Method of manufacturing pressed lenses

A method of manufacturing a pressed lens comprising the steps of:

• inserting a preform into a pressing mold having a first mold and a second mold disposed within a sleeve, at least one of said first and second molds being slidable within said sleeve;
• heating said preform and said first and second molds to a temperature corresponding to a viscosity of said preform of 10.sup.8.5 -10.sup.10.5 poise;
• pressing said first and second molds together after said heating step with a pressing rod which is separable from said first and second molds;
• withdrawing pressure applied in said pressing step while maintaining a molding resulting from said pressing step in contact with said first and second molds by separating said pressing rod from said first and second molds;
• cooling said molding while said molding is in contact with said first and second molds;
• and
• removing said molding from said first and second molds when the temperature of said molding falls to a value corresponding to a viscosity of said molding of not smaller than 10.sup.11.5 poise.

A method of manufacturing a pressed lens comprising the steps of:

• heating a preform to a temperature corresponding to a viscosity of said preform of 10.sup.8.5 -10.sup.10.5 poise;
• heating a pressing mold having first and second molds disposed within a sleeve, at least one of said first and second molds being slidable within said sleeve, to a temperature corresponding to a viscosity of said preform of 10.sup.8.5 -10.sup.10.5 poise;
• inserting said preform into said pressing mold after both said heating steps;
• pressing said first and second molds together with a pressing rod which is separable from said first and second molds;
• withdrawing pressure applied during said pressing step while maintaining a resulting molding in contact with said first and second molds by separating said pressing rod from said first and second molds;
• cooling said molding while said molding remains in contact with said first and second molds;
• and
• removing said molding from said pressing mold after a temperature of said molding has fallen to a value corresponding to a viscosity of said molding not smaller than 10.sup.11.5 poise.