Sector field deflection system for LV electron microscope - has several magnet sectors with uniformly excited outer pole shoe, enclosing several, identical excited inner pole shoes

摘要

The magnetic sectors form pole shoes for a microscope imaging by elastically or non-elastically spread electrons or ions. There is a uniformly excited outer pole shoe (12) surrounding several identically formed, inner, excited pole shoes (20, 22, 24) whose excitation differs from the external one providing a stigmatic doubel focussing. Pref. at least one pole shoe is differently excitable w.r.t. the other pole shoes. The illuminating and the imaging beams extend in a mirror image outside the deflection system even if the energy of the two beams is different. One inner pole shoe may be also differently excitable w.r.t. the other ones, or may carry an additional magnetic coil. USE/ADVANTAGE - Simple design and facility for deflection system operation by elastically and non-elastically spread electrons.