This paper reports on some fundamental investigations of the interaction between CO2 laser radiation and glasses. Aim of this work is the reduction of the induced thermal strain and stress to minimize the formation of microcracks during and after the process of material ablation. The following experimental results are reported: (1) The optical constants n (refractive index) and k (absorption index) of some technical and optical glasses were determined with high accuracy for the CO2 laser wavelength of (lambda) equals 10.6 micrometers by angular-dependent measurements of the surface reflection of these glasses. (2) To optimize the deposition of energy by well-adapted pulse parameters, the ablation threshold of borosilicate glass was determined by irradiating the material with single pulses, whose intensities were enhanced in well defined small steps. (3) The threshold conditions for the formation of microcracks during and after the process of material ablation were investigated. In a first step single pulses were used only and in a second step pulse series for the generation of 3D structures were tested.
"Laser material processing of glasses with CO2 lasers", Proc. SPIE 3097, Lasers in Material Processing, (18 August 1997); doi: 10.1117/12.281133; https://doi.org/10.1117/12.281133