The sharpest X-ray in the world is 10,000 times thinner than a human hair.
High energy (hard) X-ray light cannot be focused as easily as a softer visible light source, a Deutsches Elektronen-Synchroton (DESY) press release reported.
"Instead of a common lens, we use a so-called Fresnel lens which consists of several layers," co-author Dr. Markus Osterhof, said.
"The central support is a fine tungsten wire with the thickness of only a thousandth of a [millimeter]. Around the wire, nanometre-thin silicon and tungsten layers are applied in an alternating way," the press release stated.
The researcher then cut a sliver from the supporting wire.
"This slice has 50 to 60 silicon and tungsten layers, comparable to growth rings of a tree," team member Florian Döring, said.
"And the layer thicknesses have to be extremely precise," Christian Eberl, another member of the team and PhD student, added.
The two-thousandths-of-a-millimeter-thick wire is used as a lens. The lens is a bit different than is what is seen conventionally because it scatters light instead of diffracting it. The thickness of the layers is designed so that the "bright areas of the diffraction pattern coincide in the same spot."
"The more precise the lens is fabricated, the sharper becomes the X-ray focus. With this method, 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. Until recently it was even debated whether fundamental limits of X-ray optics would stand against such small focal widths. The outstanding brilliance of DESY's X-ray light source PETRA III helped to make a usable nano focus possible," the news release stated.
The technology could help create nanowires to be used in solar cells.
"Usually, when investigating the chemical composition of a sample, the beam size limits the sharpness of the image. Before this experiment, this limit was at about 20 nanometers," DESY researcher Dr. Michael Sprung, said.
The researchers hope to improve the technology by depositing the layers onto identical glass fibers.
