X Ray Waveguide Optics

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X Ray Waveguide Optics

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Author : Sarah Hoffmann-Urlaub
language : en
Publisher: Göttingen University Press
Release Date : 2017

X Ray Waveguide Optics written by Sarah Hoffmann-Urlaub and has been published by Göttingen University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.

Modern x-ray sources and analysis techniques such as lens less imaging combined with phase retrieval algorithms allow for resolving structure sizes in the nanometer range. For this purpose optics have to be employed, ensuring small focal spot dimensions simultaneously with high photon densities. Furthermore, the wave front behind the optics is required to be smooth enabling for high resolution imaging. Combining all these properties, x-ray waveguides are well suited to perform this task, since the intensity distribution behind the guide is restricted in two dimensions serving as a secondary quasi point-source without wave-front aberrations, showing also a high divergence, suitable for resolving fine features. Importantly, the radiation provided by the waveguide reveals a high degree of coherence, required by many imaging techniques. The waveguide itself consists of an air-filled channel embedded in a solid matrix; typical materials are silicon, germanium or quartz. While the entrance area is nano-sized, the channel length is in the millimeter-range, this way posing challenges to fabricate high aspect ratio geometries. Since the functioning of x-ray waveguides is based on the total reflection at small incident angles, the surface roughness of the channel walls must be as low as possible to avoid scattering and hence loss of intensity. To fulfill these demanding conditions, a process scheme involving spin-coating, electron beam lithography, wet development, reactive ion etching and wafer bonding is optimized within this work. To gain deeper insights into the principle of wave guiding finite difference simulations are performed, also opening access for advanced design considerations such as gratings, tapered and curved channels, or beamsplitters, enabling for constructing novel x-ray tools as for example time delay devices or interferometers. Waveguides in all geometries are tested at synchrotron sources, accomplishing new benchmarks in x-ray optical performance. Here, the x-ray beam leaving the channel, propagates out to a pixel array detector in the far-field region. From the recorded data the intensity distribution in the near-field directly behind the waveguide is reconstructed, revealing an outstanding agreement with the simulations and electron micrographs. Since the radiation field of the waveguide is well-characterized and also tunable to meet the requirements of both the measurement setup and the sample, they are suited of a broad field of applications in coherent x-ray imaging.

Optimization Of Waveguide Optics For Lensless X Ray Imaging

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Author : Sven Philip Krüger
language : en
Publisher: Universitätsverlag Göttingen
Release Date : 2011

Optimization Of Waveguide Optics For Lensless X Ray Imaging written by Sven Philip Krüger and has been published by Universitätsverlag Göttingen this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.

Lensless x-ray imaging is a promising method to determine the three-dimensional structure of material science and biological specimens at the nanoscale. The development of this technique is strongly related to the optimization of x-ray optics since the image formation and object reconstruction depend significantly on the properties of the illumination wave-field. Waveguide optics act as quasi-point sources and enable the spatial and coherent filtering of x-ray beams. Up to now, x-ray waveguides were severely limited in transmission and flux, restricting their use to high-contrast test structures with moderate resolution and long accumulation times. To overcome these limitations, a novel waveguide design with an optimized refractive index profile is presented which significantly minimizes the absorption of the modes propagating inside the waveguide. Experimental results along with simulations show that these two-component planar x-ray waveguides provide small beam cross-sections along with a high photon flux at the exit. By a serial arrangement of two waveguide slices an optimized illumination source has been developed for high-resolution microscopy, as demonstrated in proof-of-concept imaging experiments.

Advanced X Ray Multilayer Waveguide Optics

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Author : Qi Zhong
language : en
Publisher: Göttingen University Press
Release Date : 2017

Advanced X Ray Multilayer Waveguide Optics written by Qi Zhong and has been published by Göttingen University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.

The aim of this thesis was to design novel waveguide structures, and to analyze them in view of complex phenomena of near-field propagation. For this purpose, experimental far-field measurements were used in combination with finite-difference simulations and phase retrieval methods. Two novel structures have been designed, fabricated and characterized: the waveguide array (WGA), yielding several waveguided beams in transmission, and multi-guide resonate beam couplers (RBCs), tailored to yield two or several reflected beams. Two novel structures have been designed, fabricated and characterized: the WGA, yielding several waveguided beams in transmission, and multi-guide RBCs, tailored to yield two or several reflected beams. The WGA and the multi-guide RBCs are not only distinct in the coupling geometry. A major difference is related to the fact that the WGA principle is based on the separation (non coupling) of the different transmitted wavelets, while the RBC functions are based on a strong coupling of guided radiation in several layers.

Nanoscale Photonic Imaging

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Author : Tim Salditt
language : en
Publisher: Springer Nature
Release Date : 2020-06-09

Nanoscale Photonic Imaging written by Tim Salditt and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-06-09 with Science categories.

This open access book, edited and authored by a team of world-leading researchers, provides a broad overview of advanced photonic methods for nanoscale visualization, as well as describing a range of fascinating in-depth studies. Introductory chapters cover the most relevant physics and basic methods that young researchers need to master in order to work effectively in the field of nanoscale photonic imaging, from physical first principles, to instrumentation, to mathematical foundations of imaging and data analysis. Subsequent chapters demonstrate how these cutting edge methods are applied to a variety of systems, including complex fluids and biomolecular systems, for visualizing their structure and dynamics, in space and on timescales extending over many orders of magnitude down to the femtosecond range. Progress in nanoscale photonic imaging in Göttingen has been the sum total of more than a decade of work by a wide range of scientists and mathematicians across disciplines, working together in a vibrant collaboration of a kind rarely matched. This volume presents the highlights of their research achievements and serves as a record of the unique and remarkable constellation of contributors, as well as looking ahead at the future prospects in this field. It will serve not only as a useful reference for experienced researchers but also as a valuable point of entry for newcomers.

X Ray Waveguide Optics Beyond Straight Channels

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Author : Sarah Hoffmann-Urlaub
language : en
Publisher:
Release Date : 2016

X Ray Waveguide Optics Beyond Straight Channels written by Sarah Hoffmann-Urlaub and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.

Modern x-ray sources and analysis techniques such as lens less imaging combined with phase retrieval algorithms allow for resolving structure sizes in the nanometerrange. For this purpose optics have to be employed, ensuring small focal spot dimensions simultaneously with high photon densities. Furthermore, the wave front behind the optics is required to be smooth enabling for high-resolution imaging. Combining all these properties, x-ray waveguides are well suited to perform this task, since the intensity distribution behind the guide is restricted in two dimensions serving as a secondary ...

A Dedicated Endstation For Waveguide Based X Ray Imaging

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Author : Sebastian Kalbfleisch
language : en
Publisher: Universitätsverlag Göttingen
Release Date : 2013

A Dedicated Endstation For Waveguide Based X Ray Imaging written by Sebastian Kalbfleisch and has been published by Universitätsverlag Göttingen this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.

Wave Optical Simulations Of X Ray Nano Focusing Optics

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Author : Markus Osterhoff
language : en
Publisher: Universitätsverlag Göttingen
Release Date : 2012

Wave Optical Simulations Of X Ray Nano Focusing Optics written by Markus Osterhoff and has been published by Universitätsverlag Göttingen this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.

Curved x-ray multilayer mirrors focus synchrotron beams down to tens of nano metres. A wave-optical theory describing propagation of two waves in an elliptically curved focusing multilayer mirror is developed in this thesis. Using numerical integration, the layer shapes can be optimised for reflectivity and aberrations. Within this framework, performance of both existing and currently upgraded synchrotron beamlines is simulated. Using a more theoretical model case, limits of the theory are studied. A significant part of this work is dedicated to partial spatial coherence, modelled using the method of stochastic superpositions. Coherence propagation and filtering by x-ray waveguides is shown analytically and numerically. This comprehensive model is put forward that shall help in development and testing of new algorithms for a variety of imaging techniques using coherent x-ray beams. Advanced simulations accounting for real structure effects are compared to experimental data obtained at the GINIX instrument at the coherence beamline P10 at PETRA III, DESY. This thesis presents results of a collaboration between the Georg-August-Universität Göttingen and the European Synchrotron Radiation Facility (ESRF) Grenoble.

X Ray Standing Wave Technique The Principles And Applications

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Author : Jorg Zegenhagen
language : en
Publisher: World Scientific
Release Date : 2013-01-30

X Ray Standing Wave Technique The Principles And Applications written by Jorg Zegenhagen and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-01-30 with Science categories.

The X-ray standing wave (XSW) technique is an X-ray interferometric method combining diffraction with a multitude of spectroscopic techniques. It is extremely powerful for obtaining information about virtually all properties of surfaces and interfaces on the atomic scale. However, as with any other technique, it has strengths and limitations. The proper use and necessary understanding of this method requires knowledge in quite different fields of physics and technology. This volume presents comprehensively the theoretical background, technical requirements and distinguished experimental highlights of the technique. Containing contributions from the most prominent experts of the technique, such as Andre Authier, Boris Batterman, Michael J Bedzyk, Jene Golovchenko, Victor Kohn, Michail Kovalchuk, Gerhard Materlik and D Phil Woodruff, the book equips scientists with all the necessary information and knowledge to understand and use the XSW technique in practically all applications.

Inhomogeneous Optical Waveguides

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Author : A. Ghatak
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-03-09

Inhomogeneous Optical Waveguides written by A. Ghatak and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-03-09 with Science categories.

The propagation of electromagnetic waves in "square-law" media, i.e., media characterized by a quadratic spatial variation of the dielectric constant, has been a favorite subject of investigation in electromagnetic theory. However, with the recent fabrication of glass fibers with a quadratic radial variation of the dielectric constant and the application of such fibers to optical imaging and communications, this subject has also assumed practical importance. Comparison of experimental results on propagation, resolu tion, and pulse distortion in such inhomogeneous waveguides with theory has put the field on a sound base and spurred further work. The present book aims at presenting a unified view of important aspects of our knowledge of inhomogeneous optical waveguides. A brief discussion of homogeneous dielectric waveguides is unavoidable, since itforms a basis for the appreciation of inhomogeneous waveguides. A short course based on some chapters of this book was offered to graduate students at IIT Delhi and was well received. We consider that despite the unavoidable mathemati cal nature of the present book, the comparison of experimental results with theory throughout and the description of fabrication technology (Appen dixes A and B) should make its appeal universal. The authors are grateful to Dr. K. Thyagarajan for writing most of Chapter 9 and to their colleagues Dr. I. C. Goyal, Dr. B. P. Pal, and Dr. A.

Cone Beam X Ray Phase Contrast Tomography For The Observation Of Single Cells In Whole Organs

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Author : Martin Krenkel
language : en
Publisher: Göttingen University Press
Release Date : 2015

Cone Beam X Ray Phase Contrast Tomography For The Observation Of Single Cells In Whole Organs written by Martin Krenkel and has been published by Göttingen University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.

X-ray imaging enables the nondestructive investigation of interior structures in otherwise opaque samples. In particular the use of computed tomography (CT) allows for arbitrary virtual slices through the object and 3D information about intricate structures can be obtained. However, when it comes to image very small structures like single cells, the classical CT approach is limited by the weak absorption of soft-tissue. The use of phase information, encoded in measureable intensity images by free-space propagation of coherent x-rays, allows a huge increase in contrast, which enables 3D reconstructions at higher resolutions. In this work the application of propagation-based phase-contrast tomography to lung tissue samples is demonstrated in close to in vivo conditions. Reconstructions of the lung structure of whole mice at down to 5 μm resolution are obtained at a selfbuilt CT setup, which is based on a liquid-metal jet x-ray source. To reach even higher resolutions, synchrotron radiation in combination with suitable holographic phase-retrieval algorithms is employed. Due to optimized cone-beam geometry, field of view and resolution can be varied over a wide range of parameters, so that information on different length scales can be achieved, covering several millimeters field of view down to a 3D resolution of 50 nm. Thus, the sub-cellular 3D imaging of single cells embedded in large pieces of tissue is enabled, which paves the way for future biomedical research.