Recent Developments in High Resolution Electron Microscopy

High resolution transmission electron microscopes nowadays achieve a point resolution beyond 0.2nm so that structural information can be visualized at the atomic scale. However, since the images are strongly influenced by dynamical electron scattering and imaging parameters such as defocus and spherical aberration, it is still difficult to determine the structure directly from the images without a priori knowledge. Some recent technological developments have possibilities to solve this problem. A novel approach based on defocus-modulation image processing allows us to correct spherical aberration, leading to marked improvement of the resolution and direct retrieval of structural information from the processed images.