PARTICLE-OPTICAL APPARATUS AND PARTICLE BEAM SYSTEM

A beam deflector includes a magnetic-flux-guiding structure which has an opening through which a beam axis extends, and at least two coils arranged at the magnetic-flux-guiding structure so that they produce a magnetic field B1 having lines passing through the two coils in succession, leave the magnetic-flux-guiding structure at a first location on a first side in relation to the beam axis, cross the beam axis at a second location which is arranged at a distance along the beam axis from the magnetic-flux-guiding structure, re-enter into the magnetic flux-guiding structure at a third location on a second side lying opposite the first side, and extend around the opening from the third location to the first location within the magnetic-flux-guiding structure.