Review lecture: Ten years of X-ray interferometry

Abstract
X-ray interferometers were the first optical instruments which utilized many Bragg reflecting components in monolithic blocks of perfect crystal. They have made important contributions to our knowledge of fundamental constants, of Bragg reflexion X-ray optics, of strains and defects in crystals and of the optical constants of materials in the X-ray region of the electromagnetic spectrum. Based on an oversimplified optical analogue, their mode of operation is described in detail. Current applications of crystal interferometers and possible future work is briefly reviewed.