Gould Inc.

Design & Manufacturing Corporation

Helmut H Krueger

Donald J Koneval

Robert E Lajos

Walter H Eisele

Thomas C Tisone

Ronald S Sobecks

Richard N Tauber

A fiber optic interferometric hydrophone is based on the change in optic path length of optic fibers bonded to both sides of a bending beam which acts as an acoustically sensitive diaphragm. The bending beam is segmented into an even number of segments, acoustic windows are arranged such that opposite sides of the beam see the acoustic field in adjacent segments, and the optic fibers cross from one side of the beam to the other to maintain the phase of strain signal for the two fibers, one on each side, along the full length of the bending beam. The fringe sensitivity of the interferometer is multiplied by two since both interferometer legs are strained by the acoustic field, and of opposite sign, and further multiplied by the number of segments compared to a single simple beam bender of the dimensions of one segment. This configuraion has the further advantages of cancelling out lateral acceleration noise, and of providing a larger transducer for integrating low level sounds, both of which improve the signal-to-noise level. The small lateral dimensions of such a hydrophone are advantageous in towed arrays. Ancillary equipment such as light source, and detectors, and mechanical packaging for various purposes, are well known in the art.

Fiber optic interferometric hydrophone

A thin film strain gage structure (10, 110) for measuring the strain of an inflectible element (12, 112) wherein the gage is formed on a surface (15, 115) of the element and includes a sensing resistance (16, 116) and an adjusting resistance portion (21, 121). Connecting taps are formed in relationship to the resistors to permit adjustment of the adjusting resistor values by suitable connection to selected ones of the taps. The adjusting resistance is preferably disposed adjacent the sensing resistance so as to be subject to similar ambient conditions. The sensing resistance may be provided in the form of a Wheatstone bridge circuit with the adjusting resistors connected in series with two legs of the bridge. Adjustment of the adjusting resistance may be effected selectively by shorting out portions thereof or by suitably connecting to different portions thereof. In one form, the adjustment is effected so as to provide variable ratio between two portions of the resistance connected between legs of the bridge circuit.

Geometric balance adjustment of thin film strain gage sensors

A thin film strain gage structure (10,110) for measuring the strain of an inflectible element (12,112) wherein the gage is formed on a surface (15,115) of the element and includes a sensing resistance (16,116) and an adjusting resistance portion (21,121). Connecting taps are formed in relationship to the resistors to permit adjustment of the adjusting resistor values by suitable connection to selected ones of the taps. The adjusting resistance is preferably disposed adjacent the sensing resistance so as to be subject to similar ambient conditions. The sensing resistance may be provided in the form of a Wheatstone bridge circuit with the adjusting resistors connected in series with two legs of the bridge. Adjustment of the adjusting resistance may be effected selectively by shorting out portions thereof or by suitably connecting to different portions thereof. In one form, the adjustment is effected so as to provide variable ratio between two portions of the resistance connected between legs of the bridge circuit.

A positive temperature coefficient heater for enhancing the response time of thermal actuators is disclosed. The PTC heater is formed of a generally low resistance material that has an anomaly temperature above which the resistance of the heater increases dramatically. The anomaly temperature is chosen to substantially match the phase change temperature of a thermally expansive medium useful to power the actuator. The heater is self-regulating and provides a maximum surface area for heating the medium rapidly with a minimum of thermal mass and energy use. Preferably, the heater is formed of doped BaTiO.sub.3 in the general shape of an elongated annular cylinder.

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Elgin, IL, United States of America

Helmut H Krueger