Microfocusing of 50 keV undulator radiation with two stacked zone plates

The limitations of current fabrication methods preclude producing an effici ent Fresnel phase zone plate optimized for focusing high-energy (> 40 keV) synchrotron X-ray beams. To get around this difficulty, one can attempt a M ultiple zone plate setup that distributes the focusing task among more than one element, each of which can be manufactured. The focusing of 50 keV und ulator radiation to a 9 x 7 mum(2) spot size with a flux density gain of 24 was achieved using two stacked zone plates precisely aligned with respect to each other. The instrument was used to record elemental concentration ma ps of a geological inclusion specimen using X-ray fluorescence. The stacked zone plate approach is a viable option for microfocusing high-energy X-ray s. (C) 2001 Elsevier Science B.V. All rights reserved.