Specialty Optical Fibers Handbook

8.2.2 The Fiber Optic Gyroscope

The interferometric fiber optic sensor that has achieved the most commercial

success is the fiber optic gyroscope (FOG) [1]. In essence, a FOG is a rotation

and rotation-rate sensor that comprises up to three coils of PM fiber, one for

each degree of freedom required (in aircraft terms: roll, pitch, and yaw). Light is

launched into both ends of each coil simultaneously and recombined at a

detector. If the coil experiences a rotation, the light will undergo a Doppler-

shift (the Sagnac effect [2]) with the result that the counter-propagating beams

will recombine out of phase, creating interference that may be analyzed ...