Ultimate hard X-ray focusing

For many years, substantial effort has been devoted to developing a good mirror for preparing a small X-ray beam. Professor K. Yamauchi (Osaka University, Japan) and his colleagues have recently reported the breaking of the 10 nm barrier for hard X-rays. They employed a combination of two mirrors; the surface of the first mirror is deformable, in order to compensate for figure error of the second mirror. By such an adaptive optical system, the research group attained a beam size of 7 nm at 20 keV. The experiments were done at BL29XUL, SPring-8. For more information, see the papers, "Breaking the 10 nm barrier in hard-X-ray focusing", H. Mimura et al., Nature Physics doi:10.1038/nphys1457; published online: 22 November 2009; corrected online: 2 December 2009.