Quasi-holographic processing as an alternative to synthetic aperture sonar imaging

Abstract

By limiting attention to supersonic-like wavevectors, time-resolved holographic imaging was demonstrated to be helpful for identifying transient elastic responses of targets contributing to far field scattering [Hefner and Marston, Acoust. Res. Lett. Online 2, 55–60 (2001); 3, 101–106 (2002)]. That approach was applied to time-evolving three-dimensional wavefields scanned with a two-dimensional raster scan at a significant offset. In recent work, however, it was also demonstrated that line scan measurements of bistatic scattering could be processed quasi-holographically as an alternative to synthetic aperture sonar (SAS) imaging [Baik et al., J. Acoust. Soc. Am. 130, 3838–3851 (2011)]. The present investigation broadens the line scan approach to reversible signal extraction associated with image features, and to monostatic quasi-holographic imaging, in which the source and receiver are co-located and scanned along a line. Some applications of this approach will be illustrated such as separation of signals from edge diffraction features and specular features from those of elastic features. [Work supported by ONR and the NSWC-PCD ILIR/IAR research fund.]