利用劳条件求取双相位光栅干涉仪灵敏度  

Sensitivity Calculation for the Dual Phase Grating Interferometer by Lau Condition

作　　者：杨君 黄建衡[1] 单雨征 雷耀虎[1] 宗方轲[1] 郭金川[1] YANG Jun;HUANG Jianheng;SHAN Yuzheng;LEI Yaohu;ZONG Fangke;GUO Jinchuan(Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province,College of Physics and Optoelectronic Engineering,Shenzhen University,Shenzhen 518060,China)

机构地区：[1]深圳大学物理与光电工程学院光电子器件与系统教育部/广东省重点实验室,深圳518060

出　　处：《光子学报》2023年第1期162-170,共9页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.62075141,12075156);广东省基础与应用基础研究基金(No.2021A1515010048)。

摘　　要：目前针对双相位光栅干涉仪灵敏度的分析存在着灵敏度模型不合理、理论结果不完整等问题,制约着系统灵敏度的提高。对此,提出了新的灵敏度模型,即物体所产生的条纹移动与光源位置变化产生的条纹移动是等效的。该灵敏度模型将物体对X射线的折射作用转化成了光源的移动,同时巧妙地利用了系统的劳条件将光源移动与成像条纹移动联系起来。利用新的灵敏度模型,成功获取了双相位光栅干涉仪和Talbot-Lau干涉仪的灵敏度,为优化系统灵敏度提供了理论指导。In the past few decades, there are five major methods that can successfully perform X-ray phasecontrast imaging, namely two-beam interferometer, crystal diffraction enhancement imaging, propagationbased imaging, grating-based X-ray interferometer and the coded aperture X-ray phase contrast imaging.Among the above five methods mentioned above, grating-based X-ray interferometer has drawn a lot of attention and made much progress due to its compatibility with X-ray source with large spot size and good image quality. In a grating-based X-ray interferometer, absorption, phase-contrast and dark-field signals can be simultaneously obtained from the same data. Generally speaking, the phase-contrast signal is created by the X-ray refraction after passing through the object, which is more advantageous than the absorption signal for soft materials. Moreover, the dark-field signal, which is regarded as small-anglescattering information, is sensitive to the density fluctuations onmicrometre length scales. However, grating-based X-ray interferometer is limited by the small size of the absorption grating in clinic applications. It is a great challenge to fabricate the absorption grating over large area and high aspect ratio.To a certain extent, X-ray interferometer based on inverse geometry grating can remove the limitation of absorption grating on the field of view. It interchanges the position of the X-ray source and the detector and doesn’t need any analyzer grating. But its high system magnification can also reduce the field of view.Therefore, a dual phase grating interferometer is proposed to address the above difficulties. It consists of two phase gratings and can generate fringes with periods of tens to hundreds of microns. Due to the lack of absorption grating, the dual phase grating interferometer can realize X-ray phase-contrast and dark-field imaging with large field of view and high dose utilization. In the dual phase grating interferometer, the Lau condition affects the fringe visibility, which in turn affects t

关 键 词：X射线相衬成像 Talbot-Lau干涉仪 双相位光栅干涉仪 灵敏度 劳条件 

分 类 号：O434.1[机械工程—光学工程]