來(lái)自德國(guó)弗勞恩霍夫集成電路研究所和維爾茨堡大學(xué)及德國(guó)企業(yè)的研究團(tuán)隊(duì)于2019年在International Symposium on Digital Industrial Radiology and Computed Tomography報(bào)道了他們基于SEM改造的納米CT系統(tǒng)-XRM-II nanoCT，該系統(tǒng)基于幾何放大的原理，主要應(yīng)用于材料研究。

該系統(tǒng)由掃描電子顯微鏡 JEOLJSM7900 組成，其用于將電子聚焦在針狀鎢或鉬靶上，尖端直徑約為 80 nm。通過(guò)這種方式，作者生成了相同大小的 X 射線源點(diǎn)，以實(shí)現(xiàn)低于 100 nm 的空間分辨率。探測(cè)器方面，作者選用了捷克Advacam公司的具有 1 mm 厚 CdTe 傳感器層和1290x512 像素的光子計(jì)數(shù)、像素化探測(cè)器。由于納米X射線源的電子通量只有400nm所以參數(shù)X射線強(qiáng)度是非常弱，同時(shí)為了得到足夠的放大倍率，樣品需要離光源非常的近，探測(cè)器需要離樣品足夠的遠(yuǎn)，這樣一來(lái)到達(dá)探測(cè)器單個(gè)像素的X射線光子數(shù)就非常的少，這也是選擇，單光子靈敏、高探測(cè)器效率、高幀率的widepix探測(cè)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).

文中使用的是來(lái)自捷克Advacam公司的光子計(jì)數(shù)、混合像素X射線探測(cè)器。