Abstract: A process is described for manufacturing an ophthalmic lens containing a Fresnel microstructured surface inside the lens. The Fresnel lens is injection molded with a mold insert having a heat conductivity lower than the thermoplastic material used to form the Fresnel lens. A second thermoplastic material is overmolded to the Fresnel lens to cover and protect the microstructured surface. The mold insert is made from nickel or a thermoplastic material. The resulting lens includes two layers having different refractive indices. The Fresnel lens may be made from polycarbonate while the overmold may be made from a poly(methyl methacrylate) or a thermoplastic polyurethane.

Abstract: A process for manufacturing an ophthalmic lens containing a Fresnel microstructured surface inside the lens. The Fresnel lens is injection molded with a mold insert having a heat conductivity lower than the thermoplastic material used to form the Fresnel lens. A second thermoplastic material is overmolded to the Fresnel lens to cover and protect the microstructured surface. The mold insert is made from Nickel or thermoplastic. The resulting lens includes two layers having different refractive indices. The Fresnel lens is made from polycarbonate while the overmold is made from PMMA or TPU.