Research on influence of pump laser frequency fluctuation on the bias drift of nuclear magnetic resonance gyro

Abstract

Nuclear Magnetic Resonance Gyro (NMRG) utilizes the atomic spin to sense system angular rate. It has the advantages of small volume and high precision. The influence of the pump laser frequency fluctuation on the bias drift of NMRG has been studied in this paper. The output of NMRG in open loop is derived, and the process of 129Xe polarization via Spin-Exchange Optical Pumping (SEOP) is analyzed. The pump laser frequency fluctuation leads to the instability of the alkali atom spin polarization. As the consequence, it makes the nuclear magnetic moment instability, which results to the bias drift of NMRG. By analysis, the pump laser frequency needs to be stabilized at the alkali atoms resonance transition frequency to get high and stable alkali atomic spin polarization and low bias drift of NMRG. The pump laser frequency can be stabilized by wavelength modulation frequency stabilization method. In experiment, the bias drift of NMRG is improved from 889.68°/h (1σ) to 98.74°/h (1σ) after the pump laser frequency is controlled. We conclude that the major factor that leads to the bias drift of NMRG under the existing conditions is the pump laser frequency fluctuation.