Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.91: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
Characterization of a Fresnel Zone Plate for magnetic imaging with high harmonic radiation — •Tobias Heinrich1, Sergey Zayko1, Ofer Kfir1,2, and Claus Ropers1 — 1University of Göttingen, 4th Physical Institute, Göttingen, Germany — 2Physics Department, Technion - Israel Institute of Technology, Haifa 32000, Israel
The development of bright circularly polarized high harmonic radiation [1,2] has recently enabled nanoscale magnetic imaging with sub-50-nm resolution using x-ray magnetic circular dichroism [3]. Here, we explore possibilities of enhancing this imaging approach utilizing a Fresnel zone plate (FZP). Such a setup will provide the opportunity for a direct and robust real-space image acquisition or can be used in a combination with lensless techniques to increase the irradiance at the sample.
In this work, a Fresnel zone plate suitable for use in a high-harmonic setup was designed and characterized. The resulting wave front was analyzed using a 3-D caustic measurement. By employing a pinhole scan, wave fronts of different diffraction orders were identified and separately evaluated. Using coherent diffractive imaging, the complex exit wave of the FZP was retrieved, yielding a focal spot size of 160 nm. A total first order diffraction efficiency of 4.5 % was estimated. With such an upgrade, the high-harmonic imaging setup will benefit from the opportunity for spatially resolved x-ray photoelectron spectroscopy in a scanning geometry. [1] Fleischer et all., Nature Photonics 8, 543-549 (2014) [2] O. Kfir et all., Nature Photonics 9, 99-105 (2015) [3] O. Kfir, S. Zayko et all., arXiv:1706.07695