FIBER-OPTIC GYROSCOPE

摘要

A fibre-optic gyroscope is provided herein for measuring an angular velocity of a fibre coil by propagating light beams clockwise and counterclockwise in a specified fibre coil, by detecting an intensity of an interference beam, and calculating a phase difference between a clockwise propagated beam and a counterclockwise propagated beam. The fibre-optic gyroscope includes a light source for emitting a quasi-monochromatic light beam. A photodetector is provided for detecting an intensity of the interference beam. A defined plurality of fibre paths are interconnected in a specific defined manner, with a polarizer, a first depolarizer and a second depolarizer as well as a first coupler and a second coupler being provided in specified fibre paths. The depolarizers are constructed by coupling a polarization-maintaining fibre to the front end and/or the rear end of the polarizer at a 45.degree. inclination angle between principal axes of the polarizer and the polarization-maintaining fibre. The polarization-maintaining fibre has a difference of optical paths between the quasi-monochromatic beam and the interference beam with different principal axes being longer than a coherent length of the light source.