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Seminario
"Ultrafast, Ultra Brigh, Ultra High-Resolution imaging and holography with X-ray lasers"

Relatore: Dott. Stefano Marchesini- University of California, Lawrence Livermore National Laboratory; e Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California

Aula Newton Dipartimento di Fisica
25 Ottobre 2007 ore 16.00

Abstract
Recent advances in the development of free-electron lasers now offer the realistic prospect of imaging on the time-scale of nuclear motion. We identify Fourier transform x-ray holography1,2 as a promising tool to explore the ultrafast and the nanoworld. We show that a uniformly redundant array3 (URA) placed next to an object boost the holographic signal by a factor of 2600. The nanofabricated URAs serve as a reference binary object with a periodic autocorrelation equal to a delta function. Fourier filtering separates the multiplexed hologram, and a Hadamard transformation of the pattern recovers the wavefront. The first experimental results show structures for nano-fabricated objects and bacterial cells with 15 fs temporal and 45-nm spatial resolution. We expect with upcoming hard X-ray lasers to achieve considerably higher spatial resolution to examine biological cells at the molecular level and to obtain ultrafast movies of excited states of matter.