基于锥形单玻璃管X射线聚焦镜表征X射线光源参数

Determination of Parameters of X-Ray Source Based on Tapered Glass Monocapillary X-Ray Condenser

X射线光源的焦斑尺寸和焦深对X射线光谱学,尤其是对于微区X射线衍射与荧光分析等领域十分重要的参数。如何高效而准确的表征这些参数对于X射线光源的应用和发展至关重要。现有的光源参数表征方法,尤其在表征微焦斑光源的参数时,都存在自身的局限性。锥形单玻璃管X射线聚焦镜是一种常用的X射线聚焦器件。根据锥形单玻璃管X射线聚焦镜滤波特性和几何特点,分析得到聚焦镜的聚焦光能量上限的大小受到光源焦斑尺寸的影响,提出这个能量上限与光源尺寸和光源到聚焦镜入口的距离之间的数学关系。设计了一种基于锥形单玻璃管X射线聚焦镜的表征X射线光源参数的方法。对锥形单玻璃管X射线聚焦镜的参数进行测量和确定后,将聚焦镜放置要测量的光源前,与光源形成聚焦光路。在光路准直并确保只有在聚焦镜内发生单次全反射的X射线射出聚焦镜的情况下,通过改变聚焦镜与光源焦斑距离并利用能谱探测系统来探测聚焦光并得到多个对应的聚焦光能谱。对所得能谱进行计算与分析,得到各能谱中的能量最大值,即聚焦光的能量上限。利用聚焦光能量上限、光源焦斑尺寸和光源到聚焦镜的距离之间的关系并结合线性拟合法,可同时得到光源焦斑尺寸和焦深。选用制造商给出焦斑尺寸约60μm,焦深为20 mm的微焦斑钼靶光源作为测量对象,利用基于锥形单玻璃管X射线聚焦镜的表征方法测量的结果为焦斑尺寸为60.1μm,焦深为19.7 mm。用小孔成像法表征该光源焦斑尺寸为60.3μm,焦深为20.1 mm。相较于现有的方法,基于锥形单玻璃管X射线聚焦镜的表征X射线光源参数方法对表征微焦斑光源有一定优势,对表征高能X射线光源有潜在发展和利用价值。

The focal spot size and depth of the X-ray source are crucial parameters for X-ray spectroscopy,especially for micro X-ray diffraction and micro X-ray fluorescence.Determining these parameters efficiently and accurately is important for the application and development of the X-ray source.The existing methods for determining these paraments of X-ray source all have their limitations,especially for determining the micro focal spot X-ray source.The tapered glass monocapillary X-ray condenser(TGMXC)is a common X-ray focusing device.According to the filter property and the geometrical characteristics of the TGMXC,the conclusion that the energy upper limit of the focused X-ray of the TGMXC is affected by the focal spot size of the X-ray source can be obtained.The relation between the energy upper limit of the focused X-ray of the TGMXC andthe focal spot size of the X-ray source,and the distance between the TGMXC and the focal spot of the X-ray source was proposed.A method of determining parameters of the X-ray source based on TGMXC was designed.Measuring and determining the parameters of the TGMXC and placed the TGMXC in front of the measured X-ray source to form a focusing X-ray path.In the case that the focusing X-ray path is collimated and ensures that only the single reflected focused X-rays,TGMXC is detected,though changing the distance between the X-ray source and the TGMXC and using the energy spectrum detection system to obtain the corresponding focused X-ray energy spectrums.Though calculating and analyzing the energy spectrums,the maximum energy of each spectrum,namely the energy upper limit,is obtained.The focal spot size and the focal depth can be obtained simultaneously using the above relation and linear fitting.Parameters of a micro focal spot X-ray source with a Mo target were determined by this method.The manufacturer gave the focal spot size and focal depth as about 60μm and 20 mm and were obtained by this method as 60.1μm and 19.7 mm,respectively.The conventional pinhole imaging method was also used to determine this X-ray source,and the results were 60.3μm and 20.1 mm,respectively.Compared with existing methods,this method can determining the micro focal spot X-ray source and has potential practical value and development for determining the high-energy X-ray source.