TomoSAS images of acoustically penetrable objects

Abstract:
The long acoustic wavelengths of synthetic aperture sonar systems relative to other high-resolution acoustic imaging methods allow for enhanced acoustic penetration of objects, enabling visualization of internal features. Discrimination between internal and external features is difficult in conventional SAS images, however, because of the lack of a height dimension. Interferometry can be used to resolve the vertical location of scatterers but this technique fails to resolve vertical scattering distributions within a pixel. In contrast, synthetic aperture tomography, which makes use of multiple scans to form a multi-dimensional array, can be used to generate 3D voxel-based imagery capable of resolving vertical scatterer distributions. These volumetric images enable identification of both the internal and external features of targets. In this paper, TomoSAS images of two acoustically penetrable objects are examined: a lobster trap and a plastic barrel with a sphere suspended inside.