Hard X-ray nanoprobe with refractive X-ray lenses

Abstract

At synchrotron radiation sources, parabolic refractive x-ray lenses allow one to built both full field and scanning microscopes in the hard x-ray range. For the latter microscope, a small and intensive microbeam is required. Parabolic refractive x-ray lenses with a focal distance in the centimeter range, so-called nanofocusing lenses (NFLs), can generate hard x-ray nanobeams in the range of 100nm and below, even at short distances, i.e., 40 to 70m from the source. Recently, a 47 * 55nm2 beam with 1.7 . 108 ph/s at 21keV (monochromatic, Si 111) was generated using silicon NFLs in crossed geometry at a distance of 47m from the undulator source at beamline ID13 at the European Synchrotron Radiation Facility. This beam is not diffraction limited, and smaller beams may become available in the future. Lenses made of more transparent materials, such as boron or diamond, could yield an increase in flux of one order of magnitude and have a larger numerical aperture. Adiabatically focusing lenses and the fundamental limit for focusing with refractive optics are discussed. [on SciFinder (R)]