Mold for molding optical elements

A mold adapted to be mounted between a pair of heater blocks and to have a pressure applied thereagainst by at least one of the heater blocks for molding a molding material into an optical element, comprising:

• first and second elements, each of which includes an inner molding surface adapted to contact the molding material, an outer surface opposite said inner molding surface and adapted to contact a respective one of the pair of heater blocks, and a flange extending laterally outwardly from said outer surface so as to extend the surface area which is adapted to contact a respective one of the pair of heater blocks, said inner molding surfaces of said first and second elements defining a cavity therebetween in which the molding material is adapted to be received and molded to form the optical element;
• a first ring member mounted about said first and second elements and having means, comprising an inner surface thereof, for guiding vertical movement of said first and second elements;
• and
• a second ring member mounted about said first ring member and being formed of a material having a lower thermal conductivity than a material of said first ring member, said second ring member being vertically longer than said first ring member such that said second ring member is adapted to contact said flanges of said first and second elements, respectively, and such that said second ring member defines a means for preventing said first and second elements to be moved together beyond a predetermined separation distance so as to predetermine a thickness of the optical element.