9222483 Walsh The goal of the research supported by this award is to understand the interaction of the mid-infrared laser radiation with tissue. The overall objective is to determine the potential of these lasers for medical/surgical use. This study will focus on the dynamic changes in the optical absorption properties of water and tissue in the mid- infrared region for high-power laser irradiation. Experimental measurements will be performed and a model to predict the effects of dynamic optical property changes on ablation rate, residual thermal damage, shock wave induced damage and ablation pressure will be developed and tested. This research is important since it could lead to fundamental improvements in the use of mid-infrared lasers for research and medical uses. ***