Fiber optic gyroscope including a 3x3 coupler and a contrast adjusting element

摘要

A fiber optic gyroscope of the type having a 3x3 coupler located between a light source and a monomode fiber coil, coupling nonpolarized light into the coil end, and at least one photodetector element associated with the coupler to generate an output signal corresponding to the light intensity transmitted by the coupler. At least one contrast-adjusting element in the form of a rotationally polarizing fiber section is located between the connection on the coil side, of the 3x3 coupler in the length of the coil-forming monomode fiber strand. The polarization rotation angle of said fiber section is adjusted so that the output signal of the photodetector element is minimal when the gyroscope is at rest.