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. 11, 1986
Filed:
Dec. 20, 1983
Nobuo Iijima, Tama, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An automatic focus control device for adjusting the height of a lens above a surface of a workpiece used in an exposure apparatus for exposing the sample with a light beam including a first light emitting device for emitting a first light ray to a sample; a second light emitting device for emitting a second light ray to the sample. First and second light detecting devices for detect the second and first light rays reflected by a surface of the sample, respectively. The first and second light detecting device have a plurality of light detecting elements. A discriminating device discriminating between an inclination of the sample and a variation of the height of the lens above the surface of the sample on the basis of an output of the first and second light detecting devices. The first light emitting device and the first light detecting device are symmetrically located with respect to the second light emitting device and the second light detecting device in relation to a center axis of a light beam for exposing the sample.