【摘要】 菲涅耳波带板直接成像,应用到激光等离子体或惯性约束聚变靶的X射线成像诊断,可实现μm甚至亚μm的空间分辨能力。在对成像进行数值模拟时,考虑到光源的光谱带宽和几何尺度对成像的影响,要进行菲涅耳-基尔霍夫衍射积分与卷积等数值计算,需占用大量计算机内存并且耗费运行机时。改进了数值计算方法,采用了蒙特卡罗积分法和新的卷积算法。模拟了菲涅耳波带板对大尺度多色X射线源的二维成像,新算法与以往算法相比,可显著减少运算机时,在台式机上实现模拟成像的快速计算。结果表明随着光源尺度增大、光谱带宽增加,像的背景增强,导致反衬度与成像质量下降。更多还原

【Abstract】 Direct X-ray imaging using a Fresnel zone plate(FZP)in the applications of laser plasma or inertial confinement fusion diagnostics has the potential for realizing high spatial resolution in the range of micrometers to sub-micrometers.For such an FZP imaging,the influences of the object size and the spectral bandwidth of the illuminating light have to be considered.In the simulations,numerical calculations such as the Fresnel-Kirchhhoff diffraction integral and convolutions have to be done,which will take a large amount of computer memories and cost a lot of computing time.In this paper we report improved algorithms for these numerical calculations by adopting the Monte-Carlo integration and a new algorithm of convolution.By simulating the twodimensional imaging of an extended polychromatic X-ray source,it shows that the new algorithm has significant advantages in reducing the computing time over the past algorithms,and thus such simulations can be done by a desktop computer.The imaging indicates that with the increase of the object size and/or the spectral bandwidth,the image background is enhanced which causes the decrease of the contrast and also the image quality.更多还原