Optimization Of Waveguide Optics For Lensless X Ray Imaging
DOWNLOAD
Download Optimization Of Waveguide Optics For Lensless X Ray Imaging PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Optimization Of Waveguide Optics For Lensless X Ray Imaging book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Optimization Of Waveguide Optics For Lensless X Ray Imaging
DOWNLOAD
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.
X Ray Waveguide Optics
DOWNLOAD
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.
A Dedicated Endstation For Waveguide Based X Ray Imaging
DOWNLOAD
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.
Advanced X Ray Multilayer Waveguide Optics
DOWNLOAD
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.
Cone Beam X Ray Phase Contrast Tomography Of Biological Samples
DOWNLOAD
Author : Matthias Bartels
language : en
Publisher: Universitätsverlag Göttingen
Release Date : 2013
Cone Beam X Ray Phase Contrast Tomography Of Biological Samples written by Matthias Bartels 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.
Three-dimensional information of entire objects can be obtained by the remarkable technique of computed tomography (CT). In combination with phase sensitive X-ray imaging high contrast for soft tissue structures can be achieved as opposed to CT based on classical radiography. In this work biological samples ranging from micrometer sized single cells over multi-cellular nerve tissue to entire millimeter sized organs are investigated by use of cone-beam propagationbased X-ray phase contrast. Optimization with respect to contrast, resolution and field of view is achieved by addressing instrumentation, sample preparation and phase reconstruction techniques. By using laboratory sources functional soft tissue within the bony capsule of mouse cochleae is visualized in 3D with unprecedented image quality. At synchrotron storage rings the technique reveals more than 1000 axons running in parallel within a mouse nerve and enables doseefficient three-dimensional cellular imaging as well as two-dimensional imaging at high resolutions below 50 nm.
Biomedical Imaging
DOWNLOAD
Author : Tim Salditt
language : en
Publisher: Walter de Gruyter GmbH & Co KG
Release Date : 2017-10-23
Biomedical Imaging written by Tim Salditt and has been published by Walter de Gruyter GmbH & Co KG this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-10-23 with Science categories.
Covering both physical as well as mathematical and algorithmic foundations, this graduate textbook provides the reader with an introduction into modern biomedical imaging and image processing and reconstruction. These techniques are not only based on advanced instrumentation for image acquisition, but equally on new developments in image processing and reconstruction to extract relevant information from recorded data. To this end, the present book offers a quantitative treatise of radiography, computed tomography, and medical physics. Contents Introduction Digital image processing Essentials of medical x-ray physics Tomography Radiobiology, radiotherapy, and radiation protection Phase contrast radiography Object reconstruction under nonideal conditions
Coherent X Ray Diffractive Imaging On The Single Cell Level Of Microbial Samples
DOWNLOAD
Author : Robin Niklas Wilke
language : en
Publisher: Göttingen University Press
Release Date : 2015
Coherent X Ray Diffractive Imaging On The Single Cell Level Of Microbial Samples written by Robin Niklas Wilke 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.
Since its first experimental demonstration in 1999, Coherent X-Ray Diffractive Imaging has become one of the most promising high resolution X-Ray imaging techniques using coherent radiation produced by brilliant synchrotron storage rings. The ability to directly invert diffraction data with the help of advanced algorithms has paved the way for microscopic investigations and wave-field analyses on the spatial scale of nanometres without the need for inefficient imaging lenses. X-Ray phase contrast which is a measure of the electron density is an important contrast mode of soft biological specimens. For the case of many dominant elements of soft biological matter, the electron density can be converted into an effective mass density offering a unique quantitative information channel which may shed light on important questions such as DNA compaction in the bacterial nucleoid through ‚weighing with light‘. In this work X-Ray phase contrast maps have been obtained from different biological samples by exploring different methods. In particular, the techniques Ptychography and Waveguide-Holographic-Imaging have been used to obtain twodimensional and three-dimensional mass density maps on the single-cell-level of freeze-dried cells of the bacteria Deinococcus radiodurans, Bacillus subtilis and Bacillus thuringiensis allowing, for instance, to estimate the dry weight of the bacterial genome in a near native state. On top of this, reciprocal space information from coherent small angle X-Ray scattering (cellular Nano-Diffraction) of the fine structure of the bacterial cells has been recorded in a synergistic manner and has been analysed down to a resolution of about 2.3/nm exceeding current limits of direct imaging approaches. Furthermore, the dynamic range of present detector technology being one of the major limiting factors of ptychographic phasing of farfield diffraction data has been significantly increased. Overcoming this problem for the case of the very intense X-Ray beam produced by Kirkpatrick-Baez mirrors has been explored by using semi-transparent central stops.
3d Virtual Histology Of Neuronal Tissue By Propagation Based X Ray Phase Contrast Tomography
DOWNLOAD
Author : Mareike Töpperwien
language : en
Publisher: Göttingen University Press
Release Date : 2018
3d Virtual Histology Of Neuronal Tissue By Propagation Based X Ray Phase Contrast Tomography written by Mareike Töpperwien 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 2018 with categories.
Deciphering the three-dimensional (3d) cytoarchitecture of neuronal tissue is an important step towards understanding the connection between tissue function and structure and determining relevant changes in neurodegenerative diseases. The gold standard in pathology is histology, in which the tissue is examined under a light microscope after serial sectioning and subsequent staining. It is an invasive and labor-intensive technique which is prone to artifacts due to the slicing procedure. While it provides excellent results on the 2d slices, the 3d anatomy can only be determined after aligning the individual sections, leading to a non-isotropic resolution within the tissue. X-ray computed tomography (CT) offers a promising alternative due to its potential resolution and large penetration depth which allows for non-invasive imaging of the sample's 3d density distribution. In classical CT, contrast formation is based on absorption of the x-rays as they pass through the sample. However, weakly absorbing samples like soft tissue from the central nervous system give nearly no contrast. By exploiting the much stronger phase shifts for contrast formation, which the sample induces in a (partially) coherent wavefront, it can be substantially increased. During free-space propagation behind the sample, these phase shifts are converted to a measurable intensity image by interference of the disturbed wave fronts. In this thesis, 3d virtual histology is performed by means of propagation-based x-ray phase-contrast tomography on tissue from the central nervous system of humans and mice. A combination of synchrotron-based and laboratory setups is used to visualize the 3d density distribution on varying lengths scales from the whole organ down to single cells. By comparing and optimizing different preparation techniques and phase-retrieval approaches, even sub-cellular resolution can be reached in mm-sized tissue blocks. The development of an automatic cell segmentation workflow provides access to the 3d cellular distribution within the tissue, enabling the quantification of the cellular arrangement and allowing for extensive statistical analysis based on several thousands to millions of cells. This paves the way for biomedical studies aimed at changes in cellular distribution, e.g., in the course of neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease or ischemic stroke.
Cone Beam X Ray Phase Contrast Tomography For The Observation Of Single Cells In Whole Organs
DOWNLOAD
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.
X Ray Waveguides And Waveguide Based Lensless Imaging
DOWNLOAD
Author : Christian Fuhse
language : en
Publisher:
Release Date : 2006
X Ray Waveguides And Waveguide Based Lensless Imaging written by Christian Fuhse and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.