Design of innovative multilayer coatings for solar imaging and spectroscopy

In recent years telescopes based on near normal-incidence multilayer (ML) technology have been employed in many missions for imaging the Sun at selected EUV wavelengths. Such coatings have not negligible bandwidth, therefore the detected signal often includes the contribution of unwanted adjacent spectral lines. In this work we propose an innovative method for designing suitable ML capping layers able to preserve the reflectivity peak of the underneath structure at the selected wavelength while rejecting the unwanted lines. Theoretical design and experimental results are presented and discussed