工作波长为13.9nm的Laminar分合束光栅研制

目的：基于衍射光栅分合束元件的软X射线Mach－Zehnder干涉系统在惯性约束聚变，X射线激光等领域都有重要的应用前景。针对该干涉系统的特点设计、制作了工作波长为13.9nm的矩形分合束光栅。方法：利用全息曝光－离子束刻蚀工艺制作了特定参数的矩形光栅，利用长行程面型仪（LTP）对其线密度进行了测量，利用原子力显微镜测量其槽深与占宽比，利用国家同步辐射实验室（NSRL）U27实验站测量其衍射效率。结果：该矩形光栅的参数为线密度1000l/mm，槽深13±0.2nm，占宽比0.4±10%，Au膜厚度为40±0.5nm；在工作波长为13.9nm，81.2°入射时，其0级与-1级衍射光衍射效率乘积的最大值为8.6％，同时0级与-1级衍射效率亦接近，约为27％和30％。结论：测量结果充分证明矩形光栅作为13.9nm激光的分合束元件是能够获得高分合束效率(>7%)，且矩形分合束元件易于制作。

Laminar grating as the splitter grating at 13.9nm

Objective: The electron density gradient and electron density of larger variety plasma will be probed by using the soft X-ray diffraction grating Mach-Zehnder interferometer (DGI). Hereby, it is very important to the Plasma Diagnosis, X-ray Laser and so on. The soft X-ray diffraction grating is the core. Method：The lamellar grating is fabricated by holographic ion beam etching. The duty cycle and the groove depth are measured by VECCO 3100 AFM; The efficiencies of the gratings were measured using the beam line U27 at National Synchrotron Radiation Laboratory (Hefei, China). Result：The grating substrate has a rectangular laminar groove profile with 1000 grooves/mm, a 13±0.2nm groove depth and a 0.4±10%duty cycle. The grating is coated with Au by 40nm thickness. Synchrotron radiation measurements at 13.9nm provide the diffraction efficiency of 27% both in the zero and the first diffracted order at an incident angle of 80.8°. From these measurements we can deduce that the product of the zero and first diffracted order is close to 8.6% at an incident angle of 81.2°, and the diffraction efficiency of the zero and the first diffracted order is approximately equal. Conclusion ：The results illustrate the potential of laminar gratings as a beam splitter at13.9nm.