X-ray monochromators: I. Theory

X-ray cyclic monochromators, which are particular cases of X-ray resonators, are considered. Conditions for the existence of a resonance wavelength in the Co-K-alpha1 line spectral interval in monolithic cyclic monochromators and polylithic tunable cyclic monochromators are discussed. Maximum reflectivity for a four-reflection monolithic monochromator is achieved when each reflection is symmetric. For a two-monolith four-reflection polylithic monochromator, maximum reflectivity is achieved when the asymmetry of one reflection in one monolith is the inverse of the other reflection in the same monolith.