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:
Feb. 19, 1991
Filed:
Jan. 25, 1989
Yoshitada Oshida, Fujisawa, JP;
Yasuhiro Yoshitake, Yokohama, JP;
Naoto Nakashima, Shiga, JP;
Masataka Shiba, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A method and a system for pattern detection are disclosed in which a laser beam high in directivity is emitted from a laser beam source, the laser beam emitted from the laser beam source is irradiated on an uneven pattern to be detected on an object, the light component of a frequency corresponding to the cut-off frequency of an objective lens is removed from the light reflected from the object when an image of the pattern on the object is formed through an objective lens, the optical image thus formed is received by a photoelectric converting device for producing a signal waveform representing the pattern free of a signal of the frequency corresponding to the cut-off frequency, and the pattern is detected from a signal produced from the photoelectric converting device.