MATHEMATICAL-MODELING OF TEMPERATURE DISTRIBUTION DURING CO2-LASER IRRADIATION OF GLASS

The irradiation of glass using a CO2 laser causes a local temperature rise which can be used for local heat treatments, e.g. polishing, cutt ing. The temperature distribution is described generally by the heat d iffusion equations. If the laser beam radius is much larger than the m aterial thickness, the two dimensional problem can be replaced with a one dimensional solution. For the simulation it is necessary to take t he strong temperature dependence of the thermal conductivity and the s pecific heat of the glass into account and also the boundary condition s. The boundary conditions only become important at irradiation times longer than 2 s; then the glass properties play a more important role. Here, the thermal conductivity influences the temperature most signif icantly, due to the strong effect of heat transfer by radiation in gla ss at high temperatures. This large thermal conductivity results in a rather even temperature distribution in the glass.