Forschungszentrum Julich Gmbh

Kernforschungsanlage Julich Gesellschaft MIT Beschrankter Haftung

Sieghart Lehwald

Harald Ibach

Heinz-Dieter Bruchmann

Dieter Bruchmann

An electrostatic deflector for energy selection of a beam of charged particles has a plurality of main deflector plates arrayed in a generally cylindrical basic shape and to which electrostatic potentials are applied. The main deflector plates are shaped and the potentials are applied to generate a path of said beam from an input side of said deflector to an output side thereof by virtue of a deflecting field which is increasingly weakened to both sides of a central portion of the beam toward the main deflector plates relative to a field of ideal cylindrical shape, thereby causing second order angular aberration of the beam to substantially vanish. A pair of end deflector plates at opposite ends of the cylindrical basic shape have a repulsive potential with respect to the beam to effect focussing of the beam perpendicular to a dispersion plane of the deflector.

Electrostatic deflector with generally cylindrical configuration

High energy resolution at high electron current at the specimen or at the detector is obtained by an electron beam guiding with focusing energy selection, in particular in an electron spectrometer with emission system and at least one energy dispersive system with different focusing in two mutually perpendicular directions, by a non-circular-symmetrical lens system placed after or before the energy dispersive system and correcting the different focusing of the electrons in the two mutually perpendicular directions such that either the virtual or the real entry stop of the energy dispersive system is imaged on an accessible image plane outside the energy dispersive system or an object outside the energy dispersive system is imaged on the virtual or real exit stop of the latter.

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Julich, Germany

Sieghart Lehwald