Beam-based back-propagation imaging

We present a beam-based back-propagation imaging scheme for point scatterers, utilizing data measured by arrays of wide-angle sources and receivers (transducers). The scheme consists of a preprocessing phase where the measured point-source/receiver data, consisting of the scattered field measured by the receivers due to all independent sources, is converted into a beams data, where the source and the receivers arrays are described as phase-space sets of beams that emerge from a discrete set of points and directions in the source/receiver domains. The beam-domain data thus correspond to the scattering amplitudes "measured" (synthetically) by each one of the receiver beams due to each one of the source beams, and the image is formed by back-propagating the measured beams and correlating them with the incident beams. As expected, the beam-domain data-matrix is sparse and well localized around the source-receiver beam pairs that intersect near the targets. This localization is utilized for spatial filtering and focusing of the data by eliminating rows and columns corresponding to source/receiver beams that do not illuminate a particular sub-domain of interest.