Bekkevold Julie Marie, Peters Jonathan J P, Ishikawa Ryo, Shibata Naoya, Jones Lewys
School of Physics, Trinity College Dublin, College Green, Dublin D02 PN40, Ireland.
Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin D02 DA31, Ireland.
Microsc Microanal. 2024 Nov 4;30(5):878-888. doi: 10.1093/mam/ozae082.
In the scanning transmission electron microscope, both phase imaging of beam-sensitive materials and characterization of a material's functional properties using in situ experiments are becoming more widely available. As the practicable scan speed of 4D-STEM detectors improves, so too does the temporal resolution achievable for both differential phase contrast (DPC) and ptychography. However, the read-out burden of pixelated detectors, and the size of the gigabyte to terabyte sized data sets, remain a challenge for both temporal resolution and their practical adoption. In this work, we combine ultra-fast scan coils and detector signal digitization to show that a high-fidelity DPC phase reconstruction can be achieved from an annular segmented detector. Unlike conventional analog data phase reconstructions from digitized DPC-segment images yield reliable data, even at the fastest scan speeds. Finally, dose fractionation by fast scanning and multi-framing allows for postprocess binning of frame streams to balance signal-to-noise ratio and temporal resolution for low-dose phase imaging for in situ experiments.
在扫描透射电子显微镜中，对束敏感材料的相成像以及使用原位实验对材料的功能特性进行表征变得越来越普遍。随着4D-STEM探测器可行扫描速度的提高，差分相衬（DPC）和叠层成像的时间分辨率也得以提高。然而，像素化探测器的读出负担以及千兆字节到太字节大小的数据集规模，对时间分辨率及其实际应用来说仍然是一个挑战。在这项工作中，我们结合了超快扫描线圈和探测器信号数字化，以表明可以从环形分段探测器实现高保真DPC相重建。与传统的从数字化DPC分段图像进行模拟数据相重建不同，即使在最快的扫描速度下，数字化DPC分段图像也能产生可靠的数据。最后，通过快速扫描和多帧进行剂量分割，允许对帧流进行后处理合并，以平衡信噪比和时间分辨率，用于原位实验的低剂量相成像。
