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. 23, 1982
Filed:
Oct. 30, 1980
Applicant:
Inventors:
Akito Iwamoto, Kamakura, JP;
Hidekazu Sekizawa, Yokohama, JP;
Assignee:
Tokyo Shibaura Denki Kabushiki Kaisha, Kanagawa, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01N / ;
U.S. Cl.
CPC ...
356239 ; 3501 / ;
Abstract
The apparatus of this invention is used for inspecting defects in a periodic pattern. The apparatus comprises a device for forming a Fourier transformed pattern of the periodic pattern and a filter for passing predetermined spatial frequency ranges of the Fourier transformed pattern. The predetermined spatial frequency ranges are lower than a spatial frequency which coincides with a first order diffraction of the Fourier transformed pattern.