Abstract: An array through a first to a second side of a three-sided junction, accessed remotely by a single mode fiber transmits a light pulse sequence to the array and receives sound modulated return light signals via the second to a third side of the junction. Within each hydrophone, butt coupled fiber joints form a continuous structure, encapsulated within a compressible plastic tube for mechanical stability. Tube volume expands and contracts linearly with variations in acoustic pressure thereby proportionally modulating the optical path therethrough. Each joint is a partial reflector reflects part of the incident light beam back via the second to third side of the junction to a posthydrophone compensating interferometer which compensates for path difference between equally spaced array joints; From the third side of the junction the reflections from the butt coupled fiber joints pass through a light detector and signal processor.

Abstract: A device for providing a controlled back-reflection of a preselected port of incident fiber-guided light while minimizing the affect to light continuing down the fiber. The back-reflected light couples to the reverse traveling fiber mode with minimal loss. These devices are used as reflectors in a pulse sampled fiber optic hydrophone array.

Abstract: An apparatus for reducing the detected optical intensity noise received f an optical interferometric sensor. One embodiment of the device comprises high pass and low pass filtering means and an arithmetic divider device, arranged so as to receive a single signal S.sub.1 and to cancel unwanted intensity noise in signal S.sub.1 prior to the transmittal of the noise free signal S.sub.out to a receiver circuit. A second embodiment of the device further includes an adder and a subtractor to receive two signals S.sub.1 and S.sub.2. The adder and subtractor are cross connected in such a way as to combine the two signals for further processing and also to still permit intensity noise cancellation in the event one of the signals is not available.

Abstract: A linear, analog, synchro control differential transmitter for implementing he common synchro CDX function whereby a scaled linear analog voltage is used as input instead of a mechanical shaft angular displacement. Alternate synchro functions of CT and CX that the invention implements are also disclosed.