Ultra-fast Digital DPC Yielding High Spatio-temporal Resolution for Low-Dose Phase Characterization

Area of Science:

• Materials Science
• Physics
• Electron Microscopy

Background:

• Scanning transmission electron microscopy (STEM) is increasingly used for phase imaging of beam-sensitive materials and in situ experiments.
• Advancements in 4D-STEM detectors improve temporal resolution for differential phase contrast (DPC) and ptychography.
• Data handling challenges from large datasets and detector readout burden limit practical adoption and temporal resolution.

Purpose of the Study:

• To develop a method for high-fidelity DPC phase reconstruction using annular segmented detectors.
• To overcome the limitations of conventional analog data processing in high-speed STEM.
• To enable low-dose phase imaging for in situ experiments with improved temporal resolution.

Main Methods:

• Integration of ultra-fast scan coils with detector signal digitization.
• Utilizing an annular segmented detector for DPC data acquisition.
• Employing dose fractionation through fast scanning and multi-framing for post-processing.

Main Results:

• Demonstrated high-fidelity DPC phase reconstruction from digitized annular segmented detector data.
• Achieved reliable data acquisition even at the fastest scan speeds, surpassing conventional methods.
• Showcased the ability to balance signal-to-noise ratio and temporal resolution via post-processing binning.

Conclusions:

• Digitized DPC-segment image processing offers a robust alternative to analog methods for high-speed STEM.
• The developed technique facilitates low-dose, high-temporal-resolution phase imaging for in situ studies.
• This approach enhances the practical utility of advanced STEM techniques for materials characterization.