Electron beam apparatus.

摘要

An electron beam apparatus is provided with an energy selective device enabling energy selective measurings together with imaging. The energy selective device has its main electron trajectory in a plane outside the optical axis of the electron beam apparatus restricting the additive length of the apparatus substantially. Preferably the energy selective device shows double symmetry such that the energy dispersion has a maximum value in a central plane of symmetry where a selective slit can be introduced. Full symmetry facilitates full compensation of optical aberrations int he filter. Adding quadrupoles in a second plane of symmetry enables imaging of spectra outside the filter.