METHOD FOR AVOIDING ZERO-POINT ERRORS IN AN OPTICAL FIBRE SAGNAC-INTERFEROMETER

摘要

The invention relates to a method and a related device for avoiding zero-point errors in an optical fibre Sagnac-interferometer for measuring rotation speeds. Said device works according to a stochastic modulation method characterised in that any fault occurring in the detector path, which is proportional to the difference between two successive phase modulator values, is decorrelated from the intrinsic detector signal. In order to obtain this decorrelation, the Sagnac interferometer is designed so that the propagation time from the phase modulator (6) to the detector device (8) is greater than the time up to the next modulation change. For this purpose, it is possible either to insert an optical waveguide (7) with an appropriate length, i.e. a waveguide at least as long as the detector fibre (5), upstream from the detector (8), or to increase, by integer multiple multiplication, the detector modulation frequency f0 up to a value i.f0.