Extreme ultraviolet multilayers for solar physics applications: a brief review

A review of extreme ultraviolet (EUV) multilayers for solar physics applications is presented. Several promising material couples, as well as different optimization strategies, have been explored to optimize the peak reflectance at different wavelengths. For example, ad-hoc capping layers can be employed both to protect the structure underneath and to enhance the reflectance performance at a specific wavelength or to achieve other features such as spectral width and purity. Wide-band and multiband EUV coatings can be achieved by using a-periodic designs, which are still largely unexplored. Aperiodic structures provide novel solutions to be considered in view of future space missions. All the proposed designs are discussed considering their stability in time and along space missions.