Determination of Vibrating Structure Patterns Using Acoustic Waves

The objective of this work was to develop an acoustic field based technique that would be capable of remote sensing and reproduction of vibrating structure patterns. Knowledge of vibrating pattern characteristics is of interest in many applications, including minimization of noise generation in different media and design and optimization of piezoelectric transducers used in diagnostic ultrasound imaging. The technique is based on the angular spectrum method of wave-field analysis, and is applicable to both continuous and wideband pulsed waves. It also allows the effects of acoustic parameters such as absorption, dispersion, refraction, and phase distortion to be accounted for. Examples of remotely reconstructed surface velocity distributions of complex acoustic radiators operating in the low MHz (1–3MHz) range of frequencies will be presented. The examined geometries include single focused and plane axi-symmetric sources and arrays similar to those employed in both diagnostic and therapeutic ultrasound applications. The initial results obtained demonstrate the applicability of the angular spectrum approach and its extension to the analysis of acoustic field propagation through nonlinear liquid media. The method holds particular promise for use as a tool in the design and optimization of acoustic radiators. The ultimate goal of this research is to develop the model useful in optimization of ultrasound transducer performance and providing information on the degradation of transducer performance due to propagation through complex nonlinear media such as biological tissue.