A Hybrid Approach to Calibrate the Affine Transformation Between Scan-Camera Coordinates for 4D-STEM Datasets

Abstract

Accurate geometrical calibration between scan-camera coordinates is critical in four-dimensional scanning transmission electron microscopy (4D-STEM) [1] for both quantitative imaging and ptychographic reconstructions. Such calibration is, however, not a trivial task since (i) 4D-STEM is more sensitive to the vortical nature of electron trajectories caused by the electromagnetic lenses compared to other STEM imaging modes that use detectors with circular symmetries; (ii) Most 4D-STEM experiments still need relatively long dwell time (e.g., > 100μs per pixel) making them highly susceptible to instrumental instabilities and environmental disturbances.