Prospects for aberration-free electron microscopy

Future aberration-corrected electron microscopes that will enable sub-Ångstroem spatial and sub-eV energy resolution are outlined . The sub-Ångstroem transmission electron microscope (SATEM) only compensates for the spherical aberration and reduces the chromatic aberration disc by means of a monochromator. In order to correct for both aberrations, two novel correctors, the ultracorrector and the superaplanator are proposed which will yield a resolution limit of about 0.5 Å and a large field of view of more than 4×106 image points. The superaplanator is best suited for obtaining an achromatic aplanat required for the realization of the high-performance in situ electron microscope of the TEAM project.