The Science
X-ray free-electron lasers, such as the Linac Coherent Light Source (LCLS), have had a significant impact on many scientific disciplines. LCLS produces brilliant and short pulses of X-rays for researchers to view the details of samples with unprecedented temporal and spatial resolutions. The challenge for the instrument scientists at the LCLS is how to focus the X-ray beam on the sample without distorting the beam’s quality? X-ray lenses require precision manufacturing. Instead of attempting a “LASIK surgery” on the lenses at the beamline, researchers found a way to put X-ray “eyeglasses” on the X-ray beam.
The Impact
The team’s “eyeglasses” provide a path to aberration-free X-ray optics to obtain detailed images of matter. Better optics will harness the full potential of current and future light sources. This approach also opens up new opportunities in fields as diverse as high-resolution imaging and plasma physics. These opportunities could lead to the materials needed for more powerful computers, damage-resistant aircrafts, and cleaner sources of energy.
Summary
Various optical elements are routinely used in modern synchrotron sources and X-ray free-electron lasers to confine the X-ray beam and focus it onto the sample under investigation. These elements include multilayer mirrors and compound refractive lenses. The fabrication of these X-ray optical elements requires high precision using the most advanced fabrication technologies, such as lithographic nanofabrication and thin film deposition. Any imperfection in the optical elements due to the fabrication process or to the limitations of available technologies results in a non-ideal (that is, aberrated) focused beam. At the Matter in Extreme Conditions endstation at LCLS, researchers have found a new way to correct for the imperfections introduced by a series of compound refractive lenses in the focused beam. The scientists used two techniques to characterize the aberrations for the entire unit. Then, they used a short pulse laser ablation technique to make a phase plate that corrects for aberrations (just like making eyeglasses for a patient but the patient in this case is the X-ray beamline).
Funding
Use of the Linac Coherent Light Source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract DE-AC02-76SF00515. The Matter in Extreme Conditions instrument is supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under contract SF00515. This work is supported by the German Ministry of Education and Research under grant 05K13OD2, the German Research Foundation (DFG) under grant SCHR 1137/1-1 and the Swedish Research Council. F.S., A.S. and C.Rö. acknowledge the Peter Paul Ewald fellowship from the Volkswagen Foundation.
Publications
F. Seiboth, A. Schropp, M. Scholz, F. Wittwer, C. Rödel, M. Wünsche, T. Ullsperger, S. Nolte, J. Rahomäki, K. Parfeniukas, S. Giakoumidis, U. Vogt, U. Wagner, C. Rau, U. Boesenberg, J. Garrevoet, G. Falkenberg, E.C. Galtier, H.J. Lee, B. Nagler, and C.G. Schroer, “Perfect X-ray focusing via fitting corrective glasses to aberrated optics.” Nature Communications 8, 14623 (2017). [DOI: 10.1038/ncomms14623]
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