DESIGN OF GRAZING-INCIDENCE MULTILAYER SUPERMIRRORS FOR HARD-X-RAY REFLECTORS

Extremely broadband grazing-incidence multilayers for hard-x-ray refle ction can be obtained by a gradual change of the layer thicknesses dow n through the structure. Existing approaches for designing similar neu tron optics, called supermirrors, are shown to provide respectable per formance when applied to x-ray multilayers. However, none of these app roaches consider the effects of imperfect layer interfaces and absorpt ion in the overlying layers. Adaptations of neutron designs that take these effects into account are presented, and a thorough analysis of t wo specific applications (a single hard-x-ray reflector and a hard-x-r ay telescope) shows that an improved performance can be obtained. A mu ltilayer whose bilayer thicknesses are given by a power law expression is found to provide the best solution; however, it is only slightly b etter than some of the adapted neutron designs. (C) 1995 Optical Socie ty of America