US Patent 7353666 Method for press molding a glass optical element

A molding apparatus for molding a press-molded product by heating and softening a material and press-molding the material into a predetermined shape by the use of a mold, includes a pair of dies which form the mold, each of which comprises a molding surface facing with the other, and one of which is fixed to a structure member of the molding apparatus, driving means for moving the other die towards and away from the one die, heating means for heating the dies, detecting means for detecting the displacement of a part displaced by thermal deformation of the structure member, and a control section for calculating a correction value for a moving distance of the other die with reference to the result of detection by the detecting means and delivering an instruction to the driving means so as to move the other die in accordance with the moving distance corrected by the correction value.