Depth of field of multi-slice electron ptychography: Investigating energy and convergence angle

Abstract

Multi-slice electron ptychography has attracted significant interest in recent years, thanks to notable experimental successes in ultra-high resolution, depth-resolved imaging of atomic structure. However, the theoretical dependence of depth of field on experimental parameters is not well understood. In this paper we use simulated data to compare the depth of field of through focal annular-dark field and multi-slice electron ptychography over a range of acceleration voltages and convergence angles. We show that at both low convergence angle and at low electron energy, multi-slice ptychography has significantly improved depth of field over through focal ADF imaging.