METHOD AND APPARATUS FOR MANUFACTURING LARGE DOUBLE-SIDED CURVED FRESNEL LENS

摘要

A method of manufacturing a large double-sided curved Fresnel lens. The method includes a machining step (A) of performing ultra-precise three-dimensional machining on an upper mold and a lower mold to each have an upper transfer surface and a lower transfer surface engaging an upper surface and a lower surface of a thermoplastic resin plate, respectively. Further, the method includes a hot press molding step (B) of pressing the thermoplastic resin plate between the upper and lower molds by a predetermined pressure with the resin plate being held at a temperature higher than a softening temperature thereof and lower than a melting temperature thereof so that the thermoplastic resin plate is curved, and both lens surfaces for the double-sided Fresnel lens are respectively transferred to an upper surface and a lower surface of the thermoplastic resin plate.