Societe D'applications Generales D'electricite

Claude Leclerco

Jacques Rochereau

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. The circuit reverses the slope of the phase shift sawtooth whenever the phase shift exceeds +.pi./2 or is beyond -.pi./2, and algebraically sums the changes in the sign of the sawtooth.

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Nesles La Vallee, France

Claude Leclerco