Antton Goicoechea - ESPCI - Multiple scattering of acoustic waves: from Anderson localization to imaging

In this talk I will discuss the transport of waves in strongly scattering media. I will start off from a fundamental physics point of view by considering anisotropic media with an emphasis on the regime close to the Anderson transition. We demonstrated experimentally that the transport anisotropy (characterized by the ratio between the different components of the diffusion tensor) is sensitive to disorder : in the diffusive regime the transport anisotropy remains constant across the whole frequency range studied, whereas close to the critical point (strong disorder regime) anisotropy disappears. I will comment on how this result compares to existing theoretical and numerical work.
I will then switch to application driven work. Multiple scattering is generally difficult to deal with from an imaging perspective, because all of the information gets mixed as the wave propagates. I will show results about detection of a target embedded in a strongly scattering medium in reflection, for which conventional imaging techniques fail. This procedure opens up exciting perspectives for medical applications as well as rheology for example.