ELECTRONIC ENERGY FILTER

摘要

An electron energy filter includes a first pair of magnetic poles (21) for generating a first deflecting magnetic field and a second pair of magnetic poles (22) for generating a second deflecting magnetic field in the same direction as the first deflecting magnetic field. The incident electrons are deflected about 90 DEG with a trace radius of AM1 through the effect of the first deflecting magnetic field, passed through a free space having a distance DL2 that is about a half of the trace radius AM1 and then are incident to the second deflecting magnetic field. The electrons are deflected about 180 DEG with a trace radius AM2 that is about a half of the curvature radius AM1 and are passed through the free space DL2. Then, the electrons are incident to the first deflecting magnetic field again where those electrons are deflected about 90 DEG . The deflected electrons are traveled like a gamma trace so that those electrons outgo in the same direction as the incident one. This filter so designed is made compact and to have a smaller aberration. <IMAGE>