利用毛细管X光透镜共聚焦微束X射线荧光技术对单根头发中元素空间分布进行无损扫描分析

头发中的元素与人的饮食和健康状况有关，对头发中元素的分析，不仅可用于刑事物证鉴别，还可为疾病的预防和治疗提供依据，因此，如何检测头发中元素分布等信息倍受人们关注。本文利用基于毛细管X光透镜和实验室普通X射线光源的共聚焦微束X射线荧光技术对单根头进行了无损扫描分析，分析了单根头发中元素的空间分布。在该毛细管X光透镜共聚焦微束X射线荧光技术中，毛细管X光会聚透镜的出口焦斑和毛细管X光平行束透镜的入口焦斑处在共聚焦状态，从而形成共聚焦微元，探测器只能探测到来自该共聚焦微元中的X射线信号，降低了背底信号对X射线荧光谱的影响，从而有利于提高该共聚焦X射线荧光技术的分析精度。该共聚焦技术中采用了具有高功率密度增益的毛细管X光会聚透镜，降低了该共聚焦X射线荧光技术对X射线光源功率的要求，从而保证了该共聚焦技术可以采用实验室普通X射线光源，降低了实验成本。实验表明，毛细管X光透镜共聚焦微束X射线荧光技术在单根头发元素分布检测中具有应用价值。

Application of Confocal Micro-Beam X-Ray Fluorescence in Nondestructive Scanning Analysis of the Distribution of Elements in a Single Hair

The confocal micro X-ray fluorescence (XRF) based on polycapillary X-ray lens and conventional X-ray source was used to carry out the scanning analysis of the distribution of the elements in a single hair. The elemental distribution in the single hair was obtained. In the confocal micro XRF technology, the output focal spot of the polycapillary focusing X-ray lens and the input focal spot of the polycapillary parallel X-ray lens were adjusted confocally. The detector could only detect the X-rays from the overlapping foci. This confocal structure decreased the effects of the background on the X-ray spectra, and was accordingly helpful for improving the accuracy of this XRF technology. A polycapillary focusing X-ray lens with a high gain in power density was used to decrease the requirement of power of the X-ray source used in this confocal technology, and made it possible to perform such confocal micro XRF analysis by using the conventional X-ray source with low cost. Experimental results indicated that the confocal micro X-ray fluorescence based on polycapillary X-ray lens had potential applications in analyzing the elemental distribution of individual hairs.