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:
Oct. 28, 1980
Filed:
Jul. 14, 1978
Applicant:
Inventors:
Masana Minami, Kawasaki, JP;
Tomohide Watanabe, Kawasaki, JP;
Assignee:
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Primary Examiner:
Int. Cl.
CPC ...
G01J / ;
U.S. Cl.
CPC ...
250201 ; 250204 ;
Abstract
An automatic focusing apparatus includes a lens for leading a laser beam onto a sample surface at a predetermined incident angle, a beam splitter to divide the reflected beam from the sample surface in accordance with the vertical shift thereof, a pair of photo diodes to respectively receive the divided beams and produce electric signals, a differential amplifier to produce a differential signal between the electric signals and a mechanism to vertically shift the stage by means of the differential signal to automatically focus a lens system on said sample surface.