Computer Simulation of Pressure Fields Generated by Acoustic Lens Beamformers

by Kevin Fink

Master of Science in Electrical Engineering, University of Washington. 1994


Abstract

The Acoustic Lens Simulation Software Package (ALSSP) was developed to analyze acoustic lens systems; specifically, to predict the performance of a system design before fabrication. Given a design, the simulation calculates the complex pressure field behind the lens as a function of temperature, frequency, source position, and the transducer element. It also calculates beam patterns and finds focal points. The simulation uses a hybrid geometric/wave acoustic model which utilizes geometrical acoustics within the lens system and wave acoustics in image space. Ray tracing in two or three dimensions is used to implement the geometrical acoustics section, while numerical integration of the Kirchhoff integral or a complex summation of virtual sources may be used in the wave acoustics section. Lens systems may have any number of components placed arbitrarily in three dimensional space. The components are specified by their interfaces, which may be planar, spherical, or aspherical (including paraboloids, hyperboloids, and ellipsoids), and the parameters of the material between the interfaces. Several sound sources and transducer element types are available. The primary contribution of ALSSP is its applicability to a wide variety of acoustic lens systems and its inclusion of environmental effects.

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