用于闪光照相的准直器设计及性能

为了实现高度准直同时较好地保留飞层界面信息，针对高能闪光照相实验中常用的准直技术，改进了设计方法，以法国实验客体（FTO）为例，利用蒙特卡罗程序对光子电子耦合输运过程进行数值模拟实验，验证了所提出的准直器的性能，对采用该准直器技术下的模拟照相结果进行了准直器光程扣除方法研究，结果表明：改进的准直器将客体芯部区域的散射照射量降低99.8%，接收平面处的客体信号动态范围降低99.7%，同时在图像中完整地保留了客体外界面信息；对准直器轴向分层照相的方法可以获得误差小于0.1的客体光程。

Design and performance of an improved collimation system for high-energy flash radiography

In order to achieve high-level collimation and the complete conservation of the flyer boundary in high energy flash radiographic experiment, this paper proposes a new kind of design method of the collimator. The coupling transport process of photons and electrons, taking FTO as the object, is simulated by the means of Monte Carlo method to validate the characteristics of the improved collimator. And the deduction method of the optical path of the improved collimator is investigated. The result shows that the scatter exposure at the core region of the object is reduced by 99.8%. The dynamic range of the signal is reduced by 99.7%,which is great benefit for designing the detector. And the outer boundary is completely preserved in the image. The optical path of the object with relative error less than 0.1 is obtained by the way of layering the secondary collimator along the axial direction.