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Effect of Focusing Optics on X-ray Speckle Contrast
| Content Provider | Semantic Scholar |
|---|---|
| Author | Retschl, Cornelia C. Wang, Yuxin Frigol, Sean P. McNulty, Ian Lurio, Laurencce O. B. Stephenson, G. Brian |
| Copyright Year | 2000 |
| Abstract | We investigated the behavior of speckle contrast and size under various experimental conditions using 1.82 keV x-rays. In this paper, we report the comparison of lwo different setups for x-ray speckle experiments: one employing a focusing zone plate and one in which a pinhole selects the size of the coherent x-ray beam. We found a strong dependence of the speckle contrast and size on the type of setup. In general, the pinhole setup results in higher contrast but smaller speckle size. On the other han~ the zone plate setup allows one to target much smaller areas of interest in the sample, down to submicron dmensions, and also to adjust the speckle size. We anticipate that these results will be usefil in future time-correlation spec&oscopy experiments. A disordered system illuminated with temporally and spatially cohererit light produces a speckle pattern, which is an interference pattern of all the waves scattered by the various scattering centers in the sample. To a first approximation the average shape of a speckle in an experiment with a circular aperture is an Airy pattern (l), () ~=2J1 (V) 2 v=gAq, ‘ 9 2 (1) v where D is the diameter of the illuminated spot on the sample and Aq is the radial distance from the center of the speckle in momentum transfer g. Therefore, the average fill-width at half-maximum (FWHM) size of a speckle is approximately 2n/D, being inversely proportional to the illuminated spot size. We explored two different scattering geometries at the SRI-CAT beamline 2-ID-B at the Advanced Photon Source: a pinhole setup (Figure la) and a zone plate setup (Figure lb). Details of the beamline can be found elsewhere (2). So far, only pinhole sefips are “used routinely in x-ray speckle experiments (3,4). However. a zone date The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acling on its behalf, a paid-up, nonexclusive, irrevocable worldwide Ficensein said article to reproduce, prepare derivative works, distribute copies to the pubfic, and perform pubficly and display pubficly, by or on behalf of the Government. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://digital.library.unt.edu/ark:/67531/metadc709336/m2/1/high_res_d/750574.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Aperture (software) Coherence (physics) Copy (object) Diagnostic radiologic examination Diameter (qualifier value) Experiment Full Width at Half Maximum Interference (communication) Kiloelectronvolt Linear algebra Manuscripts Order of approximation Preparation Radial (radio) Radiation Roentgen Rays Small Views:Finding:Point in time:To be specified in another part of the message:Narrative:XR |
| Content Type | Text |
| Resource Type | Article |
