Abstract: A noise reducer for reducing the results in the system output signal of optical noise introduced into an optical subsystem therein, having a phase modulator, by a source through obtaining a noise representation signal used to offset the noise components in the signal obtained from the output of the optical subsystem. This noise representation signal is not delayed in the obtaining thereof by any more than half the delays of the waves emitted from the source in reaching the optical subsystem output. The noise reducer may incorporate a device for adjusting the amplitude of the noise representation signal. It may also include another device for adjusting the phase of the noise representation signal, which may be used to affect the amplitude of the noise representation signal. These adjustments can result in an optimization of the noise representation signal so as to better effectively cancel the optical noise signal at the output of the fiber optic gyro having the noise reducer.

Abstract: A rotation sensor for sensing rotation, particularly about an axis of a coiled optical fiber, wherein the coiled optical fiber has with light waves propagating in opposite directions in the coiled optical fiber, the phase relationship of the counter-propagating light waves providing a basis for indicating rotation of the sensor. A portion of the coiled optical fiber is a part of and affected by a bias optical phase modulator which causes a varying phase relationship between the light waves at a fundamental frequency. However, the varying phase relation ship has at least one harmonic which is due to mechanical vibration of the optical fiber that is a part of the modulator. This harmonic contributes to an erroneous indication of rotation. The amplitude of such harmonic is reduced by lowering the Q of the resonating fiber. This is effected by applying a damping material to the optical fiber and a portion of the modulator.

Abstract: An amplitude reset controller for a resonator fiber optic gyroscope using a feedback loop and modulation to control amplitudes of a serrodyne waveform provided by a serrodyne signal generator at an operation frequency depending on resonance conditions in the resonator. The controller with a single serrodyne signal generator switches between such control at greater rotation rates and the removal of such control at smaller rotation rates, using instead a reference command. Also, a blanking operation mode can be additionally used to eliminate signals controlling the controlled frequency adjustment signal generator operation frequency during phase resets in its output serrodyne signal.

Abstract: An error reducer for reducing rotation rate errors, arising because of polarization modes coupling and differing polarization modes characteristics associated with a coiled optical fiber in a rotation sensor, by causing an electromagnetic wave source to direct electromagnetic waves propagating in one of said opposing directions to oscillate in frequency value between frequencies occurring in adjacent opposite polarization mode resonances of those waves.

Abstract: An electrically passive fiber optic position sensor having a course measurement indicator and a fine measurement indicator combined to determine the overall position, whether linear or angular, of an object measured. The coarse measurement sensor depends on bending loss of optic fiber in one embodiment and on the Faraday effect in another embodiment. The fine measurement indicator depends on the Faraday effect in both embodiments. The invention avoids the problems of contaminated optics as the light need not leave the optic fiber.