Do smaller probes in a scanning transmission electron microscope result inmore precise measurement of the distances between atom columns?

Conventionally, the design of annular dark-field (ADF) scanning transmissio n electron microscopy (STEM) experiments is mostly based on resolution crit eria related to direct visual interpretability. However, the future of imag e interpretation lies in quantitative structure determination. Since this i s a different purpose, the design has to be reconsidered. In this paper, a precision-based performance measure is proposed, which follows from a simpl ified model. From this, the optimal experimental design for a quantitative ADF STEM experiment is derived. The outcome of this optimization is that th e probe should not be as small as possible, but that the optimal width depe nds strongly on the material under investigation. Furthermore, it turns out that the radius of the hole in the detector should be as large as the opti mal aperture radius.