摘要 |
Ring interferometer rotation sensors wherein the transit time differences produced in a waveguide 1 by the Sagnac effect are compensated 8 by means of the Faraday effect, the strength of the magnetic field required for this purpose thus being a measure of any angular speed. In order that the Faraday effect may be used, means 61, 62, 61', 62' are provided for circularly polarising the light coupled into the ends of the waveguide 1. The sign of the angular speed may be determined by superimposing on the waveguide 1 a periodic non-reciprocal phase shift, e.g. by agitating the sensor or, as shown, by means of Faraday effect 9, and by feeding signals from photodetectors 41, 41' to a phase-sensitive detector 15 coupled to the means 13 providing the periodic phase shift. <IMAGE> |