Abstract: An ultrasonic probe including one or more piezoelectric ceramic elements mounted on an acoustically damping support body. Desired acoustic signals are transmitted and received through a front portion of the probe while unwanted acoustic signals are dampened by the support body at the rear portion of the probe. The present invention generates and efficiently focusses a main lobe of a beam of the acoustic signals. Furthermore, the invention provides for apodization of the acoustic beam to reduce extraneous acoustic signals corresponding to side lobes of the acoustic beam. Each element has a respective rear face and a respective first piezoelectric ceramic layer integral therewith to provide efficient acoustic coupling between the element and the acoustically damping support body. The respective first piezoelectric layer of each element includes shallow grooves disposed on the respective rear face of each piezoelectric element.

Abstract: An acoustic transducer having impedance matched layers that can be deployed in environments having wide temperature variations. An anisotropic layer provides a low coefficient of thermal expansion orthogonally to the direction of sound wave propagation. The anisotropic layer may be a solid matrix embedded with fibers, such as glass, arranged in a common orientation.

Abstract: An acoustic transducer assembly is provided having a one or two dimensional array of transducer elements, an electrical circuit element such as a circuit element and a backing for interconnecting transducer elements to corresponding contacts or traces of the circuit element. The backing is a block of acoustic attenuating material having a conductor extending therethrough between each transducer element and the corresponding circuit contact. The block has acoustic properties, including acoustic impedance and acoustic velocity, to achieve a desired degree of acoustic match with the transducer elements and/or to permit coupling of acoustic energy from the conductors into the block. The block may be of a single material or may have different volumes of two or more materials having different acoustic properties to achieve desired results. Multiple thin conductors or conducting fibers or foils may be utilized for each transducer element to reduce or eliminate acoustic coupling into the conductors.

Abstract: An ultrasonic probe includes a piezoelectric material layer having a pair of electrodes provided on both main surfaces thereof for applying voltage thereto, and a backing material provided on one electrode. The backing material has an acoustic impedance lower than that of the piezoelectric material layer. Interposed between the backing material and one electrode is an acoustic reflecting material layer which has a thick first portion and a thin second portion. The second portion may have a substantially zero thickness to allow the backing material to be in partial contact with one electrode. Thereby, the ultrasonic probe can transmit and receive ultrasonic waves at its resonance frequencies. Also provided is an ultrasonic diagnostic apparatus which displays an image resultant from combining images having the frequencies obtained by driving the ultrasonic probe.

Abstract: A transducer assembly providing a conversion between the electrical and sonic energy, the transducer assembly being adapted for operating submerged at great depths in ocean waters. The transducer assembly is formed by a front and back plate which are affixed in one embodiment to the ends of a first mechanically distributed impedance member, a second mechanically distributed impedance member located between the front and the back plate and a transducer of electroacoustical material mechanically coupling the first and second members for imparting sonic vibrations to these members. In a preferred embodiment, the transducer is bonded at one end thereof to the back plate and at the other end thereof to the second member. External hydrostatic pressure present at the front and back plates does not compress the electroacoustical material.

Abstract: A hydrophone for calibrating lithotripters includes a spot poled disc of piezoelectric material which is mounted on a brass cylinder backing. A coaxial cable is electrically connected to one surface of the disc through the brass backing and the opposing surface of the disc. A mixture of polymeric material and microballoons is provided to protect the interconnection of the center conductor and the opposing surface of the disc and prevent damage due to the incident ultrasonic shock waves. The brass backing is placed in a suitable housing of phenolic material. A process in fabricating the piezoelectric disc and assembling the hydrophone is disclosed.

Abstract: An acoustic matching member for a sonic transducer is disclosed which comprises a solid material, for example, a glass, in which a plurality of voids have been formed. A method is also included of forming an acoustic matching member for a transducer which includes the steps of forming the member from a material in which a plurality of voids have been introduced whereby the velocity of sound in the material with voids is substantially less than that of the material without voids in the direction of sound propagation of the member.

Abstract: The sonar transducer is protected from explosion shock by a variable impedance device, such as a metal oxide varistor, connected in parallel with the energy conversion component. The varistor normally has a very high electrical impedance, but becomes conductive upon application of the very high voltage output of the energy conversion component as a result of a rapid increase in mechanical energy, such as would accompany an underwater explosion in the vicinity of the transducer, to limit both voltage and current to a safe level so that the transducer can thereafter operate within acceptable parameters.

Abstract: Disclosed is an ultrasonic probe for use in medical diagnostic systems for examination within a human body. The ultrasonic probe comprises an array of transducer elements for transmission of ultrasonic wave into an examined body and for reception of echo waves returning from the examined body. Further included in the ultrasonic probe is an ultrasonic propagation medium which is provided between the transducer element array and the examined body. The ultrasonic propagation medium is made of a synthetic rubber having an acoustic impedance close to that of the examined body and having a low acoustic attenuation coefficient. Preferably, the synthetic rubber is one of butadiene rubber, butadiene-styrene rubber, ethylene-propylene rubber, and acrylic rubber.

Abstract: A hydrophone for the detection of sound or vibrational waves, comprising a piezo electric transducer within a Faraday cage such that it is in contact with and yet isolated from a deformable pressure transmitting medium that carries vibrations. The Faraday cage reduces noise interference. The deformable medium is usually a fluid and preferably a vegetable oil, but can also include a silastic compound couple. One side of the Faraday cage is a ground plane of a surface-mount printed circuit board. Components of an electronic circuit for conditioning the signal are mounted on the printed circuit board and include a buffer having an ultra-high impedance input and a very low impedance output. The circuit has a low power draw and is powered by a replaceable battery.

Abstract: A deep submergence, acoustically stable directional transducer uses a wavide and an encapsulant to channel sound. The waveguide forms an air space with a housing so that radiated sound is totally reflected at the air space interface. The encapsulant is matched to the acoustic impedance of the sea water at the intended operating depth to minimize reflection at the encapsulant-to-sea water interface.

Abstract: A shock wave generator for use in an extracorporeal lithotripsy apparatus has a liquid-filled housing with an exit aperture for shock waves which are electromagnetically generated and conducted to a focusing element for focusing onto the calculi, and a plate-shaped element having a smaller cross-sectional area than the emitted shock wave is disposed in the path propagation of the shock wave. The plate-shaped element consists of a material having an acoustic impedance substantially corresponding to the acoustic impedance of the liquid in the housing, and having a propagation speed of sound therein which deviates from the propagation speed of sound in the liquid.

Abstract: An automatic, ultrasonic system for controlling the filling of different sizes of beverage containers which may or may not contain various quantities of ice. The system includes a transducer assembly and a control module, both preferably connected to a beverage dispenser valve assembly. The transducer assembly includes at least two piezo-electric crystals for separately transmitting and receiving ultrasonic wave energy from the grate, the cup lip, the top of any ice in the cup, and the rising liquid level, and for generating signals corresponding to the travel time of the ultrasonic energy. The control module includes a microcomputer and associated circuitry. The system can include two separate transmitter and receiver crystals, or in a preferred embodiment two transmitter-receiver pairs of crystals.

Abstract: An acoustic characteristics changing device includes a frame member disposed in an acoustic energy field, electro-acoustic conversion means attached to the frame member to constitute at least a portion of the device, variable impedance means connected as an electrical load to the electro-acoustic conversion means, and impedance control means for controlling an equivalent impedance of the variable impedance means. The equivalent impedance is variably controlled, so that an acoustic impedance and then its decrease frequency or decrease amount can be electrically, continuously and finely controlled.

Abstract: This invention is basically, an ultrasonic transducer that can be configured with good reproducibility, that includes an acoustic impedance matching member that gradually changes the acoustic impedance, and which is characterized byAn acoustic impedance matching member(2) configured with multiple unit layers (21, 22, 23, . . . 2n), each layer being thinner than a quarter-wavelength of an ultrasonic wave, andeach unit layer having a laiminated structure make up of heavy metal(52) and plastic(51) layers with a thickness ratio set between them to change gradually from the unit layer close to the ultrasonic oscillator to the unit layer close to the subject.

Abstract: A method of testing piezo-electric transducers includes locating one end (11) of a rod (10) of solid material over the active head (20) of the transducer, the rod (10) simulating the normal acoustic impedance presented to the transducer by the normal medium, in which the transducer is intended to operate, energizing the transducer and detecting the acoustic wave propagated through the rod at the other end of the rod. A loading rod for use in testing a piezo-electric transducer is an elongated solid body so dimensioned as to simulate the normal operating acoustic impedance presented to a piezo-electric transducer to be tested.

Abstract: An acoustic transducer array includes a number of transparent continuous aperture transducer elements which are aimed at various angular sectors in a field of view and are embedded in an acoustically transparent material such as casting resin. Each transducer provides a beamformed output, and the transparency of the elements ensures that each element observes an acoustic field that is unperturbed by the other elements. A high resolution and a wide field of view are obtained by overlapping the transducer elements so that each element captures an increased area of acoustic signal. Preferably, the transducer elements are cut from thin, flexible metalized sheets of voided piezeoelectric polymer such as polyvinylidene fluoride or polyvinyl fluoride co-polymer. The polymer transducers are broad band in nature, and permit multiple frequency, multiple beam sonar configurations.

Abstract: Tracking and location of a high speed water rentry vehicle is assured by the inclusion of an acoustic source. An acoustic generator in the form of a piezoelectric transducer is potted in polyurethane and fills a volume aft of a disc-shaped wall in the re-entry vehicle. The potting compound couples the acoustic generator to the metal skin to enable acoustic transmission from the vehicle to the tracking range. Optionally, a layer of material is interposed between the potting compound and the vehicle's metal skin to aid in acoustically coupling the generator's output to the metal skin. No structural modifications of the entry vehicle are required yet the pinger is capable of sustaining re-entry shock.

Abstract: An acoustic damper for substantially reducing the reverberation echoes at the junction between an acoustic signal propagating fluid and a material having an acoustic impedance substantially different from that of the fluid. The damper, which is particularly adapted for use in ultrasonic transducers, is formed of a material having an acoustic impedance which substantially matches the acoustic impedance of the fluid, such material preferably being a foam plastic material having sufficient hardness to be acoustically stable. For preferred embodiments, the damper is formed of a laminate of the layer described above and a second layer of a material which provides high acoustic attenuation, such as cork material.

Abstract: An acoustically transparent voided, polyvinylidene fluoride (PVDF) hydrope made of material whose impedance matches the characteristic acoustic impedance (.rho.c) of sea water, having drastically reduced diffraction and resonance effects. The frequency response is thus flat at frequencies less than one-half elastic wavelength in the PVDF material. An array of such hydrophones in front of a projector saves space without affecting projector performance.

Abstract: An adaptation layer for an ultrasound applicator which contains a mixture of synthetic resin and ceramic powder. Through the addition of ceramic powder, the acoustic impedance of the applicator can be easily adjusted. Impedance values selectable in the range of e.g., 6 to 12.times.10.sup.6 kg/m.sup.2 sec are possible.

Abstract: There is provided by this invention a broad band acoustic transducer comprising a piezoelectric crystal with a two layer dampening backing having very high attenuation properties. Each layer has an impedance matching the acoustical impedance of the crystal, however, the second layer has an attenuating additive that greatly increases its attenuation factor. The surface interface between the two dampening layers is tilted and roughened to induce wave scattering that prevents back reflections.

Abstract: An underwater acoustic wave transmitting and receiving unit having excellent characteristics for both transmitting and receiving and providing stable characteristics over long operating periods. A plate-shaped polarized piezoelectric resonator is provided formed of at least one plate made of a complex of fluorosilicon rubber and lead titanate. The resonator is sealed in a rubber casing filled with an insulating liquid matching the water around the casing in acoustic impedance.

Abstract: An ultrasonic transducer comprises a support body, a piezoelectric layer of a material with a relatively high dielectric constant and high acoustic impedance, a first impedance matching layer and a second impedance matching layer (10). The first matching layer consists of silicon.

Abstract: An ultrasonic probe for an ultrasonic medical diagnostic apparatus which is composed of a piezoelectric vibrator with electrodes attached onto both surfaces thereof and one or two acoustic matching layers which are provided on the surface of one electrode of the piezoelectric vibrator. One of the acoustic matching layers is made of thermosetting resin such as epoxy resin mixed with magnetic material. A backing load member which is made of ferrite rubber or plastic mixed with tungsten powder is provided on the surface of the other electrode of the piezoelectric vibrator. An acoustic lens which is made of silicone rubber may be disposed on the upper acoustic matching layer. The acoustic matching layers may be formed by pouring the materials, thereby to form the ultrasonic probe without an intermedium of a different kind of material on the piezoelectric vibrator.

Abstract: The disclosed device is a marine seismic source which emits a constantly varying FM signal in the 10 to 100 H.sub.z range. The seismic source utilizes an adjustable length cantilever spring rotatably attached to stiff acoustic radiators, which create a signal in the water. Varying the length of the cantilever spring as a function of the frequency will permit the device to be continuously tuned for maximum power output.

Abstract: A shock-hardened hydrophone comprising a sensor electrically connected to a ow output-impedance preamplifier by a circuitboard. The sensor includes two metal cups, each cup with a piezoelectric ceramic disk positioned therein for generating a potential difference between the first and second surfaces of the disk. The cups are bolted together with the circuitboard positioned between the disks. The second surfaces of the disk are in pressure contact with the cups while the first surfaces are in pressure contact with a first electrode disposed on both sides of the circuitboard. A wire connects one of the metal cups to a second electrode disposed on either side of the circuitboard thereby completing the electrical connection of the disks to the electrodes on the circuitboard. The preamplifier is mounted on the circuitboard where the input to the preamplifier is the voltage difference between the first and second electrodes.

Abstract: Ultrasonic transducers comprising an ultrasonic transducer element, a pair of electrodes provided on opposite sides of the element, and an acoustic impedance-matching layer formed on an ultrasonic wave-radiating surface of the element through one electrode. The acoustic impedance-matching layer is made of a porous polymer film or a composite material comprising thermally expanded resin microspheres dispersed in a cured product of thermosetting resin and has an acoustic impedance not larger than 0.6.times.10.sup.6 Ns/m.sup.3. Two-layer constructions may also be used as the acoustic impedance-matching layer.

Abstract: A seismic data gathering system includes a seismic cable having a plurality of cable sections, each including a seismic detector and a pair of signal lines for carrying the seismic energy signals produced by the detector in response to seismic energy waves. A shunting resistance is located in each cable section with one end connected to one of the pair of signal lines and the other end connected through a mating connector to the other of the pair of signal lines in the next succeeding cable section so that a shunting resistance is added to the seismic cable each time a detector is added to the seismic cable. In this manner the electrical damping of each seismic detector remains constant when the seismic cable is coupled to a data acquisition unit regardless of the number of detectors included within the seismic cable.

Abstract: The disclosed device is a marine seismic source which produces a varying FM signal in the low end of the acoustic spectrum. The seismic source uses stiff oscillating radiators to create a signal in the water. These radiators are attached to devices acting as springs with a variable spring rate. Variation of the spring rate as a function of the frequency permits the device to be tuned for maximum power output.

Abstract: A microwave system uses a high dielectric constant waveguide embedded in a ow dielectric constant sheath with mechanical properties matched to those of the surrounding geological material with an end microwave reflecting surface to create a standing wave to permit measurement of particle and shock velocities resulting from an explosion.

Abstract: An acoustic array for use at high hydrostatic pressures comprises an acouc isolation baffle positioned adjacent to the hull; an intermediate acoustic conditioning module supported over the isolation baffle; and an outer layer containing a plurality of hydrophone units. The acoustic isolation baffle comprises alternating layers of rigid and compliant materials bonded together in sandwich fashion, wherein the compliant layer is provided with a regular pattern of air cells. In adjoining compliant layers the pattern of air cells is translated relative to each other so that the load bearing walls of one compliant layer overlap the open cell regions of the adjacent compliant layer with only a rigid layer disposed therebetween. The acoustic conditioning module comprises spaced coverplates with spacer elements extending therebetween to form a plurality of chambers which contain viscoelastic damping elements bonded to the outer coverplate.

Abstract: An underwater acoustic array comprises an acoustic skirt baffle positioned djacent to a hull surface for reducing the transmission of shipboard noise; an acoustic conditioning module positioned over the acoustic skirt baffle; and an outer layer secured to the acoustic conditioning module and containing a plurality of hydrophone units.The acoustic conditioning module comprises inner and outer spaced coverplates; a plurality of spacer elements extending between the coverplates to form a plurality of closed chambers therebetween; and "tuned" viscoelastic damping elements secured to the outer coverplate.

Abstract: A sonar transducer especially adapted for use when subjected to high hydrostatic pressures and extreme mechanical and explosive shock. The sonar transducer includes a conventional casing, ruggedized to withstand high pressures and a hostile environment. The casing is closed on all sides but one. An array of piezoelectric ceramic stacks are suspended inside of the casing and sandwiched between a single front mass and individual rear masses. The single front mass is positioned closest to the open side of the casing. A flexible cover is sealed over the open side of the casing and pressurized oil is placed inside the housing. Appropriate channels are provided to enable the oil to freely flow throughout the interior of the unit, including flowing inside of and about the ceramic stacks. Electrical connections are made with the ceramic stacks to allow external voltages to electrically stress the stacks, and also to allow external sensing of the voltages generated when the stacks are mechanically stressed.

Abstract: A seismic amplifier for use in marine seismic survey work involving the transmission of signals from remote signalling stations over cable pairs to signal processing equipment. These signalling stations are comprised of capacitive transducers. The seismic amplifier of the surveying system includes operational amplifiers electrically interconnected with a feedback circuit comprised of a balanced resistive-reactive network which is a lumped parameter equivalent circuit of the transmission line and capacitive transducer. The lumped parameter equivalent circuit used for feedback provides a flat, zero-phase shift overall response over the cable pair from the transducer to the output of a differential amplifier stage which is connected to the operational amplifier outputs to improve common mode rejection.

Abstract: An ultrasonic transducer array with high sensitivity, for use in water tanks and with human subjects in steered beam imagers to make wide angle sector scans, has narrow transducer elements and one or more quarter-wavelength impedance matching layers on the front surface of each element. The matching layers as well as the piezoelectric ceramic are completely cut thorugh and guide acoustic energy incident at any angle to the ceramic. A continuous covering or wear plate is attached to the matching layers and a continuous damping material can cover the backs of the elements.

Abstract: A fluid-filled compliant tube immersed in seawater to detect low frequency sound waves. The tube has only a middle portion of its length exposed to incident acoustic energy waves and a mode conversion causes a corresponding frequency acoustic wave in the tube, but of greatly reduced wavelength. Transducers are positioned at either end of the tube to detect the waves in the tube, the length of which is chosen to be a half wavelength of the waves in the tube.

Abstract: A piezoelectric crystal has a concave active surface and a high acoustical impedance. A flat layer of molded material having a low acoustical impedance faces the active surface of the crystal to form a space therebetween. An intermediate layer of molded material having an intermediate acoustical impedance fills the space between the crystal and the flat layer. Preferably, the intermediate material has a sonic velocity near that of water, and the flat layer has a uniform thickness of approximately 1/4 of the average wavelength of the ultrasonic energy emitted by the crystal. A housing supports the crystal, the flat layer, and the intermediate layer.

Abstract: An ultrasonic wave transducer which can generate a convergent ultrasonic sound beam. The transducer comprises liquid contained in a housing, a piezoelectric material in said liquid, and interdigital electrode arranged on the surface of said piezoelectric material, an alternating voltage being applied to said interdigital electrode.

Abstract: A piezoelectric resonator, particularly for pressure, acceleration, temperature and load transducers, consisting of a resonator core having holding discs on its opposite sides, said holding discs being formed of solid body layers, said layers consisting alternatively of materials having strongly different acoustic impedance for unit cross-sectional area.

Abstract: An ultrasound liquid level detector system for automatically controlling the dispensing of a post-mix beverage, including microprocessor-controlled circuitry for monitoring and implementing the automatic dispensing process. The microprocessor is interfaced with an ultrasonic transducer which transmits ultrasonic wave energy towards the container to be filled and receives reflected ultrasonic wave energy, the characteristics of which are analyzed within the microprocessor to implement control functions of the automatic dispensing process. Dispensing is initially stopped before the liquid level reaches the top of the container to allow for dissipation of foam on the top of a carbonated beverage and dispensing is reinitiated to top off the level of beverage adjacent the top of the container. The disclosed system also utilizes the ultrasonic transducer to measure the level of ice within the container prior to dispensing and precludes dispensing of the beverage if the level of ice exceeds a predetermined limit.

Abstract: A conformable acoustic coupler for ultrasonically testing an article. The upler has an ultrasonic transducer with an active surface which transmits ultrasonic energy pulses to an article to be tested. A sensor receives and measures an ultrasonic echo from the tested article. The article to be tested is acoustically mated to the active surface by a medium of a gelatinous material layer on the active surface and a flexible film on the gelatinous material layer. The combination of the gelatinous material and film conforms to the shape of the article and provide acoustic coupling between the active surface and the article without leaving a residue of the medium on the article.