RESONANT INTERFEROMETER FIBER OPTIC GYROSCOPE

Abstract

A passive resonator gyroscope in which a laser beam is split into two equal intensity beams in a waveguide, each of the beams being coupled to counterpropagate around a fiber optic ring. The beams, after splitting, are frequency modulated with a voltage having a serrodyne waveform, the polarity of the voltage applied to the modulator for the one beam being opposite to the polarity of the modulating voltage applied to the modulator for other beam. The laser frequency is locked to the optical cavity half wave resonant frequency and when the laser is so locked, the modulating voltage is applied for a first period with one polarity and then for a second period of the same duration with the opposite polarity. The output beams from the optical fiber ring are combined in the waveguide and a portion of the combined optical beam is provided to a photodetector. A circuit connected to the photodetector determines the difference between the light impinging upon the photodetector during the first period and during the second period, this difference providing a measure of the Sagnac shift produced by the rotation of the fiber optic ring.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1RAYMOND CARROLL

Sensitive facility: Cambridge MA (Draper Lab/MIT)

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