Computer-Aided Optimization and Synthesis of Electron and Ion Lenses

Abstract

The desire to produce electron and ion optical systems with prescribed first-order properties and as small aberrations as possible is as old as electron and ion optics itself. As we have seen in previous chapters, the aberrations are fundamental limitations to the performance of any beam optics. The reduction of aberrations is especially crucial for ion beams. They must be focused by electrostatic lenses to ensure that the refraction is independent of the charge-to-mass ratio of the particles. As we know, the aberrations of conventional electrostatic lenses are much higher than those of magnetic lenses. The resolution of ion probes is, therefore, always limited by aberrations. But the reduction of magnetic lens aberrations is also desirable to improve the performance of electron microscopes, electron probe instruments, etc.