Interpretable resolution of 0.2 nm at 100 kV using electron holography

Knowledge of amplitude and phase of the image wave is fundamental for numerical correction of the wave aberration. Therefore, off-axis electron holography provides a technique that could substantially improve the point resolution of an electron microscope. Correction for spherical aberration as well as choice of the appropriate defocus pushes the interpretable resolution towards the information limit. Using a thin amorphous germanium specimen covered with a very small amount of platinum, we measured the information limit of our Philips EM420ST FEG to be 0.17 nm at 100 kV. Thin amorphous tungsten foil was used to demonstrate the feasibility of the correction for coherent aberrations up to a spatial frequency of 5 nm−1, which is a major improvement compared to 3.1 nm−1 Scherzer resolution.