Greatly defocused, point-projection, off-axis electron holography

A practical and wave-optical description is given for two modes of greatly defocused point-projection electron holography that have been implemented in a scanning transmission electron microscope. A comparison is made between these electron holographic modes and those conventionally employed in TEM. The resolution, field-of-view, and phase sensitivity is discussed in general, and for our particular implementation. A method for correcting defocus aberrations in holographic images is shown. Phase contrast arising from electromagnetic fields is described. Quantitative examples are given for the determination of the mean inner potential, thickness integrated magnetization in magnetic thin films and domain structure in magnetic superlattices.