Acoustic Imaging of Solid Objects in Air Using a Small Set of Transducers

Abstract

We describe an a1 gori thm that enables 3-dimensional acoustic imaging of simple objects in a ir using an array containing o nly a small number of transducers. Each transducer provides a pulseecho measurement in an appropriate incident direction. Our probabilistic imaging procedure uses entire waveforms (i.e., they are not limited to simple time-of-flight measurement), and are based on the Kirchhoff approximation together with the assumption that the scatterer is a rigid body. We further assume that the body is flat-bottomed with its upper surface represented by a singlevalued elevation function. The imaging algorithm employs an iterative technique involving artificial smoothing initially, followed by incremental unsmoothing and linearization with respect to elevation function c orrections. We present the results of preliminary testing of this technique using synthetic data.