Interaction of VUV F_2 laser radiation with glasses

摘要

The 157nm F_2 laser wavelength is strongly absorbed by glasses, even those with high silica content, making it potentially well suited for machining these materials by ablation. This is of interest for fabricating micro-optics and micro-devices in glass, provided crack-free surfaces with minimal laser-induced stress and surface roughness can be produced. Experimental studies are reported on the ablation threshold, ablation rate and surface quality of N-BK7 and soda lime glass for exposure with the VUV F_2 laser. Optical probe techniques and etching are employed to determine the ablation threshold and removal rate and scanning electron microscopy to assess the surface quality of the glass following laser exposure. The interaction is discussed within the framework of a thermal vaporization model and the surface thermal loading is used to make a preliminary assessment of resolution attainable in micro-feature definition.