Spherical Mirror and Surface Patterning on Silicon Carbide (SiC) by Material Removal Rate Enhancement Using CO2 Laser Assisted Polishing

Silicon carbide (SiC) is well known as an excellent material for high performance optical applications because it offers many advantages over other commonly used glasses and metals. The excellent attributes of SiC include high strength, high hardness, low density, high thermal resistance, and low coefficient of thermal expansion. The effect of CO2 laser and its tool path on SiCwere investigated. The process started by creating laser pre-cracks on the desired pattern. Subsequently, laser assisted polishing was conducted on the same tool path. The surface showed a sharp increase in material removal in the areas with laser pre-cracks. This high difference in material removal was used not only to fabricate a ⌀ 1100 mm concave mirror with 127 μm in depth but also to generate macro and micro patterns. Grooves from 2 mm to 200 μm in width and 5 μm to 20 μm depth were successfully generated.