Manufacturing of Cylindrical Micro Lenses and Micro Lens Arrays in Fused Silica and Borosilicate Glass using F2-Laser Microstructuring

Abstract

The results of our investigations on direct laser fabrication of cylindrical micro lenses and micro lens arrays in fused silica and borosilicate glass using fluorine laser microstructuring technique will be presented. The process, based on the mask projection technique, enables the generation of almost perfectly curved, smooth surfaces with a defined radius of curvature. In particular, it will be shown that one calculated mask can be used to generate different radii of curvature depending on the laser pulse fluence and the pulse-to-pulse overlap. The surface roughness of the lenses depends on the process parameters as well. To generate continuous transition areas between the lenses in one array, the optimal lens spacing was determined. Moreover, it can be shown, that the surface quality of cylindrical micro lens arrays, made of fused silica, can be improved by CO2 laser smoothing. The minimal reached surface roughness is 4.6 nm RMS.