes, so as to synchronously suppress temperature fluctuation error, optical frequency shift error and low-frequency magnetic field disturbance error. The method of the present application can be modified on the original device, has simple structure and is easy to implement, thereby meeting the needs of SERF inertial measurement device experimental testing and future engineering.

[0022] The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment of the present application has the following obvious advantages: (1) different parameter combinations of gas chamber diameter, gas pressure and alkali metal atomic density are determined by theoretical derivation, reducing experimental blindness and improving experimental efficiency. (2) On the basis of not changing other hardware structures except the alkali metal gas chamber, the synchronous effective suppression of multiple error sources is realized, and the system accuracy is obviously improved; lower temperature working point combinations are selected to further improve the stability of the system to environmental disturbance. (3) The method is simple and easy to implement, without additional complex equipment, and is convenient for engineering application. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structure schematic diagram of a mixed pumping SERF atomic spin inertial measurement system involved in the SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment of the present application.

[0024] The reference signs are explained as follows: 1-pumping laser; 2-first 1 / 2 wave plate; 3-first light splitting prism; 4-first liquid crystal; 5-second light splitting prism; 6-beam expander; 7-reflection mirror; 8-second 1 / 2 wave plate; 9-third light splitting prism; 10-first 1 / 4 wave plate; 11-gas cell; 12-oven; 13-oven support; 14-magnetic field coil; 15-ferrite magnetic shielding cylinder; 16-permalloy magnetic shielding cylinder; 17-main structure; 18-first photodetector; 19-detection laser; 20-third 1 / 2 wave plate; 21-fourth light splitting prism; 22-second liquid crystal; 23-fifth light splitting prism; 24-fourth 1 / 2 wave plate; 25-sixth light splitting prism; 26-second 1 / 4 wave plate; 27-fifth 1 / 2 wave plate; 28-seventh light splitting prism; 29-second photodetector; 30-differential circuit; 31-third photodetector; 32-housing. DETAILED DESCRIPTION

[0025] The application will be described below with reference to the accompanying drawings Figure 1 and examples.

[0026] Figure 1 is a schematic diagram of a mixed-pumping SERF atomic spin inertial measurement system structure involved in the method for simultaneously suppressing multiple errors of SERF inertial measurement based on gas cell parameter adjustment. As shown in Figure 1 , the method for simultaneously suppressing multiple errors of SERF inertial measurement based on gas cell parameter adjustment comprises the following steps: step 1, using the following gas cell parameters as optimization variables: gas cell diameter, buffer gas pressure, and two alkali metal atom density ratios; step 2, establishing a mathematical model of a coupled spin system based on Bloch equations and atomic polarization theory, calculating the temperature sensitivity coefficient K T and the total optical frequency shift S tot with respect to temperature under different combinations of gas cell parameters, and determining a common temperature working point T that makes K T ≈0 and S tot ≈0; step 3, optimizing the theoretical gas cell parameter combination of a lower common temperature working point, and reducing the sensitivity to low-frequency magnetic field disturbance by reducing the working temperature of the gas cell; step 4, building a mixed-pumping SERF atomic spin inertial measurement system according to the theoretical gas cell parameter combination, and verifying the effect of simultaneously suppressing multiple errors through experiments, wherein the multiple errors include temperature fluctuation error, optical frequency shift error, and low-frequency magnetic field disturbance error. In step 4, the temperature sensitivity coefficient K T , the low-frequency magnetic field sensitivity coefficient K m , and the total optical frequency shift S tot are obtained by linear fitting through the measurement of steady-state responses under the application of ±0.05℃ temperature disturbance and ±10nT magnetic field disturbance, and the effect of simultaneously suppressing temperature fluctuation error, optical frequency shift error, and low-frequency magnetic field disturbance error is verified by using the "S-curve" method.

[0027] The gas chamber in step 1 is a high borosilicate glass gas chamber, with the optimized chamber diameter starting from 2 mm and the optimized buffer gas pressure starting from 0 atm. The buffer gas is neon. 21 Ne, the two alkali metal atoms are potassium (K) and rubidium (Rb). The mathematical model in step 2 is K-Rb- 21 The response model of the Ne three-component coupled spin system to rotation is presented. Step 2 includes obtaining the operating temperature point where the steady-state output is insensitive to fluctuations in the gas chamber temperature by differentiating the gas chamber temperature; adjusting the atomic density ratio of the two alkali metals in the gas chamber and the buffer gas pressure to change the optical frequency shift of the two alkali metal atoms, thereby achieving the cancellation of optical frequency shifts of equal magnitude and opposite direction at a certain operating temperature point, which is manifested as a total optical frequency shift of 0; and obtaining the state where the steady-state output of the SERF inertial measurement device is insensitive to fluctuations in the gas chamber temperature by adjusting the gas chamber diameter, the buffer gas pressure, and the atomic density ratio of the two alkali metals, thereby achieving synchronous suppression of gas chamber temperature fluctuation errors and optical frequency shift errors.

[0028] Step 4 includes the following expression:

[0029]

[0030]

[0031] Where V i It is the i-th data set {V i B zi The voltage difference in the magnetic field response, where A is an intermediate quantity, and B is an intermediate quantity. zi It is the i-th data set {V i B zi The z-axis bias magnetic field in} It is the z-axis magnetic field self-compensation point. It is the total optical frequency shift along the z-axis, B is an intermediate quantity, and k is the total optical frequency shift along the z-axis. c It is the conversion coefficient between the system output voltage and the polarization vector. It is polarizability. It is the relaxation rate, γ e It is the electron gyromagnetic ratio.

[0032] The pumping SERF atomic spin inertial measurement system in step 4 comprises a pumping light path, a detection light path and a main structure 17 arranged in a shell, the gas chamber 11 is arranged in an oven 12, the oven 12 is arranged in an oven support 13, the oven support 13 is arranged in a magnetic field coil 14, the magnetic field coil 14 is arranged in a ferrite magnetic shielding cylinder 15, the ferrite magnetic shielding cylinder 15 is arranged in a permalloy magnetic shielding cylinder 16, and the permalloy magnetic shielding cylinder 16 is arranged in the main structure 17. The pumping light path comprises a pumping laser 1, a first 1 / 2 wave plate 2, a first light splitting prism 3, a first liquid crystal 4, a second light splitting prism 5, a beam expander 6, a mirror 7, a second 1 / 2 wave plate 8, a third light splitting prism 9, a first 1 / 4 wave plate 10 and the gas chamber 11 connected in sequence, and the third light splitting prism 9 is connected to the first liquid crystal 4 through a first photoelectric detector 18. The detection light path comprises a detection laser 19, a third 1 / 2 wave plate 20, a fourth light splitting prism 21, a second liquid crystal 22, a fifth light splitting prism 23, a fourth 1 / 2 wave plate 24, a sixth light splitting prism 25, a second 1 / 4 wave plate 26, the gas chamber 11, a fifth 1 / 2 wave plate 27, a seventh light splitting prism 28, a second photoelectric detector 29 and a differential circuit 30 connected in sequence, and the sixth light splitting prism 25 is connected to the second liquid crystal 22 through a third photoelectric detector 31.

[0033] The application discloses a SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment. The method establishes a coupled spin Bloch model under a mixed light pumping condition, calculates the change law of a temperature sensitivity coefficient and a total light frequency shift with a gas chamber diameter, pressure and density ratio, theoretically determines a common temperature working point which is not sensitive to temperature fluctuation and has a total light frequency shift of zero, and optimally selects a parameter combination corresponding to a lower temperature, so that the influence of a low-frequency magnetic field disturbance error is effectively suppressed. The method only adjusts the alkali metal gas chamber glass chamber parameters and does not involve other hardware changes, so that the temperature fluctuation error, the light frequency shift error and the low-frequency magnetic field disturbance error can be synchronously suppressed. The method can be modified on the original device, has a simple structure and is easy to implement, thereby meeting the needs of SERF inertial measurement device experimental testing and future engineering.

[0034] A SERF atomic spin inertial measurement multi-error suppression method based on alkali metal gas chamber parameters is provided. A common temperature working point is determined by theoretical calculation, so that the SERF system simultaneously satisfies the conditions of being not sensitive to gas chamber temperature fluctuation and having a total light frequency shift of zero, and a parameter combination corresponding to a lower temperature working point is further selected, so that the low-frequency magnetic field disturbance sensitivity is effectively reduced, and the synchronous optimization of multiple errors is realized.

[0035] The alkali metal cell is made of high borosilicate glass which is non-magnetic, high-temperature resistant and high-transmittance, two kinds of alkali metal atoms and high-purity buffer gas are sealed into the cell, the diameter of the cell, the pressure of the buffer gas and the density ratio of the two kinds of alkali metal atoms are set as optimization variables, and the stability of the initial conditions of the experiment is ensured through vacuumizing, high-temperature baking and sealing processes.

[0036] Based on the Bloch equation and the atomic polarization theory, a mathematical model of the coupled spin system is established, and the temperature sensitivity coefficient K is calculated under different combinations of cell parameters T And the total optical frequency shift S tot With the change of temperature, the common temperature working point T is determined, which makes K T ≈0 and S tot ≈0.

[0037] Among the multiple parameter groups satisfying the conditions of K T ≈0 and S tot ≈0, the combination which can make the common temperature working point T lower is preferentially screened, including moderate buffer gas pressure, appropriate reduction of cell diameter and reasonable adjustment of alkali metal atom density ratio, so as to reduce the sensitivity of the steady-state output of the SERF inertial measurement device to low-frequency magnetic field disturbance.

[0038] The preferred parameter combination builds an experimental system, respectively applies ±0.05℃ temperature disturbance and ±10nT magnetic field disturbance and measures the steady-state response, and through linear fitting, the temperature sensitivity coefficient K T And the low-frequency magnetic field sensitivity coefficient K T And the total optical frequency shift S tot Is extracted by using the "S curve" method, so as to verify the synchronous suppression effect of temperature fluctuation error, optical frequency shift error and low-frequency magnetic field disturbance error.

[0039] A SERF atomic spin inertial measurement system multiple error synchronous suppression method based on parameter optimization of alkali metal cell. The common temperature working point is determined by theoretical calculation, so that the SERF system satisfies the conditions of being insensitive to cell temperature fluctuation and the total optical frequency shift being zero, and further, the parameter combination corresponding to a lower temperature working point is selected, so as to effectively reduce the sensitivity to low-frequency magnetic field disturbance, realize the synchronous optimization of multiple errors. Without changing the hardware structure except the alkali metal cell, the multiple errors of the SERF inertial measurement device are synchronously suppressed.

[0040] The optical frequency shift suppression method based on the hybrid pumping SERF atomic spin inertial measurement system, and the specific implementation steps are as follows:

[0041] Step S1, select alkali metal gas chamber material and parameter optimization range. The gas chamber is selected to be a high borosilicate quartz glass ball shell with high temperature resistance, high transmittance and no magnetism, and the diameter optimization range starts from 2mm. A proper amount of potassium and rubidium metals are sealed in the gas chamber, the density ratio selection range is not limited, and the two metals are ensured to have excess amount in the working temperature range, and high-purity neon gas 21 Ne as a buffer nuclear spin gas, the pressure optimization range starts from 0atm.

[0042] Step S2, find the gas chamber parameter combination for synchronous suppression of gas chamber temperature fluctuation error and optical frequency shift error. Using the steady-state solution of Bloch equation set, K-Rb- 21 Ne three-group element coupling spin system response model. The formula of the steady-state output of SERF inertial measurement device changing with the temperature of the gas chamber is obtained. By taking the derivative of the temperature of the gas chamber, the temperature working point that makes the steady-state output not sensitive to the temperature fluctuation of the gas chamber can be obtained. Through the optical frequency shift expressions of K atoms and Rb atoms, it can be known that the change of the optical frequency shift of the two alkali metal atoms can be realized by adjusting the density ratio and gas pressure of the gas chamber, so that the two alkali metal atoms can realize the same size and opposite direction at a certain temperature working point, so as to realize the cancellation of the optical frequency shift, which shows that the total optical frequency shift is 0. By adjusting the diameter, gas pressure and density ratio of the alkali metal atoms in the gas chamber, the two temperature points can be equalized, so as to realize the synchronous suppression of the gas chamber temperature fluctuation error and the total optical frequency shift error.

[0043] Step S3, since the parameter combination obtained in step S2 is not unique, the temperature working point corresponding to the simultaneous suppression of the gas chamber temperature fluctuation error and the total optical frequency shift error is also not unique. Since the sensitivity of the steady-state output of the SERF inertial measurement device to the low-frequency magnetic field disturbance is proportional to the size of the gas chamber temperature, the influence of the low-frequency magnetic field disturbance on the stability of the zero bias of the SERF inertial measurement device can be effectively reduced by reducing the working temperature of the gas chamber.

[0044] Step S4, according to the optimized theoretical parameters, build an experimental verification system, strictly control the gas chamber temperature and pumping light conditions, and test the synchronous suppression effect of the optimized parameters on the temperature fluctuation error, the optical frequency shift error and the low-frequency magnetic field disturbance error.

[0045] The alkali metal gas cell is installed in a non-magnetic electric heating oven. The oven is driven and controlled by a heating circuit control system. The temperature of the oven can be precisely adjusted by setting the control system value. The working temperature of the alkali metal gas cell can be adjusted to meet the experimental requirements of different atomic densities and polarization states. In order to suppress external magnetic field interference and maintain a very weak magnetic environment suitable for SERF state, the system is equipped with a three-axis magnetic compensation coil assembly, including X-direction compensation coil, Y-direction compensation coil and Z-direction compensation coil. The three-dimensional magnetic compensation system is powered and driven by a high stability current source (3). It can independently apply precise control compensation magnetic field in each axis to offset the residual magnetic field of the magnetic shielding system and maintain the magnetic zero field condition. In terms of optical system, the laser output by the pumping laser is processed by the pumping optical module to realize stable control of the laser frequency and power, expand the laser spot and adjust the light propagation direction. Then, the pumping light is converted into circularly polarized light by polarization modulation, and is vertically irradiated to the alkali metal gas cell to realize effective pumping polarization of the alkali metal atom spin state. The detection part is supplied with laser source by the detection laser. The detection light is converted into stable linearly polarized light after being processed by the detection optical module, and propagates along the axis to pass through the alkali metal gas cell, keeping the orthogonal direction with the pumping light. The outgoing light enters the polarization beam splitter, and is divided into two beams with complementary polarization states, which are irradiated to two photodetectors respectively. The photodetectors convert the incident light signal into an electric signal, and realize real-time acquisition and storage of the signal through the data acquisition system for subsequent signal demodulation and physical quantity inversion analysis. In order to realize the dynamic response characteristic test and scale factor calibration of the system, the whole system is installed on a high-precision rate turntable. By applying different angular velocity conditions, the system can complete the scale factor calibration test and linearity evaluation under the premise of maintaining the stability of the magnetic environment and temperature field, and provide experimental basis for the actual performance of the device in the application of inertial measurement.

[0046] When the system is running normally, the temperature variation of ±0.05℃ is applied by the non-magnetic electric heating oven, and the corresponding signal bias change is recorded. The slope is obtained by linear fitting, and the scale factor is obtained by the above method to obtain the temperature sensitivity coefficient of the gas cell. The magnetic field fluctuation of ±10nT is applied by the three-dimensional active magnetic compensation coil, and the corresponding signal bias change is recorded. The slope is obtained by linear fitting, and the scale factor is obtained by the above method to obtain the low-frequency magnetic field sensitivity coefficient. In the experiment, the low-frequency square wave modulation magnetic field with an amplitude of about 100pT and a frequency of several tens of millihertz is applied in the y-axis direction. The difference between the high and low levels of the magnetic field is First, adjust the z-axis magnetic field to the self-compensation point At this time, the response voltage of the system under the high-level magnetic field is V H , and the response voltage under the low-level magnetic field is V L , and the difference is V0=V H-V L Subsequently, the z-axis bias magnetic field B was gradually adjusted. z (Increasing or decreasing with a step size of 1nT), at each magnetic field value B zi Repeatedly measure the corresponding response voltage difference V at (i = 1, 2, 3...) locations. i Finally, the measured {V} i B zi Substitute the dataset into the following fitting function:

[0047]

[0048] in For self-compensation point, k c This is the conversion coefficient between the system output voltage and the polarization vector. By performing nonlinear least-squares fitting on the experimental data, the total optical frequency shift in the SERF inertial measurement system can be accurately extracted. The value is used to measure the total optical frequency shift.

[0049] The effects of air chamber temperature fluctuation error, low-frequency magnetic field disturbance error, and total optical frequency shift error on the steady-state output of the SERF inertial measurement unit can be assessed by measuring the magnitude of the air chamber temperature sensitivity coefficient, low-frequency magnetic field sensitivity coefficient, and the absolute value of the total optical frequency shift.

[0050] A method for synchronously suppressing multiple errors in a SERF atomic spin inertial measurement system based on alkali metal cell parameter optimization is presented. This invention determines a common operating temperature point through theoretical calculations, ensuring the SERF system simultaneously satisfies the conditions of insensitivity to cell temperature fluctuations and zero total optical frequency shift. Furthermore, parameter combinations corresponding to the lower operating temperature point are selected to effectively reduce sensitivity to low-frequency magnetic field disturbances, achieving synchronous optimization of multiple errors. This method achieves synchronous suppression of multiple errors in the SERF inertial measurement device without altering any hardware structure other than the alkali metal cell.

[0051] The specific implementation steps are as follows:

[0052] Step 1: Determining the Optimization Range of Gas Chamber Parameters

[0053] High-temperature resistant, high-transmittance GE180 borosilicate glass was selected as the raw material for the alkali metal cell. To reduce the polarization gradient of the alkali metal cell, two alkali metal atoms with different gyromagnetic ratios were mixed for optical pumping. The cell diameter, pressure, and alkali metal atom density ratio were used as optimization parameters. Based on existing cell manufacturing processes, the cell diameter was greater than 2 mm, the pressure greater than 0 atm, and the density ratio of the two atoms was not limited. The cell was encapsulated under vacuum, high-temperature baking, and sealing to ensure the stability of the initial experimental conditions.

[0054] Step two: theoretically determine the synchronous suppression temperature working point

[0055] A mathematical model of the SERF system is established by using the Bloch equation and atomic polarization theory, and the temperature sensitivity coefficient and total optical frequency shift are calculated under different combinations of gas chamber parameters (including buffer gas pressure, gas chamber diameter, and alkali metal density ratio) to determine the trend of temperature variation. Through simulation analysis, it is found that the system has a common temperature point at which the temperature sensitivity coefficient and the optical frequency shift are simultaneously suppressed.

[0056] Step three: optimize the parameter combination of the lower temperature working point

[0057] Based on the common temperature working point determined in step two, the parameter combination is further optimized. Since the parameter combination that meets the synchronous suppression condition is not unique, the present application preferentially selects the parameter combination corresponding to a relatively low temperature working point by additional simulation screening, which specifically includes a moderate buffer gas pressure, a properly reduced gas chamber diameter, and a reasonably adjusted alkali metal density ratio. On the basis of ensuring the synchronous suppression of temperature and optical frequency shift errors, the sensitivity to low-frequency magnetic field disturbance is effectively reduced.

[0058] Step four: experimentally verify the effect of multiple error synchronous suppression

[0059] According to the optimized theoretical parameters, an experimental verification system is built, the gas chamber temperature and pumping light conditions are strictly controlled, and the synchronous suppression effect of the optimized parameters on temperature fluctuation error, optical frequency shift error, and low-frequency magnetic field disturbance error is tested.

[0060] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art. It is pointed out that the above description is helpful for those skilled in the art to understand the present application, but does not limit the protection scope of the present application. Any 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 method for SERF inertial measurement multi-error simultaneous rejection based on gas cell parameter adjustment, characterized in that, The method comprises the following steps: Step 1, using the following cell parameters as optimization variables: cell diameter, buffer gas pressure, and two alkali metal atom density ratio; Step 2, based on Bloch equation and atomic polarization theory, a mathematical model of coupled spin system is established, and the temperature sensitivity coefficient K is calculated under different combinations of gas chamber parameters T and total optical frequency shift S tot with temperature, determine the common temperature working point T that makes K T ≈0 and S tot ≈0; Step 3, the theoretical cell parameter combination of the preferred lower common temperature working point reduces the low-frequency magnetic field disturbance sensitivity by reducing the cell working temperature; Step 4, according to the theoretical cell parameter combination, build a hybrid pumping SERF atomic spin inertial measurement system, and verify the multiple error synchronous suppression effect through experiment, the multiple error including temperature fluctuation error, optical frequency shift error and low-frequency magnetic field disturbance error.

2. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 1, characterized in that, The temperature sensitive coefficient K is obtained by linear fitting in step 4 by applying ±0.05℃ temperature disturbance and ±10nT magnetic field disturbance and measuring the steady-state response T and the low-frequency magnetic field sensitive coefficient K m and the total optical frequency shift S is extracted by using the "S-curve" method tot so as to verify the synchronous suppression effect of temperature fluctuation error, optical frequency shift error and low-frequency magnetic field disturbance error.

3. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 1, characterized in that, The gas cell in step 1 is a high borosilicate glass gas cell with an optimized range of diameters starting at 2 mm and an optimized range of buffer gas pressures starting at 0 atm, with neon gas as the buffer gas 21 Ne, the two alkali metal atoms are potassium, K, and rubidium, Rb.

4. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 1, characterized in that, The mathematical model in step 2 is K-Rb- 21 Model of the response of the Ne triad coupled spin system to rotation.

5. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 1, characterized in that, In step 2, by taking the derivative of the cell temperature, the temperature working point which is not sensitive to the fluctuation of the cell temperature is obtained; by adjusting the density ratio of the two alkali metal atoms in the cell and the buffer gas pressure, the change of the optical frequency shift of the two alkali metal atoms is realized, so that the optical frequency shift of the two alkali metal atoms at a certain temperature working point is equal in size and opposite in direction, which is manifested as the total optical frequency shift is 0; by adjusting the cell diameter, buffer gas pressure and density ratio of the two alkali metal atoms, the state of the SERF inertial measurement device which is not sensitive to the fluctuation of the cell temperature is obtained, so as to realize the synchronous suppression of the cell temperature fluctuation error and the optical frequency shift error.

6. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 1, characterized in that, In step 4, the following expressions are included: Where V i It is the i-th data set {V i B zi The voltage difference in the magnetic field response, where A is an intermediate quantity, and B is an intermediate quantity. zi It is the i-th data set {V i B zi The z-axis bias magnetic field in} It is the z-axis magnetic field self-compensation point. It is the total optical frequency shift along the z-axis, B is an intermediate quantity, and k is the total optical frequency shift along the z-axis. c It is the conversion coefficient between the system output voltage and the polarization vector. It is polarizability. It is the relaxation rate, γ e It is the electron gyromagnetic ratio.

7. The SERF-based inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 1, characterized in that, In step 4, the hybrid pumping SERF atomic spin inertial measurement system comprises a pumping light path, a detection light path and a main structure arranged in a shell, a cell located in an oven, the oven located in an oven support, the oven support located in a magnetic field coil, the magnetic field coil located in a ferrite magnetic shielding cylinder, the ferrite magnetic shielding cylinder located in a permalloy magnetic shielding cylinder, and the permalloy magnetic shielding cylinder located in the main structure.

8. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 7, characterized in that, The pumping light path comprises a pumping laser, a first 1 / 2 wave plate, a first light splitting prism, a first liquid crystal, a second light splitting prism, a beam expander, a mirror, a second 1 / 2 wave plate, a third light splitting prism, a first 1 / 4 wave plate and a cell connected in sequence, and the third light splitting prism is connected to the first liquid crystal through a first photodetector.

9. The SERF inertial measurement multi-error synchronous suppression method based on gas chamber parameter adjustment according to claim 7, characterized in that, The detection light path comprises a detection laser, a third 1 / 2 wave plate, a fourth light splitting prism, a second liquid crystal, a fifth light splitting prism, a fourth 1 / 2 wave plate, a sixth light splitting prism, a second 1 / 4 wave plate, a cell, a fifth 1 / 2 wave plate, a seventh light splitting prism, a second photodetector and a differential circuit connected in sequence, and the sixth light splitting prism is connected to the second liquid crystal through a third photodetector.

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