Large-scale CO2 laser-based sol-gel annealing of titanium dioxide on borosilicate glass

Abstract

There are several ways to create optical filters on glass, such as the low-cost sol-gel coating. However, to make this process even more effective and flexible, a laser instead of a conventional furnace process was used to anneal the borosilicate glass samples. In previous studies, it was demonstrated that it is possible to generate similar refractive indices and film thicknesses with a CO2 laser as with the furnace method. In this study, TiO2-coated borosilicate glasses are annealed with a CO2 laser. In particular, the main goal is to scan a large processing area (up to 475 x 468 mm2) and to achieve process speeds comparable to those in the furnace process. Microscopic images show a homogeneous layer and an ellipsometrically determined refractive index comparable to the reference sample from the furnace (laser sample: 2.32; furnace reference: 2.20). With a suitable process setup, it is therefore possible to process glass efficiently on an industrial scale.