FollowThe scientists have successfully developed the world’s sharpest X-ray beam which is ten thousand times thinner than a strand of hair.
Researchers led by Professor Tim Salditt from the University of Gottingen have created the fine beam of X-ray light which is barely 5 nanometres in diameter. The light allows focusing on smallest details. The thickness of the layers is selected in such a way that the bright areas of the diffraction pattern coincide at the same spot.
“Instead of a common lens, we use a so-called Fresnel lens which consists of several layers,” said co-author Dr Markus Osterhoff.
The central support is a fine tungsten wire with the thickness of only a thousandth of a millimetre. Around the wire, nanometre-thin silicon and tungsten layers are applied in an alternating way. The physicists then cut a thin slice from the coated wire.
“This slice has 50 to 60 silicon and tungsten layers, comparable to growth rings of a tree,” said team member Florian Doring.
“And the layer thicknesses have to be extremely precise,” Christian Eberl added. The wire slice with a size of only about two thousandth of a millimeter is used as a lens. However, it does not diffract light like a glass lens but scatters it like an optical grid generating a pattern of bright and dark patches.
On the principle of ‘the more precise the lens is fabricated; the sharper becomes the X-ray focus’, the physicists obtained an X-ray beam of 4.3 nanometers (millionth of a millimeter) diameter in horizontal direction and 4.7 nanometers diameter in vertical direction.
The fine X-ray beam opens up new possibilities for materials science, eg the investigation of nano wires to be used in solar cells.
The study was published in the journal Optics Express.
