Large area electron microscopy (EM) imaging has long been difficult due to fundamental limits in throughput for conventional electron microscopes. New developments in transmission electron microscopy and multi-beam scanning electron microscopy (MBSEM) imaging have however made it possible to generate large EM datasets [1,2,3]. This article describes a transmission imaging technique that is suitable for a MBSEM as it allows for a relatively straightforward way of separating the signals generated by each beam. The technique places a thin (50nm-200nm) tissue section directly on top of a coated scintillator. The electrons that are transmitted through the section generate light in the scintillator which is collected by a high NA objective and imaged onto a photon detector. This article gives a model for the contrast-to-noise (CNR) and signal-to-noise (SNR) ratio that is to be expected for this imaging technique. These parameters were calculated using Monte-Carlo simulations. It was found that the CNR increases when decreasing landing energy and SNR increases with increasing landing energy. These two trends cause that there is an intermediate energy where imaging performance is best. The energy of this optimum was calculated for various levels of heavy metal staining, section thickness, coating material, coating thickness and light collection efficiency. The model was verified experimentally on a synthetic sample.

中文翻译：

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扫描电子显微镜中闪烁体的透射成像

由于传统电子显微镜吞吐量的基本限制，大面积电子显微镜 (EM) 成像长期以来一直很困难。然而，透射电子显微镜和多光束扫描电子显微镜 (MBSEM) 成像的新发展使得生成大型 EM 数据集成为可能 [1,2,3]。本文介绍了一种适用于 MBSEM 的透射成像技术，因为它允许以相对简单的方式分离每个光束生成的信号。该技术将薄（50nm-200nm）组织切片直接放置在涂层闪烁体的顶部。传输通过该部分的电子在闪烁体中产生光，该光由高 NA 物镜收集并成像到光子检测器上。本文给出了该成像技术预期的对比度噪声 (CNR) 和信噪比 (SNR) 比的模型。这些参数是使用蒙特卡罗模拟计算的。结果表明，CNR随着着陆能量的减少而增加，SNR随着着陆能量的增加而增加。这两种趋势导致存在成像性能最佳的中间能量。针对不同水平的重金属染色、切片厚度、涂层材料、涂层厚度和光收集效率计算了该最优值的能量。该模型在合成样品上进行了实验验证。结果表明，CNR随着着陆能量的减少而增加，SNR随着着陆能量的增加而增加。这两种趋势导致存在成像性能最佳的中间能量。针对不同水平的重金属染色、切片厚度、涂层材料、涂层厚度和光收集效率计算了该最优值的能量。该模型在合成样品上进行了实验验证。结果表明，CNR随着着陆能量的降低而增加，SNR随着着陆能量的增加而增加。这两种趋势导致存在成像性能最佳的中间能量。针对不同水平的重金属染色、切片厚度、涂层材料、涂层厚度和光收集效率计算了该最优值的能量。该模型在合成样品上进行了实验验证。