A fiber optic gyroscope is a fascinating device used to measure rotation rate (angular velocity), which is a necessary parameter to be measured in through autonomous navigation systems (inertial navigation). They are based on an interferometer conceived in 1913 by the French physicist Georges Sagnac. In a Sagnac interferometer, a beam of light is split and the two beams are made to follow the same path but in opposite directions. On return to the point of entry the two light beams are allowed to exit the fiber loop (see Figure and undergo interference. If the loop rotates clockwise, the clockwise optical path becomes longer than the counterclockwise optical path (see Figure 2). The phase difference (interference) is proportional to the rotation rate (angular velocity). Derive this relationship for a fiber optic gyroscope that uses a 1 km long fiber arranged in a 25 cm spool and a laser beam with wavelength of 1.5 jum. Left-handed light Optical fiber coil Spectroscope Light source[ Receiver Polarizer Light interface Right-handed light to Rotation speed Figure 2. Schematic representation of fiber optic gyroscope (Sagnac interferometer).

A fiber optic gyroscope is a fascinating device used to measure rotation rate (angular velocity), which is a necessary parameter to be measured in through autonomous navigation systems (inertial navigation). They are based on an interferometer conceived in 1913 by the French physicist Georges Sagnac. In a Sagnac interferometer, a beam of light is split and the two beams are made to follow the same path but in opposite directions. On return to the point of entry the two light beams are allowed to exit the fiber loop (see Figure and undergo interference. If the loop rotates clockwise, the clockwise optical path becomes longer than the counterclockwise optical path (see Figure 2). The phase difference (interference) is proportional to the rotation rate (angular velocity). Derive this relationship for a fiber optic gyroscope that uses a 1 km long fiber arranged in a 25 cm spool and a laser beam with wavelength of 1.5 jum. Left-handed light Optical fiber coil Spectroscope Light source[ Receiver Polarizer Light interface Right-handed light to Rotation speed Figure 2. Schematic representation of fiber optic gyroscope (Sagnac interferometer).