We report the results of an optical design study of a multilayer mirror that provides high reflectivity in the 400 eV region. First, the material pair selection rule proposed by Yamamoto was applied to examine the coating materials. Using the optical constants table by Palik, we calculate the Fresnel coefficients for various materials at angle of incidence of 60 deg. Following the selection rule, we looked for two materials yielding strong reflection at interfaces where the distance between two points of the Fresnel coefficients on the complex plane is far apart, as well as small absorption in the multilayer structure. Then film thicknesses of the multilayer structure were optimized by numerical calculation using IMD software, which results in practical high reflectivity between 43 to 50% on the Sc/Si, Sc/Mg, and Sc/Cr multilayer mirrors at the photon energy of 397.5 eV. In this presentation, we also report grazing incidence x-ray reflectivity results for multilayer mirrors deposited by a magnetron sputtering method.
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