Patent ID: 7355799
Filing Date: 2008-04-08
Classification: G02B

Abstract:
1. A projection lens having a magnification side and a reduction side opposite the magnification side and comprising two lens groups, arranged in order from the magnification side along an optical axis, as follows: a first lens group having negative refractive power; and a second lens group having positive refractive power; wherein the distance along the optical axis between said first lens group and said second lens group is greater than the distance between any two adjacent optical surfaces of the projection lens; each of said first lens group and said second lens group includes at least one lens component that is formed of three lens elements; and the following conditions are satisfied where f f is the focal length of the entire projection lens; f D Bf is the air-equivalent distance along the optical axis between the lens surface on the reduction side of said second lens group and the image plane of the projection lens on the reduction side of the projection lens.