Filters

2020 - 20222

More filters

2021 - 20222
Reset filters

Settings

search.filters.applied.f.access: openAccess × Author: Mikkelsen, Anders ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Reference shape effects on Fourier transform holography
    (Washington, DC : Soc., 2022) Malm, Erik; Pfau, Bastian; Schneider, Michael; Günther, Christian M.; Hessing, Piet; Büttner, Felix; Mikkelsen, Anders; Eisebitt, Stefan
    Soft-x-ray holography which utilizes an optics mask fabricated in direct contact with the sample, is a widely applied x-ray microscopy method, in particular, for investigating magnetic samples. The optics mask splits the x-ray beam into a reference wave and a wave to illuminate the sample. The reconstruction quality in such a Fourier-transform holography experiment depends primarily on the characteristics of the reference wave, typically emerging from a small, high-aspect-ratio pinhole in the mask. In this paper, we study two commonly used reference geometries and investigate how their 3D structure affects the reconstruction within an x-ray Fourier holography experiment. Insight into these effects is obtained by imaging the exit waves from reference pinholes via high-resolution coherent diffraction imaging combined with three-dimensional multislice simulations of the x-ray propagation through the reference pinhole. The results were used to simulate Fourier-transform holography experiments to determine the spatial resolution and precise location of the reconstruction plane for different reference geometries. Based on our findings, we discuss the properties of the reference pinholes with view on application in soft-x-ray holography experiments.
  • Thumbnail Image
    Item
    Singleshot polychromatic coherent diffractive imaging with a high-order harmonic source
    (Washington, DC : Soc., 2020) Malm, Erik; Wikmark, Hampus; Pfau, Bastian; Villanueva-Perez, Pablo; Rudawski, Piotr; Peschel, Jasper; Maclot, Sylvain; Schneider, Michael; Eisebitt, Stefan; Mikkelsen, Anders; L’Huillier, Anne; Johnsson, Per
    Singleshot polychromatic coherent diffractive imaging is performed with a high-intensity high-order harmonic generation source. The coherence properties are analyzed and several reconstructions show the shot-to-shot fluctuations of the incident beam wavefront. The method is based on a multi-step approach. First, the spectrum is extracted from double-slit diffraction data. The spectrum is used as input to extract the monochromatic sample diffraction pattern, then phase retrieval is performed on the quasi-monochromatic data to obtain the sample’s exit surface wave. Reconstructions based on guided error reduction (ER) and alternating direction method of multipliers (ADMM) are compared. ADMM allows additional penalty terms to be included in the cost functional to promote sparsity within the reconstruction. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.