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Showing papers in "IEEE Transactions on Sonics and Ultrasonics in 1985"


Journal ArticleDOI
TL;DR: In this article, a nouvelle methode de caracterisation tres precise des materiaux is proposed, in which the caracteristiques de propagation des ondes de fuite a la limite entre l'eau et l'echantillon; the vitesse de phase and l'attenuation sont determinees a travers des mesures de la courbe V(z).
Abstract: On propose une nouvelle methode de caracterisation tres precise des materiaux. On mesure les caracteristiques de propagation des ondes de fuite a la limite entre l'eau et l'echantillon; la vitesse de phase et l'attenuation sont determinees a travers des mesures de la courbe V(z). On presente une methode d'analyse spectrale pour obtenir les proprietes acoustiques a partir des courbes V(z). Description des mesures effectuees en utilisant des materiaux isotropes ou anisotropes pour lesquels les vitesses s'etendent de 2000 a 11000 m/s. On examine tous les modes d'ondes de fuite impliques dans les phenomenes d'interferences dans les courbes V(z). Resultats experimentaux confirmant les resultats theoriques. Application a l'analyse de la structure des materiaux polycristallins

536 citations


Journal ArticleDOI
TL;DR: In this article, a selection of materiaux utilised dans les transducteurs d'ultrasons and les systemes de mesure ultrasonore is presented.
Abstract: Selection de materiaux utilises dans les transducteurs d'ultrasons et les systemes de mesure ultrasonore. Cette selection peut etre effectuee sur la base des proprietes telles que vitesse acoustique, impedance et attenuation mais egalement sur la propriete d'adherence a l'epoxyde, la linearite et la propriete d'absorption de l'eau. Table des materiaux qui ont ete mesures ou dont les proprietes ont ete obtenues a partir de references

449 citations


Journal ArticleDOI
TL;DR: In this article, the authors present technologies de couches minces de AlN for integrer the dispositifs a onde acoustique de surface, with a coefficient de variation thermique nul fonctionnant.
Abstract: De nouvelles technologies de couches minces sont indispensables pour integrer les dispositifs a onde acoustique de surface ayant un coefficient de variation thermique nul avec des dispositifs semiconducteurs actifs sur une meme pastille, ce qui donnerait un circuit integre a haute frequence sur support de silicium ou support de silicium sur saphir. Les couches minces de AlN ont un interet dans le domaine du GHz a cause de la vitesse de propagation elevee. Des lignes a retard a coefficient de variation thermique nul fonctionnant au-dela de 1 GHz sont fabriquees avec une combinaison AlN/saphir. Croissance cristalline; evaluation des parametres; pertes de propagation, dispersion en frequence, epaisseur de couches; coefficient de variation thermique du retard; insertion dans le circuit integre; effet de la temperature sur le correlateur d'ondes acoustiques de surface

386 citations


Journal ArticleDOI
TL;DR: In this paper, the PZT rod-polymer composites have been used for low-frequency hydrophone applications and the effect of temperature on the electromechanical properties of the composite has also been investigated.
Abstract: Abstmcr-The objective of the present work was to gain a deeper mensions of the transducer are much smaller than the understanding of the behavior of lead zirconate titanate (PZT) polymer composites for applications such as ultrasonic medical diagnosis in the megahertz frequency range. These composites were originally developed for low-frequency hydrophone applications. The PZT rod-polymer composites have been prepared with five to 30 volume percent PZT using 0.28 mm and 0.45 mm rods. In a disc of PZT rod-polymer composite material, there are three principal types of resonance: the planar mode, the thickness mode, and various lateral modes caused by the regular periodicity of the PZT rod in the composite. These resonance modes have been studied with the following techniques: 1) electrical impedance measurement as a function of frequency and 2) laser probe dilatometry of the dynamic displacement as a function of frequency and position in the composite lattice. The observed resonance behavior is found to be a result of lateral interactions in the composite through the epoxy medium. The effect of temperature on the electromechanical properties of the composite has also been investigated. Implications of these results for optimizing the design of ultrasonic transducers are discussed.

328 citations


Journal ArticleDOI
TL;DR: Reflexion d'ondes acoustiques de surface and changements de vitesse causes par des reseaux de rubans metalliques courtcircuites as discussed by the authors.
Abstract: Reflexion d'ondes acoustiques de surface et changements de vitesse causes par des reseaux de rubans metalliques court-circuites

204 citations


Journal ArticleDOI
TL;DR: In this article, the reflectance function R(@) of a liquid-solid interface can be obtained by inverting the complex V(z) data collected with an acoustic microscope, which is based on a nonparaxial formulation of the V(Z) integral, which establishes the Fourier transform relation between R (@) and V (z).
Abstract: Absfmet-It is demonstrated that the reflectance function R(@) of a liquid-solid interface can be obtained by inverting the complex V(z) data collected with an acoustic microscope. The inversion algorithm is based on a nonparaxial formulation of the V(z) integral, which establishes the Fourier transform relation between R(@) and V(z). Examples are given to show that with this measurement technique, the acoustic phase velocities of the propagating modes in the solid medium can easily be determined and material losses can be estimated. The same technique is also used for characterizing imaging performance of focused systems. Applications In thin-6lm measurement are also discussed.

169 citations


Journal ArticleDOI
TL;DR: Avantages des dispositifs acoustoelectriques a ondes acoustiques de surface utilisant une couche piezoelectrique de ZnO deposee sur un substrat semiconducteur as discussed by the authors.
Abstract: Avantages des dispositifs acoustoelectriques a ondes acoustiques de surface utilisant une couche piezoelectrique de ZnO deposee sur un substrat semiconducteur

135 citations


Journal ArticleDOI
TL;DR: In this paper, the electro-acoustic properties of lead zirconate titanate (PZT) rod-polymer composites relevant for ultrasonic transducer applications are reported.
Abstract: Abstmct-The electro-acoustic properties of Lead zirconate titanate (PZT) rod-polymer composites relevant for ultrasonic transducer applications are reported. Acoustic impedance of the composite materials was measured by three different techniques in the frequency range 0.33.5 MHz. Dependence of the acoustic impedance as a function of volume fraction of PZT and frequency was also modeled theoretically. Time-delay spectrometry was employed to calibrate the free-field transmitting and receiving voltage responses of the composite materials. The acoustic impedance of the composite materials was in the range of 3-10 M rayl. The figure of merit in the receiving mode of composite materials was three times that of PZT. The figure of merit for a 20percent PZT composite (2 = 7.3 M rayl) was further enhanced by 50 percent using a single-layer impedance transformer of lucite (2 =3.3 M rayl). These composite materials were molded into curved shapes by simple thermal process to fabricate focused transducers. The axial and lateral beam profiles of focused composite transducers are presented.

131 citations


Journal ArticleDOI
K. Nagai1
TL;DR: In this article, the Fourier domain recon-struction (FDR) method was proposed for ultrasonic E-scan imaging, which involves the two-dimensional Fourier transform.
Abstract: This paper presents a new synthetic-aperture focusing method for ultrasonic E-scan imaging. The method involves the two- dimensional Fourier transform and is named Fourier domain recon- struction (FDR). The performance of FDR as well as the basis for the availability of the image is derived theoretically in some detail. Conven- tional synthetic-aperture focusing is referred to as delay and sum (D&S). The computational complexity of FDR is of the order of OW2 log N) as compared to O(N3) for delay and sum in reconstructing N X N pixels. In experiments, good images of several objects have been re- constructed by FDR.

84 citations


Journal ArticleDOI
TL;DR: In this article, a technique capable of high-accuracy measurement of the phase of short RF acoustic pulses is described, and a Fourier transform approach for precision determination of linewidths comparable to the resolution spot size is also presented.
Abstract: Abstmct-The measurement and the use of phase in acoustic microscopy are discussed. It is demonstrated that in many applications phase can be used to provide sensitivity and information unparalleled by amplitude-only measurement methods. A technique capable of highaccuracy measurement of the phase of short RF acoustic pulses is described. The power of this phase measurement technique is illustrated in a number of applications. Surface material property measurements such as the Rayleigh-wave velocity and the inversion of the complex V(z) to obtain the reflectance function of a liquid-solid interface are considered. Surface topography mapping based on phase measurement is examined. A Fourier transform approach for precision determination of linewidths comparable to the resolution spot size is also presented.

71 citations


Journal ArticleDOI
TL;DR: The ability to measure elastic properties of materials and layered structures non-destructively on a microscopic scale gives rise to a new field of metrology via the reflection acoustic microscope as mentioned in this paper.
Abstract: Abstmct-The ability to measure elastic properties of materials and layered structures nondestructively on a microscopic scale gives rise to a new field of metrology via the reflection acoustic microscope. Acoustic micro-metrology accomplishes this task via the acoustic material signature (AMS), which is obtained from planar and curved surface specimens alike. The AMS constitutes a unique function that arises from interference of elastic propagating modes. These are simultaneously and coherently excited in the wide-angle lens ensembles that distinguish the acoustic microscope from other forms of ultrasonic pulse-echo systems. Several potential applications taken from diverse fields are described with experimental case studies. Examples of both materials and layered structures are described. Distinguishing features of different crystal orientations of single crystals may be readily detected. It is shown that the film thickness measurement of a wide variety of opaque materials is readily accomplished nondestructively and without a step. Machining damage in a Be surface may also be determined nondestructively. The AMS limitations imposed by frequency and material combinations, as presently viewed, are treated in the concluding section.

Journal ArticleDOI
TL;DR: The composition spatiale and the composition frequentielle as discussed by the authors is the observation of a cible a partir de different lieux dans l'espace or avec different frequences and en combinant les echos independant statistiquement for produire a image composee ont ete utilisees for reduire l'effet de speckle.
Abstract: La composition spatiale et la composition frequentielle c'est-a-dire l'observation d'une cible a partir de differents lieux dans l'espace ou avec differentes frequences et en combinant les echos independant statistiquement pour produire une image composee ont ete utilisees pour reduire l'effet de speckle. Amelioration du rapport signal sur bruit mais reduction de la resolution. On compose alors avec des signaux correles spatialement c'est-a-dire des faisceaux se recouvrant pour la composition spatiale ou des bandes passantes se recouvrant pour la composition frequentielle

Journal ArticleDOI
TL;DR: In this article, the authors present selected results of work in materials science (ceramics, single crystals, polymers, thin ams, and integrated circuits) and bio-engineering (living cells, mucous coats, and cuticle structures).
Abstract: Although the technique of scanning acoustic microscopy was introduced more than a decade ago, there still is a general lack of wide-spread applications research due to the limited number of instru- ments worldwide To enlarge the spectrum of applications, this contri- bution presents selected results of work in materials science (ceramics, single crystals, polymers, thin ams, and integrated circuits) and biol- ogy (living cells, mucous coats, and cuticle structures) and an opening angle of 100" are used The broadband design of the matching network and transducer and anti- reflection coating enables the frequency range to be cov- ered by two acoustic objectives, operating from 08 to 13 and 13 to 20 GHz, respectively The x- and y-scanning is performed by electromagnetic coil systems driving the objective in a raster mode (x-scanning frequency locked

Journal ArticleDOI
G. Busse1
TL;DR: In this article, the question of whether a temperature periodicity in time is correlated with a periodicity along the z-coordinate is investigated. But it is difficult to imagine what a thermal wave could be characterized by a time and space periodicity, since it is not symmetrical with respect to time inversion.
Abstract: (Carslaw I959), with temperature T, coordinate z, mass density p, specific heat c, thermal conductivity k, and time t. This type of equation is known from diffusion. As the equation is not symmetrical with respect to time inversion, it describes an irreversible process which steadily reduces existing gradients. On this basis it is difficult to imagine what a thermal wave could be. A wave is characterized by a periodicity in time and space. The question is, therefore, whether a temperature periodicity in time is correlated with a periodicity along the z-coordinate. If temperature is modulated at the plane z = 0 at the angular frequency cl and with amplitude ATO, then the modulation at z > 0 is (Carslaw & Jaeger 1959)

Journal ArticleDOI
TL;DR: In this paper, a 5-MHz 64-element linear array transducer composed of vinylidene fluoride and trifluoroethylene copolymer (P(VDF-TrFE)) has been developed and its performance studied.
Abstract: A 5-MHz 64-element linear array transducer composed of vinylidene fluoride and trifluoroethylene copolymer (P(VDF-TrFE)) has been developed and its performance studied. The transducer has high resolution in both lateral and depth directions and has energy conver- sion efficiency high enough to be used for practical applicalions. The electroacoustic conversion loss (CL) is 6 dB at 5 MHz, and the pulse- echo ring-down period at -20 dB is 1.0 PS. These experimental values are in good agreement with theoretical ones calculated with Mason's equivalent circuit in which the internal losses of a piezoelectric material are taken into account. The ultrasonic field distribution from the array is also in good agreement with the simulations obtained using a numer- ical Huygens' wavelet approach for pulse waves. The maximum cross coupling voltage between the nearest neighbor elements is len percent of the driving voltage. This degree of cross coupling does not appreci- ably degrade the ultrasonic field distribution. A medical echogram taken with this transducer is shown. Its lateral and depth resolutions nn the focal plane are 1.5 mm and 0.75 mm, respectively.

Journal ArticleDOI
TL;DR: In this paper, a wideband reflection acoustic microscopy (WRSIM) was constructed to carry out the experimental verification of thin and thick-film materials deposited on a substrate using widehand reflection AA microscopy.
Abstract: Abslmcf-A methodology for complete characterization of thinand thick-film materials deposited on a substrate using widehand reflection acoustic microscopy is presented. A wideband reflection acoustic microscope that covers the frequency range of 50 to 175 MHz was constructed to carry out the experimental verification. The amplitude of the reflection coefficient of the film-substrate composite was measured versus the acoustic frequency to identify the resonant frequency of the specimen at which the film thickness is equal to one quarter of the acoustic wavelength. Then both the amplitude and the phase of the reflection coefficient at the resonant frequency were measured. Using the three measured quantities, thickness, acoustic velocity, and mass density of the film material are simultaneously determined without any prior knowledge. Two types of film materials, namely Pyrex glass film sputtered on a sapphire substrate and positive photoresist coated on a Pyrex glass substrate have been characterized using the methodology. The three measured acoustic parameters, film thickness, acoustic velocity, and mass density, agree well with the published values. For the frequency range of the microscope utilized the corresponding range of measurable film thickness is 30 pm to 5 pm for most inorganic materials, and 10 pm to 2 pm for most organic materials. For the case in which the film thickness is less than one quarter of the acoustic wavelength at the highest operation frequency of the microscope, the resonant frequency cannot be identified. However. one or two of the three acoustic parameters can still be determined by measuring the amplitude and the phase of the reflection coefficient a t a fixed acoustic frequency. This capability has been demonstrated using a gold fdm deposited on fused quartz and an aluminum film evaporated on X-cut LiNbOj substrate. Three additional transducer/lens sets with staggered center frequencies are also being assembled to cover the entire frequency range from 175 MHz t o 1000 MHz so that the measurable range of the film thickness can be extended to the submicron region. Consequently, it is concluded that this characterization methodology should he highly useful For nondestructive study of thinand thick-film materials in microelectronics.

Journal ArticleDOI
TL;DR: In this paper, the propagation type aller-et-retour associee a la reconstruction des images par ce procede de microscopie acoustique is presented.
Abstract: On utilise les techniques de reconstruction tomographiques pour traiter les donnees recueillies par un microscope acoustique a laser a balayage. Avantages importants par rapport aux methodes classiques: representation aisee de la sous-surface des objets complexes, lorsque la structure consideree se situe dans divers plans bien definis. On resume les principes de la propagation type aller-et-retour associee a la reconstruction des images par ce procede de microscopie acoustique. Presentation des modifications electroniques et mecaniques necessaires pour le microscope. Formules pour determiner les limites theoriques de resolution du microscope. Resultats de simulations

Journal ArticleDOI
TL;DR: In this article, a definition for the penetration depth of the scanning re-flection acoustic microscope is given, which depends on the elastic parameters of the object, the signal-to-noise ratio, and the operation frequency of the acoustic microscope.
Abstract: A definition for the penetration depth of the scanning re- flection acoustic microscope is given. With this definition it is possible to calculate the penetration depth of a given lens geometry for a given material. The penetration depth depends on the elastic parameters of the object, the signal-to-noise ratio, and the operation frequency of the acoustic microscope. Calculations show that for high-impedance ma- terials, the penetration depth is limited by the wavelength of the surface waves and hence by frequency. For low-impedance materials the open- ing angle of the lens can be properly selected to make the longitudinal or shear wave penetration dominant, effectively increasing the penetra- tion well above the wavelength limit of the surface wave.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the velocity and attenuation of the leaky surface wave of TIN coatings and sintered AlzOn actually have close correlation with the hardness and wear resistance of these materials.
Abstract: Mechanical properties of ceramic surfaces such as hard- ness, indentation fracture toughness, and wear resistance are largely influenced by the behavior of small flaws and defects, such as micro- cracks, delaminations, voids, and inclusion located beneath the sur- face. Acoustic microscopy is particularly suited to study this phenom- enon because it can image microscopic subsurface features without sectioning. Furthermore, it has been revealed that the velocity and at- tenuation of the leaky surface wave can be measured; these are ex- pected to have close correlation with the mechanical properties of ma- terials. New results on the nondestructive observation of subsurface cracks of Si,N, and ZrO, and delamination of TIN coatings introduced by Vickers indentation or sliding contacts are presented. The mecha- nism of delamination and wear of these materials is discussed. It is shown that the velocity and attenuation of the leaky surface wave of TIN coatings and sintered AlzOn actually have close correlation with the hardness and wear resistance of these materials. The reason for these correlations is also discussed.

Book ChapterDOI
TL;DR: In this article, the angular spectrum of the measured pressure field and a propagation matrix comprised of phase factors were computed from the measured field, the distance over which the field was to be extrapolated, and a maximum spatial frequency.
Abstract: Ultrasonic fields produced by a disk transducer have been measured in two planes normal to the transducer axis and then extrapolated from one measurement plane to the other and also back to the face of the transducer. The measurements were performed with a small PVF hydrophone and a quadrature detector which yielded kthe complex values of the pressure at regularly spaced points in the scanned planes. Wave field extrapolation was carried out digitally using Fourier transformation methods which characterize the propagation of a field from one plane to another as a linear filtering operation. The filtering process was implemented as a product of the angular spectrum of the measured pressure field and a propagation matrix comprised of phase factors computer from parameters which included the wavelength of the measured field, the distance over which the field was to be extrapolated, and a maximum spatial frequency. The extrapolated field was then obtained by inverse Fourier transformation of the angular spectrum-phase matrix product. Comparisons of extrapolation results with measured data and with theoretical predictions show reasonable agreement and also demonstrate the sensitivity of the extrapolation process to the extent and shape of the spatial frequency window employed to determine the non-zero elements in the phase matrix. The results indicate fields can be extrapolated more accurately by sampling higher than the Nyquist rate and extending the size of the plane over which the measurements are made.

Journal ArticleDOI
TL;DR: In this paper, a detailed design theory of the Sezawa wave convolver is developed, and the fabrication of a high-efficiency convolver using a ZnO-Si0,-Si structure is discussed.
Abstract: A detailed design theory of the Sezawa wave convolver is developed, and the fabrication of a high-efficiency convolver using a ZnO-Si0,-Si structure is discussed. The important points to improve the efficiency are 1) an optimum choice of SAW propagation direction on the Si substrate, 2) an optimum design of the resistivily of the Si epitaxial layer and ZnO film thickness, and 3) an improvement for low- ering SAW propagation lsos and resistance of output circuit. The ex- periments were carried out for two specifications each with a 20-mm and 40-mm gate length. The highest efficiency (F,) of -35 dBm was obtained in the gate length of 20 mm while the time-bandwidth product (ET) was 107. The highest ET product of 227 was obtained in the gate length of 40 mm, while F, was -47.5 dBm. At the present time, the maximum available ETproduct is less than 320 due to the group velocity dispersion.

Journal ArticleDOI
TL;DR: In this article, an automated technique for determining the speed of sound using the scanning laser acoustic microscope (SLAM) has been developed, which can be used to develop indices that quantify the spatial gradient of the tissue's speed.
Abstract: Abstmct-An important ultrasonic propagation property for tissue characterization is the speed of sound. The scanning laser acoustic microscope (SLAM) provides the capacity to determine the speed of sound in tissue specimens or portions of specimens on the submillimeter scale. This capability potentially can be utilized to develop indices that quantify the spatial gradient of the tissue’s speed of sound. An automated technique for determining the speed of sound using the SLAM has been developed. It is now possible to study quantitatively the degree of tissue heterogeneity from SLAM measurements of the speed of sound distribution. T

Journal ArticleDOI
TL;DR: In this paper, the authors present a set of articles from the special issue of the IEEE International Journal of Distributed Sensor Networks (JSSN) 1984, with a focus on the development of a single spherical lens concentrating the energy from a large source to a narrow waist with a size determined by the acoustic wavelength.
Abstract: W HEN I was first asked to write for this special issue, I was occupied with the reorientation of our entire research program and another article on acoustics seemed like a diversion. I resisted. But the editors were very persuasive, and the special issue has proved to be irresistible. The articles of this issue form a set that is complete, but but there are a few points that can be added to fill in some of the background. This is an opportunity to talk with a special audience, to acknowledge the contributions from those who have worked with us along the way, and to express our appreciation for the people who have provided the funds. Those people in Washington and in the foundations who work so hard to fund research programs make it all possible. There is little that could have been accomplished without them. In London during the month of July 1984, manufacturers exhibited their prototypes of the commercial instruments. 1984 was a milestone year for acoustic microscopy, for the information gathered with these new models outweighs anything that has appeared before. Each of the prototypes will incorporate the essential concept that we have been exploiting for several years; the concept of a single spherical lens concentrating the energy from a large source to a narrow waist with a size determined by the acoustic wavelength. This type of lens does not suffer from spherical aberrations; it is diffraction limited . The original motivation for our work came from the biologists. We were told that it was a matter of some importaye to improve the resolution beyond the limit of 3000 A set by the optical instrument with a water immersion lens. They suggested a factor of two for the improvement. It will be some time before we know whether that is true. In the meantime, the instruments will be used in fields other than biology. I suspect that polymer chemists will be the first to acquire the commercial acoustic instruments, just as they were first to acquire the scanning electron microscopes (SEM). Why did it take so long to reach this stage? That is the interesting question. Certainly the technology was available. Sokolov’s suggestion goes back 35 years. I think that part of it may have been our own inhibitions or misconceptions. One misconception is that the image must be presented in real time, 30 frames per second, as defined by the tel-

Journal ArticleDOI
TL;DR: In this paper, the insertion loss procedure yields an attenuation coefficient uncertainty to within five percent, a dynamic range from 4 to 28 dB/mm, and an insertion loss sensitivity of 0.2 dB.
Abstract: Absrmcf-There has been a lack of an accurate procedure for the measurement of an attenuation coefficient for biological tissues at 100 MHz with the scanning laser acoustic microscope (SLAM). The solution to this problem has been approached with two general schemes. One involved a calibrated look-up table, and the other utilized the measurement of insertion loss. For the latter a procedure has been developed and verified using known biological solutions. The insertion loss procedure yields an attenuation coefficient uncertainty to within five percent, a dynamic range from 4 to 28 dB/mm. and an insertion loss sensitivity of 0.2 dB. N IMPORTANT tissue characterization property is the ultrasonic attenuation coefficient, which is the decrease in energy of the sound wave when it propagates through a material. The attenuation includes absorption and scattering. Absorption represents the loss of energy into heat within the specimen. Scattering is a redirection of the energy due to the inhomogeneities of the specimen and includes reflection, refraction, and diffraction. The scanning laser acoustic microscope (SLAM) is a useful tool for providing at 100 MHz, the ultrasonic attenuation coefficient of tissue. A number of techniques have been developed to perform this measurement with the SLAM, and this report details and evaluates these techniques. Details of ultrasonic velocity measurements are found in companion papers [l], [2].

Journal ArticleDOI
TL;DR: In this paper, an ultrasound pulse Doppler system is presented, capable of performing real time spectral analysis of data originating from a number of sample volumes, using a surface-acoustic-wave-based ultrafast spectrum analyzer.
Abstract: Abstmct-An ultrasound pulse Doppler system is discussed, capable of performing real time spectral analysis of data originating from a number of sample volumes. The use of a surface-acoustic-wave-based ultrafast spectrum analyzer allows for a large amount of Doppler data to be processed in a time equal to a few tens of microseconds for each equivalent channel. Sonograms comparable to those obtained in single gate-fast Fourier transform-based-Doppler systems can thus be simultaneously presented, showing the velocity distribution in different sample volumes as a function of time. Alternately, the instantaneous velocity profile can be mapped as a function of depth, thus allowing for the possibility of bidimensional imaging. A prototype flowmeter capable of processing Doppler data from 32 range cells in real time is described and preliminary results obtained in virro under simulated flow conditions are presented.

Journal ArticleDOI
TL;DR: In this paper, a range of reflection acoustic micrographs that demonstrate how different contrast mechanisms can lead to images useful in materials science are discussed and conditions necessary for the production of various types of image are discussed, in terms of the elastic properties of and the boundary conditions close to the feature of interest.
Abstract: A range of reflection acoustic micrographs that demon- strate how different contrast mechanisms can lead to images useful in materials science are discussed. The most important class of mecha- mism affecting contrast involves disturbance of the leaky Rayleigh wave propagating along the surface of the specimen. Pictures of very fine cracks (considerably smaller than the acoustic wavelength) and regions of plastic deformation can be obtained using this mechanism. The abil- ity of the scanning acoustic microscope (SAM) to image plastic defor- mation is a particularly important application to materials science be- cause there are serious limitations to existing techniques. Useful images may also be obtained in situations where Rayleigh-wave excitation does not predominate; in such cases interference between hulk waves can be responsible for the contrast observed. The conditions necessary for the production of various types of image are discussed, in terms of the elastic properties of and the boundary conditions close to the feature of interest.

Journal ArticleDOI
TL;DR: The diagnostic utility of quantitative backscatter imaging (B'-scan) was investigated using three groups of patients and results suggest that the B'-Scan augments the information of a conventional B-scan.
Abstract: The diagnostic utility of quantitative backscatter imaging (B'-scan) was investigated using three groups of patients. Estimates of both the attenuation coefficient and the backscatter coefficient in the first group of healthy volunteers were consistent with results reported elsewhere. The backscatter coefficient measured in a group of six sub- jects with documented cirrhosis of the liver was significantly higher than normal. In contrast, the backscatter coefficient measured in a group of six subjects with adenocarcinoma metastasis of the liver was significantly lower than normal. These results suggest that the B'-Scan augments the information of a conventional B-scan.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a method for focusing the beam from an interdigital transducer and mapping a leaky surface acoustic wave (SAW) velocity on a solid sample surface.
Abstract: Abstmt-Methods of measuring the acoustic properties of solids using acoustic beams in a liquid generated by interdigital transducers (IDT) are described. An IDT can radiate acoustic waves into a liquid in oblique directions with respect to the substrate, and the wave fronts can be arbitrarily controlled by designing the IDT shape. When the acoustic beam is incident on the solid sample-water interface near the Rayleigh angle, the reflection field is equal to the superposed fields of the specular reflection and the reradiation from the leaky surface acoustic wave (SAW) excited on the sample. One normal IDT pair on a piezoelectric substrate is used to measure the acoustic properties of a solid sample. The velocity and the attenuation of the leaky SAW on the sample can be obtained by measuring the trailing field due to the reradiation. A new method for focusing the beam from an IDT and mapping a leaky SAW velocity on a solid sample surface is shown. An interdigital electrode is divided into several sections, each of which is positioned to form a one-dimensional Fresnelphase-plate interdigital transducer (FPP IDT) on a piezoelectric substrate. It has been found that the FPP IDT generates a converging beam onto a focal plane, and the present system is suitable for measuring the two-dimensional variation of the leaky SAW phase velocity on a sample surface. T

Journal ArticleDOI
TL;DR: Quantitative analysis indicates that attachment sites have increased acoustic impedance relative to other regions within the cell as well as spatial and temporal changes in the impedance at the attachment site.
Abstract: Abstmcf-The scanning reflection acoustic microscope operating at 1.7 GHz is used to observe the contacts between living cells and their substrates. When the acoustic microscope lens is focused on the surface of the substrate, sites of cell-substrate attachment appear as darkened areas in the acoustic image. Quantitative analysis indicates that attachment sites have increased acoustic impedance relative to other regions within the cell. Acoustic images of moving cells show spatial and temporal changes in the impedance at the attachment site.

Journal ArticleDOI
TL;DR: The Quate-Lemons scanning acoustic microscope as discussed by the authors is based on a conventional optical microscope, and so comparisons between the two modes are easily made; the instrument is simple to set up and operates routinely in an industrial environment.
Abstract: Absfmct-The design and industrial applications of a Quate-Lemons scanning acoustic microscope are described. The microscope is based on a conventional optical microscope, and so comparisons between the two modes are easily made; the instrument is simple to set up and operates routinely in an industrial environment. The basis of the instrument is a miniature lens scanner, little larger than an optical objective lens, which mounts on the turret of an optical microscope. Selection between modes is simply achieved by turret rotation, ensuring good registration between images. An integrated computer system is used to control the instrument, recording images and V(z) curves into a 512point square digital frame store, and this is also used for image processing. The design of the microwave electronics is explained, and emphasis is put on the low frequency performance of the system. This is illustrated with interior images of production components.