X-ray crystal polygon-mirror and its application for absolute calibration of angular positions

X射线晶体多边形镜比光学多边形镜要紧凑得多。在实际应用中，X射线晶体多面镜是一个直径为1 mm、高度为10 mm的小硅柱。为了方便使用这个小装置，从一个二次棱镜上刮下了水晶柱，保留了10 mm立方体的基座。圆柱体的轴线为&lt；110&gt；晶体方向，其中晶体多面镜对波长为0.06968 nm的X射线有340个衍射角，在平晶面和圆柱面的边界条件下，X射线衍射角位置略有不同。但实际证明，在晶体多面镜的轴线与转台的轴线平行的情况下，柱面晶体的X射线衍射峰位置与平面的峰值位置一致，位置精度为亚弧秒。用波长为0.0696 nm的同步辐射X射线束探测了340个来自晶体多边形镜的衍射。在标定过程中，我们对装有旋转编码器的精密转台的精度进行了评估，其精度为1角秒。

An x-ray crystal polygon-mirror is much compact than that of an optical polygonmirror. In practices, the x-ray crystal polygon-mirror is a small silicon cylinder with diameter of 1mm and height of 10mm. For conveniently using this small device, the crystal cylinder was scraped from a quadratic prism with a pedestal of the sijte of 10mm cube remained. Axis of the cylinder is <110> crystal direction, where the crystal polygon-mirror has 340 diffractions for x-ray with wavelength of 0.06968nm.There is a little difference on the angular position of x-ray diffractiop under the boundary condition of a flat crystal surface and a cylinder surface. But it was conformed practically that under the condition where the axis of the crystal polygonmirror is parallel to that of the rotary table within a quantity of sub-milliradilan, the peak position of x-ray diffractions from the cylinder crystal is consistent to that of the flat surface with position accuracy of sub-arc-second.340 Diffractions from the x-ray crystal polygon-mirror were detected) using an x-ray beam of synchrotron radiation with wavelength of 0.06968nm. Fallowing the calibration process, we evaluated a precise rotary table equipped with rotary encoder within accuracy of 1 arc-sec.