The past three decades have seen the rapid development and maturation of aberration-corrected electron lenses. A new generation of high-speed, high-dynamic-range, electron microscope detectors have allowed us to record the full momentum distribution at every position of scanned, atomic-scale electron beam. The resulting (and very large) four-dimensional phase space contains complete information about the underlying scattering potential. Phase retrieval algorithms such as ptychography offer an approach to using all of these scattered electrons – potentially enhancing both the resolution and dose-efficiency. Here we show how in-focus ptychography enables imaging at more than double the diffraction limit of the lens, and how out-of-focus ptychography improves the dose efficiency compared to all traditional imaging modes.
The increased speed and dynamic range of the new detectors also makes sub-picometer precision strain mapping possible at sub-nanometer resolution for data sets recorded in under a minute. High precision imaging of magnetic, electric and polarization fields with these detectors has provided uniquely detailed maps of topological textures in polar and magnetic Skyrmions.