The fiber optic gyroscope is an essential inertial navigation instrument used in modern aviation, navigation, aerospace, and defense industries. It accurately determines the orientation of moving objects based on a sensitive element that uses an optical fiber coil. The light emitted by the laser diode propagates along the optical fiber in two directions, and the difference in the light propagation path determines the angular displacement of the sensitive element.
Fiber optic gyroscopes have many advantages over traditional mechanical gyroscopes, such as being all-solid-state, having no rotating or friction parts, having a long life, a large dynamic range, and a simple structure. They are also small in size and light in weight. Compared to laser gyroscopes, fiber optic gyroscopes are cost-effective and do not have blocking problems since they do not require precise optical path processing in the quartz block.
The realization of the fiber optic gyroscope is based on the Segnick theory, which states that when a light beam travels in a ring-shaped channel, and the channel itself has a rotational speed, the time required for the light to travel along the direction of rotation of the channel is longer than that along the channel's opposite direction. Hence, when the optical loop rotates, the optical path of the loop changes relative to its stationary state, and this change can be detected by measuring the phase difference or the change of the interference fringes of the two optical paths. This measurement allows for the angular velocity of the optical path to be determined, which is the working principle of the fiber optic gyroscope.