Ray-tracing results for focal beam images at 12.4 keV in the ideal case using the geometry of BL26B1 and BL26B2 (Fig. 1) with horizontal acceptance angle φH values of (a) 1.5 mrad and (b) 0.7 mrad. The vertical acceptance of the incident X-rays, φV, was set to 30 µrad in both cases. The light source is a 0.679 T bending-magnet source with source electron beam sizes of σx = 106 µm and σy = 13 µm and emittances of ∊x = 3.4 × 10−9 m rad and ∊y = 6.8 × 10−12 m rad (Tanaka & Kitamura, 2001). The sagittal crystal radius of curvature Rs is 3.71 m. The glancing angle of the tangential-focusing mirror θm is 3.6 mrad, and the radius of curvature Rm is 5.27 km.