Figure 2: CDW optics: principles and modifications.
From: High-contrast sub-millivolt inelastic X-ray scattering for nano- and mesoscale science

(a) Schematic of the CDW optics, comprising three asymmetrically cut crystals functioning as a collimator—C, a dispersing element—D and a wavelength selector—W, respectively. (b) CDDW optics is a modification of the CDW scheme augmented with two dispersing elements D1 and D2, ensuring enhanced dispersion rate and in-line scattering geometry. (c) CDFDW optics is another modification of the CDW scheme. Crystals C and W are combined into a single CFW crystal executing three key functions: the collimator—C, an anomalous transmission filter—F and a wavelength selector—W, in successive reflections.