Abstract: An acoustic sensor having one or more segments are electrically coupled to provide a response corresponding to an acoustic pressure applied to the segments. Each segment contains at least one substrate of a desired shape and at least two active members made from a flexible, resilient piezoelectric material, preferably, a polyvinylidene fluoride material. Each substrate includes an enclosed chamber on an outer surface wherein a first active element is within the chamber and a second active element is sealingly placed on the enclosed chamber. The second active element is preferably bonded to a compliant diaphragm sealed to the substrate to provide the sealed chamber. An output response from the first active member is combined with an output response from the second active member to provide for a combined output response having reduced noise. The second active element is covered with a protective layer of a suitable material, preferably a polymer material.

Abstract: A non-fluid-filled streamer cable or towed array for performing seismic surveys in water-covered areas includes a plurality of serially coupled active cable sections. Each active cable section includes an electromechanical cable that contains a single central strain member. A wire bundle is placed around the central strain member for transporting electrical power and data through the active section and an inner protective jacket is formed around the central strain member and wire bundle. A foam material is extruded around the inner protective jacket to provide a predetermined buoyancy to the fully assembled active cable section and an outer protective jacket is formed around the foam jacket. A potting compound is formed between, and bonds to, the inner protective jacket and outer protective jacket to provide a water block at each hydrophone location.

Abstract: The present invention provides an acoustic sensor having one or more segments that are electrically coupled to provide a response corresponding to a hydrodynamic pressure applied to the segments. Each segment contains a substrate of a desired shape with a concavity on an outer surface that is sealingly enclosed by an active member made from a flexible, resilient piezoelectric material. PVDF material is preferably used as the piezoelectric active element. The active element may be bonded to a compliant diaphragm sealed to the substrate to provide the sealed chamber. The active member is covered with a protective layer of a suitable material, preferably a polyvinyl material. In one embodiment, the diaphragm includes a standoff ledge and is placed on the outer surface of the substrate to define the sealed chamber between the diaphragm and the outer surface of the substrate.

Abstract: The present invention provides an acoustic sensor having one or more segments that are electrically coupled to provide a response corresponding to a hydrodynamic pressure applied to the segments. Each segment contains a substrate of a desired shape with a concavity on an outer surface that is sealingly enclosed by an active member made from a flexible, resilient piezoelectric material. PVDF material is preferably used as the piezoelectric active element. The active member is covered with a protective layer of a suitable material, preferably a polyvinyl material. A single segment may be used as a sensor or a plurality of suitably configured segments may be suitably coupled to form the sensor. The sensor may be used as a hydrophone on a hydrophone cable commonly used for performing seismic surveys for geophysical exploration. In such applications, a plurality of hydrophones are placed equally spaced along the cable. In the preferred embodiment, two hydrophone segments are securely be placed around the cable.

Abstract: A pressure compensated hydrophone assembly consists of a hollow mandrel that has an outer surface. The central portion of the outer surface of the mandrel defines a concavity. A flexible, resilient piezoelectric film is wrapped several times around the mandrel. The volume between the inner wrap of the film and the concavity on the outer surface of the mandrel serves as a pressure compensation chamber. The hydrophone is responsive to varying hydrodynamic pressure fields but is substantially inert to acceleration forces, localized impacts and variations in hydrostatic pressure.

Abstract: A piezoelectric film strip is wrapped a plurality of times around a flexible inert mandrel that has standoff collars on each end. The film-wrapped mandrel is hermetically sealed inside a hollow rigid inert cylinder. Electrodes provide electrical communication with the film strip which forms the active element of the transducer. Variations in hydrodynamic pressure flex the film strip in tension to generate a voltage.