Modification of the optical properties and dynamics of laser ultraviolet ablation of polyimide

An experimental investigation was made of the ablative photoetching of thin polyimide films by KrF excimer laser radiation. Reversible modification of the optical properties of the polymer was observed when the energy densities of the laser beam were below the ablation threshold. The proposed model was used to analyze possible heat release regimes in the film under conditions of below-threshold laser irradiation. The dynamics of the motion of the ablation front during the laser pulse was calculated numerically.