A novel imaging x-ray microscope based on a spherical crystal

A novel, compact, large field, and spectrally tunable imaging x-ray microsc ope is presented. It is based on the use of an isotropic point x-ray source and a spherically curved crystal. The x-ray beam intensity is modulated by the object attenuation, then monochromatized and enlarged using a spherica l crystal and, finally, imaged using a detector downstream from the crystal . We demonstrate by ray tracing simulations that this system allows microsc opy studies with high spatial resolution, high magnification ratios, and la rge field of view. Microscopes using this model can be easily built using d ifferent x-ray sources, like conventional x-ray tube generators, x rays emi tted by laser-generated plasmas or x-pinch plasmas, and also synchrotron ra diation when used in combination with other condenser optics. Preliminary e xperiments are presented to demonstrate the feasibility of the proposed set up. High resolution (similar to4 mum) monochromatic (delta lambda/lambda si milar to 10(-5)-10(-3)) images over a large field of view (few mm(2)) were recorded in the spectral range 8-14 Angstrom using a laser-generated plasma source and a spherical mica crystal. Compared to x-ray crystal imagers use d in relation with plasma sources, the new configuration produces high qual ity stigmatic images working at many different Bragg angles, thus improving the spectral tunability and allowing a more flexible design. (C) 2001 Amer ican Institute of Physics.