For the laser annealing of sol-gel layers, the laser beam is guided over the glass sample with the use of a galvanometer scanner or an axis system. In this process, a liner raster is traced to create a homogeneous heat front and shifted over the substrate. The local heating by the laser radiation leads to densification of the sol-gel layer and enables selective densification of areas and shapes of different sizes as well as lettering. After each laser densification performed, the demonstrated sample was recoated and laser-treated again until three fully annealed layers were produced.

Motivation
• Sol-gel coatings are commercially annealed by using a furnace
• For a profitable process, the furnace needs a high capacity utilization rate
• More energy-efficient annealing by the use of laser radiation
• Processing of various sol-gel materials is possible

Function / Properties / Characteristics
• Achieve equal or higher refractive indices with the laser compared to furnace annealing
• Homogeneous layer formation

Applications
• Color effect glasses
• Optical filters
• Improvement of the corrosion and wear resistance (depending on the material: zirconium
  dioxide)

Parameters
• Scanning speed: 2000 mm/s for layer one and two
                                3000 mm/s for layer three
• Focus diameter: approx. 830 µm
• Laser power: 60 W

Laser sources
• CO₂-Laser: 10.6 µm

Processed material
• Borosilicat glass
• Three layers of titanium dioxide