A magneto-optical noise suppression method for inertial measurement based on multi-element polarization

Abstract

A multi-polarization-based magneto-optical noise suppression method for inertial measurements is proposed. This method combines pulsed and continuous polarization to design a multi-polarized optical field. By separating the pulsed polarization phase from the detection phase, polarization noise is reduced. The multi-polarized optical field design enhances the nuclear spin polarizability within the gas chamber, overcoming the mutual constraint between nuclear spin polarizability and calibration coefficient improvement under continuous polarization conditions. This improves the nuclear spin self-compensation capability, achieving active magneto-optical noise suppression in atomic spin inertial measurement devices. This invention is reasonable, simple to operate, and applicable to atomic spin inertial measurement systems. It enhances magneto-optical noise suppression capabilities and provides a foundation for the development of high-precision atomic spin inertial measurement devices.

Description

Technical Field

[0001] This invention relates to the field of atomic spin inertial measurement technology, specifically to a method for suppressing magneto-optical noise in inertial measurement based on multi-polarization, which can solve the magneto-optical noise problem and provides a foundation for the development of high-precision atomic spin inertial measurement devices. Background Technology

[0002] Magneto-optical noise is a key factor limiting the improvement of sensitivity in high-precision atomic spin inertial measurements. Magnetic noise is the main source of interference in atomic spin inertial measurement systems, and nuclear spin self-compensation technology is crucial for further suppressing magnetic noise, building upon passive magnetic shielding. Polarized light enables coupled spin ensembles to sensitively input information; however, the presence of polarized light also introduces polarization noise.

[0003] Currently, research on magnetic noise suppression capabilities suggests that it requires reducing the transverse relaxation rate of nuclear spins and increasing the equivalent magnetic field of nuclear spins. However, in traditional continuous pumping modes, increasing the equivalent magnetic field of nuclear spins contradicts increasing the angular velocity measurement calibration coefficient. A commonly used method in inertial measurement to address polarization noise is through externally stabilized passive suppression, but its suppression capability is limited. Summary of the Invention

[0004] This invention addresses the deficiencies or shortcomings of existing technologies by providing a magneto-optical noise suppression method for inertial measurement based on multi-polarization. This method can solve the magneto-optical noise problem and provides a foundation for the development of high-precision atomic spin inertial measurement devices.

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

[0006] A method for suppressing magneto-optical noise in inertial measurement based on multi-polarization, characterized by comprising the following steps:

[0007] Step 1: Start the multi-polarized inertial measurement system and input a pulsed polarized light field along the z-axis to the atomic gas cell. The pulsed polarized light field is distributed in a middle band with a width limited to the y-axis on the xoy plane.

[0008] Step 2: Input a continuous polarized light field into the atomic gas cell in the reverse z-axis direction. The continuous polarized light field is divided into two parts: the front part is located on the positive y-axis side of the pulsed polarized light field, and the rear part is located on the negative y-axis side of the pulsed polarized light field. The continuous polarized light field is complementary to the pulsed polarized light field in the xoy plane but does not overlap with it.

[0009] Step 3: Input detection light into the atomic gas cell along the x-axis to achieve inertial measurement under multivariate conditions.

[0010] The central band distribution of the pulsed polarized light field is formed by blocking the two small semicircles at both ends of the circular light spot with an aperture.

[0011] The pulsed light of the pulsed polarized light field is formed by an optical switch.

[0012] The continuous polarized light field is divided into two parts by a spatial light modulator, which shapes the circular light spot into a strip-shaped middle section with no light, while only the front and rear small semi-circular light spots are retained.

[0013] The diameter of the detection light spot is equal to the width of the pulsed polarized light field.

[0014] The pulsed polarized light field is sourced from a first laser. The first laser is sequentially fed into an optical switch via a first lens group, a first polarizing beam splitter, a first λ / 4 waveplate, an aperture, and a first reflector. The pulsed polarized light field formed by the optical switch is then delivered to the atomic gas cell.

[0015] The light source of the continuous polarized light field comes from the second laser. The second laser is input to the spatial light modulator in sequence through the second lens group, the second polarizing beam splitter, the second λ / 4 waveplate and the second mirror. The spatial light modulator outputs the shaped continuous polarized light field and delivers it to the atomic gas cell.

[0016] The detection light source comes from a third laser, which is connected to the data acquisition and processing system via a polarizer, an atomic gas cell, an analyzer, and a photodetector.

[0017] The inertial measurement includes the following formula:

[0018]

[0019] Among them, P e γ is the electron spin polarizability measured by atomic spin inertial measurement during the pulsed polarization light field off phase, t is the time of decay of the oscillation signal, and γ is the electron spin polarizability measured by pulsed polarization light field off phase. e It is the electron spin gyromagnetic ratio, Q is the slowing factor, and B is the magnetic field acting on the coupled atomic ensemble. n It is the equivalent magnetic field of the inert gas nuclear spin, and Ω is the rotational input. It is the spin exchange rate of nuclear spin to electron spin, P n It is the nuclear spin polarization. It is the transverse relaxation rate of electron spin during the stable phase of damped oscillation. It is the longitudinal relaxation rate of electron spin during the stable phase of the decaying oscillation.

[0020] The inertial measurement includes the following formula:

[0021]

[0022] in, R is the z-axis polarizability of the electron spin in the continuous polarization region. pc It is the pumping rate of the continuous polarization region. It is the longitudinal relaxation rate of electron spin in the continuously polarized region. It is the z-axis polarizability of the nuclear spin in the continuous polarization region. It is the spin exchange rate between electron spin and nuclear spin. It is the longitudinal relaxation rate of nuclear spin in the continuously polarized region.

[0023] The inertial measurement includes the following formula:

[0024]

[0025] Where P is the polarizability and D is the diffusion coefficient. This formula combines the electron spin and nuclear spin polarizability in pulsed polarization and continuous polarization regions.

[0026] The technical effects of this invention are as follows: This invention provides a magneto-optical noise suppression method for inertial measurement based on multi-polarization. By combining pulsed polarization and continuous polarization to design a multi-polarized optical field, it can reduce polarization noise through pulsed polarization separated from the polarization and detection stages. By designing a multi-polarized optical field to improve the nuclear spin polarizability within the gas chamber, it overcomes the mutual constraint between nuclear spin polarizability and calibration coefficient improvement under continuous polarization conditions, thereby enhancing the nuclear spin self-compensation capability and achieving active magneto-optical noise suppression in atomic spin inertial measurement devices. This invention is reasonable, simple to operate experimentally, and applicable to atomic spin inertial measurement systems. It can improve the magneto-optical noise suppression capability, providing a foundation for the development of high-precision atomic spin inertial measurement devices.

[0027] The advantages of this invention compared with the prior art are as follows: (1) This invention utilizes multi-polarization to achieve magneto-optical noise suppression. Compared with existing methods, the improvement of nuclear spin polarizability in the continuous polarization region is no longer limited by the requirement of optimal traditional calibration coefficient. The high nuclear spin polarizability in the continuous polarization region diffuses to the pulsed polarization region, thereby improving the self-compensation capability. The atoms interacting with the detection light are within the control range of the pulsed polarized light, and the active suppression of polarization noise is achieved by separating the polarization stage from the detection stage. (2) The method of this invention is reasonable and the experimental operation is simple, providing a foundation for the development of a high-precision atomic spin inertial measurement device. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a multi-polarization inertial measurement system involved in implementing the present invention's method for suppressing magneto-optical noise in inertial measurement based on multi-polarization.

[0029] Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure of the multi-polarized light field xoy formed by the medium-pulse polarized light field and the continuous polarized light field.

[0030] The reference numerals in the attached figures are explained as follows: 1-First laser; 2-First lens group; 3-First polarizing beam splitter; 4-First λ / 4 waveplate; 5-Aperture; 6-First reflecting mirror; 7-Optical switch; 8-Pulsed polarized light field; 9-Second laser; 10-Second lens group; 11-Second polarizing beam splitter; 12-Second λ / 4 waveplate; 13-Second reflecting mirror; 14-Spatial light modulator; 15-Continuously polarized light field; 16-Atomic gas cell; 17-Third laser; 18-Polarizer; 19-Analyzer; 20-Photodetector; 21-Data acquisition and processing system; xyz-Cartesian coordinate system (i.e., x-axis, y-axis, and z-axis). Detailed Implementation

[0031] The following is in conjunction with the attached diagram ( Figures 1-2 The invention will be described in the following sections and examples.

[0032] Figure 1 This is a schematic diagram of the structure of a multi-polarization inertial measurement system involved in implementing the present invention's method for suppressing magneto-optical noise in inertial measurement based on multi-polarization. Figure 2 yes Figure 1 A schematic diagram of the xoy profile structure of a multi-polarized optical field formed by a mid-pulse polarized optical field and a continuous polarized optical field. (Reference) Figures 1 to 2 As shown, a magneto-optical noise suppression method for inertial measurement based on multi-polarization includes the following steps: Step 1, starting the multi-polarization inertial measurement system and inputting a pulsed polarized light field along the z-axis to the atomic gas cell, wherein the pulsed polarized light field is distributed in a middle band with a width limited to the y-axis on the xoy plane; Step 2, inputting a continuous polarized light field against the z-axis to the atomic gas cell, wherein the continuous polarized light field is divided into two parts, the front part being located on the positive y-axis side of the pulsed polarized light field and the rear part being located on the negative y-axis side of the pulsed polarized light field, wherein the continuous polarized light field is complementary to the pulsed polarized light field on the xoy plane but does not coincide with it; Step 3, inputting detection light along the x-axis to the atomic gas cell to achieve inertial measurement under multi-polarization conditions.

[0033] The central band-shaped distribution of the pulsed polarized light field is formed by blocking the two small semicircles at both ends of the circular light spot with an aperture. The pulsed light of the pulsed polarized light field is formed by an optical switch. The front and rear parts of the continuous polarized light field are shaped by a spatial light modulator so that the central band-shaped part is dark, leaving only the front and rear small semicircular light spots. The diameter of the detection light spot is equal to the width of the pulsed polarized light field.

[0034] The pulsed polarized light field 8 is sourced from a first laser 1. The first laser 1 is sequentially input to an optical switch 7 via a first lens group 2, a first polarizing beam splitter 3, a first λ / 4 waveplate 4, an aperture 5, and a first reflector 6. The pulsed polarized light field 8, regulated by the optical switch 7, is then delivered to the atomic gas chamber 16. The continuous polarized light field 15 is sourced from a second laser 9. The second laser 9 is sequentially input to a spatial light modulator 14 via a second lens group 10, a second polarizing beam splitter 11, a second λ / 4 waveplate 12, and a second reflector 13. The spatial light modulator 14 outputs a shaped continuous polarized light field 15, which is then delivered to the atomic gas chamber 16. The detection light is sourced from a third laser 17. The third laser 17 is connected to a data acquisition and processing system 21 via a polarizer 18, the atomic gas chamber 16, an analyzer 19, and a photodetector 20.

[0035] The inertial measurement includes the following formula:

[0036]

[0037] Among them, P e γ is the electron spin polarizability measured by atomic spin inertial measurement during the pulsed polarization light field off phase, t is the time of decay of the oscillation signal, and γ is the electron spin polarizability measured by pulsed polarization light field off phase. e It is the electron spin gyromagnetic ratio, Q is the slowing factor, and B is the magnetic field acting on the coupled atomic ensemble. n It is the equivalent magnetic field of the inert gas nuclear spin, and Ω is the rotational input. It is the spin exchange rate of nuclear spin to electron spin, P n It is the nuclear spin polarization. It is the transverse relaxation rate of electron spin during the stable phase of damped oscillation. It is the longitudinal relaxation rate of electron spin during the stable phase of the decaying oscillation.

[0038] The inertial measurement includes the following formula:

[0039]

[0040] in, R is the z-axis polarizability of the electron spin in the continuous polarization region. pc It is the pumping rate of the continuous polarization region. It is the longitudinal relaxation rate of electron spin in the continuously polarized region. It is the z-axis polarizability of the nuclear spin in the continuous polarization region. It is the spin exchange rate between electron spin and nuclear spin. It is the longitudinal relaxation rate of nuclear spin in the continuously polarized region.

[0041] The inertial measurement includes the following formula:

[0042]

[0043] Where P is the polarizability and D is the diffusion coefficient. This formula combines the electron spin and nuclear spin polarizability in pulsed polarization and continuous polarization regions.

[0044] This invention relates to a method for suppressing magneto-optical noise in multi-polarization inertial measurement systems, specifically for active magneto-optical noise suppression in atomic spin inertial measurement devices. This method combines pulsed and continuous polarization to design a multi-polarized optical field. Polarization noise is reduced through pulsed polarization separated from the polarization and detection phases. The multi-polarized optical field is designed to enhance the nuclear spin polarizability within the gas chamber, overcoming the mutual constraint between nuclear spin polarizability and calibration coefficient improvement under continuous polarization conditions, thereby improving the nuclear spin self-compensation capability. This invention is reasonable, simple to operate, and applicable to atomic spin inertial measurement systems. It can improve the magneto-optical noise suppression capability, providing a foundation for the development of high-precision atomic spin inertial measurement devices.

[0045] The specific implementation structure of the present invention is as follows: Figure 1 As shown. The multi-element light field form of the present invention is as follows. Figure 2 As shown, Figure 2 The pulsed polarized light field 8 shapes the light spot into the shape of the vertically filled portion shown by the aperture 5. The continuous polarized light field 15 shapes the light spot into the shape shown by the horizontally filled portion shown in the figure by the spatial light modulator 14. The pulsed polarized light field 8 and the continuous polarized light field 15 do not overlap in space and together form a circular polarized light that acts on the atomic gas cell 16.

[0046] This invention relates to a method for suppressing magneto-optical noise in multi-polarization inertial measurements, comprising the following parts:

[0047] Part (1): A pulsed polarized light field 8 is formed by a first laser 1, a first lens group 2, a first polarizing beam splitter 3, a first λ / 4 waveplate 4, an aperture 5, a first reflector 6, and an optical switch 7.

[0048] Part (2): A continuous polarized light field 15 is formed by a second laser 9, a second lens group 10, a second polarizing beam splitter 11, a second λ / 4 waveplate 12, a second reflector 13 and a spatial light modulator 14.

[0049] Part (3): The detection system consists of a third laser 17, a polarizer 18, an analyzer 19, a photodetector 20, and a data acquisition and processing system 21.

[0050] Part (4): Pulsed polarized light field 8, continuous polarized light field 15, detection system working together with atomic gas cell 16.

[0051] In part (1), the pulsed polarized light is blocked by the aperture, which blocks the two semicircles at both ends of the circular spot, leaving only a spot with a width of 1 mm that coincides with the detection light in space. The switching period is set according to the electron spin precession frequency to achieve the measurement of the complete electron spin decay oscillation signal during the detection phase. For example, when the electron spin resonance frequency f is about 200 Hz, at least 5 cycles of decay oscillation signal need to be measured, i.e., 25 ms. The alkali metal electron spin dynamics evolution equation in the stable oscillation frequency stage after the pump light is turned off is:

[0052]

[0053] Among them, P e γ is the electron spin polarizability measured by atomic spin inertial measurement during the pulsed polarization light field off phase, t is the time of decay of the oscillation signal, and γ is the electron spin polarizability measured by pulsed polarization light field off phase. e It is the electron spin gyromagnetic ratio, Q is the slowing factor, and B is the magnetic field acting on the coupled atomic ensemble. n It is the equivalent magnetic field of the inert gas nuclear spin, and Ω is the rotational input. It is the spin exchange rate of nuclear spin to electron spin, P n It is the nuclear spin polarization. It is the transverse (x-axis and y-axis) relaxation rate of the electron spin during the stable phase of the damped oscillation. It is the longitudinal (z-axis) relaxation rate of the electron spin during the stable phase of the decaying oscillation.

[0054] As can be seen from the formula, the dynamic equation for signal testing based on the pulsed polarization light off-phase does not contain terms such as pump rate and optical frequency shift caused by the pump light. The measurement of angular velocity comes from its own response to it and from the equivalent magnetic field of the inert gas nuclear spin. Therefore, using the decayed oscillation signal after the pump light is turned off for testing can achieve sensitivity to angular velocity information and suppression of polarization noise.

[0055] In part (2), the continuous polarization light field is shaped by a spatial modulator into a light spot with a 1mm width of no light in the middle and two semicircles at both ends with uniformly distributed light intensity. The light intensity of the continuous polarization light field is intended to achieve complete polarization of the alkali metal in the region where the continuous polarization light field acts. The z-axis polarizability of the electron spin and nuclear spin polarization directions in the continuous polarization region is:

[0056]

[0057] in, R is the electron spin z-axis axial polarizability in the continuous polarization region. pc It is the polarizability of the continuous polarization region. It is the longitudinal (z-axis) relaxation rate of electron spin in the continuously polarized region. It is the z-axis polarizability of the nuclear spin in the continuous polarization region. It is the spin exchange rate between electron spin and nuclear spin. It is the longitudinal (axis) relaxation rate of nuclear spin in the continuously polarized region.

[0058] The formula shows that the nuclear spin polarizability in the continuously polarized region is positively correlated with the pump rate. Based on the fact that the nuclear spin self-compensation capability, i.e., the magnetic noise suppression capability, is proportional to the nuclear spin polarizability, the nuclear spin in the continuously polarized region is polarized to its maximum value.

[0059] The pulsed polarized light field in part (1) and the continuous polarized light field in part (2) do not coincide in the xoy plane. The spin diffusion equation is:

[0060]

[0061] Where P is the polarizability and D is the diffusion coefficient. This formula combines the electron spin and nuclear spin polarizability in the pulsed polarization region and the continuous polarization region. Based on the typical parameters of atomic spin inertial measurement systems, the nuclear spin diffusion rate is much greater than its longitudinal relaxation rate, while the electron spin diffusion rate is less than its longitudinal relaxation rate. This means that the design of a multi-polarized optical field can achieve a relatively uniform and high nuclear spin polarizability within the gas chamber without affecting the electron spin response in the detection light interaction region.

[0062] The detection light in part (3) is a circular spot with a diameter of 1 mm, and its effective range is the range that overlaps with the pulsed polarized light field.

[0063] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, and / or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A method for suppressing magneto-optical noise in inertial measurement based on multi-polarization, characterized in that, Includes the following steps: Step 1: Start the multi-polarized inertial measurement system and input a pulsed polarized light field along the z-axis to the atomic gas cell. The pulsed polarized light field is distributed in a middle band with a width limited to the y-axis on the xoy plane. Step 2: Input a continuous polarized light field into the atomic gas cell in the reverse z-axis direction. The continuous polarized light field is divided into two parts: the front part is located on the positive y-axis side of the pulsed polarized light field, and the rear part is located on the negative y-axis side of the pulsed polarized light field. The continuous polarized light field is complementary to the pulsed polarized light field in the xoy plane but does not overlap with it. Step 3: Input detection light into the atomic gas cell along the x-axis to achieve inertial measurement under multi-polarization conditions; The diameter of the detection light spot is equal to the width of the pulsed polarized light field; The switching period of the pulsed polarized light is set based on the electron spin resonance frequency in order to obtain a complete electron spin decay oscillation signal during the detection phase when the pulsed polarized light is turned off. The light intensity of a continuously polarized light field is intended to achieve complete polarization of the alkali metal in the region affected by the continuously polarized light field.

2. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The central band distribution of the pulsed polarized light field is formed by blocking the two small semicircles at both ends of the circular light spot with an aperture; the pulsed light of the pulsed polarized light field is formed by an optical switch.

3. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The continuous polarized light field is divided into two parts by a spatial light modulator, which shapes the circular light spot into a strip-shaped middle section with no light, while only the front and rear small semi-circular light spots are retained.

4. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The pulsed polarized light field is sourced from a first laser. The first laser is sequentially fed into an optical switch via a first lens group, a first polarizing beam splitter, a first λ / 4 waveplate, an aperture, and a first reflector. The pulsed polarized light field formed by the optical switch is then delivered to the atomic gas cell.

5. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The light source of the continuous polarized light field comes from the second laser. The second laser is input to the spatial light modulator in sequence through the second lens group, the second polarizing beam splitter, the second λ / 4 waveplate and the second mirror. The spatial light modulator outputs the shaped continuous polarized light field and delivers it to the atomic gas cell.

6. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The detection light source comes from a third laser, which is connected to the data acquisition and processing system via a polarizer, an atomic gas cell, an analyzer, and a photodetector.

7. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The inertial measurement includes the following formula: Among them, P e γ is the electron spin polarizability measured by atomic spin inertial measurement during the pulsed polarization light field off phase, t is the time of decay of the oscillation signal, and γ is the electron spin polarizability measured by pulsed polarization light field off phase. e It is the electron spin gyromagnetic ratio, Q is the slowing factor, and B is the magnetic field acting on the coupled atomic ensemble. n It is the equivalent magnetic field of the inert gas nuclear spin, and Ω is the rotational input. It is the spin exchange rate of nuclear spin to electron spin, P n It is the nuclear spin polarization. It is the transverse relaxation rate of electron spin during the stable phase of damped oscillation. It is the longitudinal relaxation rate of electron spin during the stable phase of the decaying oscillation.

8. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The inertial measurement includes the following formula: in, R is the z-axis polarizability of the electron spin in the continuous polarization region. pc It is the pumping rate of the continuous polarization region. It is the longitudinal relaxation rate of electron spin in the continuously polarized region. It is the z-axis polarizability of nuclear spin in the continuous polarization region. It is the spin exchange rate between electron spin and nuclear spin. It is the longitudinal relaxation rate of nuclear spin in the continuously polarized region.

9. The inertial measurement magneto-optical noise suppression method based on multi-polarization according to claim 1, characterized in that, The inertial measurement includes the following formula: Where P is the polarizability and D is the diffusion coefficient, this formula combines the electron spin and nuclear spin polarizability in the pulsed polarization region and the continuous polarization region.

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