Suppression of the Bias Error Induced by Magnetic Noise in a Spin-Exchange Relaxation-Free Gyroscope

Spin-exchange relaxation-free gyroscope (SERFG) is a promising rotation sensor, and the bias error is one of its most important characteristics. It is identified that rotation measurement noise induced by thermal magnetization fluctuations inherent in the ferrite shield in a SERFG limits its bias stability. The root cause of this error lies in the low-frequency magnetic field sensitivity dominated by the nuclear spin relaxation rate. In this paper, the steady state response model of the SERFG is modified considering the non-negligible nuclear relaxation rate and the pressure-dependent magnetic field sensitivity is experimentally studied. Our results show that reducing nuclear spin relaxation is an effective method to suppress the bias error induced by thermal magnetization fluctuations. Finally, in case of Pneon = 1 atm, it is estimated that a bias stability limit of 5 × 10 -4 deg/h is set by the lowest thermal magnetization noise of 4.4 f -1/2 fT ever reported in a ferrite shield.