Patent ID: 6097028
Filing Date: 2000-08-01
Classification: H01J

Abstract:
An omega-type energy filter for being positioned along the optical axis of an electron beam device comprising:an entrance window;an exit window aligned with said entrance window along the optical axis forming a slit plane;magnetic fields between the entrance window and exit window, said fields comprising a first magnetic field M.sub.1, a second magnetic field M.sub.2, a third magnetic field M.sub.3, and a fourth magnetic field M.sub.4 produced in this order to deflect an electron beam into an .OMEGA.-shaped orbit from said entrance window to said exit window;said fourth magnetic field M.sub.4 having an exit end surface spaced a distance of L.sub.5 from said exit window; andan exit pupil plane spaced a distance of LL from said exit window; and whereinLL/L.sub.5 >2.