Usefulness of X-ray lasers for science and technology

Recent realization of saturated X-ray lasers (XRL's) has considerably extended the range of optical properties of soft X-ray sources toward high brightness and large coherence length. Consequently, new results may be expected from studies previously experienced with traditional sources such as synchrotron radiation. On the other hand, XRL's open new fields of research owing to their high brightness. In this paper, we present some of the first experiments utilizing XRL sources.