Thermal modeling of laser-densified microlenses

A three-dimensional transient thermal modeling of laser-densified gel-silica microlenses is described. This model simulates the three-dimensional temperature distribution in a porous gel-silica glass irradiated by a CO(2) laser. The heat induced by the laser gives rise to a gradient in temperature, which creates a gradient in density and index of refraction. The laser-densified region functions as a microlens. The modeling results include a temperature distribution with time within a volume of 2 mm × 2 mm × 2 mm. The calculated temperature distributions compare well with the measured property distributions of the microlens including microhardness and the peak positions of the Si-O-Si stretching vibration mode in IR spectra across the lens.