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. 22, 2000
Filed:
Jan. 12, 1998
Applicant:
Inventors:
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01J / ; H01J / ; H01J / ; G21K / ;
U.S. Cl.
CPC ...
25049223 ; 2503 / ; 2503 / ;
Abstract
An optical element includes two electrodes 1 and 2 arranged at a distance to oppose each other and configured to converge an electron beam. The opposing surfaces of the electrodes 1 and 2 are so formed as to be cylindrically symmetrical along the beam passing direction and to form curves obtained by deforming hyperbolas in a direction perpendicular to the beam passing direction, in order that an electric field whose effective part except for an arbitrary constant of the field potential is given by