Polarization properties in prism laser gyro with mechanical dither bias

Specially for the phenomenon that amplitude of output voltage signal is modulated by dither bias in the laser gyros consisting of totally reflecting prisms, theoretical analysis and experimental research on the polarization properties of output light in gyro are carried out. Taking the effect of stress birefringence of prism into account, analytical formula of output light intensity in gyro and the relationship between polarization parameter and the amplitude modulation of the output signal are obtained and discussed. For the first time, the polarized power value of output light is adopted as a basis to estimate the output signal amplitude fading extent of laser gyros. Experimental results demonstrate that when the value of polarized power of output light is below 25.5% of that in ideal static case, the standard error is over 0.0337 dBm, and the displacement extent of prism is higher than 53% of radius of the beam waist in gyro cavity, the amplitude modulation extent of gyro output signal can reach up to 16%, which badly influences measurement accuracy of laser gyro. Using this polarized power detecting measurement method can make gyro repaired in its fabricating process immediately, improve the testing and producing efficiency and shorten the product development cycle.