Abstract: An underwater acoustical projector consisting of a spaced apart pair of polygonal shaped end plates, a ceramic driver of smaller cross-sectional size than each end plate, positioned between the end plates, and a set of staves secured from one end plate to the other, each stave being bent concavely inwardly towards the driver and being separated from each other by a gap.

Abstract: A ring-shell projector capable of simple disassembly and reassembly. The underwater transducer has a driving ring and a pair of flexible diaphragms on either side of the ring with their rims attached to the ring. The ring is formed of an array of electrostrictive elements and spacer elements, each spacer element having a pair of radial, outward extensions. A pair of coupling rings are provided each adapted to be positioned between the rim of one flexible diaphragm and a corresponding array of spacer element extensions to provide sealing engagement between the flexible diaphragms and the driving ring. Besides simplifying the repair of a projector, the improved design is more versatile, allowing a single driving ring to be used with different sets of shells, having different resonance frequencies and/or bandwidths. Moreover, an expensive step in the construction of a ring-shell projector is obviated, namely, the bolt holes in the metal staves and the subsequent custom matching of the shell holes.

Abstract: A piezoelectrically-driven, resonant-pipe projector has formed therein vents to broaden the response of certain cavities resonances and to increase the response between these resonances. The projector exhibits a relatively high electroacoustical efficiency, is capable of medium to high power output over the operating band, and is not depth dependent or depth limited.

Abstract: A sensor for resolving the left-right ambiguity encountered in horizontal line hydrophone arrays consists of an orthogonal pair of dipole hydrophones, a monopole hydrophone, and a tilt sensor, the tilt sensor connecting the dipole hydrophones so as to provide a single dipole hydrophone which is always oriented horizontally. The tilt sensor consists of two variable capacitors made from hollow cylinders of high permittivity dielectric material, partially filled with a quantity of liquid mercury which forms the variable inner electrodes of the capacitors. The outer electrodes of the capacitors, on the outside of the cylinders, having a sinusoidally-shaped perimeter and being oriented at right angles to each other, are connected to the crossed dipoles in order to provide the required horizontal dipole hydrophone.

Abstract: A method of modulating the output of a solid state diode laser by directly straining the laser chip. The chip is mechanically coupled to a transducer such as a piezoelectric crystal in such a manner that a dimensional variation in the transducer is translated into a corresponding variation in the chip. It is contemplated that the modulated output will have application in communication systems and in particular a hydrophone system.

Abstract: An electromagnetic apparatus comprises a magnetic assembly having an annular air gap, a wire coil, and an arrangement for energizing the coil only in the air gap, the magnetic assembly being disposed coaxially of the coil so that the coil is movable in the air gap relative to the magnetic assembly. The preferred coil is formed of a plurality of narrow segments axially adjacent and electrically connected in series, successive segments abutting one another, each segment being spirally wound from radially overlapping and abutting turns of wire, the abutting segments being alternately wound inwardly and outwardly such that adjacent sections spiral radially in opposite directions and being electrically connected so that current will flow in the same circumferential direction throughout the coil.

Abstract: An underwater transducer in which a ring of piezoelectric ceramic elements vibrates radially in response to an applied voltage. Spacer elements formed of steel are placed between pairs of ceramic elements and used to couple the ring movement to convex diaphragms. Each diaphragm is formed with radially extending fingers, which attach to the spacer elements. A water bladder assembly within the transducer forms a passive internal pressure compensation system. Preferably, the water bladder assembly is attached to the ring in a manner that mechanically decouples the bladder assembly from the ring.

Abstract: An optical fiber hydrophone system in which a single optical fiber is used for all of the acoustical sensors in the system. A signal source and detector provides an optical signal in selected form, such as continuous or pulsed and detects and extracts an identifiable output signal. Each sensor is in the form of a sensing portion of the single optical fiber. Each sensing portion includes two optical reflectors separated one from another by a predetermined length of said optical fiber. Variations in acoustical pressure incident on the sensing portion causes a change in the predetermined length. This causes reflected portions of the optical signal to interfere with one another. Such interference is detectable for extraction of the identifiable output signal. In one form each sensing portion has two terminal branches of a mechanically deformable material, deformable in response to the fluctuations in acoustical pressure.

Abstract: A self-deploying instrument assembly includes a plurality of instruments for example hydrophones, mounted on a flexible sheet. A series of resilient rods extend from one side of the sheet from positions spaced around the periphery thereof to a hub. The resilient rods are deflectable laterally inwardly with consequent folding of the sheet to place the assembly in a storable configuration smaller than its normal operative configuration. A suitable container for storing the instrument assembly is also described.