CLOSED LOOP SYSTEM OPTICAL FIBER GYRO

PROBLEM TO BE SOLVED: To provide a closed loop system optical fiber gyro in which the scale factor linearity is stabilized. SOLUTION: A closed loop system optical fiber gyro comprising a light source 2, an optical fiber coil 5, a coupler 3 which branches and binds light from the light source 2 in the clockwise and counterclockwise directions around the optical fiber coil 5, a phase modular 4 which is arranged between the optical fiber coil 5 and the coupler 3 and modulates the phase of light passing therethrough, a light receiver 6 which converts the interference light intensity from the coupler 3 into an electric signal, an amplifier which amplifies the signal from the light receiver, and an A/D converter 8 which A/D converts the signal amplified by the amplifier 15, the optical fiber gyro executing signal processing of the output from the A/D converter in a digital manner, wherein the electric signal outputted from the light receiver 6 is branched into two, a feedback signal and a signal for automatic control of maximum phase shift, and signals amplified at mutually different amplification degrees are used. COPYRIGHT: (C)2005,JPO&NCIPI