Imaging energy filter for electrons and other electrically charged particles and method for energy filtration of the electrons and other electrically charged particles with the imaging energy filter in electro-optical devices

摘要

An imaging energy filter for deflecting electrons and other charged particles filters an object formed by these particles at the filter inlet by means of an energetic selection of charged particles in the region of a dispersion screen. The filter includes two concentric and spherical electrodes, which produce an electrostatic field that deflects the charged particles at an angle alpha that is greater than pi and less than 2pi. The dispersion screen, operating as a deflecting element that generates a deflection field, is disposed at an intersection point of the inlet axis and the outlet axis and in a plane of symmetry of the angle alpha, wherein the plane of symmetry simultaneously is an electro-optical plane. The deflection field generated by the deflecting element deflects the charged particles at an angle pi-alpha/2, leading to a total deflection angle of 2pi and co-linearity of the inlet axis and outlet axis.