ABSTRACT
The microscope was manually aligned to the coma-free axis and the two-fold astigmatism corrected using on-line diffractograms of the amorphous carbon support film. Focal series of images were recorded with the microscope under automatic control using scripts running under the Gatan Digital Micrograph software. For each orientation a series of 30 images was recorded of a thin crystal edge beginning underfocus with a nominal focal increment of 10 nm between images. A fmal image at the starting defocus was recorded to assess the focal drift. The image processing techniques subsequently employed to recover the modulus and exit-plane wave function are described elsewhere (Kirkland eta/., 1995, 1997, 1999; Meyer eta/., 2002).
