Molding method for optical element

A method for molding an optical element, comprising the steps of:

• disposing an upper mold and a lower mold for forming optical functional surfaces of the optical element and a side mold for guiding the upper and lower molds;
• forming a gap between the lower mold and the side mold;
• inserting a glass material between the upper mold and the lower mold;
• heating the upper mold, the lower mold and the glass material to a predetermined temperature;
• pressing the glass material between the upper and lower molds by applying pressure to the upper mold such that an adhesive force results between the glass material and the lower mold;
• cooling the molded glass article, while the adhesive force causes a movement of the lower mold toward the glass article in an axial direction which follows a shrinkage of the molded glass article;
• and
• limiting the movement of the lower mold in the axial direction within the gap which movement is caused by said adhesive force so as thereby control the thickness of the molded glass.

A method for molding an optical element, comprising the steps of:

• disposing an upper mold, a lower mold and a side mold for forming optical functional surface of the optical element, with the side mold supporting at least the lower mold;
• forming a gap between the upper mold and the side mold;
• inserting a glass material between the upper mold and the lower mold;
• heating the upper mold, the lower mold, and the glass material to a predetermined temperature;
• pressing the glass material between the lower mold, which is held at a fixed position, and the upper mold, which is moved in an axial direction by applying pressure to the upper mold such that an adhesive force results between the glass material and the upper mold;
• cooling the molded glass article while the adhesive force causes a movement of the upper mold toward the glass article in the axial direction which follows a shrinkage of said molded glass article;
• and
• limiting them movement of the upper mold in the axial direction within the gap which movement is caused by said adhesive force so as to thereby control the thickness of the molded glass.

A method for molding an optical element, comprising the steps of:

• preparing a forming mold having an upper mold with an optical functional surface and a flange portion to be impinged against a side mold, a lower mold having an optical functional surface and a flange portion, a side mold having a guide portion for guiding the upper and lower molds, and a bottom plate for retaining the lower mold, wherein the upper and lower molds are fitted into the side mold so that a center axial line of the upper and lower molds aligns with a center axial line of the guide portion of the side mold, and movement of the upper and lower molds in an axial direction is regulated by the guide portion of the side mold, with the side mold including upper and lower surfaces arranged so as to be perpendicular to the center axial line of the guide portion, with the upper surface being capable of contacting the flange portion of the upper mold and the lower surfaced being capable of contacting the bottom plate, with the flange portion of the upper mold having a lower surface capable of contacting the side mold and the lower mold having a lower surface capable of contacting the bottom plate and being arranged so as to be perpendicular to the center axial line of the guide portion of the side mold, wherein a gap is formed between an upper surface of the flange portion of the lower mold and the side mold when the lower mold contacts the bottom plate, with a dimension and accuracy of each mold being structured so that when the molds contact each other, a cavity shape is formed between the upper and lower molds and substantially corresponds to a predetermined shape of the optical element, the cavity shape being corrected according to a variation of mold shape due to difference of thermal expansions of each mold;
• heating the forming mold and a glass material;
• positioning the glass material between the upper and lower molds of the forming mold until the forming mold and the glass material reach a moldable temperature,
• pressing the upper mold to allow the lower surface of the flange portion of the upper mold to contact the upper surface of the side mold to mold the glass material to the cavity shape formed between the upper and lower molds, such that an adhesive force results between the glass material and the lower mold;
• cooling the forming mold and the resulting molded glass product while the adhesive force causes a movement of the lower mold in the axial direction and toward the glass;
• and
• limiting said movement of the lower mold in the direction within the gap between the lower mold and the side mold which movement is caused by said adhesive force so as to thereby control the thickness of the molded glass product as it contracts.