X-ray Telescopes

The German physicist Hans Wolter was attempting to make an X-ray microscope in the early 1950s. He applied the well-known fact that X-rays can be reflected if they strike a smooth metal surface at a grazing angle. He created 3 designs for systems which would focus, or image, X-rays. He never made his microscope, however, because at the time, mirrors could not be manufactured which were smooth enough. Riccardo Giacconi, however, realized that the same designs could be inverted and made as a telescope without such a stringent constraint on the smoothness of the mirror.