MECHANICAL-STRESS POWER MEASUREMENTS DURING HIGH-POWER LASER-ABLATION

Laser-induced stresses have been studied extensively to understand mac roscopic phenomenon during high-power laser ablation of solids. Recent ly, a norm of stress times the rate of change in stress, similar to me chanical stress power, was monitored acoustically in the target and am bient medium during high-power laser-material interactions, and compar ed with stress measurements. This study investigates the relationship between stress and the stress powerlike measurements (P), and their d ependence on laser energy, intensity, and spot size. The importance of different components of stress on the measurements is also considered . Results from ablation of aluminum targets by a 30 ns uv excimer lase r are presented that show changes in P with laser energy coupling, an d the dependence of P on laser intensity and stress components. Poten tial issues are raised for further study of stress power as a diagnost ic tool of laser-material interactions and as a fundamental mechanism of laser-energy coupling. (C) 1996 American Institute of Physics.