Imprinting a focused x-ray laser beam to measure its full spatial characteristics

0450793 - FZÚ 2016 RIV US eng J - Journal Article
Chalupský, Jaromír - Boháček, Pavel - Burian, Tomáš - Hájková, Věra - Hau-Riege, S.P. - Heimann, P.A. - Juha, Libor - Messerschmidt, M. - Moeller, S.P. - Nagler, B. - Rowen, M. - Schlotter, W.F. - Swiggers, M.L. - Turner, J.J. - Krzywinski, J.
Imprinting a focused x-ray laser beam to measure its full spatial characteristics.
Physical Review Applied. Roč. 4, č. 1 (2015), "014004-1"-"014004-11". ISSN 2331-7019. E-ISSN 2331-7019
R&D Projects: GA MŠMT(CZ) LH14072; GA MŠMT(CZ) ME10046
Institutional support: RVO:68378271
Keywords : free-electron laser * phase-recovery code * PHARE
Subject RIV: BH - Optics, Masers, Lasers
Impact factor: 4.061, year: 2015

The new generation of x-ray free-electron lasers opens up unique avenues for exploring matter under exotic and extreme conditions. We present a direct method of in-focus numerical phase recovery exploiting multishot desorption imprints in poly(methyl methacrylate). Shapes of the imprints serve as input data for the newly developed code PHARE (phase recovery), inspired by the iterative Gerchberg-Saxton algorithm. A procedure of dynamic input-output mixing guarantees that the algorithm always converges to a selfconsistent paraxial Helmholtz equation solution, which is thereafter optimized for transverse spatial coherence. Very good agreement with single-shot ablation imprints in lead tungstate (PbWO4) is found. The experiment is carried out at LCLS with a focused beam monochromatized at 800 eV. The results of the coherence optimization indicate that the act of monochromatization may have an effect on otherwise very good transverse coherence of free-electron laser beams.
Permanent Link: http://hdl.handle.net/11104/0251994