23 September 2011 Partially coherent x-ray beam simulations: mirrors and more
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Abstract
Penetration, 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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Markus Osterhoff, Tim Salditt, "Partially coherent x-ray beam simulations: mirrors and more", Proc. SPIE 8141, Advances in Computational Methods for X-Ray Optics II, 81410C (23 September 2011); doi: 10.1117/12.893003; https://doi.org/10.1117/12.893003
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