2 results
Search Results
Now showing 1 - 2 of 2
- ItemExperimental evaluation of signal-to-noise in spectro-holography via modified uniformly redundant arrays in the soft x-ray and extreme ultraviolet spectral regime(Bristol : IOP Publ., 2017-05-08) Günther, Christian M.; Guehrs, Erik; Schneider, Michael; Pfau, Bastian; von Korff Schmising, Clemens; Geilhufe, Jan; Schaffert, Stefan; Eisebitt, StefanWe present dichroic x-ray lensless magnetic imaging by Fourier transform holography with an extended reference scheme via a modified uniformly redundant array (mURA). Holographic images of magnetic domains simultaneously generated by a single pinhole reference as well as by a mURA reference are compared with respect to the signal-to-noise ratio (SNR) as a function of exposure time. We apply this approach for spectro-holographic imaging of ferromagnetic domain patterns in Co/Pt multilayer films. Soft x-rays with wavelengths of 1.59 nm (Co L3 absorption edge) and 20.8 nm (Co M2,3 absorption edges) are used for image formation and to generate contrast via x-ray magnetic circular dichroism. For a given exposure time, the mURA-based holography allows to decouple the reconstruction SNR from the spatial resolution. For 1.59 nm wavelength, the reconstruction via the extended reference scheme shows no significant loss of spatial resolution compared to the single pinhole reference. In contrast, at 20.8 nm wavelength the single pinhole reveals some very intricate features which are lost in the image generated by the mURA, although overall a high-quality image is generated. The SNR-advantage of the mURA scheme is most notable when the hologram has to be encoded with few photons, while errors associated with the increased complexity of the reconstruction process reduce the advantage for high-photon-number experiments.
- ItemMulti-color imaging of magnetic Co/Pt heterostructures(Melville, NY : AIP Publishing LLC, 2017) Willems, Felix; von Korff Schmising, Clemens; Weder, David; Günther, Christian M.; Schneider, Michael; Pfau, Bastian; Meise, Sven; Guehrs, Erik; Geilhufe, Jan; Merhe, Alaa El Din; Jal, Emmanuelle; Vodungbo, Boris; Lüning, Jan; Mahieu, Benoit; Capotondi, Flavio; Pedersoli, Emanuele; Gauthier, David; Manfredda, Michele; Eisebitt, StefanWe present an element specific and spatially resolved view of magnetic domainsin Co/Pt heterostructures in the extreme ultraviolet spectral range. Resonantsmall-angle scattering and coherent imaging with Fourier-transform holographyreveal nanoscale magnetic domain networks via magnetic dichroism of Co at theM2,3 edges as well as via strong dichroic signals at the O2,3 and N6,7 edges of Pt.We demonstrate for the first time simultaneous, two-color coherent imaging at afree-electron laser facility paving the way for a direct real space access toultrafast magnetization dynamics in complex multicomponent material systems.