Lensless Fourier Transform Holography With Soft X Rays Reference Sources And Simulation
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Lensless Fourier Transform Holography With Soft X Rays Reference Sources And Simulation
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Author : Scott Miller
language : en
Publisher:
Release Date : 2000
Lensless Fourier Transform Holography With Soft X Rays Reference Sources And Simulation written by Scott Miller and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Fourier transform optics categories.
Lensless Fourier Transform Holography With Soft X Rays
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Author : William F. Schlotter
language : en
Publisher:
Release Date : 2007
Lensless Fourier Transform Holography With Soft X Rays written by William F. Schlotter and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
Holography For The New Millennium
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Author : Jacques Ludman
language : en
Publisher: Springer Science & Business Media
Release Date : 2006-04-28
Holography For The New Millennium written by Jacques Ludman 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 2006-04-28 with Science categories.
A half century after its invention, and after several waves of optimism and pessimism, holography is now poised to achieve widespread application. Holograms are now being used as tools in many industries, from heads-up displays in aircraft to directing interconnections in massively parallel computing. Acoustic holograms can provide three-dimensional images of internal organs without surgery or dangerous radiation, and holography forms the basis of several other forms of nondestructive testing. This book provides both a review of the development of the field and of the applications likely to be important in the 21st century. It begins with a review by Dennis Leith, one of the inventors of holography - or re-inventors, after Denis Gabor's original work in 1947. Two chapters discuss the frontiers of holographic imaging, including color holograms and stereographic movies. Several subsequent chapters describe novel methods of forming and viewing holographic images, including the use of low-coherence sources or even computers to generate the holograms. The book concludes with a sampling of new applications of holography, including its uses in improving the efficiency of solar cells, in nondestructive testing, in improving the coherence properties of light, in data storage, and in investigations of fundamental physics.
Lensless Holography Methods For Soft X Ray Resonant Coherent Imaging
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Author : Diling Zhu
language : en
Publisher: Stanford University
Release Date : 2010
Lensless Holography Methods For Soft X Ray Resonant Coherent Imaging written by Diling Zhu and has been published by Stanford University this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
The ability to interpret and inverse x-ray diffraction patterns from crystals has largely shaped our understanding of the structure of matter. However, structure determination of noncrystalline objects from their diffraction patterns is a much more difficult task. The dramatic increase in available coherent x-ray photon flux over the past decade has made possible a technique known as lensless coherent diffractive imaging (CDI), that addresses exactly this problem. The central question around CDI is the so-called phase problem: upon detection of the diffraction intensity, the phase information of the diffracted wave is inevitably lost. Generally, the phase problem is approached using iterative phase retrieval algorithms. Holographic methods, through interference with reference diffractions, encode the phase information directly inside the measured x-ray holograms, and are therefore able to avoid the stagnation and uniqueness problems commonly encountered by the iterative algorithms. This dissertation discusses two novel holographic methods for coherent lensless imaging using resonant soft x-rays. The first part focuses on generalizing the multiple-wavelength anomalous diffraction technique, a highly successful method for solving the crystal structures of biomacromolecules, into a multiple-wavelength holography technique for nanoscale resonant x-ray imaging. Using this method I show element specific reconstructions of nanoparticles and magnetization distribution in magnetic thin films with sub 50 nm resolution. The second part discusses progress in X-ray Fourier holography, an ultrafast lensless imaging platform that can be used with the upcoming x-ray free electron lasers. In particular, I will present experiments using two novel types of extended reference structures that bring the resolution beyond the precision of reference fabrication, previously regarded as the resolution limit for x-ray Fourier transform holography. Finally, future applications of holographic methods, especially experimental considerations for time-resolved studies of nanostructures using X-FELs, will be discussed.
Lasers And Masers
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Author :
language : en
Publisher:
Release Date : 1974
Lasers And Masers written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Lasers categories.
References and abstracts to international literature (mostly journal articles). Classified arrangement. Subject, author, and source indexes. Ser. 1, 1974: 8256 references.
Physics Briefs
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Author :
language : en
Publisher:
Release Date : 1979
Physics Briefs written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1979 with Physics categories.
Methods For Coherent Lensless Imaging And X Ray Wavefront Measurement
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Author : Manuel Guizar-Sicairos
language : en
Publisher:
Release Date : 2010
Methods For Coherent Lensless Imaging And X Ray Wavefront Measurement written by Manuel Guizar-Sicairos and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
"Advancement and research on phase retrieval techniques are in large part motivated by their application in high resolution lensless laser imaging and x- ray diffractive imaging. In the former a high resolution image can be obtained from measuring the intensity pattern of the propagated field without the use of any imaging optics, thus providing an imaging system that does not increase its thickness along the optical axis as the aperture diameter is increased. For x- ray coherent diffractive imaging, on the other hand, high-resolution conventional imaging is difficult to achieve at these wavelengths because of the difficulty of manufacturing and aligning x-ray focusing elements with sufficient numerical aperture and precision. Thus, in order to achieve resolutions on the order of a nanometer, a coherent x-ray beam is used to illuminate the object of interest and the object is reconstructed from a measurement of its far-field diffraction intensity without any imaging optics. Thus the advancement and application of lensless imaging techniques has become an increasingly important topic of research. X-ray diffractive imaging is set apart from other high-resolution imaging techniques (e.g. scanning electron or atomic force microscopy) for its high penetration depth, which enables tomographic 3D imaging of thick samples and buried structures. Furthermore, using short x-ray pulses, it enables the capability to take ultrafast snapshots, giving a unique opportunity to probe nanoscale dynamics at femtosecond time scales. In this thesis we present improvements to phase retrieval algorithms, assess their performance through numerical simulations, and develop new methods for both imaging and wavefront measurement. Using numerical simulations we identified and explained the origin of the twin-image problem in iterative transform phase retrieval with a centrosymmetric support constraint. We proposed and numerically demonstrated the effectiveness of a modified phase retrieval algorithm that uses Fourier weighted projections to increase the quality and resolution of the reconstructions by mitigating a problem arising from the finite measurement window and finite support constraint. Such an approach is particularly useful when the object presents large phase variations on a length- scale significantly smaller than the resolution, i.e. reconstruction of fully developed speckled images. In order to accurately and efficiently assess phase retrieval algorithm performance, we have developed algorithms for subpixel image registration. Despite being particularly well suited for comparing images from data collected in the Fourier domain (e.g., phase retrieval and holography), these algorithms have al- ready shown a substantial success in other applications as well. Building on the original work by Faulkner and Rodenburg, we developed an improved reconstruction algorithm for phase retrieval with transverse translations of the object relative to the illumination beam. Based on gradient-based non- linear optimization, this algorithm is capable of estimating the object, and at the same time refining the initial knowledge of the incident illumination and the object translations. The advantages of this algorithm over the original iterative transform approach are shown through numerical simulations. Phase retrieval has already shown substantial success in wavefront sensing at optical wavelengths. Although in principle the algorithms can be used at any wavelength, in practice the focus-diversity mechanism that makes optical phase retrieval robust is not practical to implement for x-rays. In this thesis we also describe the novel application of phase retrieval with transverse translations to the problem of x-ray wavefront sensing. This approach allows the characterization of the complex-valued x-ray field in-situ and at-wavelength and has several practical and algorithmic advantages over conventional focused beam measurement techniques. A few of these advantages include improved robustness through diverse measurements, reconstruction from far-field intensity measurements only, and significant relaxation of experimental requirements over other beam characterization approaches. Furthermore, we show that a one-dimensional version of this technique can be used to characterize an x-ray line focus produced by a cylindrical focusing element. We provide experimental demonstrations of the latter at hard x-ray wavelengths, where we have characterized the beams focused by a kinoform lens and an elliptical mirror. In both experiments the reconstructions exhibited good agreement with independent measurements, and in the latter a small mirror misalignment was inferred from the phase retrieval reconstruction. These experiments pave the way for the application of robust phase retrieval algorithms for in-situ alignment and performance characterization of x-ray optics for nanofocusing. We also present a study on how transverse translations help with the well-known uniqueness problem of one-dimensional phase retrieval. We also present a novel method for x-ray holography that is capable of reconstructing an image using an off-axis extended reference in a non-iterative computation, greatly generalizing an earlier approach by Podorov et.al. The approach, based on the numerical application of derivatives on the field autocorrelation, was developed from first mathematical principles. We conducted a thorough theoret- ical study to develop technical and intuitive understanding of this technique and derived sufficient separation conditions required for an artifact-free reconstruction. We studied the effects of missing information in the Fourier domain, and of an im- perfect reference, and we provide a signal-to-noise ratio comparison with the more traditional approach of Fourier transform holography. We demonstrated this new holographic approach through proof-of-principle optical experiments and later ex- perimentally at soft x-ray wavelengths, where we compared its performance to Fourier transform holography, iterative phase retrieval and state-of-the-art zone-plate x-ray imaging techniques (scanning and full-field). Finally, we present a demonstration of the technique using a single 20 fs pulse from a high-harmonic table-top source. Holography with an extended reference is shown to provide fast, good quality images that are robust to noise and artifacts that arise from missing information due to a beam stop."--Leaves viii-xi.
Multiple And Extended References In Fourier Transform Holography
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Author : René Könnecke
language : de
Publisher: Sudwestdeutscher Verlag Fur Hochschulschriften AG
Release Date : 2011-01
Multiple And Extended References In Fourier Transform Holography written by René Könnecke and has been published by Sudwestdeutscher Verlag Fur Hochschulschriften AG this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-01 with Fourier transformations categories.
The Fourier Transform Holography (FTH) in the range of soft X- rays is a fast growing research field supported by the development of Free Electron Lasers (FEL). In the conventional FTH with only one pinhole as reference, the signal intensity is very weak when it comes to measurements on a very short time scale. Fortunately, the high transverse coherence of the FEL- beam enables the creation of expanded reference structures leading to a high signal intensity in a short exposure time. In this thesis two expanded reference structures are investigated, the multiple and the extended reference structure. The former reference structure is a combination of many separate pinholes, whereas the latter one can have any shape in combination with at least one corner. As a representative for the multiple reference structure the Uniformly Redundant Array and for the extended reference structure the HERALDO-Pattern, standing for Fourier Transform Holography with Extended Reference by Autocorrelation Linear Differential Operation, are introduced. Both reference patterns are promising candidates for future soft X-ray FTH-experiments, especially for femtosecond time resolved imaging.
Image Deblurring Using Lensless Fourier Transform Holography
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Author : Gregory P. McCoy
language : en
Publisher:
Release Date : 1980
Image Deblurring Using Lensless Fourier Transform Holography written by Gregory P. McCoy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1980 with Fourier transformations categories.
"Using lensless Fourier transform holography the problem of deblurring an out-of-focus image on a photographic transparency was studied. First a lensless Fourier transform hologram of an out-of-focus image was taken using a point reference source. By replacing this hologram into the recording plane and re-illuminating it with coherent light, the imaging wave transmitted through the hologram immediately gives, by Fourier transformation, the restored, deblurred image. A bar target was photographed out-of-focus, and using this method, with subjective analysis at 95% confidence, the deblurred image was judged better than the original. This method of image deblurring does indeed work, but the restoration process is limited by the amount the transparency was out-of-focus to begin with."--Abstract.
Curiosity Oriented Research
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Author : R. D. Medford
language : en
Publisher:
Release Date : 1974
Curiosity Oriented Research written by R. D. Medford and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Holography categories.