Patent ID: 7362518
Filing Date: 2008-04-22
Classification: G02B

Abstract:
1. A wide angle lens having an optical axis, the wide angle lens comprising, in order from an object side: a first positive convex lens element made of an optical glass, the first positive convex lens element defining: a second concavo-convex negative lens element made of an optical plastic, the second concavo-convex negative lens element defining: a third lens element made of an optical plastic, the third lens element defining: wherein, each of the lens elements is disposed approximately symmetrically about an optical axis of the lens, and the lens elements statisfy the following data: where: R is the curvature radius of the surface's optical center; d is the thickness of the lens element or space between surfaces of two adjacent lens elements; D is the effective aperture of the surface; and k is the conic constant, wherein the conic constant and the aspheric surfaces of the lens are defined by the equation, where: z is the surface sag; c=1/R, where R is the curvature radius of the surface's optical center; k is the conic constant; r is the distance from the optical axis; and a surface data for the aspheric lenses are as follows: