Abstract: There is provided a two-dimensional array for use in an acoustic imaging system which comprises a plurality of transducer segments each having a trace for exciting an electrode on each of the transducer segments, the trace and the electrode being formed of the same material. The two-dimensional array disclosed is capable of imaging deeper in the human body at higher frequencies and provides more reliable lead attachments to the respective segments forming the array. Methods of manufacturing the two-dimensional array are further provided.

Abstract: A method of forming a transducer device having integral transducer and impedance matching portions includes forming grooves partially through a thickness of a piezoelectric member. A groove volume fraction at the impedance matching portion controls the electrical impedance. The impedance matching portion may be at either or both of the front and rear surfaces of the transducer portion, which generates acoustic wave energy in response to application of a drive signal. The drive signal is introduced by electrodes. In one embodiment, the electrode at the impedance matching portion extends into the grooves, but preferably a filler material is selected and deposited to allow use of a planar electrode. An alternative embodiment to fabricating the transducer device is to assemble piezoelectric material. For example, an integral transducer and impedance matching portions may be formed by using molding techniques or by stacking dimensionally different thin piezoelectric layers.

Abstract: A method and apparatus is disclosed for making a sliced phased array transducer formed from a single piezoelectric disk which has been bonded to a metal coated support surface. After bonding, the disk and attached metallic coating are cut into a plurality of conductively isolated staves which are then wired into a sequence which allows the array to emit two beams in opposite directions at a depression angle of about 60 degrees. In use, two of the arrays are used adjacent to each other with one emitting beams along the port and starboard sides of the vessel and the other being rotated 90 degrees to emit beams to the force and aft of the vessel, the four beams thereby forming a Janus configuration. Alternatively, the beams could be rotated 45 so that two beams are directed to both the port and starboard sides.

Abstract: A piezoelectric transducer chip comprising a plurality of transducer elements. At least one of the transducer elements is a multi-layer element which comprises a plurality of piezoelectric layers, each of which is separated from the adjacent piezoelectric layers by an electrode layer so that a plurality of capacitive elements is electrically connected in parallel. The plurality of piezoelectric layers are comprised of a plurality of piezoelectric members separated from adjacent members by a gap to form a composite piezoelectric layer. Also disclosed is a method of making a multilayer transducer of a composite piezoelectric material. Alternate embodiments include two-dimensional ultrasonic transducer arrays having multilayer elements formed of a composite piezoelectric material.

Abstract: A method for determining a unique signal representing the earth's response between a transmitter and receivers when conducting a seismic survey involves the steps of receiving a seismic signal set that comprises a plurality of different output frequency signals having known amplitude and phase characteristics, selectively combining the different output frequency signals to form the unique signal, and recording values of amplitude, phase, and frequency of the unigue signal. A method of conducting a modulated seismic survey involves the steps of providing seismic sensors capable of receiving a modulated seismic signal comprised of different frequency signals, transmitting modulated seismic energy information into the earth, and recording indications of reflected and refracted seismic waves sensed by the seismic sensors in response to transmission of the modulated seismic energy information into the earth.

Abstract: A system and method provide a low distortion hydrophone. A first known piezoelectric element is mounted so as to receive a pressure signal. A second piezoelectric element is provided with a means of receiving and enhancing the same pressure signal. Since a piezoelectric element is a capacitor, another capacitor is coupled in parallel with the second element to serve as a divider. The output voltage of the combination of the two elements is taken as the difference between the positive terminals of the two elements. Thus, the effect of the pressure enhancer and capacitance divider is to provide a difference in potential between the fundamentals from the two elements, while rendering the amplitude of the second harmonics equal. The two equal second harmonics cancel each other out at the output terminals, while retaining a useful fundamental for further signal processing.

Abstract: A method and apparatus for acoustic array calibration. A housing with an opening on one side contains the acoustic transducer element. An acoustically transparent window covers the opening in the housing. A separate piece of substantially acoustically transparent planar transducer film is positioned in front of each transducer element. This film monitors the acoustic energy transmitted by the transducer elements, or alternatively transmits energy to the transducer elements. The transducer film can also operate as an independent hydrophone.A method for calibrating acoustic arrays is also disclosed. The transducer film monitors the acoustic energy transmitted by each acoustic transducer. The level of transmitted acoustic energy is independently measured by external calibration equipment. The acoustic energy received by each transducer film is compared with that measured by the external equipment to determine a calibration factor for each transducer element.

Abstract: An acoustic antenna includes at least one surface sensor formed by a stack of conducting materials and dielectric layers of piezo-electric material enclosed in a sheathing of flexible material. The assembly forms a flat panel 2 mounted against the hull 5 of a navel vessel and takes the shape of the hull. The mounting of the panel on the hull is achieved by two streamlined edging sections 3, 4 while leaving an intermediate water layer 6 remaining between the panel 2 and the hull 5. The sheathing includes an envelope of flexible material filled with a visco-elastic lining material and the piezo-electric material of the dielectric layers of the sensor is preferably a polyvinylidene fluoride film.

Abstract: The invention relates to a dual frequency sonar transducer assembly which may be operated at low and/or high frequencies in a sonar array. The assembly comprises a low frequency unit of tonpilz design including a low frequency driver, a low frequency tail mass and a composite head mass, the composite head mass acting as a single low frequency water driving piston and comprising a plurality of high frequency units forming individual high frequency water driving pistons. The high frequency units are also of tonpilz design, with independent drivers, independent head masses, and a common tail mass. The use of a common tail mass simplifies the design without compromising high frequency operation. The design leads to more efficient operation at both frequencies by minimizing the head mass to tail mass ratios.

Abstract: A multiple frequency acoustic transducer is constructed as a stacked confration of N groups of multi-layer transducer elements separated from one another by an electrical insulating material. Each multi-layer transducer element in an n-th one of the N groups has a layer of acoustically transparent electroacoustic transducer material whose thickness is determined by the n-th frequency of operation. Each multi-layer transducer element has opposing planar surfaces with electrically conductive material deposited thereon. For each multi-layer transducer element, the electrically conductive material is formed into parallel strips electrically isolated from one another on at least one of each element's opposing planar surfaces. The parallel strips associated with each multi-layer transducer element in any one of the n-th groups have a unique angular orientation in the n-th group.

Abstract: An electro-acoustical transducer arrangement for underwater antennas comprised of a plurality of hydrophones (10) which are arranged at equal distances in a linear array, and are to be disposed vertically above each other on a support. For reasons of a simplified assembly along with good receiving properties, the hydrophones (10), together with a reflector (11) disposed behind them in the direction of incoming sound, are embedded in an acoustically transparent rigid cast enclosure (20) of an elastomer, preferably polyurethane, which can be worked in a casting process. The connecting lines (12) of the hydrophones (10) of the enclosure 20 are combined in a common plug (13), which is accessible on a front end of the rigid cast enclosure (20). The rigid cast enclosure (20) is provided with devices for fastening the enclosure to the support.

Abstract: A system and process for electrically connecting all elements in a transducer array from one side. A flat block of piezoelectric ceramic material is patterned and drilled with a high-powered laser. The drilling is precisely controlled to define a series of vias which penetrate the ceramic block in the thickness direction. These vias facilitate electrical connection from one side of the ceramic block to the other side when the vias are sputtered or plated with electrically conductive material. In this way the electrodes on the front face of the transducer elements can be electrically connected from the rear to common ground or a signal source.

Abstract: An ultrasonic probe having one or more piezoelectric ceramic elements, each having a respective bulk acoustic impedance. Each element has a respective front face and a respective piezoelectric ceramic layer integral therewith to provide efficient acoustic coupling between the probe and a medium under examination by the probe. The respective piezoelectric layer of each element includes shallow grooves disposed on the respective front face of each piezoelectric element. A groove volume fraction of the piezoelectric layer is selected to control acoustic impedance of the piezoelectric layer so as to provide a desired acoustic impedance match between the bulk acoustic impedance of the element and an acoustic impedance of a medium under examination by the probe. Electrodes extend into and contact the grooves, imposing electrical boundary requirements that support a desired electrical field distribution within the element.

Abstract: Disclosed is an encapsulated hydrophone assembly for use in a towed hydrophone array. The assembly comprises (1) a hydrophone element having a hydrophone electrical conductor, (2) an insulated input electrical lead and an insulated output electrical lead coupled to the hydrophone electrical conductor, (3) an electromagnetic shield surrounding the hydrophone element and the hydrophone electrical conductor, the input electrical lead and the output electrical lead extending from the electromagnetic shield and (4) a layer of encapsulating material surrounding the hydrophone element, the hydrophone electrical conductor, a portion of the input electrical lead, a portion of the output electrical lead and the electromagnetic shield to thereby form the hydrophone assembly.

Abstract: A hydrophone for a marine seismic streamer has a pressure sensor with outer membrane surfaces on which piezoelectric sensors (4, 5) are secured. The pressure sensor is formed from two spaced steel disks (1, 2) having recesses directed toward one another and which are laser-welded at the edges in a gas-tight manner. The pressure sensor is electrically insulated from its external environment by a synthetic resin coating, which may enclose the entire pressure sensor, including the connecting wires. A method of making the hydrophone is also disclosed. The hydrophone can be manufactured so as to be small in dimensions and weight, is mechanically sturdy and capable of withstanding overload, as well as being protected by the synthetic resin coating against short circuiting and corrosion.

Abstract: A multilayer two-dimensional array of ultrasonic transducer elements includes four via segments at the four corners of each transducer element. A first pair of diagonally opposed via segments provide signals to signal electrode layers of each transducer element. A second pair of diagonally opposed via segments interconnect ground electrode layers. Thus, a redundant interconnection scheme is achieved. If the transducer elements include piezoelectric layers having a square cross section parallel to a transducer radiating surface, four-fold symmetry is maintained, despite the formation of the four via segments. Also disclosed is a method of forming a two-dimensional array.

Abstract: The current invention discloses a construction of a hydrophone body and hydrophone sensors which provides a significantly enhanced wide band frequency sensor capability within the construction of a sensor array towed in a cable. This construction extends a tuned resonator or sensor along the hydrophone body and into an adjacent section of interconnecting cable. This elongated sensor, in the form of a tubular sensor, provides an enhanced, very low frequency sensing capability within the overall hydrophone array, supplementing the frequency range of the encased hydrophone sensor.

Abstract: An acoustic sensor and projector module for sonar applications includes a first acoustic transducer element operating as a projector to generate an acoustic beam, and a second acoustic transducer element acting as a hydrophone to sense pressure wave returns. When the second acoustic transducer element operates in a sensing mode, the first acoustic transducer element serves in conjunction with a baffle structure to baffle acoustic signals presented to the hydrophone. Similarly, when the first transducer element operates in a projecting mode to generate an acoustic beam, the second transducer element acts in combination with a baffle structure to baffle acoustic signals emitted by the projector.

Abstract: An ultrasonic device having an acoustic transducer with a lamination of parallel integrated circuit chips having active circuitry. A backing member made of a material for attenuating acoustic waves provides Z-axis conduction of signals from the parallel integrated circuit chips to individual piezoelectric elements. Preferably, each piezoelectric element is operatively associated with a particular circuit that is within the acoustic shadow of the element, so that the lamination of chips does not add to the cross sectional area of the transducer. The integrated circuit chips are coterminus at first edges to provide a planar contact surface having a pad grid array of contact pads for connection with conductors extending through the backing member. In one embodiment, the piezoelectric elements provide a two-dimensional array of elements that corresponds to the pad grid array. Circuitry on the integrated circuit chips can include protective diodes, preamplifiers and one or more multiplexers.

Abstract: A piezoelectric transducer chip comprising a plurality of transducer elements arranged in a two-dimensional array is disclosed. At least one of the transducer elements is a multi-layer element which comprises a plurality of piezoelectric layers, each of which is separated from the adjacent piezoelectric layers by an electrode layer so that a plurality of capacitive elements is electrically connected in parallel. A first via connects a first set of alternating electrode layers, and a second via connects a second set of alternating electrode layers. The first via is insulated from the second set of alternating electrode layers, and the second via is insulated from the first set of alternating electrode layers. At least one of the plurality of multi-layer elements has an internal edge. At least one of the vias of a multi-layer element is an internal via. Also disclosed are an ultrasonic transducer which includes such a piezoelectric chip, and an ultrasonic scanner which includes such a transducer.

Abstract: An element responsive to acoustic particle acceleration for sensing acoustic signals in a region of low acoustic pressure is disclosed. The element may be isolated from acoustic noise when positioned adjacent an acoustic noise generating high acoustic impedance structure by a baffle which provides isolation from radiated and evanescent acoustic signals and structure vibration.

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 acoustic array having polymer hydrophones is disclosed. The array compes a plastic roll, a plurality of polymer piezoelectric sensors affixed to the roll and electrodes that interconnect the sensors to utilization means such as those found for underwater detection systems or geophysical detection systems such as seismic detectors. The plastic roll has a pliant characteristic so as to readily assume a predetermined shape as well as, preferably, having a strong tendency to unravel and is of a relatively thin material. Similarly, the piezoelectric sensors have a pliant characteristic, are relatively thin, and are affixed to one of the surfaces of the plastic roll. Further, the electrodes have a pliant characteristic, are relatively thin, and are affixed to the same surface of the roll as the sensors.

Abstract: A non-invasive, synthesizing array of "N" reciprocal transducers is driven by "N" linearly independent inputs for three-dimensional sound field specification at "N" locations either within, or on, an isotropic or anisotropic acoustic/elastodynamic medium. Towards these ends, the impulse response, or Dyadic Green's Function Matrix, characteristic of the medium is determined, and the desired sound field response at "N" locations either within, or on, the surface of the medium is specified. This results in a system of "N" equations, which can be solved to obtain the "N" linearly independent inputs required to create the "N" desired, three-dimensional sound field responses. This permits precise focusing and spatial manipulation of sound intensity, as well as amplitude control within a specific volume or region of convergence within, or on, the medium.

Abstract: A composite ultrasound transducer (array) contains piezoelectric ceramic transducer elements which radiate substantially in the longitudinal direction, and are embedded in a polymer matrix. The transducer elements have such a geometrical structure, and are arranged relative to each other, so that the development of oscillation modes perpendicular to the longitudinal direction of the transducer elements is suppressed. A method for manufacturing the composite ultrasound transducer includes the steps of filling a plastic form, having a "negative" of the desired shape of the transducer elements, with ceramic slurry, and pyrolyzing the plastic form after the slurry dries therein. The resulting voids between the hardened ceramic elements are filled with polymer to create the overall composite transducer.

Abstract: An ultrasonic wave curing device according to the present invention, can set the optimum ultrasonic wave focusing condition for curing, by using at least one of an ultrasonic wave oscillator, a conical reflector having a conical reflecting surface to reflect an ultrasonic wave, which comes from the ultrasonic wave oscillator, and a reflecting case having a concave, reflecting surface to focus to a position to be cured, an ultrasonic wave which is reflected, again, by the reflecting surface, after it is reflected by conical reflecting surfaces that are arranged around the periphery of the conical reflector.

Abstract: A low-frequency hydrophone for a sonar array comprises at least a lacunary ceramics element with open porosity saturated by a viscous fluid, on which metal electrodes have been deposited. This hydrophone forms a high-pass filter whose cutoff frequency is adjusted by modulating the area of the electrodes. The present invention may find particular application in towed linear arrays and passive sonars.

Abstract: A hydrophone is provided for use with a hydrophone array enclosed in a streamer cable that is deployed in a body of water. The active transducer elements of the hydrophone are electrically isolated from the sealed metal case in which they are mounted. The signal input and output terminals are protected from short-circuiting due to water invasion of a faulty streamer cable jacket.

Abstract: An electro-acoustic transducer comprises two transducer units each having first and second ends, a tubular supporting member disposed between the two transducer units, and a pair of oppositely disposed supporting components between which the transducer units and tubular member are disposed. One of the transducer units is compressively clamped between one of the supporting components and one end of the tubular member, and the other of the transducer elements is compressively clamped between the other of the supporting components and the other end of the tubular member.

Abstract: An improved electromechanical transducer is provided for use in an acoustic telemetry system. The transducer of this invention comprises a stack of ferroelectric ceramic disks interleaved with a plurality of spaced electrodes which are used to electrically pole the ceramic disks. The ceramic stack is housed in a metal tubular drill collar segment. Thick metal spacer plate are selectively sandwiched between electrodes in order to promote thermal cooling of the ceramic stack. In accordance with an important feature of this invention, the thick metal spacer plates are comprised of a material (such as copper alloys, aluminum alloys or the like) which is softer than the relatively hard, brittle ceramic disks thus reducing the stresses upon the disks when the assembly is subjected to bending, torsion and the like, and thereby minimizing the risk of structural failure of the disks when in operation within a downhole acoustic signal generator.

Abstract: Apparatus for destroying calculi in a living body by ultrasonic waves, wherein a plurality of ultrasonic transducers are arranged on the plane surface of a supporting member, with their axes being inclined in such a manner that the axes of the ultrasonic beams produced by the transducers meet at a point where a calculus to be destroyed is positioned.

Abstract: A piezoelectric transducer having plural piezoelectric transducer elements which can generate mechanical vibrations converging substantially on one point. The transducer is formed to control the convergent point by insulating piezoelectric transducer elements mechanically, arranging them concentrically and driving them independently and separately from each other.

Abstract: A transducer assembly which includes a plurality of staves releasably arranged around the periphery of a torpedo. Each stave includes a transducer backing member such as foam polyurethane to simulate an air backing, and a solid acoustically transparent transducer support member, such as polyurethane, disposed in front of it. A curved reflector made up of a plurality of sheets of onionskin paper is positioned between, and compressed by, the backing and transducer support members. A plurality of transducer active elements is arranged vertically within the transducer support member with the arrangement imparting a certain desired directivity pattern to receiving beams associated with such apparatus.

Abstract: In a phased array acoustic transducer which has elements of different sizes, the piezoelectric material of large elements is subdiced to produce smaller segments to limit the overall piezoelectric segment size variation within the array to up to 55% or more without significant adverse effect on phased array processsing.

Abstract: A piezoelectric ultrasonic array transducer has its individual elements connected to external electronics via a high density interconnect structure which facilitates signal connection and uniformity from array-to-array. The array fabrication process is preferably modified for use with a high density interconnect structure in order to obtain maximum transducer quality.

Abstract: An electroacoustic transducer according to the invention comprises a stacking of annular plates (13) made of piezoelectric ceramics alternating with annular electrodes (14) and pressed by an axial prestressing stem (15). The contact faces between each plate and the adjacent ones are made of two flat parts (16a, 16b) whose surface is smaller than the maximum cross section, due to the chamfers (19a, 19b, 20a, 20b) which truncate the edges of each plate. One application is the construction of low frequency sonar transmitters. Referenced elements refer to FIG. 3.

Abstract: Various configurations of cylindrically shaped transducers are used as borehole seismic wave sources. The basic class of transducers of this invention has an outer shell that is generally cylindrical, and may be comprised sections. The shell or the sections may be pre-stressed or preformed to encourage certain bending motions. Depending on the configuration of the transducer, it approximates a monopole, dipole, or quadrupole radiator. Various actuating means, including magnetostrictive forces and piezoelectric forces, are used to drive the motions of the transducer. These transducers are especially useful for generating compressional, shear, or other elastic waves in solids. For example, in geophysical applications, the transducers are placed in boreholes for either hole-to-hole or single hole measurements.

Abstract: A transducer array designed for towing at an extended distance behind a sace vessel includes electroacoustical transducer elements connected in opposition to the active elements of the array. A surrounding acoustic isolation structure effectively isolates the dummy transducer elements from the ambient noise field while permitting cancellations of self-induced noise.

Abstract: The housing of a transducer supports both dynamic and static pressure sensors to obtain depth information as well as pressure wave signals. A semiconductive diaphragm with diffused resistances connected in a bridge is used as the static sensor which is centrally located on an end face of the housing. Several parallel-connected dynamic sensor elements are arrayed around the static sensor. Each dynamic sensor element is an edge supported brass disk with a thin piezoelectric ceramic disk soldered to it such that the disks flex in response to low frequency pressure waves to generate corresponding electrical signals. A low noise amplifier and filter is capacitively coupled to the dynamic sensor array to process hydrophone signals at a frequency below 1 Hz.

Abstract: An elastic pulse generator including a piezo-electric or magnetrostrictive transducer which is focussing or associated with a focussing device, having a plurality of elementary emitting surfaces generating elastic signals. These signals are superimposed, after propagation over a certain distance, in a focal region. Several groups of elementary emitting surfaces are periodically exciting at a predetermined rate with respective separate electric signals. The emitting surfaces belong to transducer elements electrically isolated from each other and having different transfer functions. Delay lines are provided for phase shifting the elastic signals emitted by the transducer elements.

Abstract: An improved bimorph piezoelectric transducer provides higher input impedance and allows operation at higher operating voltages. First and second piezoelectric elements have opposing electrode patterns which define a plurality of capacitors connected in series. This allows such transducers to be directly connected to high voltage audio distribution systems without the need for an impedance matching circuit.

Abstract: An electroacoustic transducer having a truncated hemispheric propagation or esponse pattern is disclosed. The transducer comprises an assembly of fish-bone shaped piezoelectric elements, each characterized by a plurality of rod portions extending from a spine portion. The assembly is pivotally mounted within a liquid filled acoustic window means.

Abstract: An ultrasonic probe includes a first group of one or more piezoelectric elements extending concentrically, and a second group of one or more piezoelectric elements extending concentrically and extending outward of the elements in the first group. The elements in the first and second groups form a front surface via which ultrasonic wave is transmitted and received. The elements in the first and second groups are separated by predetermined gaps. Areas of the respective elements in the second group over the front surface are substantially equal to each other within an accuracy corresponding to areas of the gaps over the front surfaces. Areas of the respective elements in the first group over the front surface are substantially equal to half the areas of the respective elements in the second group within an accuracy corresponding to the areas of the gaps.

Abstract: A streamer-cable assembly is provided having a tubular outer jacket enclosing an open-cell and closed-cell foam core. The foam core provides an axial hole for retaining a plurality of pressure sensors and a plurality of off-axial holes providing passages for the transmission bundle. Longitudinal channels along the exterior of the foam inserts receive substantially rigid stress members which provide longitudinally strength to the streamer. Cable noise associated with the cable jerk and cable whip/vibration is radially reduced by the open-cell foam core and rigid stress members while the closed-cell foam core provides buoyancy to the streamer cable at the connectors between sections.

Abstract: A sensor, having a sandwich configuration, is able to sense a transduce out parameter in situ without significantly affecting the parameter. The sensor comprises an inner sheet of a polymer having a transducer property. A conductive layer is deposited on parts of at least one of the two surfaces of the inner sheet. A pair of outer sheets of plastic are attached to each side of the inner sheet. Two layers of conductive material may be deposited on the outer, unattached, surfaces of the outer sheets, one layer on each surface.

Abstract: The intensity profile of an ultrasound beam in an ultrasound imaging system is adjusted by driving the individual piezoelectric crystals with drive signals having adjustable pulse durations. The duration of the drive pulse determines the frequency spectrum of the pulse and therefore determines the amplitude of the emitted ultrasound wave. The pulse durations may be selected such as to compose a desired profile of the ultrasound beam.

Abstract: An omnidirectional acoustic transducer achieves a broadband radiation or reception pattern with high efficiency by using several transducer rings located side-by-side with each ring comprising a plurality of radially directed individual transducer elements. The transducer elements in each of the rings are tuned to a particular natural frequency and are designed accordingly. Within each ring the transducer elements are energized in phase with one another. The natural frequency of the individual transducer elements differs from one ring to the other.

Abstract: A large number of piezoelectric elements are arranged in a mosaic pattern on a spherical surface so that ultrasonic waves generated by the elements converge on a single point. The arrangement of the elements constitutes a transducer. With the transducer applied to a subject through a liquid bag filled with water, ultrasonic shock waves from each piezoelectric element are concentrated on a lithotresis object, or a calculus so as to break it. The ultrasonic shock waves are generated by applying driving impulses (voltage) to each piezoelectric element. In order to locate the calculus, the transducer is coupled to an ultrasonic diagnosis apparatus having a mechanical scanning type ultrasonic probe. The piezoelectric elements have resonance frequencies set such that the piezoelectric element positioned at the center of the transducer has the lowest resonance frequency and the resonance frequency of each piezoelectric element is increased in accordance with its distance from the center.

Abstract: A flextensional transducer having an elliptically-shaped shell is compressed at its ends by either piezoelectric or magnetostrictive drive assemblies which are constrained from longitudinal movement by a rigid mount. The compression may be provided by a rigid mount having a gap into which a distended shell and the drive assemblies are inserted. After removing the force producing the distended shell, the mount exerts a compressive force on the ends of the shell. Alternatively, the compression of the shell may be obtained by mechanical forces produced by screw mechanisms forming part of the mount.

Abstract: A two-dimensional ultrasonic phase array is a rectilinear approximation to a circular aperture and is formed by a plurality of transducers, arranged substantially symmetrical about both a first (X) axis and a second (Y) axis and in a plurality of subarrays, each extended in a first direction (i.e. parallel to the scan axis X) for the length of a plurality of transducers determined for that subarray, but having a width of a single transducer extending in a second, orthogonal (the out-of-scan-plane, or Y) direction to facilitate dynamic focussing and/or dynamic apodization. Each subarray transducer is formed of a plurality of sheets (part of a 2-2 ceramic composite) all electrically connected in parallel by a transducer electrode applied to juxtaposed first ends of all the sheets in each transducer, while a common electrode connects the remaining ends of all sheets in each single X-coordinate line of the array.