Depth profile of a time-reversal focus in an elastic solid
Résumé
The out-of-plane velocity component is focused on the flat surface of an isotropic solid sample using the
principle of time reversal. This experiment is often reproduced in the context of nondestructive testing
for imaging features near the surface of the sample. However, it is not clear how deep the focus extends
into the bulk of the sample and what its profile is. In this paper, this question is answered using both
numerical simulations and experimental data. The profiles of the foci are expressed in terms of the wavelengths
of the dominant waves, based on the interpretation of the Lamb’s problem and the use of the diffraction
limit.