Kohn V G
National Research Centre `Kurchatov Institute', Kurchatov Square 1, 123182 Moscow, Russia.
J Synchrotron Radiat. 2018 Mar 1;25(Pt 2):425-431. doi: 10.1107/S1600577517018495. Epub 2018 Feb 15.
Results of computer simulations of the transmission of an X-ray beam through a two-dimensional photonic crystal as well as the propagation of an X-ray beam in free space behind the photonic crystal are reported. The photonic crystal consists of a square lattice of silicon cylinders of diameter 0.5 µm. The amount of matter in the path of the X-ray beam rapidly decreases at the sides of the cylinder projections. Therefore the transmission is localized near the boundaries, and appears like a channeling effect. The iterative method of computer simulations is applied. This method is similar to the multi-slice method that is widely used in electron microscopy. It allows a solution to be obtained with acceptable accuracy. A peculiarity in the intensity distribution inside the Talbot period z in free space was found when the intensity is approximately equal to the initial value at a distance 0.46z, and it is shifted by half a period at distance 0.5z. The reason for this effect is the existence of a periodic phase of the wavefunction of radiation inside the intensity peaks. Simulations with zero phase do not show this effect. Symmetry rules for the Talbot effect are discussed.
报道了X射线束通过二维光子晶体的传输以及光子晶体后方自由空间中X射线束传播的计算机模拟结果。光子晶体由直径为0.5 µm的硅圆柱体的正方形晶格组成。在圆柱体投影的侧面，X射线束路径中的物质数量迅速减少。因此，传输集中在边界附近，呈现出一种沟道效应。应用了计算机模拟的迭代方法。该方法类似于电子显微镜中广泛使用的多层方法。它能够以可接受的精度获得解决方案。当强度在距离0.46z处近似等于初始值，且在距离0.5z处偏移半个周期时，在自由空间中塔尔博特周期z内发现了强度分布的一个特殊之处。这种效应的原因是强度峰值内辐射波函数存在周期性相位。零相位的模拟未显示出这种效应。讨论了塔尔博特效应的对称规则。
