Focusing XFEL SASE pulses by rotationally parabolic refractive x-ray lenses

22nd International Congress on X-Ray Optics and Microanalysis

Seiboth, Frank^1 ; Schropp, Andreas^1,2 ; Hoppe, Robert^1 ; Meier, Vivienne^1 ; Patommel, Jens^1 ; Lee, Hae Ja^2 ; Nagler, Bob^2 ; Galtier, Eric C.^2 ; Arnold, Brice^2 ; Zastrau, Ulf^2 ; Hastings, Jerome B.^2 ; Nilsson, Daniel^3 ; Uhlén, Fredrik^3 ; Vogt, Ulrich^3 ; Hertz, Hans M.^3 ; Schroer, Christian G.^1

Institute of Structural Physics, Technische Universität Dresden, D-01062 Dresden, Germany^1

Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, United States^2

Biomedical and X-Ray Physics, KTH/Royal Institute of Technology, KTH-AlbaNova, SE-106 91, Stockholm, Sweden^3

关键词: Chromatic aberration;    Crystal monochromators;    Lens materials;    Linac Coherent Light Source;    Nano-focusing;    Parabolic refractive x-ray lens;    Refractive x-ray lens;    Self-amplified spontaneous emission;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/499/1/012004/pdf
DOI  :  10.1088/1742-6596/499/1/012004

来源: IOP

【 摘 要 】

Using rotationally parabolic refractive x-ray lenses made of beryllium, we focus hard x-ray free-electron laser pulses of the Linac Coherent Light Source (LCLS) down to a spot size in the 100 nm range. We demonstrated efficient nanofocusing and characterized the nanofocused wave field by ptychographic imaging [A. Schropp, et al., Sci. Rep. 3, 1633 (2013)] in the case of monochromatic LCLS pulses produced by a crystal monochromator that decreases the LCLS bandwidth down to ΔE/E 1.4 · 10-4. The full spectrum of LCLS pulses generated by self-amplified spontaneous emission (SASE), however, fluctuates and has a typical bandwidth of a few per mille (ΔE/E 2 · 10-3). Due to the dispersion in the lens material, a polychromatic nanobeam generated by refractive x-ray lenses is affected by chromatic aberration. After reviewing the chromaticity of refractive x-ray lenses, we discuss the influence of increased bandwidth on the quality of a nanofocused SASE pulse.