Spatial harmonic rejection in a large offset rotated-inclined double crystal monochromator at BL15XU in SPring-8

A 100 mm offset rotated-inclined double crystal monochromator has been installed at BL15XU in SPring-8. The spatial profiles of the exit X-ray beam by using Si(1 1 1) in inclined geometry was measured from 5 to 20 keV. The vertical deviation, due to refraction, between the first and the higher order was more than 0.7 mm. The large deviation enables to eliminate the higher-order reflections by spatial screening with horizontal blade slits. The intensity ratio of the higher-order reflection to the first order was less than 10−5 over the whole energy range.