This dissertation descibes the development and the application of a planar acoustic microscope lens. The prototype lens consists of a pair of concentric circular metal electrodes plated on the interface between a piezoelectric solid and a liquid medium. These two circular electrodes excite Rayleigh waves of velocity V(,R) which are converging towards the common centre but which are phase matched to the compressional waves of the velocity V(,c) in the liquid in a very narrow range of zenith angle about a value given by (phi)(,m) = sin('-1)V(,c)/V(,R). The waves radiated into the liquid are thus in the form of a hollow cone converging onto a common focal spot on the lens axis at a distance determined by this zenith angle and the radius of the electrodes. This planar acoustic microscope lens is called the Rayleigh-to-Compressional Conversion (RCC) lens. / Since the lens behavior is determined by the geometry of the electrodes and because of the simplicity of the photolithographic fabrication process of the RCC lens, more complicated configurations can be made as easily as the prototype; for example, semicircular lenses have been produced and analyzed. / A mathematical analysis based on a spatial impulse of stress applied on the solid/liquid boundary has been used to calculate the focussing characteristics of the RCC lens. For isotropic solid not only the particle displacements of the compressional wave in the liquid have been computed, but also that of the waves radiated into the solid. For anisotropic solids only the radiation pattern of the compressional wave in the liquid, which is the one of most interesting, has been investigated using an isotropic equivalent model. In the model the circular shape of the electrodes has been considered to consist of many line segments and it has been used to analyze the focal properties of partial circles and anisotropic substrate. / This planar acoustic microscope lens has been employed in standard transmission and reflection imaging experiments to demonstrate the structure of its focal spot and in particular the lack of spherical aberration when traversing a metal surface. Because of the hollow conical nature of the beam away from the focal region the RCC lens is inherently adapted to dark field microscopy. Some properties of semicircular lens are also given as examples in linear and nonlinear operation. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI

Pianos are machines. Their sound output is determined by acoustic efficiency which is a measure of acoustic energy produced per input mechanical work. The piano as an instrument is unique from other chordophones like violins and guitars as it uses hammers to cause string vibrations. Where work is done directly on the strings in a guitar, pianos utilize a two-step procedure in converting mechanical work into acoustic energy. First, mechanical energy is used to depress a piano key which lifts a hammer. Second, this hammer strikes the strings and acoustic energy is produced. Thus, pianos should be less efficient than strict chordophones. An index of acoustic efficiency as a function of frequency was generated using an F-note from each of the seven full octaves of a Yamaha upright piano (T118PE). Experimental results indicate an inversely proportional relationship between acoustic efficiency and key frequency.

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