Patent ID: 8970964
Filing Date: 2015-03-03
Classification: G02B,G03F

Abstract:
1. A projection objective lens system comprising, from an object plane to an image plane: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a negative refractive power; a fifth lens group having a positive refractive power and including a first sub-lens group and a second sub-lens group; and an aperture stop positioned between the first sub-lens group and the second sub-lens group; wherein the projection objective lens system includes at least two types of optical materials including high refractive index materials having a refractive index of greater than 1.6 at a working wavelength and low refractive index materials having a refractive index of smaller than 1.6 at a working wavelength; wherein all lenses of the first sub-lens group are positive lenses formed of low refractive index materials; wherein the second sub-lens group includes a negative lens which has an aspheric rear surface and is formed of a high refractive index material; and wherein the following formula is satisfied: ΔR/R<1%, where ΔR represents a difference between a radius at the aperture stop of a marginal field beam bundle and a radius at the aperture stop of a central field beam bundle, and R represents a radius at the aperture stop of a central field beam bundle.