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) arrangement for detection of acoustic and weak shock waves in fluids. The arrangement gives us the possibility to acquire temporally resolved information (signal waveforms) on single and non-reproducible events in several points of space. We have applied the new arrangement to investigate spherical shocks generated during laser ablation of metallic targets in air. For each ablation event we determine shock transit times at several points in space and fit the data to the theoretical shock trajectory in order to determine the blast energy released in the shock wave. This multiple-point procedure improves the accuracy and reliability of blast energy measurement.