The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 19, 1998
Filed:
Jun. 29, 1995
Kazuo Ushida, Tokyo, JP;
Koichi Matsumoto, Tokyo, JP;
Nikon Corporation, , JP;
Abstract
The projection optical system of the present invention decreases particularly the secondary spectrum of chromatic aberration and minimizes restrictions on lens design. The projection optical system of a projection exposure apparatus which irradiates a light beam from a light source on a mask to expose a pattern of the mask onto a photosensitive substrate through the projection optical system has at least one diffraction optical element, at least one quartz lens, and at least one fluorite lens. The diffraction optical element has a positive power, the quartz lens has a negative power, and the fluorite lens has a positive power. An Ar--F laser is preferably used as a light source.