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. 13, 1979
Filed:
Jan. 27, 1978
Applicant:
Inventor:
Shinjiro Katagiri, Katsuta, JP;
Assignee:
Hitachi, Ltd., , JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
250441 ; 250457 ; 250310 ; 2504 / ;
Abstract
A specimen chamber is which a specimen to be irradiated by an electron beam is arranged is evacuated by an evacuation device. The evacuation device includes a nonvaporative bulk getter vacuum pump and an oil rotary pump. The oil rotary pump is used for evacuating the specimen chamber from the atmospheric pressure to 10.sup.-1 - 10.sup.-2 Torr, while the nonvaporative bulk getter vacuum pump is used for continuously evacuating the specimen chamber to 10.sup.-5 - 10.sup.-6 Torr. The steady vacuum of 10.sup.-5 - 10.sup.-6 Torr is maintained by only the nonvaporative bulk getter vacuum pump.