US 8,477,434 B2Granted

Imaging lens

AssigneeOptical Logic Inc.

InventorsYoji Kubota, Kenichi Kubota, Hitoshi Hirano, Ichiro Kurihara

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Abstract

An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having positive refractive power; and a fourth lens having positive refractive power, arranged from an object side to an image plane side. In the first lens, a curvature radius on an object-side surface is positive and a curvature radius of an image-side surface is negative. In the second lens, curvature radii of an object-side surface and an image-side surface are both positive. In the third lens, curvature radii of an object-side surface and an image-side surface thereof are both negative. When the whole lens system has a focal length f and a distance from the object-side surface of the first lens to an image-side surface of the fourth lens is L14, the imaging lens satisfies the following expression: 0.5<L14/f<0.8

Claims8

Dependent claims

An imaging lens comprising:

a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having positive refractive power;
and
a fourth lens having positive refractive power, arranged in this order from an object side to an image plane side,
wherein said first lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive and a curvature radius of a surface thereof on the image plane side is negative,
said second lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive,
said third lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both negative, and
said first lens has the surface on the object side away from a surface of the fourth lens on the image plane side by a distance L14 on an optical axis and an Abbe's number νd1, said second lens has an Abbe's number νd2, said third lens has an Abbe's number νd3, and said fourth lens has an Abbe's number νd4 so that the following expressions are satisfied:
0.5<L14/f<0.8
|νd1−νd4|<10
|νd2−νd3|<10
where f is a focal length of a whole lens system.

10 more elements

An imaging lens comprising:

a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having negative refractive power;
and
a fourth lens having positive refractive power, arranged in this order from an object side to an image plane side,
wherein said first lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive and a curvature radius of a surface thereof on the image plane side is negative,
said second lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive,
said third lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both negative, and
said first lens has the surface on the object side away from a surface of the fourth lens on the image plane side by a distance L14 on an optical axis so that the following expression is satisfied:
0.5<L14/f<0.8
where f is a focal length of a whole lens system.

8 more elements

Dependencies are inferred from the claim text.