Double-Sided Polishing of Hard Substrate Materials

A method for simultaneously polishing both surfaces of an optical substrate comprising:

• providing an upper platen and a lower platen, each covered with a polishing pad material;
• providing at least one carrier having an aperture for holding the optical substrate between the upper platen and the lower platen and adapted to allow the polishing pad material of the upper platen and the lower platen to simultaneously contact an upper surface and a lower surface of the optical substrate, respectively;
• setting a first location of the aperture of the carrier such that a center of the optical substrate is offset from a center of the carrier and at least a portion of an outer perimeter of the optical substrate extends outwardly beyond at least a portion of at least one of an outer perimeter and an inner perimeter of the upper platen and the lower platen;
• rotating the upper platen and the lower platen with respect to the carrier;
• and
• rotating the carrier with respect to the upper platen and the lower platen.