Patent ID: 7426079
Filing Date: 2008-09-16
Classification: G02B

Abstract:
1. An optical system comprising: a refractive optical element composed of a solid material, the Abbe number νd and the partial dispersion ratio θgF of the solid material satisfying the following conditions: wherein a height of a paraxial marginal ray passing through a forefront lens surface of the optical system is less than, as measured from an optical axis, a maximum height of the paraxial marginal ray passing through a lens surface positioned at the rear of an intersection point of the optical axis with a paraxial chief ray, and wherein the refractive optical element is disposed at the front of the intersection point and has a shape so that the thickness of the refractive optical element at a position of about 70% of the maximum effective ray diameter is greater than a thickness of the refractive optical element on the optical axis.