Abstract

Abstract

Abstract
A low coherence interferometric system with large tracking range and self-initialization to be used for remote signal processing of fiber optic accelerometers is investigated. The tracking range of the low coherence system is 1.1 mm at low frequency. Phase resolution better than 1 mrad/ square-root Hz at frequencies below 600 Hz is obtained, with a dynamic range of almost-equal-to 90 dB. Data are presented which show that if the system were used to process the output from a compliant cylinder-type accelerometer, resolutions of approximately 10(-7) g/ square-root Hz could be achieved.

Abstract
A scheme to frequency multiplex a group of sensors based on all-fiber Michelson interferometers is presented. Lead insensitivity is obtained by using the two fibre leads of the configuration as an extra Michelson interferometer whose differential phase is kept constant by active compensation. Topics concerning the system design, sensor sensitivity, and crosstalk between sensors are investigated. Experimental and numerical computational results are presented.

Abstract
We describe and demonstrate a new hybrid current sensor system which uses a novel time division multiplexed fiber network for the measurement of three-phase currents at high potential. The sensor arrangement combines a conventional current transformer with a fiber-optic interferometer such that the signal is transmitted optically to ground. Sensitivities of ~0.5 A/vHz are obtained in each phase at the line frequency of 50 Hz. The sensitivity and dynamic range of each sensor can be tailored for a specific level of current or according to an individual application.

Abstract
A detailed comparison between a low-finesse Fabry-Perot cavity and a typical two-beam interferometer is developed and checked experimentally. The consequences of approximating the true Fabry-Perot function by the two-beam function are evaluated for commonly used signal-processing schemes in order to quantify the final error introduced in various fiber sensing schemes employing this configuration.