Accurate Evaluation of Aberration for Probe-Forming System and Influence of Aberration on High-Resolution STEM image

The influence of residual three-fold astigmatism on high-resolution STEM imaging of graphene has been investigated. The aberration was measured by the segmented Ronchigram auto-correlation function method using the graphene lattice. In the presence of residual threefold astigmatism the graphene lattice showed a lower three-fold rotational symmetry where three C atoms in the six membered ring had a higher intensity.