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This research deals with acoustoelectric interactions in CdS. The first part is devoted to an experimental study of acoustoelectric effects occurring under high field conditions. An acoustic amplifier in which trapping effects are important is described, the decay time for current saturation is measured, and extreme non-uniformities in field distributions are measured and discussed. [...]

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No description available.

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Micromachined microphones with diffraction-based optical displacement detection are presented. A compliant membrane is made part of a phase sensitive diffraction grating, and the deflection resulting from external acoustic pressure alters the intensities of the diffracted orders which are monitored with integrated photodiodes. The scheme provides the displacement sensitivity of a Michelson interferometer and can be integrated without beam splitters or critical alignment problems into volumes on the order of 1mm³. The method is implemented and characterized using microphone membranes with integrated diffraction grating back electrodes fabricated on silicon using Sandia National Laboratories' dedicated processing platform. Detailed response characterization in both air and vacuum environments is performed to extract the diaphragm properties and high frequency cutoff frequencies of the microphone. Results from a finite element model of the microphone structure are in good agreement with measured data. The sensor's internal noise is characterized with measurements performed in the anechoic acoustic test facility at Georgia Tech. While utilizing 2.4mW of laser power, an (A) weighted displacement resolution of 6×10⁻⁴Å/√Hz is measured which is limited by thermal acoustic noise caused by the microphone's back-plate flow resistance.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2009. / Includes bibliographical references.

Requirements exist for a unique type of underwater acoustic source. The transducer is in the form of a linear array of discrete elements and is required to have a constants transmitting voltage response and carefully controlled directivity characteristics over a two octave bandwidth. A generalized model of a linear array of cylindrical piezoelectric ceramic acoustic radiators is developed and applied to the design of a prototype which operates over approximately one half of the required bandwidth. The prototype transducer was built and the measured results are compared with those predicted by the model. Recommendations are made for improving the performance of both the prototype and the array required to meet the full bandwidth specified.