Abstract: A closed loop fiber optic gyro features signal processing wherein square wave phase modulation is added to a modulation drive signal after overflow logic so that the square wave modulation will not cause a phase modulation ramp to exceed overflow/underflow logic limits. The arrangement is such that the phase modulation causes a retrace with each modulation period when the amplitude of the ramp is within predetermined limits. A variable time constant in a retrace correction loop gives better retrace limit correction performance when the gyro is first turned on as during a "warm-up" period. The amplitude of the gyro square wave output is determined by taking the difference between the output of the first half cycle of the square wave modulation and the average of adjacent second half cycles thereof. An error signal for a retrace limit is developed by considering changes in the square wave amplitude and not the square wave amplitude itself.

Abstract: A closed loop fiber optic gyro features signal processing wherein square wave phase modulation is added to a modulation drive signal after overflow logic so that the square wave modulation will not cause a phase modulation ramp to exceed overflow/underflow logic limits. The arrangement is such that the phase modulation causes a retrace with each modulation period when the amplitude of the ramp is within predetermined limits. Corrections to the retrace limit are implemented so as to scale a digital output, which enables the determination of accumulated gyro angle with a finer resolution than simple output pulse accumulation as has heretofore been the case.

Abstract: A closed loop fiber optic gyro features signal processing wherein square wave phase modulation is added to a modulation drive signal after overflow logic so that the square wave modulation will not cause a phase modulation ramp to exceed overflow/underflow logic limits. The arrangement is such that the phase modulation causes a retrace with each modulation period when the amplitude of the ramp is within predetermined limits. The square wave amplitude from a cycle immediately after a retrace is considered as errant data that should be excluded from a phase nulling loop. Thus, the phase nulling loop has more accurate input data so that feedback will be accomplished more effectively for improved gyro performance.

Abstract: A pair of resonant optical cavities are used to measure shifts in length of a beam which deflects under acceleration. One end of each optical cavity is highly reflective and the other end partially reflective, thus permitting resonating light to exit the resonators. The light outputs of the two resonators is combined and the resultent beat frequency is used to detect deflections of the beam.

Abstract: Optical interferometric techniques are used in order to measure deflection in a cantilever beam. Light is directed through plural light paths which are changed in length during deflection of the beam. The light recombines and light interferance is used to measure deflection of the beams.