Coherent diffraction imaging using laboratory light sources

Odstrčil, M., Baksh, P. and Brocklesby, W.S. (2014) Coherent diffraction imaging using laboratory light sources. EXTATIC Welcome Week Workshop, Warsaw, Poland. 25 - 29 Jun 2014.

Abstract

Coherent diffractive imaging, also called lenses imaging methods, are now a standard tool for Xray imaging on synchrotron devices [1,2,3]. The diffractive imaging methods can avoid limitations of imperfect optics in the Xray region and also limit the dose exposed to the sample. Therefore, these methods allow to reach higher resolution compared to the standard lens based methods. Moreover, lensless methods allow to extract full information about the wavefront behind the sample and hence relative phase and amplitude can be recovered. Finally, advanced lensless methods such as ptychography allow to extract information about the illumination that can be used for beam metrology purposes [3]. In recent years, the coherent diffractive imaging is getting to be used also with the laboratory sources and longer wavelengths such as EUV and visible light region. Limitation of the laboratory EUV sources is lower signal, worse coherence properties and generally lower time stability of the signal. The requirements for lateral and temporal coherence can be slightly relaxed if the reconstruction is sufficiently overconstrained [4,5,6]. In this work, we will introduce and compare numerical methods that can significantly help to improve convergence and reconstruction quality. We will introduce the methods using numerical examples and also real measured data from EUV and IR light experiments. We will use ptychography method for the reconstruction, although most of the proposed methods can be used also with other lensless imaging techniques.

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Contributors

Author: W.S. Brocklesby

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