Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components

A new regime for silica glass machining for micro-optical fabrication applications, which uses pulsed C[O.sub.2] laser radiation in the 2.5-100-[micro]s pulse width region that has been generated by an acousto-optic modulator, is investigated. A filamentary melt ejection process that generates fibers and significant melt displacement limits machining quality below 30-[micro]s pulse width. Ablation and melt ejection thresholds are quantified relative to pulse width, and the region from 30 to 50 [micro]s is identified for low-threshold, smooth machining without melt displacement and ejection effects.