Polish Synchrotron Radiation Society Award

A paper describing an innovative X-ray lens, manufactured by the team of CFEL group leader Saša Bajt, has won the Polish Synchrotron Radiation Society Award 2018 for the best peer-reviewed publication in the topics of synchrotron radiation and free-electron laser research. The 'high numerical aperture multilayer Laue lenses' can produce sharper and brighter images of the nano world than were possible before. An advanced version of these lenses was also recently distinguished as one of the top ten microscopy innovations 2018 by the Microscopy Society of America.

Some of the members of the team working with Saša Bajt (right). Credit: DESY

In contrast to conventional optics, multilayer Laue lenses (MLL) do not refract light but work by diffracting the incident X-rays in a way that concentrates the beam on a small spot. To achieve this, they consist of alternating layers of two different materials with nanometer thickness. Bajt's team realized that for the optimal lens the individual layers need to be slightly tilted against each other: all layers of such a “wedged” MLL must lie perpendicular on a circle with a radius of twice the focal length. The researchers invented a new production process for these optics that could not be produced with existing techniques.

The paper describes innovative analysis of these lenses using one dimensional interference method (ptychography) developed by Andrew Morgan in the group of Henry Chapman. The behavior of the lenses was understood through advanced numerical wave propagation of Andrzej Andrejczuk (University of Bialystok, Poland) and Jacek Krzywinski (SLAC National Accelerator Laboratory, USA).

Scanning electron microscope image of the novel X-ray lens. The dark area is the substrate. The height of the lens is 16 micrometers. Credit: Mauro Prasciolu/CFEL

Measurements were made at the P11 beamline at DESY's ultra-brilliant X-ray source PETRA III using the new high frame rate LAMBDA detector, also developed at DESY. The tests showed that the lens focused the X-ray beam to a thin line, just eight nanometers wide, which was close to the design value. The lens transmitted up to 60 per cent of the incoming X-rays to the sample. To focus an X-ray beam in two dimensions, two perpendicular lenses have to be combined.

Other authors on the paper include Mauro Prasciolu (CFEL/DESY), Alke Meents (CFEL/DESY), David Pennicard (CFEL/DESY), Heinz Graafsma (CFEL/DESY), Anton Barty (CFEL/DESY), Richard Bean (DESY), Miriam Barthelmess (D CFEL/DESY ESY), Dominik Oberthür (CFEL/DESY and University of Hamburg), Oleksandr Yefanov (CFEL/DESY), Andrew Aquila (European XFEL) and Henry Chapman (CFEL/DESY and University of Hamburg)