Abstract: An acoustic sensor used in underwater applications. The sensor includes a reflective material adhered to a structure, such as an outer submarine hull or any marine vessel hull. A laser interferometer is placed on the side of the structure with the reflective material. The laser interferometer sends a plurality of laser beams, in sequence or all at one time, to a plurality of points across the retro-reflective material. The laser beams reflect back to the interferometer, which captures the reflected beams using receiving optics. The phase modulation of the reflected laser beams is compared to a reference laser beam within the interferometer to obtain the vibration velocity characteristics of the hull surface structure. Since the reflective material is adhered to the structure, the structure vibration is the same as the vibration of the reflective material. From this vibration, the acoustic pressure associated with the structure may be calculated.

Abstract: A composite transducer array comprises a piezoelectric polymer composite panel, a continuous electrode coupled to a first surface of the composite panel, and a plurality of electrically-isolated electrode segments coupled to a second surface of the composite panel. Each electrode segment is shaped as an angular segment of a circular ring. The electrode segments are arranged to define an array of concentric circular rings of electrode segments.

Abstract: A method of measuring the vapor-liquid boundary surrounding a supercavitational high speed underwater vehicle includes the steps of arranging a sensor on a surface of the vehicle. The sensor has a transmit source for emitting an optical signal and a plurality of optical detectors for receiving a reflected optical signal. The reflected optical signal is detected with one of the optical detectors, and a duration of time between the emitting of the optical signal and the receiving of the reflected optical signal is measured. The method determines a separation distance from the transmit source to the receiving optical detector. The duration of time and the separation distance are combined to compute a boundary distance.

Abstract: A modular sub-array assembly of a composite towed array includes a multi-chamber support structure with plural discrete chambers, an acoustically absorptive hub formed at a central axis of the multi-chamber support structure, and a sensor element in each of the chambers of the multi-chamber support structure. The multi-chamber support structure is an integrally formed viscoelastic cylindrical housing with an array of radially oriented chambers. Each sensor element is secured within the selected chamber of the multi-chamber support structure and to an outer radial surface of the acoustically absorptive hub by a structural adhesive. Plural sub-array modules may be assembled together to form a single towed array.

Abstract: In accordance with the present invention, a photon transducer system is provided for obtaining information on acoustic signals within a fluid environment. The photon transducer system uses a laser-based Doppler interferometer located within a pressure release surface. The pressure release surface is formed by generating a gas pocket in the fluid, creating a boundary layer between the laser light source and the surrounding fluid. Laser light is reflected from the boundary and is detected by the interferometer to obtain the Doppler velocity of the pressure release surface. The pressure incident on the boundary can be determined from the measured velocity, providing information on the incident acoustic pressure.

Abstract: A vertical acoustic array system and method for acoustically imaging the tents of a partially or completely buried tank which can contain radioactive solids and may not be entirely filled. The transducer array is placed proximate a side of a tank in a vessel such as a tube filled with water. Dirt or other filler material located between the tube and the tank is saturated with water, allowing the acoustic signal to propagate through the side of the tank and into the tank. The vertical array consists of one or more transmitting units and receiving units set in a vertical array including dipole receiving elements which allow horizontal directionality. The signals are analyzed by a field unit which includes a portable self-powered trailer providing signal transmitting and analysis devices. The field unit can transmit signals to a second unit which provides further signal analysis.