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:
Jul. 06, 1993
Filed:
May. 21, 1992
Miyuki Matsuya, Tokyo, JP;
Jeol Ltd., Tokyo, JP;
Abstract
An electron microscope capable of switching its depth-of-focus mode between a first and a second mode. The microscope includes an electron gun, a first condenser lens, a second condenser lens, an objective aperture, scan coils, and an objective lens arranged in this order in the direction of travel of the electron beam. The mode is switched by changing the excitation of the first and second condenser lenses and of the objective lens so that the electron beam is in focus at the specimen surface. The distance a between the principal plane of the objective lens and the focal point of the second condenser lens in the first mode and the distance b between the principal plane of the objective lens and the focal point of the second condenser lens in the second mode are set sufficiently larger than the maximum distance w.sub.2 between the principal plane of the objective lens and the specimen.