Kantatsu Co., Ltd.

Optical Logic Inc.

Ichiro Kurihara

Yoji Kubota

Hitoshi Hirano

Kenichi Kubota

Yoshio Ise

Tomohiro Yonezawa

Sumio Fukuda

Yukio Sekine

Sayuri Noda

Hisanori Suzuki

Kazuo Matsuoka

Shingo Watanabe

An imaging lens includes, in this order from an object side, an aperture stop ST, a positive first lens La negative second lens Lhaving a meniscus shape that directs a convex surface on the object side near an optical axis, a positive third lens La positive fourth lens Lhaving a meniscus shape that directs a concave surface on the object side near an optical axis, and a negative fifth lens Lhaving a meniscus shape that directs a convex surface on the object side near an optical axis.

Imaging lens

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 and a fifth lens having negative refractive power. The first lens is formed so that a curvature radius of an object-side surface is positive and the second lens is formed so that a curvature radius of an object-side surface and a curvature radius of an image plane-side surface are positive. The third lens is formed so that a curvature radius of an object-side surface is positive, and the fifth lens is formed so that a curvature radius of an object-side surface and a curvature radius of an image plane-side surface are both positive. An Abbe's number from the first and the third to the fifth lens is greater than 45, and an Abbe's number of the second lens is less than 35.

An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; and a fifth lens, arranged from an object side to an image plane side. The first lens is formed in a shape so that a curvature radius of a surface on the object side is positive. The third lens is formed such that a curvature radius of a surface on the object side is positive. The fourth lens is formed such that a surface on the object side and a surface on the image plane side are aspheric. The fifth lens is formed such that a surface on the object side and a surface on the image plane side are aspheric, and a curvature radius of the surface on the image plane side is positive near an optical axis thereof. The fourth lens and the fifth lens have specific Abbe's numbers.

An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; and a fifth lens, arranged from an object side to an image plane side. The first lens is formed such that a curvature radius of a surface on the object side is positive. The third lens is formed such that a curvature radius of a surface on the object side is positive. The fourth lens is formed such that a surface on the object side and a surface on the image plane side are aspheric. The fifth lens is formed such that a surface on the object side and a surface on the image plane side are aspheric, and a curvature radius of the surface thereof on the image plane side is positive near an optical axis thereof. The first lens and the third lens have specific focal lengths.

An imaging lens includes, in this order from an object side, an aperture stop ST, a positive first lens L, a negative second lens Lhaving a meniscus shape that directs a convex surface on the object side near an optical axis, a positive third lens L, a positive fourth lens Lhaving a meniscus shape that directs a concave surface on the object side near an optical axis, and a negative fifth lens Lhaving a meniscus shape that directs a convex surface on the object side near an optical axis.

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; a fourth lens having negative refractive power; and a fifth lens having object-side and image plane-side surfaces thereof being aspheric, arranged in this order from an object side to an image plane side. The first lens has a shape so that a curvature radius of a surface thereof on the object side is positive. The fifth lens has a shape so that a curvature radius of the surface thereof on the object side and a curvature radius of the surface thereof on the image plane side are positive. The second lens, the third lens, and the fourth lens are arranged so that a specific conditional expression is satisfied.

An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having positive refractive power, arranged in the order from an object side to an image plane side. The first lens and the third lens have object-side surfaces and image plane-side surfaces, curvature radii of which are both positive. When the first lens has refractive power P, the second lens has refractive power P, the third lens has refractive power P, the first lens has a focal length f, and the third lens has a focal length f, the imaging lens satisfies the following conditional expressions:5.0&#x3c;(1+3)/2&#x3c;8.56&#x3c;3/1&#x3c;30.

An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having negative refractive power, arranged in the order from an object side to an image plane side. The first lens and the third lens respectively have an object-side surface and an image plane-side surface whose curvature radii are both positive. The second lens has an image plane-side surface whose a curvature radius is negative. In addition, when the first lens has refractive power P1, the second lens has refractive power P2, the third lens has refractive power P3, the curvature radius of the image plane-side surface of the second lens is R2r, and the curvature radius of the object-side surface of the third lens is R3f, the imaging lens satisfies specific conditional expressions.

An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; and a third lens having positive refractive power, arranged in this order from an object side to an image plane side. Further, the first lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive. The second lens is formed in a shape so that a curvature radius of a surface thereof on the object side is negative and a curvature radius of a surface thereof on the image plane side is positive. The 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 positive.

An imaging lens includes a positive first lens; a negative second lens with a meniscus lens shape directing a convex surface thereof to an object side near an optical axis; a positive third lens; a negative fourth lens with a meniscus lens shape directing a concave surface thereof to the object side near the optical axis; a negative fifth lens with a meniscus lens shape directing a convex surface thereof to the object side near the optical axis, arranged in this order from the object side. The imaging lens satisfies the following conditional expressions when the first lens has a focal length f, the second lens has a focal length f, the third lens has a focal length f, the fourth lens has a focal length f, and the fifth lens has a focal length f1&#x3c;3and|2|&#x3c;33&#x3c;|4|and|2|&#x3c;|5|.

An imaging lens includes a first lens; a second lens; and a third lens arranged from an object side to an image plane side. The first lens has an object-side surface with a positive curvature radius. The second lens has an object-side surface and an image plane-side surface with negative curvature radii. The third lens has an object-side surface and an image plane-side surface with positive curvature radii. The object-side surface and the image plane-side surface of the third lens are respectively formed as an aspheric shape having an inflexion point. When the whole lens system has a focal length f, the first lens has a focal length f, the second lens has a focal length f, and the third lens has a focal length f, the imaging lens satisfies the following conditional expressions:1&#x3c;21.0&#x3c;1/1.50.7&#x3c;2/3&#x3c;1.2.

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Tochigi, Japan

Ichiro Kurihara