复色光源X射线光栅衍射效率

Diffraction Efficiency of X-ray Grating with Polychromatic Source

基于Fresnel衍射理论，分析了复色光源X射线光栅衍射效率．研究了X射线光栅不同材料、不同槽深、源的谱分布及不同占空比对衍射效率及成像质量的影响，给出这些参量的选择方法．主要考虑了各种参量对光栅0级及1级衍射强度的影响．发现高Z元素的物质不适合做X射线光栅材料，低Z元素Be、Si、Al及有机物PMMA等较适合18-30keV波段的X射线光栅．源的谱分布决定了光栅槽深选择．数值计算给出了Si光栅各种参量的具体值．

The diffraction performance of X-ray grating based on the Fresnel diffraction theory is presented in the case of polychromatic source. Efficiency of grating influenced by various factors, which consist of material, height of groove of grating, spectrum of source and aspect ratio, is discussed. And how to choose the parameters is presented. It takes into account diffraction intensity of zero order and first order. Compared with high Z elements,material consist of low Z elements is applicable to x-ray grating, such as Be,Al,Si and C5 H802 （PMMA） with bandwidth of 18-30 keV. The height of groove of the grating should be according to the spectrum of source.