Stability of electron ptychography at low electron dose.

Electron ptychography provides a promising avenue towards dose-efficient, high-resolution materials characterisation. Prior work demonstrates the feasibility of this approach, but an overarching view on the reliability of ptychographic images in low-dose scenarios is required. Here, we address this limitation with a systematic study of image clarity across dose, thickness and convergence semi-angle, on a range of materials science specimens. With the now widespread adoption of 4D-STEM and ptychographic imaging, the establishment of the practical parameter space in which one can anticipate a reliably interpretable phase image is urgently needed. In some cases, our parameter space exploration confirms high-resolution imaging at doses of 200  $e^{-}$ Å ${}^{-2}$ .