The electron potential of an electron beam is switched between different values without moving the focal plane by effectively changing the axial position of the electron source at the same time that the electron potential is changed. The effective change in axial position of the electron source exactly compensates for the altered effectiveness which magnetic lenses have upon an electron beam of altered electron potential such that the final focal plane remains at the same position without adjusting the field strength of any magnetic lens.
申请公布号
DE3380504(D1)
申请公布日期
1989.10.05
申请号
DE19833380504
申请日期
1983.03.25
申请人
INTERNATIONAL BUSINESS MACHINES CORPORATION
发明人
CHANG, TAI-HON PHILIP;COANE, PHILIP JAMES;HOHN, FRITZ-JURGEN;KERN, DIETER PAUL