Manufacturing and testing of a laterally graded division parameter multilayer inferential mirror for XUV

A laterally graded (gamma) multilayer interferential mirror (MIM), (where the division parameter (gamma) is the ratio between the thickness of the high refractive index material and the MIM's period), has been manufactured by means of a sputtering technique. The multilayer design is carefully described. This special MIM has been characterized by specular reflectivity X-ray measurements using a diffractometer equipped with a diffracted beam monochromator and Cu-K (alpha ) (1.5418 angstroms) radiation. It exhibits the properties expected by the so-called X-ray diffraction dynamical theory. We give an experimental law of variation of (gamma) which has been used as a calibration curve. Moreover, results are shown to be in good agreement with computer simulations and transmission electron microscopy study. Absolute reflectivity measurements at 930 eV confirmed these properties. The rocking curves for various (gamma) values of the sample have been measured by means of an original reflectometer. The results presented in the paper show the feasibility of a laterally graded (gamma) MIM. Practical applications in X-ray spectroscopy are obvious and this enhances the potentialities of the MIMs compared with the familiar crystals used in X-ray spectroscopy.