Harmonic-free and fixed-exit monolithic X-ray monochromator

It is shown that if the second wall of a channel-cut crystal x-ray monochromator is properly curved, the monochromator is harmonic free for all. Moreover, if the first wall is suitably inclined to the diffracting planes, the position of the exit beam may be kept constant for all. This requires a correction of the position of the monochromator for each by its axial and radial translation.