Patent ID: 7966844

Claim:
An optical element manufacturing method that uses a press mold comprising a lower mold formed with a molding surface, an upper mold formed with a molding surface facing the molding surface of said lower mold, a first sleeve allowing said upper and lower molds to be inserted thereinto from its both end sides, and a second sleeve provided inside said first sleeve, thereby press-molding a molding material between said upper and lower molds, the molding surface of said lower mold having a convex surface, a diameter of said molding material being smaller than an inner diameter of said second sleeve, said lower mold including a first outer peripheral portion and an second outer peripheral portion having an outer diameter larger than an outer diameter of said first outer peripheral portion, a stepped portion for holding said second sleeve thereon being formed at the boundary between said first outer peripheral portion and said second outer peripheral portion, said second sleeve held on said stepped portion having an outer diameter equal to or smaller than the outer diameter of said second outer peripheral portion, an inner surface of said first sleeve slidingly contacting an outer surface of said upper mold and an outer surface of said second outer peripheral portion, thereby coaxially guiding said upper and lower molds, and suction vent holes being provided to establish communication between a bottom surface of the lower mold and the stepped portion, the manufacturing method comprising: a first step wherein, in the state where said upper and lower molds are separated from each other, the molding material is supplied such that at least part of an outer peripheral portion of said molding material is supported by said second sleeve surrounding an outer periphery of the molding surface of said lower mold, thereby preventing position offset of said molding material, and a second step wherein said molding material is press-molded by causing said upper and lower molds to approach each other while regulating a horizontal relative position between said upper and lower molds by said first sleeve, wherein said second sleeve is held in tight abutment to the lower mold by sucking the atmospheric gas through the suction vent holes.