ABLATIVE ETCHING OF NITROCELLULOSE WITH INFRARED AND ULTRA-VIOLET LASER-RADIATION

The ablative etching of nitrocellulose membranes with CO2 (lambda = 10 .6 mu m), Nd:YAG (lambda = 1.06 mu m) and XeCl (lambda = 308 nm) laser s has been studied. From etch rate measurements the threshold fluence was estimated and the energy deposition at threshold fluence was calcu lated for the three wavelengths. The electron microscope examination o f the infra-red laser ablated areas reveals a fairly clean etching und er CO2 laser irradiation, confirming that melting of the crater surrou ndings cannot be considered as a criterion for the thermal mechanism, It is proposed that the CO2 laser, which also possesses some operation al advantages, compared with excimer lasers, can be effectively used f or the clean ablation of the nitrocellulose film dielectric.