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:
May. 24, 1988
Filed:
Oct. 20, 1986
John B French, Thornhill, CA;
Donald J Douglas, Toronto, CA;
John E Fulford, Holland Landing, CA;
Peter Arrowsmith, San Jose, CA (US);
MDS Health Group Limited, Etobicoke, CA;
Abstract
A mass analyzer in which an ion signal, typically from a plasma, travels through an orifice into a vacuum chamber, and through a focussing system in the vacuum chamber into a mass spectrometer and ion detector. Drift of the detected ion signal, and differences in drift of the detected ion signal for different elements, are greatly reduced by a small shadow stop placed in the vacuum chamber immediately behind the orifice. The shadow stop and plate containing the orifice are both preferably grounded. The focussing system includes a Bessel box lens, and drift is further reduced by insulating the stop in the Bessel box lens from the barrel and biasing the Bessel stop differently from the barrel.