超快数字DPC实现低剂量相位表征的高时空分辨率
Ultra-fast Digital DPC Yielding High Spatio-Temporal Resolution for Low-Dose Phase Characterisation
AI总结：
本研究提出利用信号数字化实现超快数字DPC，从环形分段或像素化探测器获得高保真相位重建，并通过剂量分馏与多帧分箱平衡信噪比和时间分辨率，用于低剂量原位相位成像。
摘要：
在扫描透射电子显微镜中，对束敏感材料的相位成像以及利用原位实验表征材料功能性质的应用正日益普及。随着4D-STEM探测器实际扫描速度的提升，差分相位衬度（DPC）和叠层衍射成像所能达到的时间分辨率也随之提高。然而，像素化探测器的读出负担以及吉字节至太字节规模的数据集大小，仍然对时间分辨率及其实际应用构成挑战。在本工作中，我们展示了通过信号数字化，可以从环形分段探测器或具有相对较少单元的像素化阵列实现高保真度的DPC相位重建。与传统模拟数据不同，即使在最快的扫描速度下，基于数字化DPC分段图像的相位重建也能产生可靠数据。最后，通过快速扫描和多帧采集实现剂量分馏，允许对帧流进行后处理分箱，以平衡信噪比和时间分辨率，从而适用于原位实验中的低剂量相位成像。
英文摘要：
In the scanning transmission electron microscope, both phase imaging of beam-sensitive materials and characterisation 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 show that a high-fidelity DPC phase reconstruction can be achieved from both annular segmented detectors or pixelated arrays with relatively few elements using signal digitisation. Unlike conventional analog data, even at the fastest scan speeds, phase reconstructions from digitised DPC-segment images yield reliable data. Finally, dose fractionation by fast scanning and multi-framing allows for post-process binning of frame streams to balance signal-to-noise ratio and temporal resolution for low-dose phase imaging for in-situ experiments.
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