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C E Tommy Thomas, T M Biewer, L R Baylor, S K Combs, S J Meitner, J Rapp, D L Hillis, E M Granstedt, R Majeski, R Kaita
A project has been started at ORNL to develop a dual-wavelength digital holography system for plasma facing component erosion measurements on prototype material plasma exposure experiment. Such a system will allow in situ real-time measurements of component erosion. Initially the system will be developed with one laser, and first experimental laboratory measurements will be made with the single laser system. In the second year of development, a second CO2 laser will be added and measurements with the dual wavelength system will begin...
November 2016: Review of Scientific Instruments
Rajib Ahmed, Ali K Yetisen, Anthony El Khoury, Haider Butt
Advances in holography have led to applications including data storage, displays, security labels, and colorimetric sensors. However, existing top-down approaches for the fabrication of holographic devices are complex, expensive, and expertise dependent, limiting their use in practical applications. Here, ink-based holographic devices have been created for a wide range of applications in diffraction optics. A single pulse of a 3.5 ns Nd:YAG laser allowed selective ablation of ink to nanofabricate planar optical devices...
December 1, 2016: Nanoscale
Masahiro Yamaguchi
A perfect three-dimensional (3D) display that satisfies all depth cues in human vision is possible if a light field can be reproduced exactly as it appeared when it emerged from a real object. The light field can be generated based on either light ray or wavefront reconstruction, with the latter known as holography. This paper first provides an overview of the advances of ray-based and wavefront-based 3D display technologies, including integral photography and holography, and the integration of those technologies with digital information systems...
December 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
L T Bang, H Y Wu, Y Zhao, E G Kim, N Kim
Multilayer images of living cells are typically obtained using confocal or multiphoton microscopy. However, limitations on the distance between consecutive scan layers hinder high-resolution three-dimensional reconstruction, and scattering strongly degrades images of living cell components. Consequently, when overlapping information from different layers is focused on a specific point in the camera, this causes uncertainty in the depiction of the cell components. We propose a method that combines the Fresnel incoherent correlation holography and a depth-of-focus reduction algorithm to enhance the depth information of three-dimensional cell images...
December 1, 2016: Journal of Microscopy
Christina Hesseling, Tim Homeyer, Joachim Peinke, Gerd Gülker
The intensity and phase reconstructed from digital in-line holograms by the convolution approach are analyzed. Distortions of particle images depending on their position in the plane transverse to the optical axis are identified. For this purpose, the object fields of numerically simulated particle holograms as well as of experimental data are reconstructed. The results of three-dimensional correlations of numerical and experimental data are superior when the numerically generated reference volumes are adapted to the transverse locations of the particle...
November 20, 2016: Applied Optics
Mikael Brudfors, Verónica García-Vázquez, Begoña Sesé-Lucio, Eugenio Marinetto, Manuel Desco, Javier Pascau
BACKGROUND: A difficulty in computer-assisted interventions is acquiring the patient's anatomy intraoperatively. Standard modalities have several limitations: low image quality (ultrasound), radiation exposure (computed tomography) or high costs (magnetic resonance imaging). An alternative approach uses a tracked pointer; however, the pointer causes tissue deformation and requires sterilizing. Recent proposals, utilizing a tracked conoscopic holography device, have shown promising results without the previously mentioned drawbacks...
November 21, 2016: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
C Kisielowski, H Frei, P Specht, I D Sharp, J A Haber, S Helveg
This article summarizes core aspects of beam-sample interactions in research that aims at exploiting the ability to detect single atoms at atomic resolution by mid-voltage transmission electron microscopy. Investigating the atomic structure of catalytic Co3O4 nanocrystals underscores how indispensable it is to rigorously control electron dose rates and total doses to understand native material properties on this scale. We apply in-line holography with variable dose rates to achieve this goal. Genuine object structures can be maintained if dose rates below ~100 e/Å(2)s are used and the contrast required for detection of single atoms is generated by capturing large image series...
2017: Advanced Structural and Chemical Imaging
Trevor P Almeida, Adrian R Muxworthy, András Kovács, Wyn Williams, Leslei Nagy, Pádraig Ó Conbhuí, Cathrine Frandsen, Radchagrit Supakulopas, Rafal E Dunin-Borkowski
The thermal demagnetization of pseudo-single-domain (PSD) magnetite (Fe3O4) particles, which govern the magnetic signal in many igneous rocks, is examined using off-axis electron holography. Visualization of a vortex structure held by an individual Fe3O4 particle (~250 nm in diameter) during in situ heating is achieved through the construction and examination of magnetic-induction maps. Stepwise demagnetization of the remanence-induced Fe3O4 particle upon heating to above the Curie temperature, performed in a similar fashion to bulk thermal demagnetization measurements, revealed that its vortex state remains stable under heating close to its unblocking temperature and is recovered upon cooling with the same or reversed vorticity...
August 28, 2016: Geophysical Research Letters
Wenbin You, Han Bi, Wen She, Yu Zhang, Renchao Che
Developing microwave absorption materials with ultrawide bandwidth and low density still remains a challenge, which restricts their actual application in electromagnetic signal anticontamination and defense stealth technology. Here a series of olive-like γ-Fe2 O3 @C core-shell spindles with different shell thickness and γ-Fe2 O3 @C@α-MnO2 spindles with different volumes of dipolar-distribution cavities were successfully prepared. Both series of absorbers exhibit excellent absorption properties. The γ-Fe2 O3 @C@α-MnO2 spindle with controllable cavity volume exhibits an effective absorption (<-10 dB) bandwidth as wide as 9...
November 15, 2016: Small
Daisuke Shindo, Toshiaki Tanigaki, Hyun Soon Park
Advances and applications of electron holography to the study of electromagnetic fields in various functional materials are presented. In particular, the development of split-illumination electron holography, which introduces a biprism in the illumination system of a holography electron microscope, enables highly accurate observations of electromagnetic fields and the expansion of the observable area. First, the charge distributions on insulating materials were studied by using split-illumination electron holography and including a mask in the illumination system...
November 17, 2016: Advanced Materials
Dario Donnarumma, Alexey Brodoline, Daniel Alexandre, Michel Gross
An original technique that combines digital holography, dual illumination of the sample and cleaning algorithm 3D reconstruction is proposed. It uses a standard transmission microscopy setup coupled with a digital holography detection. The technique is 4D, since it allows to determine, at each time step, the 3D locations (x,y,z) of many moving objects that scatter the dual illumination beam. The technique has been validated by imaging the microcirculation of blood in a fish larvae sample (the moving objects are thus red blood cells RBCs)...
November 14, 2016: Optics Express
Pablo Cencillo-Abad, Nikolay I Zheludev, Eric Plum
Effectively continuous control over propagation of a beam of light requires light modulation with pixelation that is smaller than the optical wavelength. Here we propose a spatial intensity modulator with sub-wavelength resolution in one dimension. The metadevice combines recent advances in reconfigurable nanomembrane metamaterials and coherent all-optical control of metasurfaces. It uses nanomechanical actuation of metasurface absorber strips placed near a mirror in order to control their interaction with light from perfect absorption to negligible loss, promising a path towards dynamic diffraction and focusing of light as well as holography without unwanted diffraction artefacts...
November 18, 2016: Scientific Reports
Xiong Li, Lianwei Chen, Yang Li, Xiaohu Zhang, Mingbo Pu, Zeyu Zhao, Xiaoliang Ma, Yanqin Wang, Minghui Hong, Xiangang Luo
As nanofabrication technology progresses, the emerging metasurface has offered unique opportunities for holography, such as an increased data capacity and the realization of polarization-sensitive functionality. Multicolor three-dimensional (3D) meta-hologram imaging is one of the most pursued applications for meta-hologram not yet realized. How to reduce the cross-talk among different colors in broad bandwidth designs is a critical question. On the basis of the off-axis illumination method, we develop a novel way to overcome the cross-talk limitation and achieve multicolor meta-holography with a single type of plasmonic pixel...
November 2016: Science Advances
Weimin Ye, Xin Li, Juan Liu, Shuang Zhang
Benefiting from efficient local phase and amplitude control at the subwavelength scale, metasurfaces offer a new platform for computer generated holography with high spatial resolution. Three-dimensional and high efficient holograms have been realized by metasurfaces constituted by subwavelength meta-atoms with spatially varying geometries or orientations. Metasurfaces have been recently extended to the nonlinear optical regime to generate holographic images in harmonic generation waves. Thus far, there has been no vector field simulation of nonlinear metasurface holograms because of the tremendous computational challenge in numerically calculating the collective nonlinear responses of the large number of different subwavelength meta-atoms in a hologram...
October 31, 2016: Optics Express
Yohsuke Tanaka, Shunsuke Tani, Shigeru Murata
This paper presents a phase retrieval method for digital holography with two high-speed cameras in particle measurement. The conditions for recording two holograms are derived theoretically. We focus in particular on the distance between the two holograms. The relative misalignment of the two holograms is also evaluated by numerical simulations. Finally, we experimentally compared settling particles reconstructed by the presented method and the Gabor method.
October 31, 2016: Optics Express
Vladimir Katkovnik, Igor Shevkunov, Nikolay V Petrov, Karen Egiazarian
A variational algorithm to object wavefront reconstruction from noisy intensity observations is developed for the off-axis holography scenario with imaging in the acquisition plane. The algorithm is based on the local least square technique proposed in paper [J. Opt. Soc. Am. A21, 367 (2004)]. First, multiple reconstructions of the wavefront are produced for various size and various directional windows applied for localization of estimation. At the second stage, a special statistical rule is applied in order to select the best window size estimate for each pixel of the image and for each of the directional windows...
October 31, 2016: Optics Express
Dusan Sarenac, Michael G Huber, Benjamin Heacock, Muhammad Arif, Charles W Clark, David G Cory, Chandra B Shahi, Dmitry A Pushin
We use a Mach-Zehnder interferometer to perform neutron holography of a spiral phase plate. The object beam passes through a spiral phase plate, acquiring the phase twist characteristic of orbital angular momentum states. The reference beam passes through a fused silica prism, acquiring a linear phase gradient. The resulting hologram is a fork dislocation image, which could be used to reconstruct neutron beams with various orbital angular momenta. This work paves the way for novel applications of neutron holography, diffraction and imaging...
October 3, 2016: Optics Express
Yang Li, Yueming Zhou, Mingrui He, Min Li, Peixiang Lu
Backscattering photoelectron hologram (BPH) originating from direct and backward-rescattering electrons encodes important structural information and ultrafast dynamics of the underlying processes. However, the BPH is usually overshadowed by other interference structures in the photoelectrons momentum spectra, preventing a direct extraction of information using BPH. Here we theoretically demonstrate disentanglement of the BPH from other types of interference with the orthogonal two-color field, where a weak orthogonal component is used to streak the BPH...
October 17, 2016: Optics Express
Jie Xiang, Andrii Varanytsia, Fred Minkowski, Daniel A Paterson, John M D Storey, Corrie T Imrie, Oleg D Lavrentovich, Peter Palffy-Muhoray
A cholesteric liquid crystal (CLC) formed by chiral molecules represents a self-assembled one-dimensionally periodic helical structure with pitch [Formula: see text] in the submicrometer and micrometer range. Because of the spatial periodicity of the dielectric permittivity, a CLC doped with a fluorescent dye and pumped optically is capable of mirrorless lasing. An attractive feature of a CLC laser is that the pitch [Formula: see text] and thus the wavelength of lasing [Formula: see text] can be tuned, for example, by chemical composition...
November 2, 2016: Proceedings of the National Academy of Sciences of the United States of America
Christina Hesseling, Tim Homeyer, Joachim Peinke, Gerd Gülker
In digital holographic particle image velocimetry, hologram truncation is a very prominent problem when the projection of the particle position to the sensor is close to the sensor edge. Using the convolution approach to reconstruct such a hologram yields a deformed particle image compared to a particle image resulting from a particle with a projection to the center of the sensor. This Letter shows that the deformation complicates particle position detection based on an algorithm originally developed for analog holography by Choo and Kang, and later applied to digital holography by Yang and Kang...
November 1, 2016: Optics Letters
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