Live processing of momentum-resolved STEM data for first moment imaging and ptychography

TL;DR

This paper presents a real-time data processing approach for 4D STEM that enables live imaging and analysis, improving in-situ imaging of weakly scattering specimens with immediate feedback for experimental optimization.

Contribution

It introduces a reformulated single-sideband ptychography method for live data analysis in STEM, integrated into the open-source LiberTEM platform, allowing real-time imaging and parameter adjustments.

Findings

Live processing of experimental and simulated data demonstrates real-time structural imaging.

Single sideband method compares favorably to other techniques for thicker specimens.

Qualitative live results enable instrument and sample optimization during experiments.

Abstract

A reformulated implementation of single-sideband ptychography enables analysis and display of live detector data streams in 4D scanning transmission electron microscopy (STEM) using the LiberTEM open-source platform. This is combined with live first moment and further virtual STEM detector analysis. Processing of both real experimental and simulated data shows the characteristics of this method when data is processed progressively, as opposed to the usual offline processing of a complete dataset. In particular, the single side band method is compared to other techniques such as the enhanced ptychographic engine in order to ascertain its capability for structural imaging at increased specimen thickness. Qualitatively interpretable live results are obtained also if the sample is moved, or magnification is changed during the analysis. This allows live optimization of instrument as well as specimen parameters during the analysis. The methodology is especially expected to improve contrast- and dose-efficient in-situ imaging of weakly scattering specimens, where fast live feedback during the experiment is required.