Excimer laser ablation of low and high absorption index polymers

A comparative study of laser ablation of bulk samples of Upilex polyimide and low density polyethylene, which represent extremes in terms of absorption index at the ArF laser wavelength, is reported. High Speed Shadow Photography (HSSP), Probe Beam Deflection (PBD) and Time Resolved Interferometry (TRI) techniques have been used to provide information about the ablation process. It is shown that HSSP allows the laser generated shock wave and particulate products to be visualised as they expand away from the ablation site. PDB signals are seen to correlate well with the HSSP results and allow data to be obtained for an ablation regime in which no visible plume is observed. The TRI technique gives complementary, time-space resolved, information about the nature of the product expansion.