Journal Article X-ray optics X-ray imaging X-ray microscopy compound refractive lens dark-field X-ray microscopy high-heat-load optics thermal deformation wavefront propagation 3DXRD Research Support, Non-U.S. Gov't X-ray diffraction X-ray monochromator anisotropic Poisson's ratio anisotropic elasticity of silicon bent mirror characterization coalescence coherence cryogenic cooled monochromator cryogenic cooling crystal orientation data analysis diffraction imaging diffraction microstructure imaging finite element finite element analysis finite-element analysis gallium nitride geometrical optics