Patent ID: 6935136

Claim:
A method for fabrication of an optical element having a metal ring in which the metal ring having a diameter slightly smaller than an inside diameter of a body die and an optical material are disposed inside the body die that is served to define a peripheral side surface configuration by which the optical element is positioned, and in which the optical material is pressed by a first mold to form a desired optically functional surface and the diameter of the metal ring is expanded toward the body die to obtain the optical element having the metal ring with a desired outside diameter, wherein the metal ring disposed inside the body die is provided with a thin-wall sleeve a diameter of which is expanded toward a peripheral direction by means of pressure received from an optical material disposed inside the metal ring to thereby obtain a final peripheral side surface size, a thin-wall portion having an inside periphery near an extension of an inside peripheral surface of the thin-wall sleeve on an aperture of the thin-wall sleeve, and a holding portion comprising a flange that projects from an edge of the aperture toward the aperture, wherein the holding portion has a space between the optical material and a second mold so that the optical material does not contact the mold when an unsoftened optical material is disposed, wherein an edge provided with a polygonal aperture that is circumscribed with an inside peripheral edge of the thin-wall sleeve is formed on the aperture of the metal ring, wherein a portion near a vertex of the polygonal aperture is made thin-walled, and wherein a portion between a polygonal side and the thin-wall sleeve is formed as the flange.