International Standard Electric Corporation

Walter Steudle

Friedemann Mohr

Wilfried Auch

Eberhard Schlemper

In the measuring instrument, a light beam generated by a laser (1) is split into two component beams (L(CW), L(CCW)) which travel along a coiled optical waveguide (7) in opposite directions. After traversing the optical waveguide, the two component beams are superimposed on each other (5) and directed to an optical/electrical transducer (8). One of the two component beams (L(CW)) is frequency-modulated in a Bragg cell (6) before entering the optical waveguide (7), switchover being effected between two modulation frequencies (f1, f2) at a given frequency (F.sub.S). The modulation frequencies are chosen so that, after traversal of the optical waveguide (7), the phase differences (.phi..sub.B1, .phi..sub.B2) between the two component beams (if the rotation rate .OMEGA.=0) are .pi./2 and 3.pi./2 or even integral multiples thereof. In case of rotation, the phase difference (.phi..sub.S) caused by the Sagnac effect is superimposed on these phase differences. The output signal of the optical/electrcal transducer (8) is passed through a band-pass filter (10) whose midfrequency is equal to the frequency at which switching takes place between the two modulating signals. The amplitude of the band-pass output signal is directly proportional to the rotation rate (.OMEGA.). From this signal, a control signal can be derived which can be used to compensate for the phase difference (.phi..sub.S) caused by the Sagnac effect.

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Schlaitdorf, Germany

Walter Steudle