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:
Mar. 25, 2003
Filed:
Mar. 20, 2000
Tomowaki Takahashi, Yokohama, JP;
Nikon Corporation, Tokyo, JP;
Abstract
An object of the present invention is to provide a projection optical system having a large numerical aperture in which the maximum effective diameter of lens of the optical system is satisfactorily small. There is provided a projection optical system for projecting an image on a first surface onto a second surface, comprising a first lens group G of positive refracting power including two or more positive lenses, a second lens group G of negative refracting power including two or more negative lenses, a third lens group G of positive refracting power including three or more positive lenses, a fourth lens group G of negative refracting power including two or more negative lenses, and a fifth lens group G of positive refracting power including at least six or more consecutive positive lenses, in the named order from the first surface side to the second surface side, wherein either the fourth lens group G or the fifth lens group G has one aspherical surface *, the fifth lens group G has an aperture stop AS inside thereof, a portion of a diverged light flux right before the aperture stop AS has a first air lens LA of negative refracting power, the radius of curvature rA of the lens surface on the first surface side of the first air lens LA is positive, and a portion of a converged light flux at the rear of the aperture stop AS has a second air lens LB of negative refracting power.