US 9,001,439 B2Granted

Imaging lens

AssigneesOptical Logic Inc., Kantatsu Co., Ltd.

InventorsYoji Kubota, Kenichi Kubota, Hitoshi Hirano, Tomohiro Yonezawa

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Abstract

An imaging lens includes a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a stop; and a fourth lens having positive refractive power arranged in the order from an object side to an image plane side. The first lens has an image plane-side surface having a positive curvature radius. The second lens has an image plane-side surface having negative curvature radius. The third lens has an image plane-side surface having a negative curvature radius. The fourth lens has an object-side surface having a positive curvature radius and an image plane-side surface having a negative curvature radius. The first lens has a specific focal length and a specific Abbe's number to satisfy specific conditional expressions.

Claims8

Dependent claims

An imaging lens comprising:

a first lens having negative refractive power;
a second lens having positive refractive power;
a third lens having positive refractive power;
a stop;
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 surface thereof on the image plane side have a positive curvature radius,
said second lens is formed in a shape so that a surface thereof on the image plane side have a negative curvature radius,
said third lens is formed in a shape so that a surface thereof on the image plane side has a negative curvature radius,
said fourth lens is formed in a shape so that a surface thereof on the object side has a positive curvature radius and a surface thereof on the image plane side has a negative curvature radius, and
said first lens has a focal length f1 and an Abbe's number νd1 so that the following conditional expressions are satisfied:
−75<f1/f<−5.0
45<νd1<70
where f is a focal length of a whole lens system.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/090,464Filed 26 Nov 2013
Priority: JP 2012-26209530 Nov 2012
Published: US 2014/0153116 A15 Jun 2014
Granted: 7 Apr 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G02B 13/004
Having at least one aspherical surface: having four lenses
G02B 9/34
Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -: having four…
G02B 27/0025
Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00: for optical correction, e.g. distorsion,…
G02B 1/11
Optical coatings produced by application to, or surface treatment of, optical elements: anti-reflection coatings