US Patent 7815309 Bifocal plastic lens

A bifocal plastic lens having a bench lens and a small lens with different refractive powers. The small lens not protruding above a surface of the bench lens, a boundary between the constituent lenses being difficult to see. The small lens may be provided on a preparatory lens member including the small lens. Alternatively, the preparatory lens member has a concave portion for a small lens molding surface. A resin having a higher refractive index than a resin constituting other portions of the lens is adhered to a surface provided with the small lens or the concave portion to be the small lens molding surface in the preparatory lens member, and is cured and integrated.