Ultrafast imaging of optical damage dynamics and laser-produced wave propagation in polymethyl methacrylate

A high-power ultrafast laser spectrometer with image acquisition capability, the "picosecond microscope" is used to study optical surface damage processes in a transparent polymer, polymethyl methacrylate. Optical damage is a fast, violent, inhomogeneous solid-state chemical reaction. We observe three distinct fast processes: creation and growth of a dark absorbing damage volume, the "damage core," creation and propagation of a hypersonic shock wave in the surrounding atmosphere, and creation of large amplitude acoustic waves which propagate outward from the core at the velocity of sound.