Catoptric projection optical system
AssigneeCanon Kabushiki Kaisha
InventorsTakahiro Sasaki, Toshihiro Sunaga, Koshi Hatakeyama
Life of this patent
Estimating the term…
Abstract
A catoptric projection optical system for projecting a pattern on an object surface onto an image surface includes plural mirrors, wherein a second mirror from the image surface through the optical path receives convergent pencil of rays, and has a paraxial magnification of −0.14 or smaller.
Claims3
A catoptric projection optical system for projecting a pattern on an object surface onto an image surface, said catoptric projection optical system comprising six mirrors that include, in order from the object surface to the image surface and along an optical path of said catoptric projection optical system, a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror, and a six mirror to sequentially reflect light,
- wherein the first mirror has a convex or plane shape, and the fifth mirror receives convergent pencil of rays,
- wherein said six mirrors are arranged, in order a near distance along an optical axis from the object surface as follows:
- the second mirror, the first mirror, the fourth mirror, the sixth mirror, the third mirror and the fifth mirror,
- wherein an intermediate image is formed between the fourth and third mirrors.
Dependencies are inferred from the claim text.