MEASUREMENT OF ENERGY-CONVERSION EFFICIENCY DURING LASER-ABLATION BY A MULTIPLE LASER-BEAM DEFLECTION PROBE

We have developed a novel multiple-pass laser beam deflection (LBD) ar rangement for detection of acoustic and weak shock waves in fluids. Th e arrangement gives us the possibility to acquire temporally resolved information (signal waveforms) on single and non-reproducible events i n several points of space. We have applied the new arrangement to inve stigate spherical shocks generated during laser ablation of metallic t argets in air. For each ablation event we determine shock transit time s at several points in space and fit the data to the theoretical shock trajectory in order to determine the blast energy released in the sho ck wave. This multiple-point procedure improves the accuracy and relia bility of blast energy measurement.