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Theory of Imaging a Perfect Crystal under the Conditions of X‐Ray Spherical Wave Dynamical Diffraction
Author(s) -
Kohn V.G.,
Snigireva I.,
Snigirev A.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200011)222:2<407::aid-pssb407>3.0.co;2-x
Subject(s) - diffraction , spherical wave , x ray , crystal (programming language) , physics , dynamical theory of diffraction , optics , classical mechanics , computer science , acousto optics , diffraction grating , programming language
A theory of the formation of interference patterns due to X‐ray spherical wave two‐beam dynamical diffraction in a perfect crystal is presented. An asymmetrical Laue case is analyzed in detail, when a polychromatic focus is realized with different distances in front of and behind the crystal. Such a property is essential for high‐energy X‐rays produced by synchrotron radiation sources of the third generation because of the long distance between source and object. It is shown that a monochromatic X‐ray spherical wave is focused due to dynamical diffraction when a definite relation between distances and crystal thickness is held. An X‐ray beam of less than 10 μm width may be obtained. A two‐dimensional intensity distribution (topograph) may be registered with a wedge‐shaped crystal. It shows interference fringes of different kinds depending on crystal thickness and asymmetry rate. It is also discussed how a slit in front of the crystal influences the interference pattern. An example of an interference pattern is presented under the condition of highly asymmetrical diffraction which was obtained by a computer simulation technique. Fringes of a new kind are observed and their physical nature is discussed.