Passive imaging of localized reflectors and interfaces in open media

Previous experiments in open media showed the possibility of reconstructing the direct (ballistic) wave between two passive sensors from the time correlations of elastic or acoustic scattered wave fields. Here we illustrate how the passive imaging technique can also retrieve detailed features of the Green's function, beyond the ballistic wave. Two ultrasonic experiments are presented. In the first one we reconstruct the complete signature of two well-separated scatterers with a perfect distribution of distant sources. In the second experiment we image an aluminum/water interface with only a few sources. The lack of sources is compensated for by taking advantage of a multiple scattering slab. (c) 2006 American Institute of Physics.