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. 28, 1999
Filed:
Sep. 17, 1997
Nikon Corporation, Tokyo, JP;
Abstract
Wavefront aberration-measuring apparatus are disclosed that can easily and accurately correct interference-fringe distortions arising from aberrations of an optical system in an interferometer and that can reduce wavefront aberration-measurement errors arising from such distortion. The apparatus comprise an interferometer that forms an interference fringe from a synthesis of a wavefront of light reflecting from a reference surface and a wavefront of light from a test object (such as a reflective surface or lens). The apparatus also comprises an image-pickup element for detecting the interference fringe, and an arithmetical calculator that calculates the wavefront aberration between the test object and the reference surface based on an output from the image-pickup element. Between the test object and the image-pickup element is an optical system (e.g., converging lens) that transmits a wavefront that is perpendicularly incident to a surface of the test object. An interference-fringe distortion corrector corrects the interference-fringe distortion based on a distortion aberration calculated in advance.