Abstract: A sonar transducer mounted on a probe inserted in a vessel or container emits a sonar wave for measuring the level of fluid interfaces within the vessel or container. The sonar transducer includes a housing closed by a diaphragm at one end. A piezoelectric crystal located within the housing is biased against the diaphragm and is electrically connected to an energizing source. The travel time of the sonar wave emitted by the piezoelectric crystal and reflected by the fluid interfaces is measured. The sonic wave measurements are communicated to a microprocessor and the levels of the liquid interfaces within the vessel or container are calculated.

Abstract: A pressure-pulse therapy apparatus, including a dome-shaped reflector, at least one ring section, a central x-axis, an open end, a flexible diaphragm capping the open end, a fluid medium within the reflector and diaphragm, a pressure-pulse source immersed in the fluid medium and located on the x-axis for generating a primary pressure pulse, and a power supply for the pressure-pulse source. The reflector includes a center section that has a predetermined first curvature and associated reflective characteristics to reflect the primary pressure pulse to form a first subordinate pressure pulse of a compound pressure pulse. The ring section is substantially concentric with the center section and has a predetermined second curvature and associated reflective characteristics to reflect the primary pressure pulse to form at least one additional subordinate pressure pulse of the compound pressure pulse.

Abstract: A microfabricated acoustic transducer with suppressed substrate modes includes a diaphragm containing an upper electrode suspended above a substrate containing a lower electrode; the substrate may or may not contain electronic circuits. The substrate modes are suppressed by either thinning the substrate such that a longitudinal ringing mode occurs outside of the frequency band of interest or applying a judiciously designed damping material that absorbs acoustic energy from the substrate on the backside of the transducer substrate, or by both thinning the substrate and applying the damping material. The damping material has an acoustic impedance that matches the acoustic impedance of the substrate and is lossy.

Abstract: The invention refers to a driving device for hydroacoustic transmitters, including at least one actuating element (1), arranged to execute a reciprocating movement, wherein the movement of the actuating element (1) includes an increase and a decrease of the distance between two ends thereof, and at least one spring member (5, 27) which is connected to the actuating element (1) at said ends and which extends along a curved line between said ends, wherein the increase and the decrease of the distance between said ends result in a change of the curve of the spring member (5, 27) and thereby a movement of it. The device includes an element (12, 13, 28) for displacement of a mass, which displacement element (12, 13, 28) is connected to the spring member (5, 27) so that the movement of the latter is transmitted to the displacement element (12, 13, 28) and generates a displacement thereof, resulting in said mass displacement.

Abstract: A flextensional transducer projector shell design is disclosed. The shell design has a shape formed so as to reduce the stress placed on the transduction driver as compared to other shell designs. The shell design includes first and second bulbous end portions, which can each be adapted to receive a respective end of a transduction driver. A middle portion of the shell design has both concave sections and convex sections, thereby defining a wave profile.

Abstract: An underwater acoustic projector comprising a pair of spaced apart end walls with an acoustic driver positioned between the end walls, the driver having smaller cross-sectional dimensions than the end walls. Each end wall close one end of open ended tubular pipe waveguides and is mechanically coupled to one end of a piezoelectric acoustic driver.

Abstract: An underwater acoustic projector comprising a pair of spaced apart end caps with an acoustic driver positioned between the end caps, the driver having smaller cross-sectional dimensions than the end caps to which the driver is mechanically coupled. The projector has a flextensional outer wall surrounding the driver with flanges at ends of that outer wall being secured to the end caps by a heat shrunk ring.

Abstract: The damping of membranes of ultrasound transducers in an arrangement occurs at the front side directly on the membranes by applying a polymer layer, whereby the working temperature dependent on the operating frequency of the ultrasound transducer lies within the glass transition range of the polymer layer.

Abstract: A plurality of applications for a micro-machined ultrasonic transducer (MUT) including an improved MUT array containing optimized transmit MUT elements and optimized receive MUT elements, a MUT array in which staggered MUT elements increase the sensitivity of the array, and a MUT array for multiple plane scanning.

Abstract: The present invention relates to a flextensional transducer device comprising a multi-resonant shell and push-pull driving system for driving the shell so as to provide at least two tunable resonant modes, thereby increasing the operational bandwidth of the device. The push-pull driving system is formed by four rings of active drive material grouped to operate as two opposing push-pull pairs. The shell has a dog-bone configuration with two arcuately shaped interior web portions joined to the pairs of rings, end sections joined to the interior web portions, and a central concave section which functions as the primary radiating surface. Upon application of a desired current to the push-pull ring pairs, the interior web portions are caused to vibrate, which vibrations are transmitted to the end sections and the central concave section.

Abstract: There is described a capacitive micromachined ultrasonic transducer array which is configured to minimize the excitation and propagation of plate waves traveling in the substrate and ultrasonic waves propagating at the interface between the array surface and the immersion fluid.

Abstract: A device for generating acoustic shock waves, comprising at least two electrodes which form a spark discharge gap G in a fluid volume and a reflector for the acoustic shock waves generated during the spark discharge made of an electrically conductive material, and wherein the power to one of the electrodes is supplied by way of the reflector.

Abstract: A method of manufacturing a diaphragm for an electroacoustic transducer which operates in accordance with the electrodynamic principle and has portions with different thicknesses made from a thermoplastically deformable material having a constant thickness, wherein, in a first work step, that portion of the diaphragm material which is to have the greater thickness in the finished diaphragm, is held by an inner positioning device, while the remaining area of the diaphragm is additionally held by an outer positioning device, and the remaining area of the diaphragm is pulled or stretched with the influence of tension and heat to reduce the thickness thereof. In a second workstep, the entire diaphragm is thermoplastically stamped in a mold.

Abstract: An ultrasonic transducer (10) includes a housing (12) having a main section (14) and a base section (16). Retainer elements (20) on the main and base sections (14 and 16) of the housing (12) are engageable only when the main and base sections of the housing are in a predetermined orientation relative to each other. The retainer elements (20) press the main and base sections (14 and 16) of the housing (12) together and securely interconnect the main and base sections of the housing. A diaphragm (82) is formed in an end portion of the main section (14) of the housing (12) opposite from the retainer elements (20). A ridge (88) projects axially outward from the diaphragm (82) to protect the diaphragm and decouple the diaphragm from a side wall (74) of the housing (12). Acoustically absorptive material (114 and 116) is disposed in the housing.

Abstract: A solid state silicon-based condenser microphone comprising a silicon transducer chip (1). The transducer chip includes a backplate (13) and a diaphragm (12) arranged substantially parallel to each other with a small air gap in between, thereby forming an electrical capacitor. The diaphragm (12) is movable relative to the backplate (13) in response to incident sound. An integrated electronic circuit chip (3) or ASIC is electrically coupled to the transducer chip (1). An intermediate layer (2) fixes the transducer chip (1) to the integrated electronic circuit chip (3) with the transducer chip (1) on a first side of the intermediate layer (2) and the integrated electronic circuit chip (3) on a second side of the intermediate layer (2) opposite the first side. The intermediate layer (2) has a sound inlet (4) on the same side as the ASIC giving access of sound to the diaphragm.

Abstract: A fiber optic hydrophone structure comprises a casing around which is wound an optical fiber. The casing includes complementary top and bottom diaphragm members that mesh together and which are separated by a spacer ring. The spacer ring is tapered to knife edges which abut the inside surfaces of the top and bottom diaphragm members. The spacer thus acts as a fulcrum when a seismic signal causes motion of the diaphragms.

Abstract: There is provided an acoustic transducer which includes a membrane of selected size and shape supported at its edges spaced from a first conductive electrode by an integral support structure with the second conductive electrode comprising a thin metal film on the membrane. The active membrane area is undisturbed by etch vias.

Abstract: Drive assembly for acoustic sources with vibrating surfaces (1) capable of being set in vibrational motion, especially for use in seismic studies, comprising a frame (4) comprising at least one preferably centrally positioned drive part (3, 13). The drive assembly also comprises: two or more fastening devices (2) mounted in relation to the sound emitting surfaces (1) and positioned on opposite sides of the frame (4); two or more flexible transmission elements (5) connecting the fastening devices (2) to each other and extending on both sides of the axis between the two fastening devices;5 two or more second drive parts (6, 7, 16, 17) connected to the transmission elements (5) and positioned in cooperation with said first drive parts (3, 13) in order to make electromagnetic drives; and that each of the electromagnetic drives are adapted to provide a controlled oscillating relative motion between the related drive parts (3, 6, 7, 16, 17).

Abstract: A monolithic micromechanical piezoelectric acoustic transducer with integrated control circuit includes a support member; a piezoelectric medium disposed on the support member; first and second electrodes engaging the piezoelectric medium; and a control circuit monolithically integrated with the piezoelectric medium and electrodes on the support member and including a switching circuit for selectively interconnecting the electrodes with an I/O bus and a signal processing circuit for conditioning signals propagating between the electrodes and the I/O bus; an array of such acoustic transducers that form an acoustic retina; and a method of making such transducers and arrays.

Abstract: An elongated, electrically conductive diaphragm is placed in a strongly magnetic field to produce a linear and an elongated sound source giving a high sound energy. At least two elongated diaphragms are positioned between intermediate and enclosing protected magnet elements, whereby the transverse length of the diaphragms are at least of the same size as that of the intermediate protected magnet elements. In this way, a sound without considerable interference merges at a short distance from the sources of the sound. By placing additional such sources of sound alongside each other, a broad sound source with a surface producing an essentially homogeneous sound field is achieved.

Abstract: An ultrasonic capacitance transducer having a sealed membrane supported above a conductive substrate by thin insulating material to form a sealed evacuated cavity whereby the transducer can operate immersed in fluid.

Abstract: An impulsive snap-through acoustic pulse generator may be used to generate n acoustic pulse in an aqueous environment without gas bubbles. The impulsive snap-through acoustic pulse generator includes a support structure having an open end; a resilient shell mounted to the support structure to define a chamber, and a gas vent in fluid communication with the chamber through which a gas passes for changing the pressure in the chamber so that the resilient shell transitions from a first stable state to a second stable state, thereby generating an acoustic pulse.

Abstract: An apparatus for producing an acoustic output in an underwater environment ncludes a radiator having a generally elongate, circular x-section with first and second ends, the outer surface of the radiator having a curved shape; an end cap attached to each end of the radiator; and a plurality of piezoceramic elements positioned and arranged to form stacks located exterior to the radiator and between the end caps. The radiator and the end caps seal off the interior of the radiator and provide an air tight cavity interior to the radiator. When a fluctuating voltage is applied across the piezoceramic stacks, the stacks are caused to longitudinally expand and contract in concert with the applied voltage thus inducing a displacement of the end caps. Since the ends of the radiator are attached to the end caps, the radiator is caused to flex inwardly and outwardly as the end caps move longitudinally.

Abstract: A broadband microfabricated ultrasonic transducer which includes a plurality of resonant membranes of different sizes and/or shapes supported above a conductive substrate.

Abstract: The piezoelectric-acoustic transducer of the present invention has a hollow case provided with a sound hole. A piezoelectric actuator is disposed inside this case that has one end fixed to the case and that bends in the direction of the thickness of the case when voltage is applied. A diaphragm is secured to one portion of the piezoelectric actuator and is positioned at a distance from the piezoelectric acturator in the direction of the thickness of the case.

Abstract: A microphone for use in underwater applications. The microphone includes a dynamic magnet and coil assembly in a housing which incorporates a hydrophobic membrane. The membrane is sufficiently porous to permit air to pass therethrough. However, water cannot pass through the membrane. The housing permits water to drain away whereby a superior underwater microphone is obtained. This invention provides the diver with a military-style noise canceling microphone that retains exceptional sound reproduction quality because it is not encapsulated. However, the new microphone can be repeatedly exposed to the marine environment without failure.

Abstract: An underwater acoustic projector comprising a pair of spaced apart end plates with an acoustic driver positioned between the end plates, the driver having smaller cross-sectional dimensions than the end plates. The end plate's edges are secured to an outer one-piece thin walled shell that provides a waterproof enclosure for the driver. That thin walled shell has a concavely inwardly bent surface between the end plates and a plurality of axially extending corrugations to provide a predetermined axial compliance and radial-to-axial transformation ratio.

Abstract: Flextensional acoustic source with sound-emitting surfaces (1, 2, 3, 4) adapted to be excited into vibrational movement, and for use in seismic exploration at sea. The source comprises a drive unit (21) being through the intermediary of at least one push element (22A, 22B) adapted to impose vibrational movement to the sound-emitting surfaces. Between at least one push element (22A, 22B) and the associated sound-emitting surface(s) (1, 2, 3, 4) there is provided a non-linear spring element (27, 28) the spring constant of which is controllable. Two oppositely acting push elements (22A, 22B) are arranged in axial alignment and preferably centrally in the source, and in addition thereto there are provided at least two tension elements (39, 40) with associated controllable, non-linear spring elements (35, 36, 37, 38) and being coupled to the sound-emitting surfaces (1, 2, 3, 4).

Abstract: A piston transducer having a central longitudinal axis and at least one piston member and an active transducer section displaced from one another along the longitudinal axis. Movement of the active transducer section is generally in a plane perpendicular to the longitudinal axis and a series of lever arms couple the movement of the active transducer section into a corresponding axial movement of the piston member and which axial movement is with a uniform velocity across the radiating surface thereof. For two-sided radiation, another piston member and series of levers may be connected to the active transducer section.

Abstract: A sound or ultrasound sensor is provided for transmitting and/or receiving sound or ultrasound, which is mechanically robust and chemically resistant and which has an adjustable emission characteristic, for example having a preferably small beam angle, having an emitting element (3) which has a flat front surface (34), and having a transducer element (1), the transducer element (1) causing the front surface (34) to oscillate on the basis of an excitation frequency, such that the entire front surface (34) carries out virtually in-phase deflections with virtually equal amplitude parallel to the normal to the front surface (34), and in which sensor concentric webs (32) are arranged on the front surface, there being a concentric gap (33) in each case between two adjacent webs (32), and a disk (5) sealing the sound or ultrasound sensor flush at the front, which disk is firmly connected to the webs (32) and has segments which are not connected to the webs (32) and are used as membranes (51).

Abstract: A surface element for a device for generating sounds by influencing opposite extremities of a surface element to oscillate from and towards each other and thereby the surface element to oscillate transversely thereto and generate sounds has at least a portion formed in the thickness direction thereof by at least two first layers (12) and an intermediate layer (13) having a lower average density than the density of the two first layers.

Abstract: A flextensional transducer for use in surface ship applications requiring the capability of withstanding underwater explosive shock is described. The transducer includes a plurality of ceramic stacked drivers disposed between an elliptical outer shell having opposing slots disposed along an inner surface of the shell and a flextensional limiting support block. The drivers are mounted on ball joint sockets which allow pivoting during high acceleration loading conditions. The support block further has a pair of curved surfaces which will generally follow, in close proximity, the inner surface of the shell and a member coupled to the opposing slots of the elliptical shell. The block can be fixed to a rigid mount disposed over at least one end of the transducer using a plurality of tie rods.

Abstract: The underwater sound projector disclosed herein employs, as radiating surfaces or pistons, stiff, lightweight panels whose mass is substantially less than the inertial component of the radiation impedance over the operating frequency range. The panels are driven in opposition by a plurality of linear actuators, e.g., piezoelectric stacks, distributed essentially uniformly over the panels so that each stack drives an essentially equal area of the panel and flexing of the panel is avoided. The compliance reactance of the actuators is made to cancel the inertial reactance of the radiation impedance at all frequencies within an at least decade-wide frequency band. In this way, operation, similar to resonance with its high efficiency, is achieved continuously over a wide frequency band.

Abstract: A method for making polyurethane acoustic windows. A molding material is lied to a reservoir connected to the bottom of the mold to fill the mold under the influence of a vacuum applied at the top of the mold. After initialling filling the mold, a second reservoir connects to the vacuum port and additional material is added to the first reservoir to partially fill the second reservoir. Thereafter the mold with the reservoirs attached is located in a pressure oven for curing. After curing the mold an acoustic window is removed from the mold for post molding operations.

Abstract: Acoustic source assembly for offshore seismic exploration, comprising at least one active vibration transducer (1) adapted to be excited by a sweep signal within a desired frequency range. At least one further and passive vibration transducer (2,3) is positioned at such small spacing (B) between the transducers that interaction therebetween provides for a relative enhancement of the frequency response of the whole source assembly at low frequencies.

Abstract: An electrostatic ultrasonic transducer formed on a semiconductor substrate by micro-machining wherein the transducer includes a silicon nitride membrane supported above the surface of the substrate by insulating supports; and the substrate and membrane define the electrodes of the transducer.

Abstract: The invention relates to directional electro-acoustic transducers compris a sealed shell consisting of two portions.A transducer according to the invention comprises one or more electro-acoustic drivers (1) composed for example of a stack of piezoelectric plates (1a, 1b, . . . 1n) located inside a sealed shell. This shell comprises a first portion (3A) symmetrical as to a plane (PP') fitted with two flanges at its ends, these flanges being coupled mechanically and acoustically by means of a rod (7) and two bolts (8) With each driver (1). The shell includes a second portion (3b) which is complementary to the first portion and which is acoustically uncoupled from the first portion and from the drivers.An application of the invention is the construction of low-frequency transmitter of acoustic waves in the water in a given direction.

Abstract: A diaphragm for use with an electro-acoustic transducer includes a diaphragm portion, an edge portion and a supporting portion. The diaphragm portion is molded by a synthetic resin material, such as polypropylene or the like. The edge portion is molded integrally with the supporting portion by a thermoplastic synthetic resin material and provided at the outer peripheral side of the diaphragm portion. The edge portion is molded integrally with the diaphragm portion by dichromatic molding.

Abstract: The invention relates to electro-acoustic transducers comprising a flexible nd sealed transmitting shell referred to as flextensional transducers. A transducer according to the invention comprises one or more electro-acoustic drivers, e.g., a stack of piezoelectric plates 1a, 1b . . . 1n, located inside a flexible and sealed shell. Each piezo-electric driver comprises, at both its ends, a counter-mass coupled mechanically and acoustically with the stack and the ends of the shell by means of an axial threaded rod and two nuts screwed on the ends of the rod. The mass of the two counter-masses and the dimensions of the stack are determined so that the fundamental frequency of the axial oscillations of this mechanical assembly will be close to the natural frequency of the bending oscillations of the shell. An application of the invention is the construction of sonar transmitters.

Abstract: An underwater acoustic transducer for providing high amplitude low frequency acoustic output wherein a plurality of flextensional transducer ovals are formed into a mechanical transformer ring with a corresponding plurality of transducer drivers received therein. A corresponding plurality of radiating surface plates are fixed to the flextensional transducer ovals so as to form a flextensional ring which has disposed on both ends thereof an end plate. Furthermore, a sealing boot is disposed around the flextensional ring which receives the necessary power to operate the transducer drivers so as to vibrate the flextensional transducer ovals to provide the desired motion. Additionally, the flextensional rings can be configured into a tube so as to provide increased levels of acoustic energy.

Abstract: A transducer device and method include affixing a preamplifier or other suitable circuit to a thin piezoelectric membrane. The membrane fully supports the circuit at an inactive region of the membrane. The membrane has at least one piezoelectrically active region that is connected to the circuit by a signal line. Preferably, the signal line is fabricated onto the membrane using integrated circuit fabrication techniques. In the preferred embodiment, the piezoelectrically active region has a diameter of less than one hundred microns and the membrane has a thickness of less than ten microns. A potting compound provides structural support of the membrane and insulates the on-membrane circuit.

Abstract: An acoustic transducer has an electrically energized crystal in contact with a flexible plate. The crystal drives the plate in a flexural mode. Particularly, the plate is oscillated so that different circular areas of the plate, referred to as nodes, do not vibrate. The nodes separate adjacent annular anti-node areas referred to as positive anti-nodes and negative anti-nodes which oscillate oppositely. An impedance matching material of uniform thickness is disposed between the plate and the surrounding medium to improve efficiency. To avoid cancellation of waves, concentric plastic layer rings are disposed between the impedance matching layer and the oscillating disk. The plastic rings act as a barrier to negative anti-nodes, thus eliminating cancellation between waves from the positive and negative anti-nodes.

Abstract: In accordance with the invention, a new type of microphone utilizes a magnetoresistive sensing element. Specifically, acoustical energy causes vibrations between a magnetoresistive element and a magnet, producing a variation in the resistance which can be used to convert an acoustical signal into a corresponding electrical signal.

Abstract: Ultrasonic piezoelectric transducer comprising a piezoelectric material having a profile whereby the transducer transmits and/or receives ultrasonic vibrations in a dilational (quasilongitudinal) mode. The profile is curved and includes a point of inflection. Possesses a vibrational peak in the frequency range 10 KHz-200 KHz. Construction is performed via profiling and tensioning the piezoelectric material.

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 self-orienting seismic detector for detecting vertical acceleration regardless of the device's horizontal orientation. The detector comprises a housing fitted with diaphragms capable of generating signals. A mass is internally suspended within the housing between the diaphragms by means of a filament which is connected at each of its ends to one of the diaphragms. Vertical motion of the detector causes internal displacement of the mass within the housing. Motion by the mass within the cylinder is translated by the filament to the diaphragms which generate signals which may then be recorded. The detector may be incorporated within or attached to an undersea cable to form a seismic detection system primarily suitable for placement on an ocean bottom, but which may be employed in a towed array. In a primary embodiment, the detector is sealed from external pressure changes such that the stresses placed upon the detector's diaphragms will be governed by particle acceleration changes rather than pressure changes.

Abstract: Gas-operated apparatus (2) for making a noise underwater, comprising a body (4), a diaphragm (6) which extends over the body (4) to define a chamber (8) between the body (4) and the diaphragm (6), a gas inlet nozzle (10) which extends into the chamber (8) and which engages an inner surface (12) of the diaphragm (6), and gas outlet means (14) for enabling gas in the chamber (8) to leave the chamber (8), the diaphragm (6) being made of an elastic material, the diaphragm (6) being such that it has an outer surface (16) which is in contact with a liquid, and the apparatus (2) being such that in use gas under pressure passes through gas inlet nozzle (10) and causes the diaphragm (6) to expand and collapse over a region of the diaphragm (6) that is in contact with the gas inlet nozzle (10) thereby to create noise which is adapted for optimum underwater transmission due to the diaphragm (6) being in contact with the liquid.

Abstract: A flextensional transducer includes a stack of driving elements disposed ng a linear axis to convert a driving power into vibrational energy. End pieces, disposed at each end of the stack, have outwardly facing arcuate surfaces. A flexural shell, formed into a loop, is disposed to circumscribe the stack and the end pieces to present an elliptical cross-section with the major axis thereof being generally coincident with the stack's linear axis. The shell is reactively coupled to the end pieces at the outwardly facing arcuate surfaces. A pliant assembly is positioned between each end piece and the flexural shell for maintaining conformal engagement between portions of the end pieces and the flexural shell. The pliant assembly is designer such that its stiffness may be adjusted.

Abstract: A drive package for acoustic transmitters includes a frame (6) of magnetic material with windows for accommodating driving members (20) and prestress devices (22) . Two windows with driving members and an intermediate window with a prestress device form a column which, by way of pressure studs (24) in the driving members and holes (14) in the frame, clamp pressure rods (4) located inside the transmitter against the shell (1) of the transmitter. The drive package may include several columns.

Abstract: In an electroacoustic transducer (1) having a diaphragm (5), behind which a partition wall (24) is situated, which partition wall extends transversely of the transducer axis (9) and is traversed by partition openings (29, 30, 31, 32) having a small cross-sectional area of at the most 0.2 mm.sup.2, and having a mask wall (38) arranged adjacent the partition wall and provided with mask-wall openings (39, 40, 41, 42) of large cross-sectional area, in the other wall (38) being coincident with at least one opening (29, 30, 31, 32) of small cross-sectional area, each opening (29, 30, 31, 32) of small cross-sectional area is situated between two spacer elements (49, 50, 51, 52, 53, 54, 55, 56) arranged between the two walls (24, 38), and each time two spacer elements (49, 50, 51, 52, 53, 54, 55, 56) together with the two walls (34, 38) bound a duct-like gap (57, 58, 59, 60) between the two walls (24, 38) in order to form an acoustic resistance.