The characteristics of optics polished with a polyurethane pad.

The effect of polishing an optical workpiece with a polyurethane pad was studied in this paper, including material removal rate, surface roughness and subsurface damage. Usually, optical polishing pitch is applied to polish optical workpieces, but the material removal rate (MRR) of pitch is quite low, and polyurethane foam is thus substituted for polishing pitch. With the polyurethane pad a much higher MRR was obtained. Surface roughness and subsurface damage of workpieces were also examined. We were gratified to find that there was almost no subsurface damage in the workpieces manufactured with pad polishing and surface roughness was comparable to the result of pitch polishing. Finally, a hypothesis was proposed in an attempt to explain the result that workpieces were defect-free.