Fig. 1: Overview of 4D STEM.
From: Unsupervised deep denoising for four-dimensional scanning transmission electron microscopy
a Schematic 4D STEM set-up. At each probe position a convergent electron beam scatters through a material and forms a convergent beam electron diffraction (CBED) pattern. b Experimental CBED patterns from aluminium ([001] zone axis, 300 keV electrons, 15 mrad convergence semiangle, 0.2 Å probe spacing and 8 × 106 e−. Å−2 dose). Visual features in the patterns change smoothly in position, intensity and shape across adjacent probe positions, a kind of geometric flow, with prominent examples indicated by white and orange arrows. c STEM imaging of the total number of electrons in each pattern in the 4D STEM data. The red box indicates the region from which the patterns in (b) are taken. d The probe-position averaged CBED (PACBED) pattern for data in (c), with the bright and dark field regions indicated.
