来自德国弗劳恩霍夫集成电路研究所和维尔茨堡大学及德国企业的研究团队于2019年在International Symposium on Digital Industrial Radiology and Computed Tomography报道了他们基于SEM改造的纳米CT系统-XRM-II nanoCT，该系统基于几何放大的原理，主要应用于材料研究。

该系统由扫描电子显微镜 JEOLJSM7900 组成，其用于将电子聚焦在针状钨或钼靶上，尖端直径约为 80 nm。通过这种方式，作者生成了相同大小的 X 射线源点，以实现低于 100 nm 的空间分辨率。探测器方面，作者选用了捷克Advacam公司的具有 1 mm 厚 CdTe 传感器层和1290x512 像素的光子计数、像素化探测器。由于纳米X射线源的电子通量只有400nm所以参数X射线强度是非常弱，同时为了得到足够的放大倍率，样品需要离光源非常的近，探测器需要离样品足够的远，这样一来到达探测器单个像素的X射线光子数就非常的少，这也是选择，单光子灵敏、高探测器效率、高帧率的widepix探测器的主要原因。

XRM-II nanoCT SEM based computed tomography

Abstract: We present the XRM-II nanoCT, a laboratory nano-CT system based on geometric magnification, which is used for material characterization. The prior system, XRM-II, was presented in 2016 and was the starting point for our development. The new system is composed of a scanning electron microscope JEOL-JSM7900, which is used for focusing electrons on a needle shaped tungsten or molybdenum target with a tip diameter of about 80 nm. In this way we generate a X-ray source spot of the same size to accomplish a spatial resolution below 100 nm. In comparison to the prior system the target can be handled independently from the object stage, while maintaining the full functionality of the SEM. Furthermore, we use a photon counting detector with a 1 mm thick CdTe sensorlayer and a resolution of 1290x512 pixels. The XRM-II nanoCT is also capable of element mapping by using a built-in EDS system. Therefore, the system provides multi-modal imaging using three different image-contrasts (SEM, EDS, nano-CT) on the same sample. The acquisition time for a CT, consisting of 1200 projections, is about 34 hours. By using image correlation to compensate the problem of electron beam drift, the data acquisition is fully automated. Due to the high spatial resolution, sample-drift and positioning inaccuracies need to be compensated during the CT reconstruction. A customized algebraic reconstuction method allows to improve the low signal-to-noise ratio of the CT projections by regularization and to get rid of geometric deviations. We present details about the experimental setup, high resolution radiographies and reconstruction results of a 3D nano-CT of a metallic alloy.

原文信息：

Lutter, Fabian, et al. "XRM-II nanoCT–SEM based computed tomography." Digital Industrial Radiology and Computed Tomography (2019).

文中使用的是来自捷克Advacam公司的光子计数、混合像素X射线探测器。