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:
Dec. 18, 1990
Filed:
Mar. 31, 1989
Seishi Akado, Tokyo, JP;
Jeol Technics Co., , JP;
Abstract
In an automatic focusing apparatus according to the invention, a focusing lens is provided for focusing an electron beam which scans a specimen. Charged particles emanating from the specimen are then detected. The excitation current energizing the lens is varied in accordance with a sweep signal that changes linearly. The electron beam scans at each different value of the sweep signal. An evaluating signal is produced indicating the degree to which the focusing lens is focused. The excitation current supplied to the lens is set according to the output signal from the evaluating signal-producing means. The linearly swept excitation current is modulated with a periodic signal. Plural cases are determined where the evaluating signal assumes maximum values. In each case, the average value of the linearly swept signal is calculated. The excitation current is set to a value to be supplied to the focusing lens, corresponding to the average value. The focusing lens is energized with electric current having the set value to focus the beam onto the specimen.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile