Patent ID: 9541767
Date: 2017-01-10
CPC Classifications: G02B

Claim:
1. An imaging lens for an image sensor which includes elements arranged in order from an object side to an image side, comprising: a first lens having positive refractive power and a convex surface on the object side; an aperture stop; a second lens that is a meniscus double-sided aspheric lens having negative refractive power and a concave surface on the object side; and a third lens that is a meniscus double-sided aspheric lens having positive refractive power near an optical axis and a concave surface on the image side, wherein a diffractive optical surface is formed on the object-side surface of the second lens; the aspheric object-side and image-side surfaces of the third lens have pole-change points off an optical axis; and conditional expressions (1) to (4) below are satisfied: where fdoe: focal length of the diffractive optical surface, f: focal length of an overall optical system of the imaging lens, vd1: Abbe number of the first lens at d-ray, vd2: Abbe number of the second lens at d-ray, vd3: Abbe number of the third lens at d-ray, and ih: maximum image height.