为了拓宽软X射线平场全息凹面光栅的工作波段, 提出了并联平场全息凹面光栅的优化设计方法。利用遗传算法, 将两块工作波段不同的平场光栅设计在同一基底上。两块平场光栅的工作波段分别为2~5 nm 和5~30 nm, 两者使用结构完全相同。应用光线追迹的方法, 研究了并联平场光栅的分辨特性, 其分辨率与现有商用平场光栅的分辨率相当。基于光程函数理论, 给出了并联平场光栅的制作光路, 理论设计值和光路优化值的线密度偏差在±1 line/mm以内。 数值模拟结果显示, 并联平场光栅既拓宽了工作波段, 又保证了分辨率与现有平场光栅分辨率相当, 其设计适用于记录更宽波段的软X射线光谱。

In order to broaden the wavelength range of flat-field holographic concave grating (FHCG), the optimization method of parallel flat-field holographic concave gratings (PFHCGs) is proposed. Two flat-field gratings working in different wavebands, one for 2~5 nm and the other for 5~30 nm, are designed on the same substrate based on genetic algorithm, and the two gratings can work simultaneously because of the same working structure. Theoretical spectral resolution of PFHCGs is studied via ray-tracing method, which is pretty the same as that of existing commercial FHCG. Based on the optical path function theory, the recording optical path of PFHCGs is given. The results demonstrate the line density deviation is less than ±1 line/mm between theoretical value and optimization value. Simulation results show that the waveband of HPFCGs is broaden and the resolution is also ensured, so it is suitable for recording wider waveband of soft X-ray.