EXCIMER-LASER ABLATION OF ND-YAG AND ND-GLASS

The excimer laser ablation of neodymium (Nd) doped glass and Nd doped yttrium aluminium garnet (YAG) crystals has been performed using 193 a nd 248 nm radiation. Etch rate versus fluence (energy per unit area) p lots show that the ablation thresholds are in the range 0.5-1.6 J/cm(2 ). The effective absorption coefficients thus measured were found to b e of the order of 10(4)-10(5) cm(-1), two or three orders of magnitude greater than the small signal absorption coefficient. The ablation of Nd:YAG and Nd:grass at 193 nm produced etch pits of superior quality to those pits produced using 248 nm laser exposure. Time integrated em ission spectra of the ablated plumes in vacuum showed up to one hundre d lines for Nd:YAG at both wavelengths while the Nd:glass spectra were simpler, considerably so for 248 nm irradiation.