Patent ID: 8064147

Claim:
An imaging lens, comprising: at least three lens blocks each including a lens substrate that is a plane-parallel plate and a lens contiguous with at least one of object-side and image-side substrate surfaces of said lens substrate, said lens exerting a positive or negative optical power; and an aperture stop restricting light amount, wherein, in each of said lens blocks, said lens is formed of a material different from a material of which said lens substrate is formed; wherein said lens blocks comprise a first lens block disposed at a most object-side position; wherein the first lens block includes, as said lens substrate, a first lens substrate, and as said lens, a lens L[LS 1 o ] contiguous with an object-side substrate surface of the first lens substrate; wherein an object-side lens surface of the lens L[LS 1 o ] is convex to an object side; wherein the first lens block excerts a positive optical power; wherein said lens blocks comprise a second lens block disposed to an image side of the first lens block; wherein the second lens block includes, as said lens substrate, a second lens substrate, and as said lens, a lens L[LS 2 o ] contiguous with an object-side substrate surface of the second lens substrate; wherein an object-side lens surface of the lens L[LS 2 o ] is concave to an object side; wherein said lens blocks comprise a third lens block disposed to an image side of The second lens block; wherein the third lens block includes, as said lens substrate, a third lens substrate, And as said lens, a lens contiguous with at least one of object-side and image-side substrate surfaces of the third lens substrate, the lens being a lens L[Ls 3 o ] if contiguous with the object-side substrate surface of the third lens substrate, and being a lens L[Ls 3 m ] if contiguous with the image-side substrate surface of the third lens substrate; wherein at least one of an object-side lens surface of the lens L[Ls 3 o ] and an image-side lens surface of the lens L[LS 3 m ] is aspherical; and wherein conditional formula (B1) below is fulfilled; 0.6 ≦f[L[LS 1 o]o]/f[all]≦ 2.0 (B1) where f[L[LS 1 o ]o] represents a focal length of the object-side lens surface of the lens L[LS 1 o ], and f[all] reprsents a focal length of the entire imaging lens.