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:
Dec. 12, 1995
Filed:
Jan. 14, 1994
Shigeru Hirukawa, Kashiwa, JP;
Eiji Takane, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
In order to measure inclination of a leveling plane with respect to the best image forming plane rapidly at a high accuracy without using a special super-flat wafer, the images of five focus measuring marks are exposed on shot areas partially overlapping with each other, on one hand, in a first exposure area when a focal position is made to coincide with a first focal position by operating a leveling mechanism and, on the other hand, in each of exposure areas when the focal positions are changed gradually. The best focal position is obtained by using an average of the mark lengths of the images of the marks as the mark lengths of the images of marks of measuring points at the upper left corners of the focal positions.