Analysis of the dynamics of the interaction of ultraviolet lasers with organic polymers

The time-dependent treatment of the dynamics of the ablation of polymers that was proposed by Sutcliffe and Srinivasan has been used here to analyze the etching of several polymers by pulsed, ultraviolet laser radiation. For five polymers which span a wide range of absorptivities in the ultraviolet, the ablation threshold which is expressed in terms of the “useful” photon density in the ablation volume falls within a narrow range (±50%). The most intense absorbers show the most deviation from the average value. The flux threshold which defines the absorbed photon level above which the photons are useful in producing ablation is strongly influenced by the absorptivity of the polymer. The extension of these ideas to the ablation of tissue which contains only 20% polymer is also discussed.