Mo/Si and MoSi₂/Si nanostructures for multilayer Laue lens

To develop a multilayer Laue lens (MLL), we fabricated depth-graded Mo/Si and MoSi₂/Si multilayers with each boundary according to the Fresnel zone configuration. The multilayers were deposited by magnetron sputtering. From the result of SEM image analysis of the multilayer cross sections, MoSi ₂/Si multilayer had smaller layer-thickness errors than Mo/Si multilayer. In addition, from the result of the focusing test by using 20-keV X-rays, the measured beam size of MoSi₂/Si MLL had a small blurring from the diffraction limited beam size. These results suggest that MoSi ₂/Si multilayer is better suited than Mo/Si multilayer for use as an MLL in hard X-ray nanofocusing.