Method of manufacturing a glass optical element

A method of manufacturing a non-circular glass optical element comprising:

• providing an upper die having a cylindrical surface worked so as to have an upper die generatrix for connecting intersection points between a non-arc axis and a cylindrical section and between an arc center axis and the cylindrical section;
• providing a lower die having a cylindrical surface worked so as to have a lower die generatrix for connecting intersection points between a non-arc axis and a cylindrical section and between an arc center axis and the cylindrical section;
• pressing a side surface forming member against an upper die reference surface worked so that a distance from the upper die generatrix obtains a default and against a lower die reference surface worked so that a distance from the lower die generatrix obtains a default;
• moving one or both of the upper and lower dies such that a distance between the upper die and the lower die is reduced while the upper die reference surface and the lower die reference surface are maintained in one plane;
• molding a glass material arranged between the upper die and the lower die to form the glass optical element;
• and
• transferring a surface plane of the side surface forming member onto the glass optical element.