Modeling the response of an acoustical spiral wave front transducer.

Abstract

Listen

Translate article

An acoustical spiral wave front transducer radiates a field whose phase varies linearly with the azimuthal angle around the transducer. The phase of the field, therefore, carries information about the location of a receiver relative to the spiral transducer. There are two transducer designs that can produce this type of wave front. The first is a “physical spiral” transducer that creates the phase change by physically deforming the active element of the transducer. While this is the simplest design, the physical deformation produces a discontinuity in the active element that affects both the amplitude and phase of the outgoing field. The effect of this discontinuity is examined through both a finite element model and a baffled source approximation. The second technique uses an array of elements, each driven with an appropriate phase to produce a “phased spiral” transducer. The output of this transducer depends on the wavenumber of the outgoing field as well as on the radius and number of the elements of the transducer. Simulations and approximations show that by tuning these parameters, the variations in either the amplitude or the phase of the outgoing field can be minimized. [Work supported by the Office of Naval Research.]