Interferometric closed-loop fiber-optic gyroscopes

摘要

The operation of Fiber Optic Gyro is based on the Sagnac Effect which states that light beams propagating along opposite directions in a rotating frame experience an optical path length difference. These two counter-propagating waves propagate within a closed fiber coil, and when this coil rotates the resultant phase difference is proportional to the rotation rate Q. Fiber optic gyroscopes are desirable devices for many navigation and guidance applications because, being solid state devices, they have several major advantages including light weight, long working lifetimes, no moving parts and operate using low voltage power. In this paper the Optolink's single-axis and three-axis fiber optic gyroscopes are described. The Optolink's FOGs consist of the light-emitting diode, one or three photodetectors, circulators and polarization maintaining fiber couplers to divide the light into two or three parts, one or three sets of ring interferometers to sense one or three orthogonal angular rates, and installed PCB signal processing circuits. The ring interferometer consists of a multifunction integrated optic chip and polarization maintaining fiber coil, both these components are designed and fabricated by Optolink. The results illustrate the versatility of the technology, showing its potential to meet both the low-cost, compact sized needs of tactical guidance, as well as the very high performance needs of inertial navigation and precision applications. The optic and electronic blocks of closed-loop gyroscopes with integrated optic components are also considered in this paper.