Open AccessCombining flat crystals, bent crystals and compound refractive lenses for high‐energy X‐ray optics
Author(s) -
Shastri S. D.
Publication year - 2004
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049503023586
Subject(s) - monochromator , optics , beamline , x ray optics , collimated light , focal length , monochromatic color , bent molecular geometry , physics , resolution (logic) , undulator , photon energy , beam divergence , lens (geology) , beam (structure) , materials science , photon , x ray , laser , wavelength , beam diameter , artificial intelligence , laser beams , computer science , composite material
Compound refractive lenses (CRLs) are effective for collimating or focusing high‐energy X‐ray beams (50–100 keV) and can be used in conjunction with crystal optics in a variety of configurations, as demonstrated at the 1‐ID undulator beamline of the Advanced Photon Source. As a primary example, this article describes the quadrupling of the output flux when a collimating CRL, composed of cylindrical holes in aluminium, is inserted between two successive monochromators, i.e. a modest‐energy‐resolution premonochromator followed by a high‐resolution monochromator. The premonochromator is a cryogenically cooled divergence‐preserving bent double‐Laue Si(111) crystal device delivering an energy width , which is sufficient for most experiments. The high‐resolution monochromator is a four‐reflection flat Si(111) crystal system resembling two channel‐cuts in a dispersive arrangement, reducing the bandwidth to less than , as required for some applications. Tests with 67 and 81 keV photon energies show that the high‐resolution monochromator, having a narrow angular acceptance of a few microradians, exhibits a fourfold throughput enhancement due to the insertion of a CRL that reduces the premonochromatized beam's vertical divergence from 29 rad to a few microradians. The ability to focus high‐energy X‐rays with CRLs having long focal lengths (tens of meters) is also shown by creating a line focus of 70–90 m beam height in the beamline end‐station with both the modest‐energy‐resolution and the high‐energy‐resolution monochromatic X‐rays.