Efficient sub 100 nm focusing of hard x rays

An x-ray beam with energy of 20.5keV has been efficiently focused down to a spot size as small as 90nm×90nm by a Kirkpatrick-Baez reflecting mirrors device. The first mirror, coated with a graded multilayer, plays both the role of vertical focusing device and monochromator, resulting in a very high flux (2×10¹¹photons/s) and medium monochromaticity (ΔE/E∼10^-2). Evaluation of the error contributions shows that the vertical focus is presently limited by the mirror figure errors, while the horizontal focus is limited by the horizontal extension of the x-ray source. With a gain in excess of a few million, this device opens up new possibilities in trace element nanoanalysis and fast projection microscopy.