Multilayer coated optics are promising candidates for optical schemes at XUV & X-ray Free Electron Lasers. They can fulfill the extreme requirements in terms of figure and roughness errors, wavefront preservation, and stability. Such optics enable deflection angles much larger than those reasonably achieved with single material mirrors. In addition, due to their good wavelength selectivity, they can be used as narrow bandpass filters. However, since damage of the optical surface is a possible limitation, resistivity studies of MoSi multilayers were carried out at the XUV Free Electron Laser FLASH in Hamburg. The results, reported in , show that the leading damage mechanism is melting of the amorphous silicon layer, followed by Mo atoms diffusion into Si, leading to molybdenum-silicide formation. These studies have been extended to the soft X-ray part of the spectrum at the LCLS FEL facility. Although a similar final state of damage was observed, the damage threshold appeared to be strongly wavelength dependent. A possible explanation will be discussed during the presentation. The results are important for the design and further development of the optical coatings for the new generation of the short wavelength light sources, not only for the multilayers but for the single metallic layer coatings as well.
|Place of Publication||Prague|
|Publication status||Published - 2011|