Abstract

A novel process for polishing fused silica with CO₂-laser radiation is presented. Due to the increasing demand in the optics industry to use aspherical or freeform lenses in optical systems new manufacturing processes for these geometries are required. Laser polishing reduces the roughness of fused silica surfaces to Ra<6 nm (Rms<10 nm [1]). The processing rates - up to 1 cm²/s - are several times faster than conventional polishing techniques especially for geometries like aspheres or freeform optics. The laser radiation is absorbed in a thin layer of about 40 µm thickness. The temperature of this thin layer rises and therefore the viscosity is lowered. Due to the surface tension material flows from the peaks to the valleys and the surface is polished. Material removal is not desired. The samples are preheated to avoid cracks resulting from thermal stresses. Polishing results on plane samples and on spherical lenses are presented.

© 2010 OSA, SPIE