Patent ID: 9383554
Filing Date: 2016-07-05
CPC Classification: G02B

Claim Text:
1. An optical system, comprising: a first lens having positive refractive power of which an object-side surface is convex and an image-side surface is concave; a second lens having negative refractive power and being convex toward the object side and concave toward an image side; a third lens having positive refractive power and an image-side of the third lens is convex in a paraxial region; a fourth lens having a refractive power and being concave toward the object side and convex toward the image side; and a fifth lens having a refractive power and being convex toward the object side, the fifth lens comprising an image-side surface being concave in the center and convex at the periphery, wherein: one or more inflection points are formed on the image-side surface of the fifth lens, the first lens, the second lens, the third lens, the fourth lens and the fifth lens are arranged in order from the object side toward the image side, a thickness of the fifth lens is thicker than the first lens, the second lens, the third lens, and the fourth lens, and a radius R31 of curvature of an object-side surface of the third lens and a focal length f of the optical system satisfy the following conditional expression: wherein the optical system satisfies the following conditional expression: f2<f5, where f2 is a focal length of the second lens and f5 is a focal length of the fifth lens.