  The advantages of convergent beam electron diffraction for symmetry
determination at the scale of a few nm are well known. In practice, the
approach is often limited due to the restriction on the angular range of the
electron beam imposed by the small Bragg angle for high energy electron
diffraction, i.e. a large convergence angle of the incident beam results in
overlapping information in the diffraction pattern. Techniques have been
generally available since the 1980s which overcome this restriction for
individual diffracted beams, by making a compromise between illuminated area
and beam convergence. Here, we describe a simple technique which overcomes all
of these problems using computer control, giving electron diffraction data over
a large angular range for many diffracted beams from the volume given by a
focused electron beam (typically a few nm or less). The increase in the amount
of information significantly improves ease of interpretation and widens the
applicability of the technique, particularly for thin materials or those with
larger lattice parameters.
