Catadioptric projection lens
AssigneeNikon Corporation
InventorYasuhiro Omura
Life of this patent
Estimating the term…
Abstract
A catadioptric projection lens comprising a first lens group (G1) disposed along a first optical axis (16a), a mirror (18) which creates a second optical axis (16b), a beam splitter (20) which creates a third optical axis (16c), a second lens group (G2) including a concave mirror (L22) disposed along the third optical axis on one side of the beam splitter, and a third lens group (G3) disposed along the third optical axis on the side of the beam splitter. The first and third optical axes are parallel, a configuration which reduces aberrations arising from gravitational deformation of the lens elements, when the first and third axes are aligned with the direction of gravity.
Claims30
A catadioptric projection lens having an object plane and an image plane, the lens comprising in order from the object plane to the image plane:
- a.) a first lens group having one or more refractive lens elements and disposed along a first optical axis;
- b.) a first mirror which creates a second optical axis that is not parallel to said first optical axis;
- c.) a beam splitter, disposed along said second optical axis, which creates a third optical axis that is parallel to said first optical axis;
- d.) a second lens group having one or more refractive lens elements and a concave mirror, said second lens group disposed along said third optical axis adjacent said beam splitter and opposite the image plane;
- e.) a third lens group having one or more refractive lens elements and disposed along said third optical axis immediately adjacent the image plane;
- and
- f.) wherein all refractive lens elements in the catadioptric projection lens have optical axes that extend in parallel.
A catadioptric reduction projection optical system comprising:
- a.) a plurality of refractive lens elements, each having an optical axis;
- b.) a plane mirror;
- c.) a beam splitter;
- d.) at least one concave mirror;
- e.) wherein optical axes of all the refractive lens elements in the catadioptric projection optical system are mutually parallel;
- f.) reduction imaging is performed from a first surface to a second surface by the catadioptric reduction projection optical system;
- and
- g.) the first surface and the second surface are parallel to each other.
Dependencies are inferred from the claim text.