Patent ID: 8441744
Filing Date: 2013-05-14
Classification: G02B

Abstract:
1. An optical image system comprising, in order from an object side to an image side: a first lens element with positive refractive power and having a convex object-side surface; a second lens element with positive refractive power; a third lens element with negative refractive power and having a concave object-side surface and a convex image-side surface, wherein the third lens element is made of plastic material, and the object-side surface and the image-side surface of the third lens element are aspheric; and a fourth lens element with refractive power and having a concave image-side surface, wherein the fourth lens element is made of plastic material, an object-side surface and the image-side surface of the fourth lens element are aspheric, and the fourth lens element has at least one inflection point formed on at least one of the object-side surface and the image-side surface thereof; wherein when a focal length of the optical image system is f, a focal length of the first lens element is f