Method for producing a curved glass die having an aspherical polished concave face

摘要

A method of making a glass die for moulding progressive concave-convex ophthalmic lenses of organic glass, i.e. of synthetic polymeric material, which have their convex surface of aspheric shape, wherein a glass blank for the die is formed with its convex surface of aspheric shape and is then supported on a support member having a concave spherical support surface while being heated to a temperature at which the glass deforms without flowing, so that the convex surface sags to conform with the spherical support surface and the aspheric character is transferred to the concave surface.