Subsampled STEM-ptychography
Subsampled STEM-ptychography
复制标题
子采样 STEM 叠层摄影术
DOI：
10.1063/1.5040496
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发表时间：
2018
影响因子：
4
通讯作者：
N. Browning
中科院分区：
文献类型：
--
作者：
A. Stevens;Hao Yang;W. Hao;L. Jones;C. Ophus;P. Nellist;N. Browning
印刷术已被证明是扫描透射电子显微镜（STEM）的一种有效的相衬成像技术。STEM-ptychography使用快速像素化探测器在二维光栅扫描的每个探针位置收集由二维电子衍射图案组成的“四维”数据集。该四维数据集可用于相位图像的恢复。不幸的是，目前的相机技术只能实现几千个探测器帧每秒（fps）的帧速率，这意味着4D数据集的采集时间比传统STEM的扫描速度慢1000倍，从而限制了该方法在剂量脆弱和动态标本中的潜在应用。在这封信中，我们证明了子采样提供了一种有效的方法，通过减少探测器像素的数量和探针位置的数量来优化平面采集。使用随机移除检测器像素和探针位置的实验四维数据集展示了四维数据集的子采样和恢复。压缩感知恢复后，应用Wigner分布反卷积得到相位图像。探针位置和检测器的随机采样率为10%，为相位检索提供了足够的信息，并将采集时间减少了100倍，从而使STEM-ptychography与传统STEM相竞争。印刷术已被证明是扫描透射电子显微镜（STEM）的一种有效的相衬成像技术。STEM-ptychography使用快速像素化探测器在二维光栅扫描的每个探针位置收集由二维电子衍射图案组成的“四维”数据集。该四维数据集可用于相位图像的恢复。不幸的是，目前的相机技术只能实现几千个探测器帧每秒（fps）的帧速率，这意味着4D数据集的采集时间比传统STEM的扫描速度慢1000倍，从而限制了该方法在剂量脆弱和动态标本中的潜在应用。在这封信中，我们证明了子采样提供了一种有效的方法，通过减少探测器像素的数量和探针位置的数量来优化平面采集。以一个随机分布的实验四维数据集为例，给出了四维数据集的子采样和恢复过程。
Ptychography has been shown to be an efficient phase contrast imaging technique for scanning transmission electron microscopes (STEM). STEM-ptychography uses a fast pixelated detector to collect a “4-dimensional” dataset consisting of a 2D electron diffraction pattern at every probe position of a 2D raster-scan. This 4D dataset can be used to recover the phase-image. Current camera technology, unfortunately, can only achieve a frame rate of a few thousand detector frames-per-second (fps), which means that the acquisition time of the 4D dataset is up to 1000× slower than the scanning speed in a conventional STEM, thereby limiting the potential applications of this method for dose-fragile and dynamic specimens. In this letter, we demonstrate that subsampling provides an effective method for optimizing ptychographic acquisition by reducing both the number of detector-pixels and the number of probe positions. Subsampling and recovery of the 4D dataset are shown using an experimental 4D dataset with randomly removed detector-pixels and probe positions. After compressive sensing recovery, Wigner distribution deconvolution is applied to obtain phase-images. Randomly sampling both the probe positions and the detector at 10% gives sufficient information for phase-retrieval and reduces acquisition time by 100×, thereby making STEM-ptychography competitive with conventional STEM.Ptychography has been shown to be an efficient phase contrast imaging technique for scanning transmission electron microscopes (STEM). STEM-ptychography uses a fast pixelated detector to collect a “4-dimensional” dataset consisting of a 2D electron diffraction pattern at every probe position of a 2D raster-scan. This 4D dataset can be used to recover the phase-image. Current camera technology, unfortunately, can only achieve a frame rate of a few thousand detector frames-per-second (fps), which means that the acquisition time of the 4D dataset is up to 1000× slower than the scanning speed in a conventional STEM, thereby limiting the potential applications of this method for dose-fragile and dynamic specimens. In this letter, we demonstrate that subsampling provides an effective method for optimizing ptychographic acquisition by reducing both the number of detector-pixels and the number of probe positions. Subsampling and recovery of the 4D dataset are shown using an experimental 4D dataset with randomly r...