Projection lens system and apparatus
AssigneeNikon Corporation
InventorsKotaro Yamaguchi, Kiyoshi Hayashi, Tomawaki Takahashi
Life of this patent
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Abstract
A high-performance dioptric reduction projection lens and projection exposure apparatus and projection exposure method using same. The projection lens includes six lens groups and has a positive negative positive negative positive refractive power arrangement. The third and fifth lens groups have overall positive refractive power and include at least three lens elements having positive refractive power. The fourth lens group has negative refractive power and includes at least three lens elements having negative refractive power. At least one lens element in either the fourth lens group or the fifth lens group includes an aspheric surface. The projection lens preferably satisfies at least one of a number of design conditions.
Claims24
A projection lens having an object plane and an image plane and comprising objectwise to imagewise:
- a) a first lens group having positive refractive power;
- b) a second lens group having negative refractive power;
- c) a third lens group having overall positive refractive power, and including at least three lens elements having positive refractive power;
- d) a fourth lens group having overall negative refractive power and including at least three lens elements having negative refractive power;
- e) a fifth lens group having overall positive refractive power and including at least three lens elements having positive refractive power;
- f) a sixth lens group having positive refractive power;
- g) wherein at least one of said fourth lens group and said fifth lens group includes at least one aspheric surface;
- and
- h) the projection lens having a numerical aperture larger than 0.6.
Dependencies are inferred from the claim text.