Multiple mirror catadioptric optical system
AssigneeNikon Precision Inc.
InventorLeslie D. Foo
Life of this patent
Estimating the term…
Abstract
A reduction projection system (10) characterized by large numerical aperture has an unobscured optical path without the need to resort to truncated lens elements. The system includes first and second reduction stages. The first reduction stage includes a first mirror group (20) and a first lens group (30). The second reduction stage includes a second mirror group (40) and a second lens group (50). Together, the first mirror group and the first lens group form an intermediate reduced image of the object at an intermediate image region (70). The second mirror group and the second lens group form a further reduced image at an image plane (15).
Claims37
A catadioptric reduction projection optical system for producing a reduced image of an object, comprising, in a light path sequence from the object:
- a first reduction stage, including a first mirror group having at least one concave mirror, forming an intermediate image of reduced size at an intermediate image region;
- and
- a second reduction stage, including a second mirror group and a lens group, forming a final image of further reduced size at a final image plane, said second mirror group including a plurality of mirrors.
A catadioptric reduction projection optical system for producing a reduced image of an object, comprising, in a light path sequence from the object:
- a first mirror group;
- a first lens group consisting entirely of full diameter elements;
- said first mirror group and said first lens group forming an intermediate image of reduced size at an intermediate image region;
- a second mirror group including a plurality of mirrors;
- and
- a second lens group, said second mirror group including a plurality of mirrors;
- said second mirror group and said second lens group forming a final image of further reduced size at a final image plane.
A catadioptric reduction projection optical system for producing a reduced image of an object, comprising, in a light path sequence from the object:
- a first mirror group including first and second concave mirrors and a folding mirror located between said first and second concave mirrors;
- a first lens group consisting entirely of full diameter elements;
- said first mirror group and said first lens group forming an intermediate image of reduced size at an intermediate image region;
- a second mirror group including first and second concave mirrors and a convex mirror between said first and second concave mirrors;
- and
- a second lens group consisting entirely of full diameter elements;
- said second mirror group and said second lens group forming a final image of further reduced size at a final image plane.
Dependencies are inferred from the claim text.