Mechanical stress power measurements during high-power laser ablation

Laser‐induced stresses have been studied extensively to understand macroscopic phenomenon during high‐power laser ablation of solids. Recently, a norm of stress times the rate of change in stress, similar to mechanical stress power, was monitored acoustically in the target and ambient medium during high‐power laser‐material interactions, and compared with stress measurements. This study investigates the relationship between stress and the stress powerlike measurements (P*), and their dependence 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 laser are presented that show changes in P* with laser energy coupling, and the dependence of P* on laser intensity and stress components. Potential issues are raised for further study of stress power as a diagnostic tool of laser‐material interactions and as a fundamental mechanism of laser‐energy coupling.