The Experts below are selected from a list of 70020 Experts worldwide ranked by ideXlab platform
Oscar Varela - One of the best experts on this subject based on the ideXlab platform.
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RHolography, black holes and Scherk-Schwarz
Journal of High Energy Physics, 2015Co-Authors: Nava Gaddam, Stefan Vandoren, Alessandra Gnecchi, Oscar VarelaAbstract:We present a construction of a class of near-extremal asymptotically flat black hole solutions in four (or five) dimensional gauged supergravity with R-symmetry gaugings obtained from Scherk-Schwarz reductions on a circle. The entropy of these black holes is counted holographically by the well known MSW (or D1/D5) system, with certain twisted boundary conditions labeled by a twist parameter rho. We find that the corresponding (0, 4) (or (4, 4)) superconformal algebras are exactly those studied by Schwimmer and Seiberg, using a twist on the outer automorphism group. The interplay between R-symmetries, rho-algebras and Holography leads us to name our construction "RHolography".
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RHolography, Black Holes and Scherk-Schwarz
arXiv: High Energy Physics - Theory, 2014Co-Authors: Nava Gaddam, Stefan Vandoren, Alessandra Gnecchi, Oscar VarelaAbstract:We present both the macroscopic and microscopic description of a class of near-extremal asymptotically flat black hole solutions in four (or five) dimensional gauged supergravity with R-symmetry gaugings obtained from Scherk-Schwarz reductions on a circle. The entropy of these black holes is counted holographically by the well known MSW (or D1/D5) system, with certain twisted boundary conditions labeled by a twist parameter \rho. We find that the corresponding (0,4) (or (4,4)) superconformal algebras are exactly those studied by Schwimmer and Seiberg, using a twist on the outer automorphism group. The interplay between R-symmetries, \rho-algebras and Holography leads us to name our construction "RHolography".
Takanori Nomura - One of the best experts on this subject based on the ideXlab platform.
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computer generated hologram based holographic data storage using common path off axis digital Holography
Optics Letters, 2020Co-Authors: Naru Yoneda, Yusuke Saita, Takanori NomuraAbstract:A reconstruction method for multilevel complex encoded data-pages is proposed to increase the recording density of computer-generated-hologram-based holographic data storage by using off-axis digital Holography. Although the detection process is based on off-axis digital Holography, the proposed method keeps the optical setup a simple and common-path configuration owing to the computer-generated Holography. Five-level complex encoded data-pages can be experimentally reconstructed.
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Single-exposure generalized phase-shifting digital Holography
2015 14th Workshop on Information Optics (WIO), 2015Co-Authors: Takanori Nomura, Masatoshi ImbeAbstract:As one of the wave-splitting phase-shifting digital Holography, single-exposure generalized phase-shifting digital Holography has been proposed. In the digital Holography, the phase-shift quantity, which corresponds to the difference between the phase quantities of the reference wave on the adjacent pixels, is not restricted but generalized. Owing to the generalized phase-shifting, a random-phase wave as the reference wave can be used. The proposed phase-shifting digital Holography enables us to record a fully-complex field of a dynamic phenomena without dc and conjugate terms using a commercially available optical devices. Constraints on the reference wave and the object wave suitable for the phase-shifting digital Holography are introduced. Experimental results are presented to confirm the constraints.
Etienne Snoeck - One of the best experts on this subject based on the ideXlab platform.
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Assessment of off-axis and in-line electron Holography for measurement of potential variations in Cu(In,Ga)Se2 thin-film solar cells
Advanced Structural and Chemical Imaging, 2016Co-Authors: Debora Keller, Patrick Reinhard, Fabian Pianezzi, Rolf Erni, Christophe Gatel, Marta D Rossell, Etienne Snoeck, Stephan Buecheler, Ayodhya N. TiwariAbstract:Electron Holography is employed to study variations of the electrostatic crystal potential in Cu(In,Ga)Se2 (CIGS) thin-film solar cells at different length scales: Long-range potential variations across the layer structure of the solar cell as well as inhomogeneities within the layers are analyzed by off-axis Holography. In-line Holography is applied to examine the local potential variation across a CIGS grain boundary. The phase reconstruction from a focal series is performed by a modified transport of intensity equation (TIE) which is optimized to reduce common artifacts. For comparison, three different microscopes of different optical configurations were used for in-line Holography. Based on the results, the impact of the used microscope as well as further acquisition parameters on the in-line Holography measurement is assessed. The measured potential variations are discussed considering the effect of different possible sources that may cause potential fluctuations. It is found that most of the variations are best explained by mean inner potential fluctuations rather than by inhomogeneities of the electronic properties. Finally, the present resolution limit of both methods is discussed regarding the feasibility of future electronic characterization of CIGS by Holography.
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Assessment of off-axis and in-line electron Holography for measurement of potential variations in Cu(In,Ga)Se_2 thin-film solar cells
Advanced Structural and Chemical Imaging, 2016Co-Authors: Debora Keller, Patrick Reinhard, Fabian Pianezzi, Rolf Erni, Christophe Gatel, Marta D Rossell, Etienne Snoeck, Stephan Buecheler, Ayodhya N. TiwariAbstract:Electron Holography is employed to study variations of the electrostatic crystal potential in Cu(In,Ga)Se_2 (CIGS) thin-film solar cells at different length scales: Long-range potential variations across the layer structure of the solar cell as well as inhomogeneities within the layers are analyzed by off-axis Holography. In-line Holography is applied to examine the local potential variation across a CIGS grain boundary. The phase reconstruction from a focal series is performed by a modified transport of intensity equation (TIE) which is optimized to reduce common artifacts. For comparison, three different microscopes of different optical configurations were used for in-line Holography. Based on the results, the impact of the used microscope as well as further acquisition parameters on the in-line Holography measurement is assessed. The measured potential variations are discussed considering the effect of different possible sources that may cause potential fluctuations. It is found that most of the variations are best explained by mean inner potential fluctuations rather than by inhomogeneities of the electronic properties. Finally, the present resolution limit of both methods is discussed regarding the feasibility of future electronic characterization of CIGS by Holography.
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Characterization of helium bubble size and faceting by electron Holography
Journal of Applied Physics, 2006Co-Authors: Etienne Snoeck, Jérôme Majimel, M. O. Ruault, Martin HÿtchAbstract:Iron-9% chromium alloy of controlled purity and microstructure was helium implanted and studied using transmission electron microscopy and electron Holography (EH). Fresnel imaging is compared with electron Holography for a set of identical helium bubbles of size 2–4 nm. Electron Holography reveals that the bubbles are, in fact, faceted and the lateral and projected dimensions of the cavities are measured. Current measurements allow the detection of 1 nm diameter bubbles using EH. The merits of conventional and holographic techniques are discussed and future improvements anticipated. Electron Holography seems to be the ideal technique for investigating the morphology of helium bubbles and cavities in general.
Ting-chung Poon - One of the best experts on this subject based on the ideXlab platform.
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review on the state of the art technologies for acquisition and display of digital holograms
IEEE Transactions on Industrial Informatics, 2016Co-Authors: P W M Tsang, Ting-chung PoonAbstract:Optical Holography for recording three-dimensional (3-D) scenes can be traced back to the early sixties. Since then, the art of Holography has been applied in many areas, primarily as a tool for 3-D imaging, processing, and display. Extension of optical Holography to other disciplines, such as optical computing and encryption, has been explored, but the scope of development is relatively limited. However, with the rapid advancements in electronics, computing, and material science technologies, most of the optical processes can be substituted with numerical or digital hardware means, thus leading to the emergence of digital Holography. A typical digital Holography framework can be encapsulated into three major stages, namely the input, processing, and output stages. The input and output stages are gatekeepers connecting the optical and digital worlds, without which the study on digital Holography could only be restricted to theoretical and numerical analysis. In the past few decades, numerous research works have been conducted on these two important areas. In this paper, we shall provide a review on the recent development in these two important areas of digital Holography. Selected pieces of important and popular works on the acquisition and display of digital holograms will be reported.
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Introduction to Modern Digital Holography: With Matlab
2014Co-Authors: Ting-chung Poon, Jung-ping LiuAbstract:1. Wave optics 2. Fundamentals of Holography 3. Types of holograms 4. Conventional digital Holography 5. Digital Holography: special techniques 6. Applications in digital Holography 7. Computer-generated Holography Index.
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optical scanning Holography with matlab
2010Co-Authors: Ting-chung PoonAbstract:Mathematical Background and Linear System.- Wave Optics and Holography.- Optical Scanning Holography: Principles.- Optical Scanning Holography: Applications.- Optical Scanning Holography: Advances.
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Digital Holography and Three-Dimensional Display - Digital Holography and Three-Dimensional Display
2006Co-Authors: Ting-chung PoonAbstract:Digital Holography.- Computer-Generated Holograms.- Digital Holography and Multi-Wavelength Interference Techniques.- Digital Holography for Bulk Image Acoustooptical Reconstruction.- Digital Holography Applied to Microscopy.- Phase-Shifting Digital Holography.- Controlling Image Recostruction Process in Digital Holography.- Tele-Metrology Based on Digital Holography.- Three-Dimensional Display Techniques.- Computer-Generated Holograms for White Light Reconstruction.- Wide-Angle Computer-Generated Holograms for 3-D Display.- Horizontal-Parallax-Only Optical Scanning Holography.- Three-Dimensional Projection Display System.- Three-Dimensional Display and Information Processing Based on Integral Imaging.- Autostereoscopic, Partial Pixel, Spatially Multiplexed, and other 3D Display Technologies.
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digital Holography and three dimensional display
dhtd, 2006Co-Authors: Ting-chung PoonAbstract:Digital Holography.- Computer-Generated Holograms.- Digital Holography and Multi-Wavelength Interference Techniques.- Digital Holography for Bulk Image Acoustooptical Reconstruction.- Digital Holography Applied to Microscopy.- Phase-Shifting Digital Holography.- Controlling Image Recostruction Process in Digital Holography.- Tele-Metrology Based on Digital Holography.- Three-Dimensional Display Techniques.- Computer-Generated Holograms for White Light Reconstruction.- Wide-Angle Computer-Generated Holograms for 3-D Display.- Horizontal-Parallax-Only Optical Scanning Holography.- Three-Dimensional Projection Display System.- Three-Dimensional Display and Information Processing Based on Integral Imaging.- Autostereoscopic, Partial Pixel, Spatially Multiplexed, and other 3D Display Technologies.
Nava Gaddam - One of the best experts on this subject based on the ideXlab platform.
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RHolography, black holes and Scherk-Schwarz
Journal of High Energy Physics, 2015Co-Authors: Nava Gaddam, Stefan Vandoren, Alessandra Gnecchi, Oscar VarelaAbstract:We present a construction of a class of near-extremal asymptotically flat black hole solutions in four (or five) dimensional gauged supergravity with R-symmetry gaugings obtained from Scherk-Schwarz reductions on a circle. The entropy of these black holes is counted holographically by the well known MSW (or D1/D5) system, with certain twisted boundary conditions labeled by a twist parameter rho. We find that the corresponding (0, 4) (or (4, 4)) superconformal algebras are exactly those studied by Schwimmer and Seiberg, using a twist on the outer automorphism group. The interplay between R-symmetries, rho-algebras and Holography leads us to name our construction "RHolography".
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RHolography, Black Holes and Scherk-Schwarz
arXiv: High Energy Physics - Theory, 2014Co-Authors: Nava Gaddam, Stefan Vandoren, Alessandra Gnecchi, Oscar VarelaAbstract:We present both the macroscopic and microscopic description of a class of near-extremal asymptotically flat black hole solutions in four (or five) dimensional gauged supergravity with R-symmetry gaugings obtained from Scherk-Schwarz reductions on a circle. The entropy of these black holes is counted holographically by the well known MSW (or D1/D5) system, with certain twisted boundary conditions labeled by a twist parameter \rho. We find that the corresponding (0,4) (or (4,4)) superconformal algebras are exactly those studied by Schwimmer and Seiberg, using a twist on the outer automorphism group. The interplay between R-symmetries, \rho-algebras and Holography leads us to name our construction "RHolography".
