Acquisition of STEM images typically requires an order of magnitude longer time than shooting fixed-beam TEM images. Since different instabilities (for instance, drift of the sample) always exist in the system, this might distort noticeably the resulted image. It is not exceptional to observe the slightly elliptic shape of the actually round particles or to see the monoclinic distortion of the actually rectangular lattice cell. These distortions can be however corrected a posteriori.
Since the STEM distortions depend on the scanning direction, the issue can be solved by taking two STEM images of the same area with the two mutually perpendicular scanning directions. The reconstruction of undistorted images can be executed at the different levels. The basic version of the plugin assumes a linear drift of an image in the course of both the acquisitions. The correction for non-linear instabilities, which is mandatory for high-resolution STEM images, is addressed in the advanced version of the plugin.
How to use temDM STEMCOR:
temDM STEMCOR 1.82 trial advanced version (GMS3 only, valid till 31.12.2021):
If you download the trial version, it is strongly recommended to download also the STEM correction learning examples below:
New: A companion plugin – temDM SICOR
Distortions in EELS or EDX elemental maps can be corrected a posteriori by comparing a slow scanned ADF image with a fast scanned overview image where STEM distortions are minimal.
temDM SICOR 1.21: