Modeling of a compound imaging system with a curved monochromator and polycapillary optics

摘要

Monochromatic x-ray beams improve image contrast but suffer from low intensity if produced with a flat monochromator crystal. A doubly-curved crystal makes more efficient use of the source. However, the beam shape is not conducive to imaging. A combination of a bent crystal followed by a polycapillary optic can be used to monochromatize and focus x rays to a small spot to perform monochromatic x-ray imaging with good resolution. Ray-tracing simulations have been developed which account for defects in both optics types. A comparison was made to measurements of focal spot sizes, angular divergence, and image quality parameters including resolution and contrast. Simulations support the experimental results that geometric blur is significantly reduced, and resolution enhanced, for magnification imaging with this optic combination.