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:
Aug. 22, 2000
Filed:
Jul. 09, 1998
Applicant:
Inventors:
Assignee:
Advantest Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G21K / ; H01J / ; H01J / ;
U.S. Cl.
CPC ...
2503 / ; 2503 / ;
Abstract
An electron beam lens has a magnetic lens provided with first and second pole pieces for influencing an electron beam and forming a magnetic field between the two pole pieces. A third pole piece is provided, but is not in magnetic contact with the two other pole pieces. The third pole piece is immersed in the magnetic field formed between the first and second pole pieces and extracts a part of such magnetic field. Also disclosed is a cathode lens and an electron beam device for use with such an electron beam lens.