紧凑型全视场高光谱分辨X射线荧光成像仪

X-ray fluorescence imaging is a powerful chemical element analysis method, which can provide the information about not only the chemical composition and content, but also the elemental distribution of a specimen, therefore, it has strong requirement in many fields such as in the industry, agriculture, chemistry, environment, material science, biology, medicine and archaeology. X-ray fluorescence imaging were conventionally realized by the scanning x-ray microprobe fluorescence, which takes a long time, and furthermore the using of the energy-resolved detector suffers the low energy resolution, that can not satisfy the analysis requirement of complex specimen.. In this research, we sugguest to develop a compact, full-filed, high energy resolution x-ray fluorescence imager based on spherically bent crystals. It use a conventional x-ray tube as the source to excitate the whole specimen, and then use the spherically bent crystal and a slit to monochromize the fluorescence x-ray from the backgroud scattering and other element's fluorescence and imaging it on an x-ray CCD. The instruments has the advantages of full-field, high energy resolution, high spatial resolution, high efficiency and fast image collection, which might meet the requirments of the analysis for elements Sc-Ge by K-shell and As-Bi by L-shell x-ray fluorescence in an ordinary laboratory.

X射线荧光成像分析是一种强大的一种化学元素分析方法，它不但能够给出样品的元素组成及含量，还能给出元素在样品中的空间分布，因此在工农业、化学、环境、材料、生物、医学以及考古学等诸多领域具有强烈的需求。当前X射线荧光成像技术主要采用基于微束的扫描成像方式，逐点扫描需要花费很长时间，并且大多数采用能量色散型探测器，能谱分辨率相对较低，难以满足复杂样品的分析需求。. 本项目提出了研制一种基于球面晶体的紧凑型全视场高光谱分辨X射线荧光成像仪，它采用常规的X射线管对样品进行整体激发，利用球面晶体和限光狭缝，把特定元素的X射线荧光从其他元素的荧光和背景散射中选单后聚焦成像在X射线CCD上。仪器具有全视场、高光谱分辨、高空间分辨、高成像效率、荧光图像采集速度快等优点，有望满足普通实验室条件下对Sc到Ge元素K壳层以及As到Bi元素L壳层的X射线荧光成像分析需求。

项目提出并研究了一种基于球面晶体的高光谱分辨X 射线荧光成像仪，对其成像原理与过程进行了理论分析、数值仿真以及实验验证。这种X 射线荧光成像技术具有较高空间分辨率（优于80 μm）、极高的光谱（能谱）分辨率（优于16.5 eV@ 6.5keV~9 keV）等优点，研究的实验结果表明该技术因光子收集效率较低，更适合在光源亮度更高的同步辐射装置上应用。项目同时发展了适用于常规实验室环境的紧凑型共聚焦型X射线荧光光谱成像技术，并研发了相应的原型样机并开展了应用实验，实验结果表明，该型样机虽然光谱分辨率受限光子计数探测的能谱分辨率（一般优于130eV），但其荧光图像采集效率很高，一次成像可同时获取并区分多种元素组分的荧光图像，具备更强的实用性。该型仪器有望在生物医学、文物、材料组分鉴别等领域发挥重要的应用价值。