Applied Optics 23 (11) 1794-1801

Metallic multilayers for x rays using classical thin-film theory

B. Vidal and P. Vincent

Successive evaporation of two correctly chosen elements now make possible 
highly efficient X-UV mirrors.However good results depend on two points: 
First we must know the manufacturing tolerances; these depends strongly on 
the spectral range and the refractive index of materials used for coating. 
The other important parameter is the rougness of each interface, which can 
result in significant losses in the reflectivity of the mirrors. This 
paper examines both points. Specular reflectance measurements at 0.159 nm 
are very sensitive to the roughness of each layer. To demonstrate the 
sensitivity we develop a method calculation of this reflectance taking 
into account the roughness of each interface of the multilayer.