PURPOSE: To obtain a Fresnel ring zone plate for X rays, by forming a concentric pattern of a Fresnel ring zone plate which is caused by the intereference of a spherical wave and parallel beams of the interfering beams in a visble range and then reducing the pattern down to a level suitable to an X-ray wavelength.

CONSTITUTION: A visible beam sent from a laser beam source is splitted to two beams by a semitransparent mirror 1. One of these two beams is focused to a focal point of a lens 9 via a mirror 6, lens systems 7 and 8 plus a mirror 5 and then turned into a spherical wave to iradiate a photographic plate 12. The other beam irradiates the plate 12 as a parallel beam via the mirrors 3 and 4, lenses 10 and 11 plus a semitransparent mirror 2. The mirrors 3 and 4 are controlled with the observation through a telescope 13 so as to obtain the minimum or maximum intensity at the center part A. Thus obtained pattern of hologram is reduced down to a level suited to the wavelength of X rays. In such way, a Fresnel ring zone plate for X rays is obtained.