SCATTERING SYMMETERIZATION IN A MULTIPLE-MODE RING LASER GYRO.

摘要

Disclosed herein is a method and apparatus for achieving scatter symmetrization in a multi-mode non-planar ring laser gyro. The retro scatter effect which results in scatter coupling in each of the left and right circular polarized sets of beams is equalized, so that the scatter coupling may be common-mode rejected during the analysis phase of the ring laser gyro operation. This equalization is achieved by unique orientation of the mirrors and the non-reciprocal polarization rotator. The non-reciprocal rotator which may be a Faraday rotator, is rotated in such a manner that its angle of rotation relative to an angle fixed at the plane of incidence of one of the mirrors of the leg is proportional to the positioning of the rotator along the axis between the mirrors of this leg. In this manner equal scatter coupling will occur in the left and right circularly polarized light and this scatter coupling may be common-mode rejected for purposes of deriving accurate rotational information. Scatter symmetrization is also achieved by configuring the mirrors in legs of equal length so the amount of image rotation attributed to each leg is proportional to the leg length.