Performance of a confocal multilayer X-ray optic

In recent years, several companies have developed the technique of arranging two multilayer mirrors in confocal optics for monochromatizing X-rays. In this study, a focusing device of Osmic Inc., with a source-to-focus distance of 1005 mm, has been used. The goal was to measure the homogeneity of the beam, the cross section at various distances from the focus and the efficiency of the optic when it is operated with vacuum and with air in the beam path. A small crystal sphere set at various distances is used to compare the intensities and the widths of reflections with those of a flat graphite monochromator. In a standard diffraction experiment (crystal size 0.25 mm), the gain factor with respect to graphite is roughly ten at a position where the beam plateau is 0.5 mm. The suppression of the Cu Kbeta radiation and of higher harmonics of Kalpha is very good.