1,721,062 research outputs found
dada – a web-based 2D detector analysis tool
No full textAbstract The data daemon, dada, is a server backend for unified access to 2D pixel detector image data stored with different detectors, file formats and saved with varying naming conventions and folder structures across instruments. Furthermore, dada implements basic pre-processing and analysis routines from pixel binning over azimuthal integration to raster scan processing. Common user interactions with dada are by a web frontend, but all parameters for an analysis are encoded into a Uniform Resource Identifier (URI) which can also be written by hand or scripts for batch processing
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No full textTestdatensatz
zu Abbildung 7a in M. Osterhoff et al: Nanosecond timing and synchronization scheme for holographic pump–probe studies at the MID instrument at European XFEL, https://doi.org/10.1107/S160057752100305
Wave optical simulations of x-ray nano-focusing optics
No full textSoftcover, 17x24Curved x-ray multilayer mirrors focus synchrotron beams down to tens of nano metres. A wave-optical theory describing propagation of two waves in an elliptically curved focusing multilayer mirror is developed in this thesis. Using numerical integration, the layer shapes can be optimised for reflectivity and aberrations. Within this framework, performance of both existing and currently upgraded synchrotron beamlines is simulated. Using a more theoretical model case, limits of the theory are studied. A significant part of this work is dedicated to partial spatial coherence, modelled using the method of stochastic superpositions. Coherence propagation and filtering by x-ray waveguides is shown analytically and numerically. This comprehensive model is put forward that shall help in development and testing of new algorithms for a variety of imaging techniques using coherent x-ray beams. Advanced simulations accounting for real structure effects are compared to experimental data obtained at the GINIX instrument at the coherence beamline P10 at PETRA III, DESY. This thesis presents results of a collaboration between the Georg-August-Universität Göttingen and the European Synchrotron Radiation Facility (ESRF) Grenoble
Real structure effects in X-ray waveguide optics: The influence of interfacial roughness and refractive index profile on the near-field and far-field distribution
No full textWe generalize the optical treatment of X-ray waveguides to index profiles of arbitrary shape. The modes of the waveguides are computed numerically by Numerov's method. The method is first validated by considering profiles for which analytical solutions exist. Next, the effects of different shape functions and of interfacial roughness on the near and far-field intensity distributions are studied. The results are helpful to judge the real structure effects, e.g. resulting from fabrication imperfections, on the optical performance, as well as to optimize optical properties by designing generalized index profiles. (C) 2009 Elsevier B.V. All rights reserved
Coherent Diffractive Imaging with Diffractive Optics
No full textWe present a novel approach to x-ray microscopy based on a multilayer zone plate which is positioned
behind a sample similar to an objective lens. However, unlike transmission x-ray microscopy, we do not
content ourselves with a sharp intensity image; instead, we incorporate the multilayer zone plate transfer
function directly in an iterative phase retrieval scheme to exploit the large diffraction angles of the small
layers. The presence of multiple diffraction orders, which is conventionally a nuisance, now comes as an
advantage for the reconstruction and photon efficiency. In a first experiment, we achieve sub-10-nm
resolution and a quantitative phase contrast
Numerische Modellierungen von Röntgenwellenleitern unter Berücksichtung von Realstruktureffekten
No full textPartially coherent x-ray beam simulations: mirrors and more
No full textPenetration, micro-resolution, and scattering were the keywords of x-ray analyses in the 20th century. Over the last 15 years, a great class of coherent imaging techniques has emerged as new tools, allowing for low-dose imaging of biological specimen on the nanoscale. Apart from experimental and technical challenges, a better understanding of partially coherent beam propagation is the key for exploiting the new methods' full performance. We present a simulation framework to calculate the mutual intensity and the degree of spatial coherence of typical x-ray focusing and filtering devices used at 3rd generation synchrotron radiation sources. We propose the following modeling scheme: A set of independent point-sources yield independent basic fields, which are superposed in a stochastic manner; by taking the ensemble average, both partially coherent intensity and degree of coherence can be obtained from the mutual intensity. By including real structure effects, like height deviations of focusing mirrors, and vibration of optical components, advanced predictions of x-ray beams can be made. This knowledge is expected to improve reconstruction results from coherent imaging experiments. Coherence simulations of focusing mirrors are presented and validated with analytical results as well as with experimental tests. Coherence filtering by use of x-ray waveguides is shown numerically. We also present first simulations for partially coherent focusing by compound refractive lenses
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