Broadband Mo/Be multilayer structures were designed for maximum uniform normal-incidence reflectivity in a broad range of 111–138 Å, which lies near and beyond the L_2,3 absorption edge of Si. A comparison was made of the capabilities of two classes of aperiodic structures and of so-called “stack” structures, which are composed of several periodic structures with different periods stacked one over the other. Six-stack Mo/Be 80-layer structures were synthesized on concave (R = 1 m) superpolished fused silica substrates. Their absolute reflectivity was measured at 13% – 14% in the 111–138 Å optimization range using a laboratory reflectometer with a laser-plasma radiation source. The normal-incidence reflection spectra of the mirrors were recorded in the configuration of a transmission-grating spectrograph using the slowly varying quasicontinuum of a laser-driven tungsten plasma. Comparing the reflectivity data with the reflection spectra recorded with a CCD permitted estimating a decrease in the detector responsivity beyond the Si L-edge. The broadband normal-incidence multilayer mirrors facilitate the development of a high-resolution imaging spectrograph covering a usable range about the Si L-edge to characterize, for instance, the L-edge fine structures and chemical states. These mirrors will also find use in imaging solar instruments with a high spectral resolution operating aboard a spacecraft and in laboratory instruments for plasma diagnostics.

中文翻译：

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基于非周期性 Mo/Be 多层结构的 111-138 Å 宽带法向入射反射镜

宽带 Mo/Be 多层结构设计用于在 111-138 Å 的广泛范围内实现最大均匀的法向入射反射率，该范围靠近和超出Si的 L _2,3吸收边缘。对两类非周期性结构和所谓的“堆叠”结构的能力进行了比较，这些结构由几个具有不同周期的周期性结构相互堆叠而成。在凹面（R= 1 m) 超抛光熔融石英基材。使用带有激光等离子体辐射源的实验室反射计，在 111-138 Å 优化范围内测量它们的绝对反射率为 13% - 14%。使用激光驱动钨等离子体的缓慢变化准连续谱，在透射光栅光谱仪的配置中记录反射镜的法向入射反射光谱。将反射率数据与用 CCD 记录的反射光谱进行比较，可以估计超出 Si L 边缘的探测器响应率的下降。宽带法向入射多层反射镜促进了高分辨率成像光谱仪的开发，该光谱仪覆盖了 Si L 边缘的可用范围，以表征 L 边缘的精细结构和化学状态。