Laser ablation of polymers studied by ns-interferometry and ns-shadowgraphy measurements

The dynamic processes during ablation are studied by nanosecond-interferometry and shadowgraphy. Most commercial polymers exhibit poor laser ablation properties, therefore special triazene polymers, with superior ablation properties were developed. The photochemical active triazene group absorbs around 330 nm whereas the absorption around 200 nm is due to the photostable aromatic groups. The ns-interferometry shows that the etching of the triazene polymer starts and ends with the laser beam after irradiation at 193 and 308 nm. Shadowgraphy of the triazene polymer and polyimide reveal that the speed of the aerial shockwave increases with fluence and is higher for irradiation at 193 nm than for 308 nm. Shockwaves with equal or higher velocities are observed for the triazene polymer compared to polyimide.