【作者】 刘振伟；

【导师】 牛憨笨；

【作者基本信息】 中国科学院研究生院（西安光学精密机械研究所） ， 物理电子学， 2013， 博士

【摘要】 国际上对于高分辨率X射线相衬显微成像技术的研究已经有二十多年的历史.如今,能够获得纳米级别空间分辨率的此项技术已在诸多领域内实现了广泛应用,如生物学、医学、材料科学以及环境科学等等.不过,总体来说, X射线纳米分辨相衬显微技术在成像机制上略显单调,而且目前实验上还无法量化地获取物体的相位分布.该论文提出并论证了一种新型的、基于X射线波带片和微分复透过率板的X射线纳米分辨微分相衬成像系统,并且有潜力同步得到微分相衬图像和量化的相位分布图像.文中主要涉及如下几个方面的工作:一、提出了一种新的高分辨率X射线微分相衬成像模型,对关键器件进行了设计,并分析了若干可以用来调节成像质量的系统参数.二、通过理论分析和数值成像模拟,证实了本系统确实能够实现具有纳米级别分辨率的、可方便调节成像质量的、典型微分相衬图像.量化讨论了物体所表现出的吸收作用对于微分相衬成像的影响,从而也在理论上拓展了此成像方法在绝大部分X射线波段上的应用前景.三、在获取微分相衬图像的基础上,进一步发展和验证了基于本系统的相位成像或相位恢复技术,同时定量地探讨了系统可调参数对于所恢复的相位分布误差的调控作用.四、分析了微分复透板的器件缺陷对微分相衬成像和相位恢复所造成的消极影响,并给出了相应的改善建议.更多还原

【Abstract】 High-resolution X-ray phase contrast microscopy traces its history back to thelate1980s in the international context. Nowadays, this imaging technique which iscapable of achieving nanoscale spatial resolution has realized a wide variety ofapplications in the fields of biology, medicine, materials science and environmentalscience, etc. Generally speaking, however, it is somewhat monotonous for X-raynanoscale-resolution microscopy in terms of imaging mechanisms. Besides, it seemsunlikely to acquire the specimens’ quantitative phase distribution experimentally atthe present time.The thesis demonstrates a bold new kind of nanoscale-resolution X-raydifferential phase-contrast imaging system, which is based on an X-ray Fresnel zoneplate and a complex-transmittance X-ray differential plate, and have the potential formanaging simultaneously the regular differential phase-contrast imaging and thequantitative phase imaging or phase distribution. The contents of this thesis consistof several aspects listed as follows:First, a fresh X-ray imaging model is proposed, which is aimed athigh-resolution differential phase contrast; corresponding design for the key X-rayoptics is done, and a few manageable parameters are also examined in detail forpursuing a high image quality.Second, by theoretical formulations and numerical simulations, it is confirmedthat this model system could truly perform the expected nanoscale-resolution,image-quality-tunable, and characteristic differential phase-contrast imaging;quantitative analysis about the effects of the specimens’ absorption on thedifferential phase contrast is completed, which, as a result, shows the promise thatthis imaging technique can be used in most of the X-ray energy range.Thirdly, based on the imaging system, it is accomplished to develop and verifythe phase imaging or phase retrieval technique in addition to the ordinary and characteristic differential phase-contrast imaging; at the same time, the role of themanageable system parameters in regulating the error in the retrieved phasedistribution is also examined.Fourthly, at the end, this thesis gives an assessment of the impact of flaws in theX-ray differential plate on imaging, and suggests a couple of measures to alleviatethis situation.更多还原