Abstract: A generally cylindrical hydrophone configuration provides compensation for longitudinal accelerations by placing four identical solid piezoelectric transducer elements along its axis with each transducer element being bonded to a head member, two of which are located generally centrally of the cylindrical housing and fastened thereto and two of which are located near the outside edges of the housing and having slight clearance therewith. Flexible polyurethane boots are clamped to the ends of the housing. The volumes between the centrally disposed and outer transducer head members and between the outer head members and the boots are filled with methyl silicon fluid. Each head member is electrically connected to one side of the electrical output, and the junction between the transducer members is connected to the opposite side, both sides being wired to an electrical contact plate located between the two centrally disposed transducer head members, this volume being filled with electrical potting material.

Abstract: A impedance matching window for an ultrasound transducer comprises a periodic array of stepped structures. Each stepped structure comprises a plurality of parallel matching strips disposed side-by-side on an active surface of a piezoelectric ceramic.

Abstract: A hydrophone configuration provides compensation for longitudinal accelerations by placing two essentially identical solid ceramic piezoelectric elements back-to-back against a centrally located bulkhead in a strong cylindrical metal housing. The opposite ends of the elements are bonded to end caps which are mechanically sealed to the inside walls of the housing. The inside walls are spaced from the elements to allow any radial expansion or contraction of the elements to take place into an air chamber which is effectively isolated from the input to the hydrophone which is axial against the outside surfaces of the end caps. In a second embodiment two pairs of parallel-connected piezoelectric elements are included for a higher capacitance.