【作者】 陈志强； 丁飞； 黄志峰； 张丽； 朱佩平；

【Author】 Zhi-Qiang Chen Fei Ding Zhi-Feng Huang Li Zhang Department of Engineering Physics,Tsinghua University,Beijing,100084,China Key Laboratory of Particle & Radiation Imaging(Tsinghua University),Ministry of Education Beijing,100084,China Pei-ping Zhu Beijing Synchrotron Radiation Facility,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing,100049,China

【机构】 清华大学工程物理系； 中国科学院高能物理研究所；

【摘要】 衍射增强成像技术是一种获取X射线相移信息来观察物体电子密度变化,从而揭示物体内部结构的无损检测技术。该技术通过测量X射线穿过物体时偏离原来传播方向的折射角来获取X涉嫌得一阶相移信息;其中,如何测量X射线的折射角是衍射增强成像中的关键问题。自1996年,Chap man等人提出几何光学近似(GOA)方法,利用摇摆曲线半高宽位置上两幅图像进行折射角信息提取之后,Maksimenk提出了一种非线性信息(EDEI)提取方法,利用同样的两幅DEI图像,通过求解摇摆曲线变换后表达式的反函数来计算折射角。基于这种思路,本文应用高斯函数表征实测的摇摆曲线,推导了EDEI方法计算折射角的近似解析表达式,通过模拟实验及在北京同步辐射装置上获取的真实实验结果与GOA方法的提取结果进行比较,验证了EDEI方法的正确性及实际应用性能。更多还原

【Abstract】 X-ray diffraction enhanced imaging(DEI)is applied to inspect internal structures of weakly absorbing low-Z sample.How to extract phase information from raw images measured in different positions of rocking curve is the key problem of DEI.In 2007,Maksimenk presented an extension-method based on anti-function solution theory.Based on this theory,we present a formula for EDEI method when the rocking curve was described by Gauss function in this paper. Refraction-angle values extracted by our formula can be more accurate than geometric-optics approximation(GOA)method.It is well proved by the computer simulation experiment and actual experiment on a plastic cylinder at the Beijing Synchrotron Radiation Facility.更多还原