Abstract: An ultrasonic sector-scan probe comprises at least an array having a plurality of ultrasonic transducer segments, a window for transmitting and receiving ultrasonic waves and an ultrasonic wave propagation medium filled in a front space between the array and the window. A group of the ultrasonic transducer segments are selectively driven as an aperture and ultrasonic waves emitted therefrom are converged into a beam for transmission and reception. By partly or entirely changing the segments in the group with the ones outside the group the scan line is shifted to a new angle, and a member under test contacted with the window on the outside thereof is sector-scanned by the ultrasonic beam. The array is arranged so that scanning lines of the groups intersect at one point in the window or in its vicinity for sector scan.

Abstract: This invention relates to a novel design of a microprobe for measuring intensity distribution, instantaneous intensity values and acoustic signal shapes of ultrasound. The probe consists of a rod-shaped electrode which is fixed with the aid of an electrically and acoustically insulating material in a sleeve-shaped electrical shield. To one end surface of said device is adhered a piezoelectric film such that the film will come in contact with the end surfaces of the electrode, the insulating material and the electrical shield. As only the outer surface of the piezoelectric film is covered by an electrically conductive layer, the rod-shaped electrode on the inner side of the film will determine the active surface of the probe.

Abstract: A transducer array and excitation circuitry for producing ultrasonic waves in a controlled pattern and for causing the waves to be scanned along the array. The array comprises a plurality of transducer elements coupled to each other in such a way as to produce a desired wave pattern when selected elements are activated. The array may be constructed from plural transducer elements or from a single plate of transducer material comprising a plurality of elements that can be individually activated, the plural elements being intercoupled to produce the desired wave pattern. The arrangement is such that a minimum number of electrical connections to the transducer elements are required to create the desired wave pattern and to scan that pattern across the face of the array.

Abstract: A mechanically assembled non-bonded ultrasonic transducer includes a substrate, a piezoelectric film, a wetting agent, a thin metal electrode, and a lens held in intimate contact by a mechanical clamp. No epoxy or glue is used in the assembly of this device.

Abstract: The invention relates to an ultrasonic converter with a plate type ceramic oscillator in which metal electrodes are fastened to the oscillator. At one end face of the ceramic oscillator an adaptation layer of plastic is present. The entire ultrasonic oscillator, except for the side of the adaptation layer facing the medium to be insonated, is provided with a foam covering, to reduce decay damping without a substantial loss in the transmission factor.

Abstract: A device for testing fuel injectors in situ. The device comprises a detector (10) having a piezoelectric crystal (50) which converts mechanical impulses caused by the fuel injector valve needle snapping back onto its seat onto electrical signals. The signals are fed to electronic processing means (15) which detects the signal amplitude and displays it on an LED bar graph display (2) as an indication of the operating efficiency of the fuel injector. A timing system using the detector (10) as a generator of timing signals is also disclosed.

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: An acoustic impedance match between an ultrasonic transducer and an adjacent transmission medium is obtained, with performance over a relatively wide bandwidth, by providing a special matching region between the transducer and the transmission medium. The matching region includes a layer having a multiplicity of tapered elements. Each of the elements tapers down in size in the direction away from the transducer.

Abstract: A high-temperature transducer for transmitting and/or receiving sonic energy having a housing with a cylindrical opening, a metallic acoustic window element closing one end of the opening, a cylindrical transducer crystal having one planar surface in engagement with the acoustic window rearward face, a cylindrical dampening member in contact with the crystal rearward face, a first and a second thrust disc received in the cylindrical opening with a thrust transmitting sphere between the discs, and a thrust producing compression screw threadably received in the cylindrical opening supplying pressure against the first of the thrust discs which pressure is applied by means of the sphere to the second thrust disc, to the dampening means and to the crystal rearward face to force the crystal into intimate engagement with the acoustic window for effective sound transmission.

Abstract: The invention relates to a convertor for converting electrical vibrations into mechanical vibrations for non-destructive testing of objects, in particular bonded joints between two or more sheets or between sheets and a honey comb structure. Said convertor comprises a polycrystalline, piezo-electric disc, with mutually insulated electrodes on both head faces. The disc is secured in a supporting element by a suspension with a resilient member pressing centrally through a metal pin against the internal head face of the disc. The supporting element is movably installed into a holder such that the supporting element can be moved from a retracted position in the direction of the extended position until such a position is reached that the piezo-electrical disc is pressured against the object to be tested with a predetermined force.The invention also relates to a method for using the convertor.

Abstract: A transducer assembly is provided which performs simultaneous imaging and flow measurement. Separate imaging and Doppler transducers are mounted on one face of the assembly. Each transducer type is backed by backing material which provides damping in accordance with the performance criteria of the different transducer types. The transducer types may be mechanically focused in the same direction so that flow measurements are made in the center of the area being imaged.

Abstract: The acoustic imaging transducer described herein incorporates an acoustic stack contained in an alumina housing which also provides structure for electrically connecting the transducer array elements to system signal processing electronics.

Abstract: The transducer housings for clamp-on transducers of a flowmeter system are cast of an aluminum zinc alloy which is sonically conductive after casting. The transducer housings have a shear mode converting surface which has a longitudinal curvature and a cross-curvature. The cross-curvature of the shear mode conversion surface defines a solid lens which tends to focus internally reflected shear mode converted energy along the line of intersection of the flat output surface of the transducer housing with a circular metal conduit. The longitudinal curvature of the shear mode converting surface adjusts the phase velocity over the transducer output surface so as to focus the beam and reduce beam spreading along the length of the pipe and generally to correct aperture dispersion. A relatively low Q transducer crystal assembly is coupled to the aluminum-zinc alloy housing.

Abstract: A plurality of transducers is arranged successively on a common impedance matching layer of a resilient material. Each transducer comprises an elongated piezoelectric element having a width expansion vibrational mode, a pair of first and second electrodes attached to opposite surfaces of the element across its thickness and an elongated block of an impedance matching material disposed between the second electrode and the common impedance matching layer. The common impedance matching layer is bent to take the shape of an arch to conform to the surface of a frame structure which is convexed in the direction of propagation of ultrasonic energy. The piezoelectric elements are secured to the frame so that they bridge the parallel side members of the frame. The piezoelectric members are divided into a plurality of subgroups, each composed of successively arranged elements.

Abstract: An ultrasonic imaging module including a housing having an internal fluid-filled chamber, and an ultrasonic transducer producing a beam of ultrasonic energy. The transducer includes a piezoelectric transducer element and a ball-shaped ultrasonic window rotatably mounted in a bearing in one wall of the chamber for transmitting the beam of ultrasonic energy to the object to be ultrasonically scanned while rolling on the object. A source of pressured fluid is connected to the chamber and the relative size of the bearing and roller-ball window are such that a film of ultrasonic coupling fluid is applied from the chamber to the surface of the object to be scanned as the roller-ball window turns in the bearing during the scanning process. An ultrasonic lens mounted in the chamber between the transducer element and the ball-window compensates for the effect of the sphericity of the window on the ultrasonic beam.

Abstract: A highly efficient piezoelectric transducer suitable for medical applications is disclosed which exhibits a 40 db ring down time of less than 3 cycles, that is, of less than 0.7 microsecond at 4.2 MHz. The subject transducer comprises a single crystal lithium niobate active element which is supported on a formed backing material which is lapped to a surface flatness of better than 0.0002 inches (0.0015 cm). The subject transducer, which is designed to be driven at 4.2 MHz further comprises a first matching layer having an impedance of 6.8-7.4.times.10.sup.6 kg/m.sup.2 sec and a second matching layer having an impedance of between 1.8-2.4.times.10.sup.6 kg/m.sup.2 sec. An alternate embodiment dual-power transducer is also disclosed which is suitable for operating at different power levels to selectively image or produce lesions in selected body tissues.

Abstract: The beam characteristics of individual array elements of a linear transducer array are altered by collimation of ultrasonic waves using critical angle effects. A phased array transducer for a medical imaging system with a 90.degree. image sensor has a collimator which is a thin sheet of polyethylene. Acoustic waves whose angle of incidence is greater than the critical angle are totally reflected. Insignificant ultrasonic energy is generated outside of the imaged sector and there is a modest insertion loss over the acceptance region.

Abstract: An ultrasonic transducer and its method of fabrication wherein bonding between an impedance matching layer on one side of a piezoelectric layer and a support layer on the other side of the piezoelectric material is made by providing onto each material a smooth, thin gold film on the smooth surfaces of the layers which are to be in contact with one another in the assembled transducer. The layers are bonded to each other by the gold films under moderate temperature and pressure to form the transducer. Sawing of the impedance matching and piezoelectric layers into a plurality of parallel transducers attached to the support layer forms an array.

Abstract: Acoustic transducer having a piezo-electric element, including a lead section connected to the piezo-electric element, the lead section being in the form of a metallic body having a high specific attenuation.

Abstract: An ultrasonic transducer system for scanning a body including an ultrasonic transducer mounted in a transducer shoe and means for applying acoustic coupling fluid to the transducer/body interface as the shoe moves along the interface. The means for applying the coupling fluid includes a fluid reservoir and a fluid dispensing channel in the transducer shoe, a position transducer for producing a signal proportional to the movement of the dispensing means along the transducer/body interface, a microprocessor responsive to the signal, and a stepping motor driven pump controlled by the microprocessor to pump fluid from the fluid reservoir to the dispensing channel in an amount determined by the movement of the dispensing means along the ultrasonic transducer/body interface.

Abstract: A linear array for rectilinear and sector scan imaging has identical approximately diamond-shaped transducer elements fabricated by making two pairs of straight line cuts at small angles through a piezoelectric slab. The Y-axis radiation pattern (parallel to element length and perpendicular to the array length) has lower side lobe levels than equal sized rectangular elements. No changes in the imager electronics among channels is required, and the shading function may be modified by changing only the transducer.

Abstract: An ultrasonic testing instrument and a method of non-destructive and non-invasive testing. The instrument and method employ a high intensity collimated ultrasonic beam. The collimated beam is achieved by means of acoustical lenses and/or reflectors.

Abstract: A piezoelectric vibration transducer is disclosed which includes a polymeric piezoelectric film as the active element. The film is a selectively or fully polarized, uniaxially oriented material selected from the group of polyvinylidene fluoride, blended material such as polyvinylidene fluoride and PZT powder, polyvinyl fluoride, polyacrylonitrile, copolymers or vinylidene fluoride such as vinylidene fluoride and tetrafluoroethylene or trifluoroethylene. The film is bonded to electrode strips formed by printed circuit methods and then overcoated with a front electrode layer. The sandwich formed by the electrode layers and intermediate polymeric piezoelectric film can be reversed so that the front electrode layer is discontinuous while the back electrode layer is continuous, or both electrode layers can be formed to be discontinuous. Special configurations for the discontinuous pattern of electrode layers can be employed such as that specified by Fresnel's theory.

Abstract: A phased array transducer is disclosed for transducing ultrasound of a predetermined frequency. The transducer includes a number of piezoelectric elements, all having the same natural frequency, and having two surfaces located opposite to each other, each provided with an electrode. The distance between the two surfaces of each element is one quarter of the wavelength of the ultrasound produced by the transducer within the piezoelectric material.

Abstract: A data acquisition head for an ultrasonic imaging system which employs a plurality of transducers is disclosed. The transducers are rotated in a liquid filled chamber at a constant rate, each about an axis perpendicular to its transmission axis. The transducers are sequentially activated as their transmission axes cross a semi-rigid membrane which is in contact with the body. The acoustic impedance of the liquid and membrane, and the thickness of the membrane, are matched to enhance transmission. In one embodiment, the membrane is one-half or a full wavelength thick and comprises a low density polyethylene and the liquid has an acoustic impedance approximately equal to that of the polyethylene.

Abstract: Method for providing ultraacoustic transducers of the line curtain or point matrix type, and products obtained therefrom, wherein it is provided the step of forming a bar (10) of piezoelectric material having any length but width and thickness almost equal to each other, metalizing the faces (2, 4) of this bar (10) normal to the polarization axis, sticking one of the non-metalized faces (3) with a face of a substrate (5), depositing at least one metallic electrode (8) on both opposite faces (6, 7) of the substrate (5) normal to the face thereof connected with the bar (10), connecting these electrodes (8) with the metalized faces (2, 4) of the bar (10) by depositing a layer (9) of conductive epoxy resin on both opposite faces (6, 7) of the substrate (5) and coating the whole assembly by a complete jacket (11) of epoxy resin. (FIG. 5).

Abstract: A high frequency ultrasonic transducer is improved by fabricating the tungsten-polyvinyl chloride composite, which backs the elements, in a specific manner. Small particle size tungsten powder and PVC powder are placed into a high pressure die. Standard processing of the powder mixture includes degasing followed by heating and compressing. To maximize the acoustic attenuation, the pressure applied to the mixture is maintained until it has cooled down. The composite is in a state of elastic compression and spontaneously expands when removed from the die, giving rise to the high levels of acoustic attenuation.

Abstract: Method for providing ultraacoustic transducers of the line curtain or point matrix type, and products obtained therefrom, comprising the steps of forming a bar of piezoelectric material having any length but width and thickness almost equal to each other, metalizing the faces of this bar normal to the polarization axis, sticking one of the non-metalized faces with a face of a substrate (5), depositing at least one metallic electrode on both opposite faces of the substrate normal to the face thereof connected with the bar, connecting these electrodes (8) with the metalized faces of the bar by depositing a layer of conductive epoxy resin on both opposite faces of the substrate and coating the whole assembly with a complete jacket of epoxy resin.

Abstract: In an ultrasonic system for detecting and distinguishing between superimposed and single sheets moving along a transport path, the frequency of the ultrasonic source is kept tuned to the natural frequency of the total system so that the phase displacement detected when a sheet-like object is present between the source and the ultrasonic receiver represents characteristics of the object itself. When no sheet-like object is present the receiver and the source are connected in a feedback circuit producing a certain natural frequency comparable to that which occurs with proximities between a microphone and a loud speaker, and the frequency of an oscillator is tuned to this natural frequency. When a sheet-like object is present the tuned oscillator frequency is applied to the ultrasonic source and its phase is compared with the phase of the ultrasonic signal at the receiver.

Abstract: An ultrasonic transducer has two impedance matching layers bonded to the transducer element which have different thicknesses and are 90.degree.-100.degree. and 35.degree.-55.degree. matching layers. This structure has a high sensitivity comparable to a broadband front surface matched transducer with quarter wavelength (90.degree. and 90.degree.) matching layers, and has primarily a single resonant mode so as to be suitable for relatively narrow band applications.

Abstract: In exemplary embodiments, a transmitting layer of material having a relatively high dielectric constant and high acoustic impedance, and a receiving layer of material having a relatively low dielectric constant and low acoustic impedance are superimposed such that an optimum construction is provided which simultaneously creates optimum results for the instance of transmission and reception. The two layers are interconnected by means of hybrid techniques such that they mate in a laminar manner.

Abstract: A metallic wave guide having a smooth protected surface is connected at one end to a metal structural member under test and at the other to a metal plate to which a piezo electric crystal transducer of preselected frequency response is attached. The lengths of primary and secondary wave guides are carefully selected to control attenuation and time delay of the acoustical energy transmitted along the wave guides to balance inputs and provide repeatable testing data.

Abstract: An ultrasonic signal transducer is characterized in that the piezoelectrically active element has a first unitary electrode over the entire surface of one face and a matrix of a plurality of individual electrodes on the opposite face. In the receive mode, such an arrangement effectively constitutes a plurality of individual transducers arranged in the matrix array while maintaining the efficacy of a unitary structure. The signals from the individual electrodes are individually amplified, full-wave rectified, and combined additively to produce a composite signal which eliminates the phase cancellation of the ultrasonic pulses distributed over the face of the transducer assembly.

Abstract: A sensor for detecting sand grains in a fluid flow comprises a ring-shaped member carrying an acoustic transducer. The ring-shaped member is supported on a rod by clamping means, and material having elastic properties is arranged on the surfaces of the ring-shaped member that contact the rod or the clamping means.

Abstract: An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

Abstract: The invention relates to a measuring probe for the acoustic determination of the specific gravity of a liquid. The probe includes a holder to which is attached at opposite ends thereof a ceramic piezoelectric transducer disc and a reflector disk. A reference element having a known acoustical impedance has one end thereof abutting the transducer disc and the other end thereof spaced from the reflector disc to form a sampling space therebetween.

Abstract: An ultrasonic transducer assembly for making measurements within a fluid, the assembly including a transducer, a backing member and a matching member all supported within a cylindrical metal housing with the transmitting face of the housing being sealed with a thin sealing element formed of a non-resilient relatively high impedance material encasing a matching layer having an acoustic impedance intermediate between that of the transducer element and the fluid. The thickness of the sealing element is between 1/10 and 1/1000th of a wavelength at the center frequency of the wave emitted by the transducer.

Abstract: The rate of decay of oscillations caused by application of driving pulses to the spaced crystals of an acoustic electric transducer that are mounted on a base is increased by provision of slots in the base so as to attenuate Rayleigh waves flowing in the surface thereof that can induce crystal oscillation in the thickness mode by mode conversion.

Abstract: The rate of decay of oscillations caused by application of driving pulses to the spaced crystals of an acoustic electric transducer that are mounted on a base is increased by making the thickness of the shield in contact with the ends of the crystals remote from the base such that asymmetrical Lamb waves flowing along the shield that can induce crystal oscillations in the thickness mode have a wavelength equal to twice the spacing between crystals so that their integrated effect is nearly zero.

Abstract: Spurious emissions caused by a newly-described vibration mode in an acosutic imaging transducer are suppressed by cancelling the net displacement of the center of mass of each piezoelectric element in the transducer array.

Abstract: A linear transducer array for 90.degree. or other wide angle sector scans is covered by a body contacting wear plate made of a material such as filled silicone rubber or polyurethane epoxy in which the longitudinal sound velocity is equal to or less than that in the body and in which the acoustic impedance for longitudinal sound waves is approximately equal to that of the body. Refraction, if it occurs, enhances the field of view without reducing the transmission of acoustic energy. The wear plate provides mechanical support for a fragile front surface matched array.

Abstract: A beam of ultrasonic energy is scanned through the use of a steerable mirror positioned in a liquid path traversed by the beam between a transmit-receive crystal and the target. The mirror is comprised of a material selected to have an angle of excitation of surface waves at the liquid-mirror interface which lies outside the range of angles of transmission and reception incidence at which the beam impinges on the mirror.

Abstract: An ultrasonic system and method for examining the structure of a subject body is disclosed. The system includes an improved ultrasonic transducer and power circuitry for electrically stimulating the transducer to produce an incident ultrasonic energy beam along a path extending into the subject. The incident beam produces echoes within the subject, some of which propagate back toward the transducer. The transducer, in response to received echoes, produces electrical signals bearing information about the structure of the subject. The system further includes circuitry for processing the electrical signals and a display apparatus responsive to the processed electrical signals for producing a visual display of subject structure.The transducer includes a concavo-convex piezoelectric emitter for producing ultrasonic energy having a dominant frequency, an acoustical impedance matching transformer and a coupling element.

Abstract: A high temperature ultrasonic transducer is described in which a piezoelectric crystal is held in contact with an acoustical diaphragm by a spring which also electrically couples the back face of the crystal to an electrical signal source. An oil film between the diaphragm and crystal provides an acoustical coupling. Air is used to insulate the spring electrical connection from the wall of the transducer.

Abstract: An ultrasonic transducer for a system for determining liquid levels by echo ranging composed of a housing including a piezoelectric crystal mounted within the housing to transmit acoustic waves, an impedance matching medium mounted within the housing adjacent the crystal and including a window layer and a diaphragm layer to transmit acoustic waves between the crystal and a gaseous environment which window layer is composed of a material having hollow glass spheres dispersed therein, and a dampening backing mounted in said housing to abut the crystal which backing includes a plurality of solid lead spheres; a tube mounted to extend from the housing to form a beam of acoustic waves propagated from said crystal, the tube having an end which is telescoped into the housing and spaced a short distance from the diaphragm to form a gap for flow communication; and a reference reflector assembly mounted to extend from adjacent said housing, which assembly includes a U-shaped member having two legs extending in slideabl

Abstract: The transducer is constructed from individual transducer elements arranged in an array and configured to exhibit a predominant, longitudinal mode transversely to the array. The elements are interconnected through thin flexible sheets. Each element is individually damped, and the transducer as a whole is electrically damped through resonance with the clamped capacitance and dissipation. Electrical control permits in-phase operation of all transducer elements or control with preselected phase differences.

Abstract: An ultrasonic probe particularly suitable for ultrasonic diagnostic equipments of the electronic scanning type is made up of a multiplicity of piezoelectric transducer elements, each in the shape of a rectangular plate with electrode films coated on both sides, arranged in a row at intervals and an acoustic impedance matching layer placed on the row of the transducer elements. The width-to-thickness ratio of each piezoelectric plate takes a value not greater than 0.8 and preferably between 0.4 and 0.7 so that the plate can vibrate in width expansion mode. It is highly preferable that the impedance matching layer has a laminated structure given by two layers which are different in acoustic impedance of the respective materials and individually have definite thicknesses.