(a) Schematic view of the focusing of X-rays from a planar kinoform single-element lens. The step length L is given by the ratio of the incident wavelength to the refractive index decrement of the lens material (L = λ/δ). The width W depends on the aperture of the lens. The kinoform lens generates a line-focus X-ray beam of nominal size ∼50 µm × 2 µm. (b) Schematic of the XRR arrangement using a focused X-ray beam generated from a kinoform lens structure. The inset shows a scanning electron micrograph of the Si kinoform lens structure.