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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 10 • Date Oct. 2004

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Displaying Results 1 - 25 of 27
  • [Front cover]

    Publication Year: 2004 , Page(s): 1 - 2
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  • [Inside front cover]

    Publication Year: 2004 , Page(s): 3
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  • [Inside back cover]

    Publication Year: 2004 , Page(s): 4
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  • Table of Contents

    Publication Year: 2004 , Page(s): 5 - 6
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  • Information for Contributors with Multimedia Addition

    Publication Year: 2004 , Page(s): 1193 - 1197
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  • A multimedia example

    Publication Year: 2004 , Page(s): 1198
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  • Frequency shifts in a piezoelectric body due to small amounts of additional mass on its surface

    Publication Year: 2004 , Page(s): 1199 - 1202
    Cited by:  Papers (5)
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  • Minimum-loss short reflectors on 128/spl deg/ LiNbO/sub 3/

    Publication Year: 2004 , Page(s): 1203 - 1205
    Cited by:  Papers (9)
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  • New type of linear ultrasonic actuator based on a plate-shaped vibrator with triangular grooves

    Publication Year: 2004 , Page(s): 1206 - 1208
    Cited by:  Papers (2)
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  • Determination of complex coefficients of radially polarized piezoelectric ceramic cylindrical shells using thin shell theory

    Publication Year: 2004 , Page(s): 1209 - 1215
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB) |  | HTML iconHTML  

    A method is presented to determine the complex coefficients E/sub 33//sup T/, s/sub 11//sup E/, s/sub 12//sup E/, and d/sub 31/ of piezoelectric materials. The real parts of these coefficients are determined using axially polarized thin discs in the ANSI/IEEE Standard but are determined here using radially polarized cylindrical shells. The coefficients are determined by iteratively refining them until the values of the low-frequency complex admittance, three resonance frequencies, and three band-widths computed using a thin-shell analytical model and the coefficients are very nearly equal to measured values. The accuracy of the method is determined by using quantities computed using a finite-element model in place of measured values. Measurement errors are accounted for by using a resolution of 10 Hz to compute the critical frequencies. The differences between the coefficients input to the finite-element model and those obtained using the iteration method are the errors. It is shown that the method is sufficiently accurate to use thin radially polarized cylindrical shells to determine the properties of new materials as well as characterize those used in hydrophones or other devices. View full abstract»

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  • IEN-CsF1 accuracy evaluation and two-way frequency comparison

    Publication Year: 2004 , Page(s): 1216 - 1224
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (702 KB) |  | HTML iconHTML  

    In this paper we report the accuracy evaluation of the Italian primary frequency standard IEN-CsF1. We discuss the shifts the frequency standard is corrected for and the procedure used for the accuracy evaluation. In the last section we report frequency comparisons of our fountain with those of remote laboratories and with International Atomic Time. View full abstract»

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  • High spectral purity microwave oscillator: design using conventional air-dielectric cavity

    Publication Year: 2004 , Page(s): 1225 - 1231
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    We report exceptionally low PM noise levels from a microwave oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator. Our approach is to increase the discriminator's intrinsic signal-to-noise ratio by use of a high-power carrier signal to interrogate an optimally coupled cavity, while the high-level of the carrier is suppressed before the phase detector. We developed and tested an accurate model of the expected PM noise that indicates, among other things, that a conventional air-dielectric resonator of moderate Q will exhibit less discriminator noise in this approach than do more esoteric and expensive dielectric resonators tuned to a high-order, high-Q mode and driven at the dielectric's optimum power. View full abstract»

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  • A cryogenic open-cavity sapphire reference oscillator with low spurious mode density

    Publication Year: 2004 , Page(s): 1232 - 1239
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (926 KB) |  | HTML iconHTML  

    In this paper, we describe the implementation of a microwave cryogenic sapphire oscillator (CSO) at the Laboratoire de Physique et Metrologie des Oscillateurs. In our realization we solved the problem of the spurious modes by operating the sapphire resonator in an open cavity. The CSO compared to a hydrogen maser demonstrates a frequency stability better than 3/spl times/10/sup -14/ at short term. Its long-term frequency instability of the order of 3/spl times/10/sup -12/ / day is limited by a random walk process. A first attempt to use this reference oscillator to characterize other signal sources is presented. View full abstract»

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  • Flexural traveling wave excitation based on shear-shear mode

    Publication Year: 2004 , Page(s): 1240 - 1246
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (686 KB) |  | HTML iconHTML  

    This paper presents a new mechanism for circular flexture traveling wave excitation, which is based on a shear-shear mode in a single piezoelectric disc with a center hole was poled along its radial direction. Its bottom electrode was divided into four parts, and the top electrode acted as common ground. By use of a pair of alternating current (AC) voltage signals (sine and cosine), at the disc's resonance frequency, a flexural traveling wave was generated circumferentially. Both finite element modeling (FEM) analysis of transducers by integration of Laplace equations (ATILA) analysis and experimental results demonstrate the concept. As an application example, a shear-shear mode prototype was constructed and characterized. View full abstract»

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  • Finite element analysis on piezoelectric ring transformer

    Publication Year: 2004 , Page(s): 1247 - 1254
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (845 KB) |  | HTML iconHTML  

    The use of a piezoelectric ring as transformer is reported and studied in this paper. By using a concentric electrode pattern, a ring-shaped transformer can be designed to operate at its high order extensional modes. Lead zirconate titanate (PZT) ceramic rings with 12.7-mm outer diameter, 5.1-mm inner diameter and 1.2-mm thickness were used to fabricate the prototypes. Three-dimensional (3-D) finite element models are built to study and analyze the vibration characteristics of the piezoelectric transformers (PTs) using higher order modes (>3). The resonant frequencies, mean coupling effect, mode shapes, and other open-circuit characteristics are simulated and compared with experimental measurements. Prototypes of PTs using mode order three and four were fabricated and characterized. Good agreement can be obtained between experimental results and finite element model (FEM) simulations. The dimensions for the PTs using mode order three and four were fabricated and characterized. Good agreement can be obtained between experimental results and finite element model (FEM) simulations. The dimensions for the PTs using higher order symmetric extensional modes are optimized by FEM. To avoid mode coupling with the thickness mode, the ideal ring thickness has to less than or equal to 0.6 mm. The ring PT offers advantages of simple structure and small size. It has a good potential in making low cost PT for low-voltage applications. View full abstract»

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  • Fabrication and modeling of high-frequency PZT composite thick film membrance resonators

    Publication Year: 2004 , Page(s): 1255 - 1261
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (707 KB) |  | HTML iconHTML  

    High-frequency, thickness mode resonators were fabricated using a 7 /spl mu/m piezoelectric transducer (PZT) thick film that was produced using a modified composite ceramic sol-gel process. Initial studies dealt with the integration of the PZT thick film onto the substrate. Zirconium oxide (ZrO/sub 2/) was selected as a diffusion barrier layer and gave good results when used in conjunction with silicon oxide (SiO/sub 2/) as an etch stop layer. Using these conditions, devices were produced and the acoustic properties measured and modeled. The resonators showed a resonant frequency of about 200 MHz, an effective electromechanical coupling coefficient of 0.34, and a Q factor of 22. Modeling was based on a Mason-type model that gave good agreement between the experimental data and the simulations. The latter showed, for the PZT thick film, an electromechanical coupling coefficient of 0.35, a stiffness of 8.65/sup */10/sup 10/ N.m/sup -2/ and an e/sub 33/,/sub f/ Piezoelectric coefficient of 9 cm/sup -2/. View full abstract»

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  • Probing acoustic fields of clinically relevant transducers: the effect of hydrophone probes' finite apertures and bandwidths

    Publication Year: 2004 , Page(s): 1262 - 1270
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1353 KB) |  | HTML iconHTML  

    The influence of finite aperture and frequency response of piezoelectric ultrasonic hydrophone probes on the free-field pulse intensity integral (PII) and mechanical index (MI) was investigated using a comprehensive acoustic wave propagation model. The model developed was capable of predicting the true pressure-time waveforms at virtually any point in the field. The input to the model used pressure amplitude data measured in the immediate vicinity of the acoustic source or transducer considered. The experimental verification of the model was obtained using a commercially available, 8 MHz, dynamically focused linear array and a single element, 5 MHz, focused rectangular source. The verification was performed at low and high excitation levels, corresponding to linear and nonlinear acoustic wave propagation, respectively. The pressure-time waveforms were recorded using piezoelectric polymer hydrophone probes that had different sensitivities, frequency responses, bandwidths, and active element diameters. The nominal diameters of the probes ranged from 50 to 500 /spl mu/m, and their useable bandwidths varied between 55 and 100 MHz. The PII, used to calculate the thermal index (TI), was found to increase with increasing bandwidth and decreasing effective aperture of the probes. The MI, another safety indicator, also was affected, but to a lesser extent. The corrections predicted using the model were used to reduce discrepancies as large as 30% in the determination of PII. The results of this work indicate that, by accounting for hydrophones' finite aperture and correcting the value of PII, all intensities derived from the PII can be corrected for spatial averaging error. The results also point out that caution should be exercised when comparing acoustic output data. In particular, hydrophone's frequency characteristics of the effective diameter and sensitivity are needed to correctly determine the MI, TI, and the total acoustic output power produced by an imaging transd- - ucer. View full abstract»

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  • A swept frequency multiplication technique for air-coupled ultrasonic NDE

    Publication Year: 2004 , Page(s): 1271 - 1279
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (995 KB) |  | HTML iconHTML  

    A new technique has been investigated for improving the signals that can be obtained in air-coupled nondestruction evaluation (NDE). This relies on the wide bandwidth available from polymer-filmed capacitive transducers. The technique relies on a swept-frequency "chirp" signal, which is transmitted from a transducer in air. The new technique differs from existing time-domain correlation techniques, such as pulse compression, in that a single multiplication process is performed in the time domain to give a difference frequency signal. This then can be isolated easily in the frequency domain. It will be demonstrated that this new swept frequency multiplication (SFM) approach gives the potential for rapid air-coupled imaging. View full abstract»

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  • Effect of electric load impedances on the performance of sandwich piezoelectric transducers

    Publication Year: 2004 , Page(s): 1280 - 1286
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    Based on the electromechanical equivalent circuit, the sandwich piezoelectric transducer with adjustable resonance frequency is studied. The underlying theory of frequency adjustment is its piezoelectric effect. In this paper, the influence of electric load impedance (including electric resistance, electric inductance, and electric capacitance) on the resonance frequency, the antiresonance frequency, and the effective electromechanical coupling coefficient is analyzed theoretically and experimentally. It is demonstrated that the electric load impedance can change the resonance frequency, the antiresonance frequency, and the effective electromechanical coupling coefficient. When the electric load resistance is increased, the resonance frequency and the antiresonance frequency are increased; the effective electromechanical coupling coefficient has a maximum value when the electric load resistance changes. When the electric load resistance becomes large, the effect of the electric load resistance on the effective electromechanical coupling coefficient is negligible. When the electric load inductance is increased, the resonance frequency and the antiresonance frequency are decreased, whereas the effective electromechanical coupling coefficient is increased. When the electric load capacitance is increased, the resonance frequency, the antiresonance frequency, and the effective electromechanical coupling coefficient are all decreased. It should be noted that when the electric load impedance becomes large, the effect of the electric load impedance on the resonance frequency, the antiresonance frequency, and the effective electromechanical coupling coefficient of a sandwich piezoelectric transducer becomes negligible. View full abstract»

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  • Guided Lamb waves and L-SAFT processing technique for enhanced detection and imaging of corrosion defects in plates with small depth-to wavelength ratio

    Publication Year: 2004 , Page(s): 1287 - 1297
    Cited by:  Papers (4)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1409 KB) |  | HTML iconHTML  

    The Lamb synthetic aperture focusing technique (L-SAFT) imaging algorithm in the Fourier domain is used to produce Lamb wave imaging in plates while considering the wave dispersive properties. This artificial focusing technique produces easy-to-interpret, modified B-scan type images of Lamb wave inspection results. The high level of sensitivity of Lamb waves combined with the L-SAFT algorithm allows one to detect and to produce images of corrosion defects with small depth-to-wavelength ratio. This paper briefly presents the formulated L-SAFT algorithm used for Lamb waves and, in more details, some experimental results obtained on simulated and real corrosion pits, demonstrating the benefit of combining L-SAFT with pulse-echo Lamb wave inspection. The obtained images of the real corrosion defects showed detection of pits with a depth-to-wavelength ratio of approximately 2/11. View full abstract»

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  • Film-loaded SAW waveguides for integrated acousto-optical polarization converters

    Publication Year: 2004 , Page(s): 1298 - 1307
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (847 KB) |  | HTML iconHTML  

    We report on a detailed theoretical and experimental investigation of film-loaded surface acoustic wave (SAW) waveguides in lithium niobate (LiNbO/sub 3/) for integrated acousto-optical (AO) polarization converters. The numerical analysis is based on both a scalar and a full-vectorial model. Dispersion plots and figures of merit for several structures are given, which lead to design parameters for optimized polarization converters. It is pointed out that very attractive structures are metal/dielectric/LiNbO/sub 3/ strip waveguides and dielectric/LiNbO/sub 3/ slot waveguides, in which metal is either gold (Au) or aluminum (Al), and the dielectric film is an optical transparent material such as silicon oxide (SiO/sub 2/), magnesium oxide (MgO), or aluminium oxide (Al/sub 2/O/sub 3/). Polarization converters with the designed acoustical waveguides have been realized and characterized by optical conversion and laser probing measurements. View full abstract»

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  • Simulation of characteristics of a LiNbO/sub 3//diamond surface acoustic wave

    Publication Year: 2004 , Page(s): 1308 - 1313
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB) |  | HTML iconHTML  

    High-frequency surface acoustic wave (SAW) devices based on diamond that have been produced to date utilize the SiO/sub 2//ZnO/diamond structure, which shows excellent characteristics of a phase velocity of over 10,000 m/s with a zero temperature coefficient; this structure has been successfully applied to high-frequency narrowband filters and resonators. To expand material systems to wideband applications, c-axis-oriented LiNbO/sub 3/ on diamond was studied and a coupling coefficient up to 9.0% was estimated to be obtained. In this paper, the characteristics of LiNbO/sub 3//diamond with the assumption that the LiNbO/sub 3/ film is a single crystal have been studied by theoretical calculations to find higher coupling coefficient conditions. Calculations are made for the phase velocity, the coupling coefficient, and the temperature coefficient of the Rayleigh wave and its higher mode Sezawa waves. As a result, LiNbO/sub 3//diamond is found to offer a very high electromechanical coupling coefficient of up to 16% in conjunction with a high phase velocity of 12,600 m/s and a small temperature coefficient of 25 ppm/deg. This characteristic is suitable for wide bandwidth applications in high-frequency SAW devices. View full abstract»

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  • Characterization and assessment of an integrated matching layer for air-coupled ultrasonic applications

    Publication Year: 2004 , Page(s): 1314 - 1323
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    A novel ultrasonic matching layer for improving coupling between piezoelectric transducers and an air load is presented and the results of a theoretical and experimental program of work are provided. A combination of a porous material that has very low acoustic impedance with a low-density rubber material forms the basis of the approach. These matching layers were first analyzed experimentally using scanning electron and optical microscopy to determine the microscopic structure. Air-coupled resonance measurements were then performed to reveal the acoustic parameters of the individual layers that were identified within this multilayered structure. These data were then incorporated into a conventional linear model, and this has been verified and used to study performance and produce designs. Close correlation between experiment and theory is demonstrated. The most efficient designs have been implemented in a pitch/catch air-coupled system, and an improvement in received signal amplitude of 30 dB was achieved when compared with the unmatched case. View full abstract»

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  • Low temperature fabrication of immersion capacitive micromachined ultrasonic transducers on silicon and dielectric substrates

    Publication Year: 2004 , Page(s): 1324 - 1333
    Cited by:  Papers (30)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1729 KB) |  | HTML iconHTML  

    A maximum processing temperature of 250/spl deg/C is used to fabricate capacitive micromachined ultrasonic transducers (CMUTs) on silicon and quartz substrates for immersion applications. Fabrication on silicon provides a means for electronics integration via post-complementary metal oxide semiconductor (CMOS) processing without sacrificing device performance. Fabrication on quartz reduces parasitic capacitance and allows the use of optical displacement detection methods for CMUTs. The simple, low-temperature process uses metals both as the sacrificial layer for improved dimensional control, and as the bottom electrode for good electrical conductivity and optical reflectivity. This, combined with local sealing of the vacuum cavity by plasma-enhanced chemical-vapor deposition of silicon nitride, provides excellent control of lateral and vertical dimensions of the CMUTs for optimal device performance. In this paper, the fabrication process is described in detail, including process recipes and material characterization results. The CMUTs fabricated for intravascular ultrasound (IVUS) imaging in the 10-20 MHz range and interdigital CMUTs for microfluidic applications in the 5-20 MHz range are presented as device examples. Intra-array and wafer-to-wafer process uniformity is evaluated via electrical impedance measurements on 64-element ring annular IVUS imaging arrays fabricated on silicon and quartz wafers. The resonance frequency in air and collapse voltage variations are measured to be within 1% and 5%, respectively, for both cases. Acoustic pressure and pulse echo measurements also have been performed on 128 /spl mu/m/spl times/32 /spl mu/m IVUS array elements in water, which reveal a performance suitable for forward-looking IVUS imaging at about 16 MHz. View full abstract»

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  • A miniaturized catheter 2-D array for real-time, 3-D intracardiac echocardiography

    Publication Year: 2004 , Page(s): 1334 - 1346
    Cited by:  Papers (24)  |  Patents (2)
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3271 KB) |  | HTML iconHTML  

    The design, fabrication, and characterization of a 112 channel, 5 MHz, two-dimensional (2-D) array transducer constructed on a six layer flexible polyimide interconnect circuit is described. The transducer was mounted in a 7 Fr (2.33 mm outside diameter) catheter for use in real-time intracardiac volumetric imaging. Two transducers were constructed: one with a single silver epoxy matching layer and the other without a matching layer. The center frequency and -6 dB fractional bandwidth of the transducer with a matching layer were 4.9 MHz and 31%, respectively. The 50 /spl Omega/ pitch-catch insertion loss was 80 dB, and the typical interelement crosstalk was -30 dB. The final element yield was greater than 97% for both transducers. The transducers were used to acquire real-time, 3-D images in an in vivo sheep model. We present in vivo images of cardiac anatomy obtained from within the coronary sinus, including the left and right atria, aorta, coronary arteries, and pulmonary veins. We also present images showing the manipulation of a separate electrophysiological catheter into the coronary sinus. View full abstract»

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Aims & Scope

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control focuses on the theory, design, and application on generation, transmission, and detection of bulk and surface mechanical waves.

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Meet Our Editors

Editor-in-Chief
Steven Freear
s.freear@leeds.ac.uk