Analysis by Coupled-Mode Theory of X-ray Multilayer Gratings

Multilayer gratings developed since the end of the ninethies are now used for various purposes in x-uv optics: polychromator, narrow bandpass monochromators…We have implemented the Coupled-Mode Theory (CMT) to calculate the performances of these devices (efficiencies, bandwidths…) especially for quasi-lamellar gratings with different shapes of the multilayer pitch. We have fabricated such gratings and compared CMT calculations with measurements obtained at the BEAR beamline of ELETTRA.