A NOVEL TECHNIQUE FOR X-RAY LASER-BEAM CHARACTERIZATION

The use of a novel diagnostic based on the Moiré effect, known as Moiré deflectometry, to characterize X-ray laser beams is described. This technique is purely geometric in nature and does not require coherent radiation for its operation. The unique feature of Moiré deflectometry is that it provides a fully quantitative laser beam diagnostic which can be operated in any wavelength region of the spectrum. This technique allows the number of transverse modes present in the beam to be determined from the inherent beam divergence. The latter is measured from the degree of reduction in the contrast of the Moiré fringes. From the same deflectogram the geometrical-beam behaviour can be determined. This includes both geometrical-beam divergence and ray-aberrations which lead to wavefront distortions. © 1990 Springer-Verlag.