Projection lens system
AssigneeOlympus Optical Co., Ltd.
InventorsYoshiko Tezuka, Keiichi Kuba
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Abstract
The present invention relates to a projection lens system well-fit for baking integrated circuit patterns onto silicon wafers using a light source having wavelengths ranging from an ultraviolet wavelength zone to a vacuum ultraviolet wavelength zone. This projection lens system is characterized by comprising a plurality of lens elements including a Fresnel lens element having negative dispersion characteristics, said Fresnel lens being located at a position lying somewhere in said projection lens system with the exception of the pupil thereof and satisfying the following condition: 2h.sub.MAX /3.ltoreq.h. Here h.sub.MAX is the maximum height of a marginal ray in said projection lens system, and h is the height of a marginal ray at the position of said Fresnel lens.
Claims13
A photographic exposure device comprising a light source, an object irradiated by light emitted from said light source, and a projection lens system for forming an image of said object on a predetermined position, wherein the wavelength of light emitted from said light source is shorter than 300 nm and said projection lens system comprising a plurality of lens elements including a Fresnel lens element having negative dispersion characteristics, said Fresnel lens element being located at a position lying somewhere in the projection lens system with the exception of the pupil thereof and satisfying the following condition:
- 2h.sub.MAX /3.ltoreq.h
- where h.sub.MAX is the maximum height of a marginal ray in said projection lens system and h is the height of a marginal ray at the position of said Fresnel lens.
A projection lens system characterized by comprising a plurality of lens elements including a Fresnel lens element having negative dispersion characteristics, said Fresnel lens element being located at a position lying somewhere in the projection lens system with the exception of the pupil thereof and satisfying the following condition:
- 2h.sub.MAX /3.ltoreq.h
- where h.sub.MAX is the maximum height of a marginal ray in said projection lens system and h is the height of a marginal ray at the position of said Fresnel lens.
Dependencies are inferred from the claim text.