Rotation and revolution rate measurement - using sagnac effect and circularly polarised light faraday phase shift control

摘要

The method and arrangement are for measuring rotations and revolution rates using the Sagnac Effect in a closed light path mainly consisting of an optical fibre and subject to rotation are designed to eliminate as far as possible the influences and non-linearities of the evaluation electronics and instabilities in the measurement system which can degrate measurement accuracy. Coherent partial light currents coupled into the fibre ends are recombined after passing through it. The rotation speed is derived from the combined light current intensity which depends on the phase shift of the interfering currents. Both partial light beams are subjected to a phase modulation. The detector output signal is rectified with phase reference to the modulation frequency. The oppositely circulating beams are circularly left or right polarised. The detector rectifies output controls a magnetic coil round the fibre so that the rotation phase difference and the Faraday phase difference sum to a whole number multiple of 2TT.