Figure 4.

Diffraction efficiencies (first order) of various FZPs with an outermost zone width dr, diameter D and zone height H measured over a wide range of X-ray energies and compared with the theoretical maximum values calculated from the tabulated X-ray optical constants. The interruption in the measured efficiencies in (a) represents a change of the experimental set-up for measurements at photon energies below 6 keV (see text).