Elektronen-Interferenzen in der Umgebung der Brennlinie einer magnetischen Quadrupollinse

Abstract

It is shown that a coherent superposition of parts of an electron wave field by magnetic fields is possible. The deflecting magnetic fields are formed by a quadrupole lens. The interference space in which the coherent superposition of three partial waves takes place is limited by a caustic surface. The interference phenomena in the neighbourhood of this surface can be described by means of an integral of the Airy type. A quadrupole lens with rectangular pole piece edges forms in great distance from its axis homogeneous magnetic fields of opposite direction. If a coherent irradiation of both these homogeneous fields can be achieved, they form a magnetic biprism if the paraxial part of the beam is stopped. The distance of interference fringes in such an interferogram would in first approximation be independent of the particle energy.