METHOD AND APPARATUS FOR COMPENSATING FOR THE RESIDUAL BIREFRINGENCE IN INTERFEROMETRIC FIBER-OPTIC GYROS

摘要

An interferometric fiber-optic gyro system (100) includes a light source (101) and a plurality of optical fiber rings (120, 121, 122) employed to measure angular displacement along three axes (x, y, z). Optical circuit elements interposed between the source and the rings include an optical switch (104) for periodically applying the optical signal to each of the rings individually along three separate optical transmission paths (134, 136, 137). Included, in each of the optical transmission paths is a modal filter (113, 114, 115), including a polarizer, and a beam splitter (116, 117, 118) which provides two separate beams to the optical ring for counter-propagation through the ring. Compensating birefringent devices (110, 111, 112) are added in the optical circuits to compensate for a residual birefringence introduced by the various optical elements in the circuits.