Patent ID: 9134507
Filing Date: 2015-09-15
Classification: G02B

Abstract:
1. An imaging lens, consisting of in order from an object side to an image side, a first lens group having a negative refractive power; a second lens group having a positive refractive power; an aperture; a third lens group having a positive refractive power; and a fourth lens group, wherein a refractive power of the fourth lens group is weakest among all of the lens groups, the first lens group consists of a negative lens a concave surface of which faces the image side, the second lens group consists of in order from the object side to the image side a negative lens a concave surface of which faces the object side, and a positive lens, or a cemented lens entirely having a positive refractive power, the third lens group consists of a cemented lens of a biconvex lens and a biconcave lens from the object side, and the fourth lens group is a single lens, or a cemented lens, a surface on the object side of which is a concave surface and a surface on the image side of which is a convex surface.