衍射增强成像方法中两种晶体排列方式的对比研究

北京同步辐射装置(BSRF)4W1A光束线形貌学实验站近两年开展了两块晶体的衍射增强成像实验研究，在实验中，晶体转轴垂直于同步辐射偏振面时的图像质量好于晶体转轴平行于同步辐射偏振面时获取的图像.本文从X光强度分布、单色器晶体的热膨胀、空间分辨率、角分辨率等方面系统地对两种晶体几何排列方式进行了比较研究.实验和理论分析的结果表明，晶体转轴垂直于同步辐射偏振面时单色器晶体上的热膨胀对成像的影响较小，因而获得了更好的成像质量. 关键词： 同步辐射 衍射增强成像 晶体衍射

Comparison between two geometrical arrangements for diffraction enhanced imaging

Diffraction enhanced imaging (DEI) with two crystals has been recently performed at the 4W1A beamline at the Beijing Synchrotron Radiation Facility (BSRF). In the first experiments, images collected with a set up where the rotation axis of the crystal was perpendieular to the orbit, show a higher quality with respect to those taken with a geometry with the rotation axis of the monochromatic crystal parallel to the orbit. When the rotation axis of the crystal is perpendicular to the orbit plane, e.g. to the polarization plane of the synchrotron radiation, the influence of both vibration and thermal expansion of the first crystal can be significantly reduced, allowing the collection of better images. In this work, a systematic comparison is male between two geometrical arrangements of crystals in DEI framework with respect to the reflectivity of crystals, spacial resolution, angular resolution and image contrast.