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:
Mar. 24, 1998
Filed:
May. 23, 1996
Susumu Takashima, Tokyo, JP;
JEOL Ltd., Tokyo, JP;
Abstract
There is disclosed a high-resolution magnetic-electrostatic compound objective lens for use in a scanning electron microscope, the objective lens having reduced spherical aberration and chromatic aberration. The lens comprises a substantially conically-shaped magnetic pole piece, a coil wound along the inner surface of the magnetic pole piece, a hollow insulator disposed along the inner surface of the coil and a high-resistivity film disposed along the inner surface of the insulator. When the coil is energized, an axially symmetrical magnetic field is produced inside the magnetic lens. The obtained axial magnetic flux density distribution has a peak near the bottom end of the magnetic pole piece. The principal plane of the magnetic lens is brought close to the specimen and results in smaller aberrations. When a high voltage is applied to the high-resistivity film from a voltage source, a feeble electrical current flows from the top end of the film to the bottom end, thus producing a voltage drop in the longitudinal direction of the film. Since the shape and the thickness of the high-resistivity film are symmetrical with respect to the optic axis, the equipotential surface is axially symmetrical.