理论分析了基于相位光栅分数塔尔博特效应的X射线相衬显微成像原理，采用菲涅耳衍射公式推导出相位光栅在两个不同距离处的成像结果公式。然后建立一个水合蛋白质细胞模型，对成像系统进行了参数设计，得出1~2 keV的中能波段X射线是兼顾大景深和高成像衬度的最优选择。针对10 μm厚的细胞模型，选取1.5 keV的中能X射线做模拟计算，采用多步相移法从模拟条纹图中恢复出了细胞模型的相位信息。模拟结果表明在相同信噪比下采用中能X射线得到的相衬图像比吸收图像具有更好的衬度和细节分辨率，为今后相关的实验奠定了基础。

A theoretical analysis of X-ray microscopy based on the fractional Talbot effect of phase grating and two different imaging formulas when the grating is placed in different locations is given. A cell model of water and protein is established. According to the imaging formulas and the cell model, a set of system parameters are designed and a conclusion which can be made is that mid-energy X-ray between 1 and 2 keV will be the optimal choice considering long focal depth and high image contrast. Then the imaging results with 1.5 keV X-ray is simulated and the phase distribution of the model is recoveried by the phase stepping method. Simulation results show that the phase contrast image with mid-energy X-ray is much better than the absorption contrast one in contrast and resolution under the same signal-to-noise ratio.