Comparative study of the photochemistry of the cutting (etching) of a synthetic polymer and bovine cornea by excimer laser radiation

Earlier work1–3 on the etching of an organic polymer by UV laser radiation has emphasized the depth of the etching/pulse If as a function of fluence F. In this work, the If vs InF curves for polymethyl methacrylate (PMMA) have been ex- tended over a larger range of fluences at 193 and 24B nm (Fig. 1). At the same time, the quantum yields for methyl methacrylate (MMA), the principal polyatomic product from PMMA, were also determined (Fig. 2). The quantum yields of MMA at 248 nm were tenfold smaller than at 193 nm and are, therefore, not inclued in Fig. 2. Etch curves for bovine cornea1 which were determined from laser exposure in vitro are shown in Fig. 3.