Kabushiki Kaisha Toshiba

Toshiya Kinoshita

Tadashi Koizumi

In a fiber optical rotation sensor, a laser wave omitted from a laser diode is guided into a one directional optical coupler and is splitted into two laser waves by the coupler. The two laser waves are propagated in an optical fiber loop in an opposite directions and the phases of the laser waves are modulated in the fiber loop by a phase modulation signal having a frequency f.sub.0. The phase-modulated light waves are combined and converted into an interference laser wave and the interference laser wave is splitted in the coupler. One of the splitted interference laser waves is guided to a photodetector and is converted into an electric signal by the photodetector. A synchronous detector detects the electric signal with a frequency of an integral multiple of the frequency f.sub.0 to extract the corresponding integral multiple signal components Sn-1, Sn, Sn+1. The signal components Sn-1, Sn, Sn+1 (n.gtoreq.1) are supplied to operation circuit. In the operation circuit, the signal components Sn-1, Sn, Sn+1 are processed to obtain Sagnac phase difference .DELTA..phi. from the following equation. ##EQU1## .

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Kawasaki, Japan

Toshiya Kinoshita