Patent ID: 8237932

Claim:
A fiber optic gyroscope comprising: a first gyroscope for detecting an angular velocity of a rotating object, the first gyroscope comprising a first light source for emitting two lights from both end surfaces thereof, a first optical fiber loop which comprises a sensor coil structured such that an optical fiber is wound in a multilayer manner, and through which the two lights emitted from the both end surfaces of the first light source travel in respective opposite directions, the first optical fiber loop constituting a laser resonant circuit with the first light source, and a first optical detector for detecting an angular velocity based on a beat frequency which is produced by the two lights traveling through the first optical fiber loop in the opposite directions; and a second gyroscope for subsidiarily detecting the angular velocity of a rotating object, the second gyroscope comprising a second light source for emitting light from one end surface thereof, an optical distributor for dividing the light emitted from the one end surface of the second light source into two lights, a second optical fiber loop which also includes the sensor coil and through which the two lights from the optical distributor travel in respective opposite directions so as to pass respectively via first and second optical couplers and enter both respective ends of the sensor coil, and a second optical detector for detecting an angular velocity based on a phase difference between the two lights traveling through the second optical fiber loop in the respective opposite directions.