软X射线双频光栅剪切干涉法研究

摘要

The M-Z interferometer with gratings or multilayer mirrors is widely used in the X-ray laser plasma diagnoses; however, this system is difficult to adjust, and results in the low success rate in experiment. Since wavefront shearing interferometers do not need a separate reference wavefront, they have inherent advantages compared with conventional interferometers. But the absence of shearing element for soft X-ray has restrained the application of the shearing interferometry in soft X-ray measurement. In this paper, a new-structured double-frequency grating was proposed and fabricated that served as the shearing element for soft X-rays, which can promote the application of shearing interferometers in the X-ray laser plasma diagnoses. The diffraction characteristics of the double-frequency grating are analyzed and tested in the synchrotron radiation beams. It is found that the intensity ratio of the two working diffracted beams is over 75%, and the intensity ratio of the rest diffracted beam to the working beam is less than 5%. An X-ray shearing interferometer using a double-frequency grating with 1000 lines/mm and 1002.5 lines/mm gratings was set up, and a clear shear interferogram was obtained. The experimental results demonstrated that the soft X-ray shearing interferometer using double-frequency grating can be applied in the X-ray laser plasma diagnoses.%　　本文中设计了一种利用软X射线双频光栅作为剪切干涉元件的剪切系统，使剪切干涉法在软X射线波段得到了应用。介绍了软X射线双频光栅的结构及衍射特性，在同步辐射光束线对双频光栅的效率分布进行了测试实验，两个剪切级次的效率比值高于75%，干扰级次效率低于5%。利用软X射线双频光栅为剪切干涉光学元件，对待测靶进行了静态检测，得到了对比度高，稳定的干涉条纹，验证了该方法在软X射线等离子体密度诊断中的可行性。