Defocus correction and noise reduction using a hybrid ptychography and Centre‐of‐Mass algorithm

Abstract Integrated Centre‐of‐Mass (iCOM) is a widely used phase‐contrast imaging method based on Centre‐of‐Mass (COM), which makes use of a 4D Scanning Transmission Electron Microscopy (STEM) dataset using an in‐focus probe. In this paper, we introduce a novel approach that combines Single‐Side Band (SSB) ptychography with COM and iCOM, termed Side Band masked Centre‐of‐Mass (SBm‐COM) and integrated Centre‐of‐Mass (SBm‐iCOM) which is applicable to weak‐phase objects. This method compensates for residual aberrations in 4DSTEM datasets while also reducing the noise contribution up to the resolution limit. The aberration compensation and noise filtering features make the SBm‐(i)COM suitable for samples that are difficult to focus or those that require minimal electron fluence. SBm‐iCOM transfers the same information as SSB ptychography but results in an intrinsic transfer function that enhances low‐frequency information.