Patent ID: 7164544

Claim:
An optical system, comprising: a refractive optical element including a solid-state material and disposed on a front side relative to an intersection point of an optical axis and a paraxial chief ray, wherein an Abbe number νd(GNL) and a partial dispersion ratio θgF(GNL) of the solid state material meets conditions of: −2.100×10 −3 ·νd ( GNL )+0.693 <θgF ( GNL ); and 0.555 <θgF ( GNL )<0.9; a negative lens component disposed on the front side relative to the intersection point; and a positive lens component disposed on the front side relative to the intersection point, wherein a maximum value of a height from the optical axis, at which a paraxial marginal ray passes through lens surfaces on the front side relative to the intersection point, is higher than a maximum value of a height from the optical axis, at which the paraxial marginal ray passes through lens surfaces on a rear side relative to the intersection point, and wherein when a refractive power of the refractive optical element is ψ(GNL), a mean partial dispersion ratio of a material of the negative lens component is θgF(N), a mean Abbe number of a material of the positive lens component is νd(P), and a refractive power of the entire optical system is ψ, the following conditions are met: 0.03<ψ( GNL )/ψ<7.5; 0.55 <θgF ( N )<0.635; and ν d ( P )<75.