Patent ID: 7365916

Claim:
An aspherical lens comprising: a substrate member, a member having a different composition from the substrate member and being formed on the substrate member, a boundary surface between the substrate member and the member having the different composition being formed by a first aspherical surface, a surface of the member having the different composition opposite to the boundary surface being formed by a second aspherical surface, a refractive index of a medium of the substrate member at d-line in which λ=587.56 nm is higher than a refractive index of a medium of the member having the different composition at d-line in which λ=587.56 nm, a thickness of a center portion of the substrate member is larger than that of the member having the different composition, and the following conditional expressions being satisfied: 0.05000≦| Na−Nb|≦ 0.50000 2.3≦PV AB /PV B ≦100 where Na denotes the refractive index of the medium of the substrate member at d-line in which λ=587.56 nm, and Nb denotes the refractive index of the medium of the member having the different composition at d-line in which λ=587.56 nm, PV AB denotes PV value of a fabrication error relative to design value of the first aspherical surface, and PV B denotes PV value of a fabrication error relative to design value of the second aspherical surface.