The same experimental technique described in other abstracts have been used to study the pre-ablation in bone. Data has been collected on the thermoelastic deformation of both bone and Plexiglas. This data allows optical and mechanical properties of these materials to be determined. Microscopic evaluation of the Plexiglas sample reveals the formation of permanent microcracks below the threshold needed to initiate ablation. This effect is analogous to cavitation in liquids.