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:
Nov. 12, 1991
Filed:
Nov. 15, 1990
Applicant:
Inventors:
Susumu Takashima, Tokyo, JP;
Kunihiko Uchida, Tokyo, JP;
Assignee:
Jeol Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
2503 / ; 3133611 ;
Abstract
There is disclosed a conical electromagnetic lens whose spherical aberration and chromatic aberration coefficients can be made small if the apex angle of the conical lens is small. The lens comprises a conical bobbin through which a beam of charged particles passes and a coil wound on the outer periphery of the bobbin. The number of turns of the coil per unit length along the axis of the lens is increased from the inlet end toward the exit end of the lens.