Enhancing Dose Efficiency of Optimum Bright‐Field Scanning Transmission Electron Microscopy Using a Phase‐Shifted Electron Probe

Observing beam-sensitive materials using scanning transmission electron microscopy (STEM) at low electron dose conditions is challenging due to the low signal-to-noise ratio (SNR) of images. In this study, we aimed to improve the SNR of optimum bright-field (OBF) STEM by introducing phase shifts to the incident electron probe using lens aberrations. Theoretical analysis and multislice simulations revealed that spherical aberration enhances low-frequency contrast without introducing image artifacts, unlike simple defocus, which causes oscillations in the contrast transfer function. This approach improves the visibility of structural features in low-dose conditions and may enable more efficient imaging of beam-sensitive materials such as zeolites.