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Eszter Lajkó, Bernadett Tuka, Ferenc Fülöp, István Krizbai, József Toldi, Kálmán Magyar, László Vécsei, László Kőhidai
The neuroprotective actions of kynurenic acid (KYNA) and its derivatives in several neurodegenerative disorders [characterized by damage to the cerebral endothelium and to the blood-brain barrier (BBB)] are well established. Cell-extracellular matrix (ECM) adhesion is supposedly involved in recovery of impaired cerebral endothelium integrity (endothelial repair). The present work aimed to investigate the effects of KYNA and its synthetic derivatives on cellular behaviour (e.g. adhesion and locomotion) and on morphology of the GP8 rat brain endothelial cell line, modeling the BBB endothelium...
January 13, 2018: Journal of Neural Transmission
Romuald A Janik, Jakub Jankowski, Hesam Soltanpanahi
We study the fully nonlinear time evolution of a holographic system possessing a first order phase transition. The initial state is chosen in the spinodal region of the phase diagram, and it includes an inhomogeneous perturbation in one of the field theory directions. The final state of the time evolution shows a clear phase separation in the form of domain formation. The results indicate the existence of a very rich class of inhomogeneous black hole solutions.
December 29, 2017: Physical Review Letters
Johannes Hagemann, Tim Salditt
We study by numerical simulation how spatial coherence affects the reconstruction quality of images in coherent diffractive x-ray imaging. Using a conceptually simple, but computationally demanding approach, we have simulated diffraction data recorded under partial coherence, and then use the data for iterative reconstruction algorithms using a support constraint. By comparison of experimental regimes and parameters, we observe a significantly higher robustness against partially coherent illumination in the near-field compared to the far-field setting...
January 8, 2018: Optics Express
Balys Momgaudis, Stephane Guizard, Allan Bilde, Andrius Melninkaitis
In this Letter, a novel method to evaluate nonlinear refractive index using time-resolved digital holographic microscopy is introduced. To demonstrate the viability of the method, cross-correlative nonlinear refractive index values for sapphire are measured experimentally: 2.75·10-20  m2/W at 1030 nm and 4.10·10-20    m2/W 515 nm wavelengths. The obtained results for sapphire are compared to those available in literature obtained by other methods.
January 15, 2018: Optics Letters
Andy Ying Guey Fuh, Yi-Lin Tsai, Ching-Han Yang, Shing Trong Wu
This Letter demonstrates optical vortex lattices based on holographic polymer-dispersed liquid crystal (HPDLC) films. The fabrication method uses a phase-only reflective spatial light modulator with numerically calculated phase profiles loaded on it to simplify multi-helical-wave interference. The beam profiles of the diffraction beams are simulated using the Fourier transform and compared with experimental results. The topological charges of the 1st-order diffraction beams reconstructed from the HPDLC films are examined using a Michelson interferometer...
January 1, 2018: Optics Letters
Jan Matrisch, Stefan Altmeyer
Simultaneous holographic multiplexing methods are used to store multiple holograms concurrently into one holographic volume. Compared to serial exposure, one advantage is the higher processing speed. Additionally, for parallel exposure the different gratings develop in a linear relation to one another, although the developing process itself is nonlinear caused by the holographic photopolymer. A mechano-optical modulator using a rotating optical flat is introduced to enable economic single-shot exposure of centimeter to decimeter-sized holograms utilizing only one laser...
January 10, 2018: Applied Optics
Shimpei Shimizu, Atsushi Okamoto, Fumiya Mizukawa, Kazuhisa Ogawa, Akihisa Tomita, Taketoshi Takahata, Satoshi Shinada, Naoya Wada
Volume holographic demultiplexers (VHDMs) provide spatial mode demultiplexing using simple optical systems. However, applying VHDM to practical optical communication systems is difficult, as typical holographic media have no sensitivity in the infrared region, which includes optical transmission bands. In this paper, we propose a VHDM scheme combined with a dual-wavelength method (DWM). Using the DWM, VHDMs are able to perform mode demultiplexing in the optical transmission bands. We experimentally demonstrated the basic operation of our proposal using experiments performed at an 850-nm wavelength...
January 10, 2018: Applied Optics
José Ángel Picazo-Bueno, Dan Cojoc, Federico Iseppon, Vincent Torre, Vicente Micó
A single-shot water-immersion digital holographic microscope combined with broadband (white light) illumination mode is presented. This double imaging platform allows conventional incoherent visualization with phase holographic imaging of inspected samples. The holographic architecture is implemented at the image space (that is, after passing the microscope lens), thus reducing the sensitivity of the system to vibrations and/or thermal changes in comparison to regular interferometers. Because of the off-axis holographic recording principle, quantitative phase images of live biosamples can be recorded in a single camera snapshot at full-field geometry without any moving parts...
January 1, 2018: Applied Optics
I S Park, R J C Middleton, C R Coggrave, P D Ruiz, J M Coupland
A hologram is a recording of the interference between an unknown object wave and a coherent reference wave. Providing the object and reference waves are sufficiently separated in some region of space and the reference beam is known, a high-fidelity reconstruction of the object wave is possible. In traditional optical holography, high-quality reconstruction is achieved by careful reillumination of the holographic plate with the exact same reference wave that was used at the recording stage. To reconstruct high-quality digital holograms the exact parameters of the reference wave must be known mathematically...
January 1, 2018: Applied Optics
Juan M Soto, José A Rodrigo, Tatiana Alieva
Quantitative label-free imaging is an important tool for the study of living microorganisms that, during the last decade, has attracted wide attention from the optical community. Optical diffraction tomography (ODT) is probably the most relevant technique for quantitative label-free 3D imaging applied in wide-field microscopy in the visible range. The ODT is usually performed using spatially coherent light illumination and specially designed holographic microscopes. Nevertheless, the ODT is also compatible with partially coherent illumination and can be realized in conventional wide-field microscopes by applying refocusing techniques, as it has been recently demonstrated...
January 1, 2018: Applied Optics
Marta Mikuła, Tomasz Kozacki, Michał Józwik, Julianna Kostencka
This paper proposes a measurement method of focusing objects with a high gradient shape of a small and large radius of curvature. The measurements are carried out on a Fourier digital holographic microscope with optimized illumination conditions maximizing the usage of the system's numerical aperture. The obtained fringe patterns are the result of interference of deformed spherical object and spherical reference waves. The key elements of the method are the aberration compensation and calibration procedures...
January 1, 2018: Applied Optics
E Serabyn, K Liewer, J K Wallace
Microscopes aimed at detecting cellular life in extreme environments such as ocean-bearing solar system moons must provide high resolution in a compact, robust instrument. Here, we consider the resolution optimization of a compact off-axis lensless digital holographic microscope (DHM) that consists of a sample placed between an input point-source pair and a detector array. Two optimal high-resolution regimes are identified at opposite extremes-a low-magnification regime with the sample located near a small-pixel detector array, and a high-magnification regime with the sample near the input plane...
January 1, 2018: Applied Optics
Johan Öhman, Mikael Sjödahl
Side scattered light from micrometer-sized particles is recorded using an off-axis digital holographic setup. From holograms, a volume is reconstructed with information about both intensity and phase. Finding particle positions is non-trivial, since poor axial resolution elongates particles in the reconstruction. To overcome this problem, the reconstructed wavefront around a particle is used to find the axial position. The method is based on the change in the sign of the curvature around the true particle position plane...
January 1, 2018: Applied Optics
Kyoji Matsushima, Noriaki Sonobe
Digitized holography techniques are used to reconstruct three-dimensional (3D) images of physical objects using large-scale computer-generated holograms (CGHs). The object field is captured at three wavelengths over a wide area at high densities. Synthetic aperture techniques using single sensors are used for image capture in phase-shifting digital holography. The captured object field is incorporated into a virtual 3D scene that includes nonphysical objects, e.g., polygon-meshed CG models. The synthetic object field is optically reconstructed as a large-scale full-color CGH using red-green-blue color filters...
January 1, 2018: Applied Optics
Zixiang Lu, Yuji Sakamoto
Volume data are widely used in many areas, especially in biomedical science and geology. However, current visualization technologies of volume data cannot satisfy the visual requirements of humans. In this study, we propose two holographic display methods for volume data. The first method is polygon-based, and the other is maximum intensity projection (MIP)-based. Both methods are able to generate computer generated holograms of volume data. The polygon-based method can obtain various and colorful holograms, while the MIP-based method can be quickly calculated...
January 1, 2018: Applied Optics
Andrew Henrie, Jesse R Codling, Scott Gneiting, Justin B Christensen, Parker Awerkamp, Mark J Burdette, Daniel E Smalley
Displays capable of true holographic video have been prohibitively expensive and difficult to build. With this paper, we present a suite of modularized hardware components and software tools needed to build a HoloMonitor with basic "hacker-space" equipment, highlighting improvements that have enabled the total materials cost to fall to $820, well below that of other holographic displays. It is our hope that the current level of simplicity, development, design flexibility, and documentation will enable the lay engineer, programmer, and scientist to relatively easily replicate, modify, and build upon our designs, bringing true holographic video to the masses...
January 1, 2018: Applied Optics
Eun-Young Chang, Jongho Choi, Sangha Lee, Soonchul Kwon, Jisang Yoo, Minsik Park, Jinwoong Kim
Recently, holographic display and computer-generated holograms calculated from real existing objects have been more actively investigated to support holographic video applications. In this paper, we proposed a method of generating 360-degree color holograms of real 3D objects in an efficient manner. 360-degree 3D images are generated using the actual 3D image acquisition system consisting of a depth camera and a turntable and intermediate view generation. Then, 360-degree color holograms are calculated using a viewing-window-based computer-generated hologram...
January 1, 2018: Applied Optics
Su-Juan Liu, Dan Xiao, Xiao-Wei Li, Qiong-Hua Wang
In this paper, a computer-generated hologram (CGH) generation method is proposed to increase the field of view (FOV) in the holographic display. The CGH is generated through accumulating interference patterns of all object points. The size of each interference pattern is equal to the sum of the size of the recorded object and the spatial light modulator (SLM), so the size of the interference pattern is increased. The position of the interference pattern is related to that of the corresponding recorded object point...
January 1, 2018: Applied Optics
Piotr L Makowski, Weronika Zaperty, Tomasz Kozacki
A new framework for in-plane transformations of digital holograms (DHs) is proposed, which provides improved control over basic geometrical features of holographic images reconstructed optically in full color. The method is based on a Fourier hologram equivalent of the adaptive affine transformation technique [Opt. Express18, 8806 (2010)OPEXFF1094-408710.1364/OE.18.008806]. The solution includes four elementary geometrical transformations that can be performed independently on a full-color 3D image reconstructed from an RGB hologram: (i) transverse magnification; (ii) axial translation with minimized distortion; (iii) transverse translation; and (iv) viewing angle rotation...
January 1, 2018: Applied Optics
Vahid Amin Nili, Ehsan Mansouri, Zahra Kavehvash, Mohammad Fakharzadeh, Mahdi Shabany, Amin Khavasi
In this paper, a closed-form two-dimensional reconstruction technique for hybrid frequency and mechanical scanning millimeter-wave (MMW) imaging systems is proposed. Although being commercially implemented in many imaging systems as a low-cost real-time solution, the results of frequency scanning systems have been reconstructed numerically or have been reported as the captured raw data with no clear details. Furthermore, this paper proposes a new framework to utilize the captured data of different frequencies for three-dimensional (3D) reconstruction based on novel proposed closed-form relations...
January 1, 2018: Applied Optics
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