Silicon-based reflection elements

The main optical elements used in EUV optics are based on multilayer (ML) film reflectors. As stated above, at 13.5 nm, a single-surface reflector made of any material has very low reflectivity. For instance, at normal incidence, the reflectivity of molybdenum is about 10 at 13.5 nm (see Fig. 14.3), which corresponds to an electric field amplitude reflectivity of about 3%. By constructing a smooth substrate, comprising a multilayer stack of alternating thin (a few nanometers) layers of molybdenum and silicon, with negligible photon absorption, it is possible to... 

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