The effect of slow fluctuation processes in the ring laser gyroscope on its bias instability

We have identified the origin of the bias instability of the laser gyroscope, which included the ring helium neon laser with mechanical dither. The data observed consist of the gyro counts of vertical projection of the Earth's angular rate and the bilateral gas discharge maintaining voltages in the ring laser. The measurements were carried out under conditions of prolonged operation after the gyroscope was started, stabilization of the discharge currents and the ambient temperature. Detected spontaneous changes in the maintaining voltages are the results of fluctuations in the contamination concentration in the active medium of the laser. The revealed process leads to the non-reciprocity of counter propagating waves, which the ring laser generates. The swing of the trend line for registered angular rate correlates with the oscillations of the bilateral gas discharge maintaining voltages. The Allan variance analysis confirms the observed value of the laser gyro bias instability that makes it possible to identify the process of the appearance of unsteady gas flows in the ring laser with changes in the concentration of contaminations in the laser active medium.