Recent Advances in Quantitative Acoustic Microscopy

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The goal of this review is to introduce recent advances in high-resolution quantitative acoustic microscopy and to provide a brief description for quantitative characterization of the contrast response in the acoustic microscope. The most popular quantitative technique in acoustic microscopy is the V(z) method [1, 2], in which the acoustic velocity and attenuation of leaky surface acoustic waves, as well as a reflectance function can be determined from the output signal V of the transducer, acquired as a function of the specimen displacement z. Together with the well known V(z) method, we will introduce other techniques for the measurement of acoustical parameters. For quantitative materials characterization, acoustic methods employing separated transmitting and receiving transducers were developed, such as an ultrasonic micro— spectrometer with spherical—planar—pair lenses for the measurement of the reflection coefficient [3, 4]. The angular spectrum of the reflected wave in such system is determined by the rotation of the lens system as a whole, relative to the specimen surface. The ultrasonic system with two transducers was also used for a measurement of the resonant transmission coefficient,[5] and for the determination of Lamb dispersion curves [6] . Obtaining the required data for the reconstruction algorithms occurred in two ways: one, the voltage of the output transducer was measured as a function of the lateral displacement of the transducer on the specimen’s surface; or two, as a function of the frequency of the probing electrical tone burst pulse. A two—dimensional recording of the avvewaveWwaP scatteredd by the specimen was nrnpoced [7] for meacuring elastic constants.KeywordsSurface Acoustic WaveLamb WaveAngular SpectrumReflectance FunctionAcoustic MicroscopyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.