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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