Real Time Integration Centre of Mass (riCOM) Reconstruction for 4D-STEM

TL;DR

This paper introduces a real-time COM-based reconstruction method for 4D-STEM that enables immediate feedback during imaging, requiring minimal memory and computation, and producing high-quality images with atomic detail.

Contribution

The paper presents a novel real-time reconstruction algorithm using COM that operates without storing diffraction patterns, allowing immediate feedback and integration of post-processing in 4D-STEM imaging.

Findings

Achieves high-quality atomic-resolution images in real time.

Requires minimal memory and computational resources.

Compatible with various camera and file types.

Abstract

A real-time image reconstruction method for scanning transmission electron microscopy (STEM) is proposed. With an algorithm requiring only the center of mass (COM) of the diffraction pattern at one probe position at a time, it is able to update the resulting image each time a new probe position is visited without storing any intermediate diffraction patterns. The results show clear features at higher spatial frequency, such as atomic column positions. It is also demonstrated that some common post processing methods, such as band pass filtering, can be directly integrated in the real time processing flow. Compared with other reconstruction methods, the proposed method produces high quality reconstructions with good noise robustness at extremely low memory and computational requirements. An efficient, interactive open source implementation of the concept is further presented, which is compatible with frame-based, as well as event-based camera/file types. This method provides the attractive feature of immediate feedback that microscope operators have become used to, e.g. conventional high angle annular dark field STEM imaging, allowing for rapid decision making and fine tuning to obtain the best possible images for beam sensitive samples at the lowest possible dose.