Interferometric fibre-optic gyroscope and method for its operation.

摘要

The invention relates to an interferometric fibre-optic gyroscope and one method for its operation. This gyroscope comprises a loop of optical fibre 10 in which two light waves are sent in opposite direction by means of a beam splitter 13 and a laser 14. The splitter 13 sends the two output beams onto a photodetector 15. The output signal serves to control a first phase modulation by the phase-cancelling (-offsetting) device 19 controlling the phase shifter 18, at a frequency 1/2 tau where tau is the optical transit time in the loop. A second phase modulation in synchronism at a frequency 1/4 tau is produced by the modulator 17 controlling the phase shifter 16, the light source being switched at the frequency 1/2 tau . The invention is applicable to fibre-optic gyroscopes using the Sagnac effect. <IMAGE>