Download or read book Lensless Imaging with High harmonic Sources written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coherent diffractive imaging (CDI) is a family of computational imaging techniques that uses iterative reconstruction algorithms to decipher the information encoded in one or more interference patterns to reconstruct an image of an object located in another propagation plane. The lensless nature of these techniques makes them well-suited for imaging with coherent extreme ultraviolet (EUV) or x-ray illumination as refractive optics are limited at these wavelengths. In particular, this work investigates the use of CDI techniques in combination with high-harmonic generation. High-harmonic generation~(HHG) sources can generate EUV illumination beams with a high degree of spatial coherence in a compact tabletop setup. In this work we use Fourier-Transform spectroscopy~(FTS) to separate sets of nearly monochromatic diffraction patterns from a broadband HHG diffraction pattern. These monochromatic diffraction patterns can used to reconstruct spectrally resolved images through reconstruction methods that are similar to those applied in conventional CDI. In Chapter 4 we describe how we use a common path interferometer and a noncollinear chirped pulse amplifier system to generate phase locked 25 fs pulse pairs with a central wavelength of approximately 800 nm and a combined pulse energy of 10 mJ. These infrared driving laser pulses are focused at slightly separated locations in a noble gas jet to upconvert them into a pair of almost identical high-harmonic pulses. In FTS-based imaging experiments, we illuminate a sample with the HHG pulse pairs and record the far-field diffraction pattern as a function of pulse-to-pulse time delay. The spatial separation of our two harmonic beams results in spatial interference between two laterally sheared copies of the diffraction pattern. As a consequence of the geometry, the spectrally separated diffraction patterns obtained in these measurements are similar, but not identical to the standard CDI case. In this work, we demonstrated an algorithm, called diffractive shear interferometry (DSI), to reconstruct images from such diffraction patterns. Using this algorithm, the information present in these diffraction patterns is used to reconstruct complex images of the sample. The reverse problem is either constrained by combining an diffraction pattern with a finite object support prior in Chapter 5 or with other diffraction patterns with a different relative orientation between the shear and the object. One of the advantages of coherent diffractive imaging techniques is that it they reconstruct the full complex electric field at the sample. In reflection mode, such phase difference can be easily attributed to height differences of the reflecting surface. However, most research in diffractive imaging has focused on transmission mode imaging. At the EUV wavelengths generated by HHG sources normal incidence reflection coefficients are vanishingly small. However towards grazing incidence the reflection coefficients approach one. Such a geometry does come at a cost of added experimental and computational complexity. While far-field diffraction between colinear planes can be described by a straight forward Fourier transform of the electric field, for the propagation between non-collinear planes, an additional non-linear coordinate transformation is required. This coordinate transformation depends on the tilt angle of the fields and becomes very sensitive to the exact tilt-angle towards grazing incidence. While CDI itself requires accurate knowledge of the wave propagation, a technique known as ptychography offers more flexibility, as it is often possible to solve for more variables than just the object field. In Chapter 7 we use that property to demonstrate an auto-calibration algorithm that can iteratively calibrate the tilt-angle during a ptychographic reconstruction. Using this approach we were able to refine the tilt angle close to the correct value even when the initial estimates were off by more than 5 degrees, greatly improving flexibility in reflection-mode lensless imaging.

Download or read book High Performance Nanoscale Lensless Imaging with Table top High Harmonic Sources written by Jan Rothhardt and published by . This book was released on 2021* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Single Shot Lensless Imaging with Coherence and Wavefront Characterization of Harmonic and FEL Sources written by Aura Inés Gonzalez Angarita and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lensless imaging techniques have broadened imaging applications to coherent sources in the short wavelength XUV domain, where optical systems to create an image are still not readily available. Furthermore, high harmonic generation sources (HHG) and free electron lasers (FEL) have the advantage of providing short temporal resolutions (atto 10-18s - femto 10-15s), opening the way towards ultrafast time resolved nanoscale imaging. Single shot imaging techniques are then highly important to exploit the shortest temporal resolution that can be reached with XUV sources. Lensless imaging is based on the direct measurement of the electric field diffracted by the sample. The diffraction pattern depends on the object transmittance but also on the source spatial coherence and wavefront. Single shot characterization of those properties thus leads to an improvement of the resolution of the object reconstruction.The results presented in this thesis are divided in two parts; the first one is focused on the characterization of the sources and the second on the development of new multidimensional imaging techniques. We will present different applications of single shot wavefront sensing of XUV sources. The results presented are the product of different experimental campaigns performed during this thesis using HH sources and FEL facilities at LCLS (Stanford) and FERMI (Trieste). Furthermore, a new method for single shot characterization of the spatial coherence that does not require the simultaneous measurement of the intensity distribution is presented. Additionally, we present a new holographic technique to improve the resolution of the object reconstruction when a partially coherent source is used.The second part is dedicated to two new multidimensional imaging techniques developed during the thesis. A new tri-dimensional imaging technique that is single shot, easy to implement and that lowers drastically the X-ray dose received by the sample, is presented. Different experimental setups for the generation of two synchronized XUV sources suitable for this ultrafast single shot 3D stereo imaging technique are presented. In addition, we present a holographic technique to extend imaging using a broadband source towards spectrally resolved single shot imaging and attosecond applications. Finally, we present the general conclusions from the work done during the thesis, together with the perspectives drawn from this work.

Download or read book Nanoscale Waveguiding Studied by Lensless Coherent Diffractive Imaging Using EUV High Harmonic Generation Source written by Sergey Zayko and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The challenge of nanometric imaging drives intense efforts in applied sciences and fundamental research. Following the physical law of diffraction, the utilization of extreme ultraviolet (EUV) or X-ray radiation for imaging extends the ultimate resolution limit given by the illumination wavelength down to nanoscale dimensions. However, despite the great potential, the resolution is governed by imperfections inherent to optical elements employed. In this cumulative thesis, a table-top source of EUV radiation based on high harmonic generation (HHG), is developed and applied for lensless coher...

Download or read book Structural Dynamics with X ray and Electron Scattering written by Kasra Amini and published by Royal Society of Chemistry. This book was released on 2023-12-20 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Supercontinuum Laser Source written by Robert R. Alfano and published by Springer Nature. This book was released on 2023-01-01 with total page 646 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, now in its fourth edition, is a well-known classic on the ultrafast nonlinear and linear processes responsible for supercontinuum generation. The book begins with chapters reviewing the experimental and theoretical understanding of the field along with key applications developed since the discovery of the supercontinuum effect. The chapters that follow cover recent research activity on supercontinuum phenomena, novel applications, and advances achieved since the publication of the previous edition. The new chapters focus on: filamentation in gases, air, and condensed media; conical emission by four-wave mixing and X-waves; electronic self-phase mechanism; higher harmonics generation; attosecond laser pulses; complex vector beam supercontinuum; higher order self-phase modulation and cross-phase modulation; nonlinear supercontinuum interference in uniaxial crystals; new nonlinear microscopes involving supercontinuum and ultrafast lasers with biomedical applications; and other current supercontinuum applications in communications. The Supercontinuum Laser Source is a definitive work by one of the discoverers of the white light effect. It is indispensable reading for any researcher or student working in the field of ultrafast laser physics. Chapter 6 is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.

Download or read book Short Wavelength Laboratory Sources written by Davide Bleiner and published by Royal Society of Chemistry. This book was released on 2014-12-04 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our ability to manipulate short wavelength radiation (0.01-100nm, equivalent to 120keV-12eV) has increased significantly over the last three decades. This has lead to major advances in applications in a wide range of disciplines such as: the life and medical sciences, including cancer-related studies; environmental science, including studies of pollution and its effects; archaeology and other cultural heritage disciplines; and materials science. Although expansion in application areas is due largely to modern synchrotron sources, many applications will not become widespread, and therefore routinely available as analytical tools, if they are confined to synchrotrons. There is a need to develop bright but small and low cost X-ray sources, not to replace synchrotrons but to complement them and this book will look at how to facilitate these developments. Written by a distinguished team of international authors, this book is based on the COST Action MP0601: Short Wavelength Laboratory Sources. The contents are divided into five main sections. the introductory section provides a comprehensive introduction to the fundamentals of radiation, generation mechanisms and short wavelength laboratory sources. The middle sections focus on modelling and simulation, source development: improvement and characterisation and integrated systems: sources, optics and detectors. The final section looks at recent applications. Aimed at academic and industrial researchers in physical chemistry and chemical physics, the contents provides practical information about the implementation of short wavelength laboratory sources and their applications.

Download or read book Nanoscale Photonic Imaging written by Tim Salditt and published by Springer Nature. This book was released on 2020-06-09 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Lensless Holography Methods for Soft X ray Resonant Coherent Imaging written by Diling Zhu and published by Stanford University. This book was released on 2010 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Ultrafast Phenomena XVI written by Paul Corkum and published by Springer Science & Business Media. This book was released on 2010-03-23 with total page 1031 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrafast Phenomena XVI presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh speed communications. This book summarizes the results presented at the 16th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.

Download or read book High Resolution Extreme Ultraviolet Microscopy written by Michael Werner Zürch and published by Springer. This book was released on 2014-11-07 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes novel approaches and implementation of high-resolution microscopy in the extreme ultraviolet light regime. Using coherent ultrafast laser-generated short wavelength radiation for illuminating samples allows imaging beyond the resolution of visible-light microscopes. Michael Zürch gives a comprehensive overview of the fundamentals and techniques involved, starting from the laser-based frequency conversion scheme and its technical implementation as well as general considerations of diffraction-based imaging at nanoscopic spatial resolution. Experiments on digital in-line holography and coherent diffraction imaging of artificial and biologic specimens are demonstrated and discussed in this book. In the field of biologic imaging, a novel award-winning cell classification scheme and its first experimental application for identifying breast cancer cells are introduced. Finally, this book presents a newly developed technique of generating structured illumination by means of so-called optical vortex beams in the extreme ultraviolet regime and proposes its general usability for super-resolution imaging.

Download or read book XUV Lensless Imaging with Spatially Shaped High harmonic Beams written by Daniel Treacher and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book X Ray Lasers 2008 written by Ciaran Lewis and published by Springer Science & Business Media. This book was released on 2009-09-29 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 11th International Conference on X-Ray Lasers had contributions in the following topical areas: Transient Collisional X-Ray Lasers, Table-Top High Repetition Rate X-Ray Lasers, Optical-Field Ionised (OFI) X-Ray Lasers, Theory and Simulation of X-Ray Lasers, High Order Harmonic Generation, XUV Optics and X-Ray Laser Applications, Capillary Discharge X-Ray Lasers, Alternative Sources of coherent XUV Radiation. The proceedings of this conference constitute a comprehensive source of reference for scientists involved in researching the development and application of coherent X-Ray sources.

Download or read book Optimization of Waveguide Optics for Lensless X ray Imaging written by Sven Philip Krüger and published by Universitätsverlag Göttingen. This book was released on 2011 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Methods for Coherent Lensless Imaging and X ray Wavefront Measurement written by Manuel Guizar-Sicairos and published by . This book was released on 2010 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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.

Download or read book Ultrafast Nonlinear Optics written by Robert Thomson and published by Springer Science & Business Media. This book was released on 2013-03-20 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of ultrafast nonlinear optics is broad and multidisciplinary, and encompasses areas concerned with both the generation and measurement of ultrashort pulses of light, as well as those concerned with the applications of such pulses. Ultrashort pulses are extreme events – both in terms of their durations, and also the high peak powers which their short durations can facilitate. These extreme properties make them powerful experiment tools. On one hand, their ultrashort durations facilitate the probing and manipulation of matter on incredibly short timescales. On the other, their ultrashort durations can facilitate high peak powers which can drive highly nonlinear light-matter interaction processes. Ultrafast Nonlinear Optics covers a complete range of topics, both applied and fundamental in nature, within the area of ultrafast nonlinear optics. Chapters 1 to 4 are concerned with the generation and measurement of ultrashort pulses. Chapters 5 to 7 are concerned with fundamental applications of ultrashort pulses in metrology and quantum control. Chapters 8 and 9 are concerned with ultrafast nonlinear optics in optical fibres. Chapters 10 to 13 are concerned with the applications of ultrashort pulses in areas such as particle acceleration, microscopy, and micromachining. The chapters are aimed at graduate-student level and are intended to provide the student with an accessible, self-contained and comprehensive gateway into each subject.

Download or read book Molecules in Superfluid Helium Nanodroplets written by Alkwin Slenczka and published by Springer Nature. This book was released on 2022-05-28 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book covers recent advances in experiments using the ultra-cold, very weakly perturbing superfluid environment provided by helium nanodroplets for high resolution spectroscopic, structural and dynamic studies of molecules and synthetic clusters. The recent infra-red, UV-Vis studies of radicals, molecules, clusters, ions and biomolecules, as well as laser dynamical and laser orientational studies, are reviewed. The Coulomb explosion studies of the uniquely quantum structures of small helium clusters, X-ray imaging of large droplets and electron diffraction of embedded molecules are also described. Particular emphasis is given to the synthesis and detection of new species by mass spectrometry and deposition electron microscopy.