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. 06, 1987
Filed:
Jan. 22, 1986
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
250311 ; 250397 ;
Abstract
A focus control system used in a transmission electron microscope includes an electron lens for imaging the electron beam transmitted through a specimen onto the imaging plate, apparatus for deflecting the electron beam irradiation angle, and several electron beam sensors disposed of the imaging plane. Output signals produced by each sensor at two irradiation angles are integrated and stored in the memory separately. The difference between each pair of integrated values in the memory is calculated, and all differences for all sensor output pairs are summed up. The lens current of the electron lens is controlled so that the summed output is a minimum value.