Direct Inversion of Digital 3D Fraunhofer Holography Maps

The Differential Fourier Holography (DFH) gives an exact mathematical solution of the inverse problem of diffraction in the Fraunhofer regime. After the first publication [1] the Differential Fourier Holography was successfully applied in many experiments to obtain amplitude and phase information about two-dimensional (2D) images. In this article we demonstrate numerically the possibility to apply the DFH also for investigation of unknown 3D Objects. The first simulation is made for a double-spiral structure plus a line as a reference object

Kristalle im Alltag und in der Forschung

Aussehen und regelmäßige Gestalt von Kristallen haben die Menschen schon immer fasziniert. Heute nutzen wir Kristalle nicht nur als Schmuckstücke sondern an vielen Stellen im Alltag und in technischen Geräten

Untersuchungen mit brillanten Röntgenquellen

Wilhelm Conrad Röntgen nannte die von ihm entdeckten Strahlen X-Strahlen, da er zwar wichtige Eigenschaften, aber nicht ihre Natur bestimmen konnte. Das vor genau 100 Jahren von Laue durchgeführte Beugungsexperiment war die Basis für die Erkenntnis, dass die X-Strahlung elektromagnetische Strahlung ist. Sie hat eine 1000-fach kleinere Wellenlänge, als sie das optische Licht aufweist. Heute werden brillante Röntgenquellen für viele Aufgaben in der Forschung, der Medizin und der Industrie eingesetzt. In jüngster Zeit haben wir extrem brillante Röntgenquellen, wie Synchrotrons und Freie Elektronen Laser, zur Verfügung, mit denen kristallisierte Biomoleküle und künftig sogar Einzelmoleküle auf ihren atomaren Aufbau hin untersucht werden können

Hard X-ray Generation from ZnO Nanowire Targets in a Non-Relativistic Regime of Laser-Solid Interactions

We present a detailed investigation of X-ray emission from both flat and nanowire zinc oxide targets irradiated by 60 fs 5 x 10(16) W/cm(2) intensity laser pulses at a 0.8 mu m wavelength. It is shown that the fluence of the emitted hard X-ray radiation in the spectral range 150-800 keV is enhanced by at least one order of magnitude for nanowire targets compared to the emission from a flat surface, whereas the characteristic K-proportional to line emission (8.64 keV) is insensitive to the target morphology. Furthermore, we provide evidence for a dramatic increase of the fast electron flux from the front side of the nanostructured targets. We suggest that targets with nanowire morphology may advance development of compact ultrafast X-ray sources with an enhanced flux of hard X-ray emission that could find wide applications in highenergy density (HED) physics

Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window

Influence of higher harmonics of the undulator in X-ray polarimetry and crystal monochromator design

The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel-cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs