Abstract: The gyroscope is based on the Sagnac effect and comprises a coiled dielectric waveguide, a source of electromagnetic waves provided with a splitter for sending two contrarotating waves from the source round the ring and an interference detector receiving the contrarotating waves. An electro-optical modulator is controlled to impart periodic alternating and symmetrical phase modulation to the waves at a period that is substantially twice the travel time in the waveguide. The modulator is placed upstream from the waveguide for one wave and downstream for the other. A second modulator receives the output of a phase shift sawtooth generator of adjustable slope and is placed upstream from the waveguide for one wave and downstream for the other. An electronic measurement circuit controls the direction and the value of the slope of the sawtooth to cancel the phase difference of the waves received by the interference detector.

Abstract: A device for reading out the position of a movable member comprising a sc carried by that member and having equidistant coded references. Each reference is different from the others. A stationary optical system forms the image of a portion of the scale on a fixed detector. The detector comprises a linear matrix of photo detectors regularly distributed at predetermined intervals and associated with electronic means which identifies the coded reference whose image is formed on the matrix and reads out the serial number of the photo element on which the leading edge of the coded reference is formed.