Bent Crystal Optics for Synchrotron Radiation Beamlines
Bent crystals have been widely used as optical elements (e.g., monochromators, focusing optics and spectrometers) of high energy synchrotron radiation beamlines. The effects of bending on the reflectivity of the crystal are discussed within the dynamical theory with a full treatment of the crystal anisotropy and biaxial bending. Such knowledge and its combination with ray tracing and wave propagation are essential in the beamline design process. Two particular examples are presented to illustrate the usage of bent crystals for modern synchrotron radiation beamlines: the design of the X-ray Powder Diffraction (XPD) beamline at NSLS-II and the optimization of high luminosity spectrometers at ESRF and XFEL.
The XPD beamline uses a sagittally bent double-Laue crystal monochromator to provide horizontally focused x-ray beam over a large energy range (30-70 keV). A multi-lamellar model is introduced and implemented in the ray tracing of the monochromator. The instrumental resolution function of the beamline is also described.
Bent crystals are also utilized for high luminosity X-ray emission detection. This presentation will compare various concepts of dispersive/non-dispersive spectrometers with different crystal geometries by means of ray tracing.