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:
May. 01, 1990
Filed:
Jun. 29, 1987
Minori Noguchi, Yokohama, JP;
Mitsuyoshi Koizumi, Yokohama, JP;
Hiroaki Shishido, Yokohama, JP;
Sachio Uto, Yokohama, JP;
Yoshimasa Ohshima, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A method of and an apparatus for detecting a fine foreign substance in which the surface of a specimen is illuminated with linearly-polarized laser beam to detect light scattered from the surface and having passed through a polarization filter, the back side of the specimen is illuminated with light from a light source such as a mercury lamp to obtain the light and darkness information or phase information on the specimen surface by transmitted light from the specimen, and fine massive and filmy foreign substances on the specimen surface are detected on the basis of information given by the scattered light and transmitted light.