Abstract

Imaging individual objects, with few nanometers resolution in space and few femtoseconds resolution in time is of fundamental importance in many areas of science and represents today a fascinating challenge. In such context, advances in coherent diffraction using new coherent ultrashort X-ray sources are actually demonstrating a high potential. Coherent diffraction imaging (CDI) overcomes many restrictions in imaging offering a mean to produce images of non-crystalline objects at a resolution in principle only limited by the wavelength. In this “lensless” technique a spatially coherent X-ray beam illuminates an isolated sample (surrounded by a zero-scattering area) and the far-field diffraction pattern of the object is recorded on an area detector. Since the detector records only the diffracted intensities the “real image” is retrieved from the amplitude and phase diffraction pattern using an iterative algorithm based on Fourier transforms [1]. This imaging technique can be scaled all the way down to atomic resolution. Since its demonstration, many researchers have taken large steps in this direction using soft and hard X-ray synchrotron radiation [2-6]. However, although atoms can be imaged in space, the conventional synchrotron sources do not allow accessing the fastest processes in matter, which is the new frontier of femtosecond to attosecond time resolution. It is only recently that this perspective has emerged thanks to the first demonstration of single shot coherent diffraction imaging using a femtosecond soft X-ray free electron laser (FEL) [7].

© 2012 Optical Society of America