To reach the theoretical performance of the new generation of artificial X-ray and X-UV Bragg reflectors, it is necessary to improve the layering qualities of the various deposition methods and the accuracy of measurements of the parameters of the produced stack. Such layered structures are not exclusively X-rays optics oriented: microelectronic and optoelectronic devices rely on superlattices structures. Such layered structures, both crystalline and amorphous, are now investigated in other fields of physics because their quasi bidimensional structures give rise to new possibilities in such field as magnetism and superconductivity .