Optical Design of DEI/ABI System at the HEX Beamline at the NSLS-II.

Bent Laue monochromator HEX is designed with a high-energy non-focusing X-ray monochromator for full-field imaging. The following design ideas apply to the imaging monochromator: The HEX center branch, which the monochromator serves, is white-beam compatible. The monochromator is located in the first optical enclosure with the following parameters: source to monochromator distance is 31 m; monochromator to sample distance is 73 m. Diffraction Enhanced Imaging (DEI) or Analyzer Based Imaging (ABI) uses a perfect crystal monochromator and matching analyzer to achieve sensitivity to X-ray refraction and ultra small-angle scattering on the order of 0.01 micro-radians. [Extracted from the article]