中子全息术中孪生像消除模拟

摘要

In neutron holography ,the reference wave and object wave propagate along the same direction and form conjugated and inseparable images in holographic recon‐struction .At certain wavelength the two images cancel each other and the corresponding nucleus disappears in the reconstruction which is called twin image problem .However , the twin image removing technique in neutron holography has not been systematically studied for the beam condition .In this paper ,the feasibility of twin image removing in neutron holography was discussed based on research reactor neutron source by simula‐ting two recording and reconstructing methods which have been successfully used in twin image removing in X‐ray holography ,and the effect of experimental parameters such as monochromator resolution , wave number recording step and wave number recording range were also quantified . The result shows that the twin image can be removed using 2‐4 holograms even in the limited monochromator resolution and finite wavelength distribution of research reactor neutron source .%在中子全息照相的记录过程中，参考波与物波近似沿同一方向传播至全息屏，并在重建时形成不可分离的原像和共轭像，在特定波长下，两者可能干涉相消，产生孪生像现象。受制于中子探测效率和单色器能量分辨率，目前中子全息成像中孪生像的消除技术尚未得到系统的理论和实验研究。本文采用数值方法对已成功应用于X射线全息孪生像消除的两种全息记录及重建技术展开模拟，讨论基于研究堆的中子全息成像技术实现孪生像消除的可行性，并从实验效率和重建质量出发，对单色器分辨率、波数记录间隔、波数记录范围等关键参数进行定量分析和优化选取。结果表明，在研究堆中子源相对较低的单色器分辨率和较窄的可选能区条件下，通过记录2～4个不同能点的全息图即可获取较理想的中子全息重建结果。