Surface curvatures and diffraction profiles of sagittally bent Laue crystals

Surface curvatures and diffraction profiles of sagittally bent Laue crystals

The performance of a bent Laue crystal monochromator crucially depends on the sagittal and meridional bending curvatures of the crystal. To optimize the design of monochromator crystals, the surface curvatures and diffraction profiles of a set of sagittally bent Laue crystals with different aspect r...

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Bibliographic Details
Published in:Journal of applied crystallography Vol. 44; no. 4; pp. 665 - 671
Main Authors: Shi, Xianbo, Ghose, Sanjit, Zhong, Zhong, Rehak, Margareta L., Kaznatcheev, Konstantine, Takacs, Peter Z., Dooryhee, Eric
Format: Journal Article
Language:English
Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01-08-2011
Blackwell Publishing Ltd
Subjects:
Aspect ratio
Bending
Crystallography
Crystals
Curvature
Diffraction
Laue crystals
Mathematical analysis
Mathematical models
monochromator crystals
Monochromators
sagittal bending
Surface chemistry
surface curvatures
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Summary:The performance of a bent Laue crystal monochromator crucially depends on the sagittal and meridional bending curvatures of the crystal. To optimize the design of monochromator crystals, the surface curvatures and diffraction profiles of a set of sagittally bent Laue crystals with different aspect ratios have been studied experimentally by optical metrology and X‐ray measurements. The results were confirmed with finite‐element analysis using large‐deformation theory. The nonlinear relationship between the curvatures necessitates an experimentally determined parameter in the theoretical modeling of the diffraction profiles. By taking into account the local stress and the aspect ratio of the sagittally bent Laue crystal, the modified analytical approach successfully predicts the rocking‐curve width and the integrated reflecting power. The effect of extreme sagittal bending on the rocking curve is also discussed. To retain high reflectivity, the bending curvature should not exceed its critical value for the specified crystal geometry. Furthermore, the uniformity of the bending curvatures across the crystal surface has been examined, which suggests that the minimum crystal dimension should be approximately twice the size of the beam footprint.
Bibliography:ark:/67375/WNG-P4FC12FK-8
ArticleID:JCRHX5128
istex:B029381E2CEA8B2B007ABBBB419704B6627351E6
ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:1600-5767
0021-8898
1600-5767
DOI:10.1107/S0021889811018711