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:
Nov. 09, 1999
Filed:
Feb. 04, 1998
Hajime Ichikawa, Yokohama, JP;
Takahiro Yamamoto, Yokohama, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A method is provided for deriving an absolute surface profile of an object having a rotationally symmetric component and a rotationally asymmetric component using a detection system for measuring a relative surface profile of the object with respect to a predetermined reference surface. The method includes the steps of positioning the object to a first predetermined position relative to the detection system, rotating the object around a predetermined measurement axis of rotation at the first predetermined position, acquiring data indicating the relative surface profile of the object with respect to the predetermined reference surface at each of a plurality of rotational positions of the object during the rotating step, averaging the data acquired in the acquiring step over the plurality of rotational positions to derive a rotationally averaged data, and processing the rotationally averaged data and the data indicating the relative surface profile of the object at at least one of the plurality of rotational positions of the object to derive the rotationally asymmetric component of the absolute surface profile of the object. The method further includes the steps of translating the object to a second predetermined position relative to the detection system, acquiring data indicating the relative surface profile of the object at the second predetermined position, and processing the data indicating the relative surface profile of the object at the second predetermined position and at least one of the rotationally averaged data and the data indicating the relative surface profile at at least one of the plurality of rotational positions of the object to derive the rotationally symmetric component of the absolute surface profile of the object, the data processing using a polynomial best fitting method for the data indicating the relative surface profile at the second predetermined position.