No Moving Parts: A Fiber Optic Gyroscope

Richard Shorthill

Abstract:	In the early 70’s fiber optics were being developed. However, polarization properties were not ideal, absorption of light was too high, and there were thermal problems, noise problems, etc. These problems made working with the early fibers difficult. The optical fiber, however, gave a promise of improved communications, unique sensor and instrument configurations. Using a special fiber geometry single mode behavior could be obtained. Dr. Vic Vali and I acquired ten meters of single mode fiber from the Corning Company. A simple single axis fiber-optic-gyroscope (FOG) interferometer (Sagnac Interferometer) was constructed. With this device it appeared possible that rotation rate could be detected. Such a device is an essential component of an inertial navigation system. Laser light is injected into a multiple loop of the fiber in both directions (the light beams counter rotate) There are no moving parts in such a device as there is in a conventional rotating mass gyroscope. While a ring-laser-gyro (RLG) serves the same function, the FOG was potentially less expensive, more accurate and easier to build. In 1976, we constructed a FOG sensitive enough that left no doubt that the FOG could be used to measure rotation rate. All that was required to commercialize this instrument was an improvement in the properties of the optical fiber. Now, twenty-five years later, the FOG has been in commercial use for more than ten years.
Published in:	Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001) June 11 - 13, 2001 Albuquerque, NM
Pages:	188 - 199
Cite this article:	Shorthill, Richard, "No Moving Parts: A Fiber Optic Gyroscope," Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001), Albuquerque, NM, June 2001, pp. 188-199.
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