X-ray monochromator with an ultra-narrow band width

（+, +）或（+）可以得到几个meV-1meV波段的单色x射线。-, -, +)设置硅晶体的高阶不对称反射。当该方法应用于亚meV时，不对称系数增大，Si晶体的辐射面积增大。在这种情况下，晶体在大面积上需要高的完美性，我们现在很难得到这样的FZ Si晶体。因此，我们尝试开发只需要小面积晶体的法布里-珀罗型x射线单色仪。它由一组面对面排列的两个晶片组成，其中满足布拉格角在π /2附近的衍射条件。两板间发生多次反射，干扰使透射的x射线带宽度超窄。作为实现法布里-珀罗式x射线单色仪的第一步，研究了正入射条件下Si晶体的反射率和透射率。它与根据达尔文方法计算出的衍射图样相当吻合。对Fabry-Perot型x射线单色仪进行了详细的模拟，结果表明，厚度为200 μ m、间隔为600 μ m的两组晶片在0 ~ 0 ~ 16反射下产生0.67997 *带宽为0.09 meV的x射线。我们制作了这种单色仪，并使用Si 999不对称反射的高分辨率单色仪对其性能进行了表征。虽然不能达到预期的分辨率，但通过改进切割工艺和采用超精细旋转的测角仪，可以实现这种新型的x射线单色仪。

Monochromatized X-ray with several meV-1meV band width can be obtained by the (+, +) or (+.-, -, +) setting of the higher order asymmetric reflection of the Si crystal. If we apply this method to reach to sub meV,the asymmetric factor increases and the radiated area of the Si crystal becomes large. In this case high perfection of the crystal is needed in the large area and we are now hard to get such a FZ Si crystal. So we have tried to develop the Fabry-Perot type X-ray monochromator which needs only a small area of the crystal. It is composed of a set of two crystal plates arranged face to face in which the diffraction condition with a Bragg angle near pi/2 is satisfied. Multiple reflection is occurred between two plates and the interference makes the transmitted X-ray with an ultra-narrow band width.The reflectivity and transitivity of Si crystal at the normal incidence condition was investigated as the first step to realize the Fabry-Perot type X-ray monochromator. It agreed fairly well with the diffraction pattern calculated on the basis of the Darwin approach. The detailed simulation of the Fabry-Perot type X-ray monochromator revealed that a set of two crystal plates with a 200 mum thickness arranged face to face with a 600 mum interval makes 0.67997 * X-ray with 0.09 meV band width by the 0 0 16 reflection. We made this monochromator and characterized its performance using the high resolution monochromator with Si 999 asymmetric reflection. The aimed resolution is not achieved, but the improvement of the process of the cutting and the used goniometer with an ultra-fine rotation may realize this novel X-ray monochromator.