Patent ID: 9036277
Filing Date: 2015-05-19
Classification: G02B

Abstract:
1. An imaging lens comprising: a first lens having negative refractive power; a second lens having negative refractive power; a third lens having positive refractive power; a fourth lens having positive refractive power; and a fifth lens having negative 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 object side and a surface thereof on the image plane side have positive curvature radii, said second lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii, said third 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, 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, said fifth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have negative curvature radii, said first lens, said second lens, said third lens, and said fourth lens are formed of a material having an Abbe's number between 45 and 75, said fifth lens are formed of a material having an Abbe's number between 20 and 40, and said fifth lens has a focal length f5 so that the following conditional expression is satisfied: where f is a focal length of a whole lens system.