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https://www.readbyqxmd.com/read/28524674/holography-of-wi-fi-radiation
#1
Philipp M Holl, Friedemann Reinhard
Wireless data transmission systems such as wi-fi or Bluetooth emit coherent light-electromagnetic waves with a precisely known amplitude and phase. Propagating in space, this radiation forms a hologram-a two-dimensional wave front encoding a three-dimensional view of all objects traversed by the light beam. Here we demonstrate a scheme to record this hologram in a phase-coherent fashion across a meter-sized imaging region. We recover three-dimensional views of objects and emitters by feeding the resulting data into digital reconstruction algorithms...
May 5, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28516906/nanometric-holograms-based-on-a-topological-insulator-material
#2
Zengji Yue, Gaolei Xue, Juan Liu, Yongtian Wang, Min Gu
Holography has extremely extensive applications in conventional optical instruments spanning optical microscopy and imaging, three-dimensional displays and metrology. To integrate holography with modern low-dimensional electronic devices, holograms need to be thinned to a nanometric scale. However, to keep a pronounced phase shift modulation, the thickness of holograms has been generally limited to the optical wavelength scale, which hinders their integration with ultrathin electronic devices. Here, we break this limit and achieve 60 nm holograms using a topological insulator material...
May 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/28509592/molecular-modeling-and-structure-activity-relationships-for-a-series-of-benzimidazole-derivatives-as-cruzain-inhibitors
#3
Ivani Pauli, Leonardo G Ferreira, Mariana L de Souza, Glaucius Oliva, Rafaela S Ferreira, Marco A Dessoy, Brian W Slafer, Luiz C Dias, Adriano D Andricopulo
AIM: Chagas disease is endemic in Latin America and no effective treatment is available. Efforts in drug research have focused on several enzymes from Trypanosoma cruzi, among which cruzain is a validated pharmacological target. METHODOLOGY: Chemometric analyses were performed on the data set using the HQSAR, CoMFA and CoMSIA methods. Docking simulations were executed using the crystallographic structure of cruzain in complex with a benzimidazole inhibitor. The top-scoring enzyme-inhibitor complexes were selected for the development of the 3D QSAR models and to assess the inhibitor binding modes and intermolecular interactions...
May 16, 2017: Future Medicinal Chemistry
https://www.readbyqxmd.com/read/28488437/strain-multiplexed-metasurface-holograms-on-a-stretchable-substrate
#4
Stephanie C Malek, Ho-Seok Ee, Ritesh Agarwal
We demonstrate reconfigurable phase-only computer-generated metasurface holograms with up to three image planes operating in the visible regime fabricated with gold nanorods on a stretchable polydimethylsiloxane substrate. Stretching the substrate enlarges the hologram image and changes the location of the image plane. Upon stretching, these devices can switch the displayed holographic image between multiple distinct images. This work opens up the possibilities for stretchable metasurface holograms as flat devices for dynamically reconfigurable optical communication and display...
May 10, 2017: Nano Letters
https://www.readbyqxmd.com/read/28482229/detecting-dynamic-responses-of-materials-and-devices-under-an-alternating-electric-potential-by-phase-locked-transmission-electron-microscopy
#5
Kentaro Soma, Stan Konings, Ryotaro Aso, Naoto Kamiuchi, Genki Kobayashi, Hideto Yoshida, Seiji Takeda
An apparatus is developed for transmission electron microscopy (TEM) to acquire image and spectral data, such as TEM images, electron holograms, and electron energy loss spectra, synchronized with the measurement of the dynamic response of a specimen under an applied alternating current (AC) electric potential (voltage, denoted VAC). From a VAC of frequency f, a shutter pulse signal is generated to open and close a pre-specimen shutter in a base TEM apparatus. A pulse is generated per VAC cycle from the targeted phase Φ to Φ +∆Φ with phase width ∆Φ (∆Φ <2π)...
April 29, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28470981/active-phase-transition-via-loss-engineering-in-a-terahertz-mems-metamaterial
#6
Longqing Cong, Prakash Pitchappa, Chengkuo Lee, Ranjan Singh
Controlling the phase of local radiation by using exotic metasurfaces has enabled promising applications in a diversified set of electromagnetic wave manipulation such as anomalous wavefront deflection, flat lenses, and holograms. Here, we theoretically and experimentally demonstrate an active phase transition in a micro-electromechanical system-based metadevice where both the phase response and the dispersion of the metamaterial cavity are dynamically tailored. The phase transition is determined by the radiative and the absorptive losses in a metal-insulator-metal cavity that obeys the coupled-mode theory...
May 4, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28463316/multiwavelength-off-axis-digital-holography-with-an-angle-of-more-than-40%C3%A2-%C3%A2-degrees-and-no-beam-combiner-to-generate-interference-light
#7
Tatsuki Tahara, Yasuhiko Arai
We propose single-shot multiwavelength digital holography with an extremely large incident angle and show the digital recording of multiple object waves at multiple wavelengths with an angle of more than 40 degrees and no beam combiner to generate interference light. Both the avoidance of the crosstalk between the object waves at different wavelengths and the space-bandwidth extension are simultaneously achieved with a single-shot exposure of a monochromatic image sensor and a reference beam even when the wavelength difference between the object waves is small...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463314/surface-structural-damage-study-in-cortical-bone-due-to-medical-drilling
#8
Cesar G Tavera R, Manuel H De la Torre-I, Jorge M Flores-M, Ma Del Socorro Hernandez M, Fernando Mendoza-Santoyo, Manuel de J Briones-R, Jorge Sanchez-P
A bone's fracture could be produced by an excessive, repetitive, or sudden load. A regular medical practice to heal it is to fix it in two possible ways: external immobilization, using a ferule, or an internal fixation, using a prosthetic device commonly attached to the bone by means of surgical screws. The bone's volume loss due to this drilling modifies its structure either in the presence or absence of a fracture. To observe the bone's surface behavior caused by the drilling effects, a digital holographic interferometer is used to analyze the displacement surface's variations in nonfractured post-mortem porcine femoral bones...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463308/computer-generated-hologram-with-occlusion-effect-using-layer-based-processing
#9
Hao Zhang, Liangcai Cao, Guofan Jin
We propose a layer-based algorithm with single-viewpoint rendering geometry to calculate a three-dimensional (3D) computer-generated hologram (CGH) with occlusion effect. The 3D scene is sliced into multiple parallel layers according to the depth information. Slab-based orthographic projection is implemented to generate shading information for each layer, which renders hidden primitives for occlusion processing. The layer-based angular spectrum with silhouette mask culling is used to calculate the wave propagations from the layers to the CGH plane without paraxial approximation...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463303/full-color-holographic-display-with-increased-viewing-angle-invited
#10
Zhenxiang Zeng, Huadong Zheng, Yingjie Yu, Anand K Asundi, Sergiy Valyukh
Among the important features of holographic displays are the wide viewing angles and the full color of the reconstructed images. The present work focuses on achievement of both features. We propose an increased-viewing-angle full-color holographic display using two tiled phase-only spatial light modulators (SLMs), a 4f concave mirrors system, and a temporal-spatial multiplexing method. The 4f optical system consists of two concave mirrors and serves to increase the viewing angle. A temporal-spatial multiplexing synchronization control (TSMSC) method is developed to achieve a full-color image and to remove the color crosstalk of the image...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463301/self-interference-compressive-digital-holography-with-improved-axial-resolution-and-signal-to-noise-ratio
#11
Tianlong Man, Yuhong Wan, Fan Wu, Dayong Wang
Fresnel incoherent correlation holography (FINCH) was proposed to break the barrier of spatial incoherent digital holographic imaging and show the potential of super-resolution imaging preferences. We developed FINCH as a compressive sensing modality and reconstruction procedure as an inverse problem in order to realize 3D tomographic imaging. Improved axial resolution is obtained via compressive reconstruction. Reconstruction guarantees and accuracy of the proposed method are discussed. Compared with the real-valued signal operation, the signal-to-noise ratio of the results is increased when reconstructing from the complex-valued hologram obtained from the FINCH system...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463300/speeding-up-image-quality-improvement-in-random-phase-free-holograms-using-ringing-artifact-characteristics
#12
Yuki Nagahama, Tomoyoshi Shimobaba, Takashi Kakue, Nobuyuki Masuda, Tomoyoshi Ito
A holographic projector utilizes holography techniques. However, there are several barriers to realizing holographic projections. One is deterioration of hologram image quality caused by speckle noise and ringing artifacts. The combination of the random phase-free method and the Gerchberg-Saxton (GS) algorithm has improved the image quality of holograms. However, the GS algorithm requires significant computation time. We propose faster methods for image quality improvement of random phase-free holograms using the characteristics of ringing artifacts...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463299/quasi-three-dimensional-particle-imaging-with-digital-holography
#13
Osku Kemppinen, Yuli Heinson, Matthew Berg
In this work, approximate three-dimensional structures of microparticles are generated with digital holography using an automated focus method. This is done by stacking a collection of silhouette-like images of a particle reconstructed from a single in-line hologram. The method enables estimation of the particle size in the longitudinal and transverse dimensions. Using the discrete dipole approximation, the method is tested computationally by simulating holograms for a variety of particles and attempting to reconstruct the known three-dimensional structure...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463297/rendering-of-specular-curved-objects-in-polygon-based-computer-holography
#14
Hirohito Nishi, Kyoji Matsushima
A realistic rendering technique is presented for creating large-scale computer-generated holograms. The technique is based on the polygon-based method, but allows specular curved surfaces to be reconstructed without increasing the number of polygons. In this technique, specular flat surfaces are transformed into curved surfaces. This is achieved by controlling the direction of reflected light, using fragmentary plane waves. An actual large-scale computer-generated hologram is created, and is used to verify the validity and practicality of the technique...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463296/shift-multiplexing-with-a-spherical-wave-in-holographic-data-storage-based-on-a-computer-generated-hologram
#15
Teruyoshi Nobukawa, Takanori Nomura
A holographic data storage system based on a computer-generated hologram (CGH) is simple and compact because a hologram of a data page is recorded through an imaging system without an additional optical path for a reference beam. In this paper, to improve the recording density of the holographic data storage based on a CGH, a shift multiplexing method using a spherical wave is proposed. A data page to be stored and a spherical wave are simultaneously reconstructed from a single CGH. This allows shift multiplexing by displacing a recording medium...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463295/autoencoder-based-holographic-image-restoration
#16
Tomoyoshi Shimobaba, Yutaka Endo, Ryuji Hirayama, Yuki Nagahama, Takayuki Takahashi, Takashi Nishitsuji, Takashi Kakue, Atsushi Shiraki, Naoki Takada, Nobuyuki Masuda, Tomoyoshi Ito
We propose a holographic image restoration method using an autoencoder, which is an artificial neural network. Because holographic reconstructed images are often contaminated by direct light, conjugate light, and speckle noise, the discrimination of reconstructed images may be difficult. In this paper, we demonstrate the restoration of reconstructed images from holograms that record page data in holographic memory and quick response codes by using the proposed method.
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463261/ultra-short-pulsed-off-axis-digital-holography-for-imaging-dynamic-targets-in-highly-scattering-conditions
#17
Ali Ziaee, Colin Dankwart, Marco Minniti, James Trolinger, Derek Dunn-Rankin
A single-shot digital holography system using an ultra-short pulsed laser is demonstrated to be very effective in suppressing the multiple-scattering noise associated with imaging dynamic targets in highly scattering environments, such as biological tissues and fuel injection systems. A planar off-axis reference wave configuration is used to generate a fixed carrier spatial frequency in the recorded holograms in order to separate coherent signal from incoherent noise in Fourier transformed holograms. The single-shot imaging system does not require averaging between multiple shots and can capture images of transient phenomena, such as the formation of diesel fuel injection sprays, and can overcome the problem of mechanical vibrations for recording holograms in industrial and laboratory environments...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463246/quantitative-study-on-a-resampling-mask-method-for-speckle-reduction-with-amplitude-superposition
#18
Wenhui Zhang, Liangcai Cao, Hua Zhang, Hao Zhang, Chao Han, Guofan Jin, Yunlong Sheng
One-shot digital holographic imaging has the advantages of high stability and low temporal cost. However, its reconstruction is degraded severely by the laser speckle. A rectangle, ellipse, and diamond resampling mask method in spatial domain for speckle reduction is proposed. The effectiveness of the method for speckle reduction is explained successfully. In the method, one hologram recorded in a certain size is divided into N=S×T sub-holograms. Angular spectrum transform is applied to the holographic reconstruction of a diffuse object...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463245/three-dimensional-image-reconstruction-of-macroscopic-objects-from-a-single-digital-hologram-using-stereo-disparity
#19
Baturay Özgürün, Duygu Önal Tayyar, Kaan Özer Agiş, Meriç Özcan
We present depth extraction of macroscopic three-dimensional (3D) objects from a single digital hologram using stereo disparity. The method does not require the phase information of the hologram but two perspectives of the scene, which are easily obtained by dividing the hologram into two parts (two apertures) before the reconstruction. Variation of the hologram division is countless since each piece of a single hologram contains all the information regarding the scene; therefore, stereo disparity can be calculated along any arbitrary direction...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463243/coded-aperture-correlation-holography-system-with-improved-performance-invited
#20
A Vijayakumar, Yuval Kashter, Roy Kelner, Joseph Rosen
Coded aperture correlation holography (COACH) is a recently introduced technique for recording incoherent digital holograms of general three-dimensional scenes. In COACH, a random-like coded phase mask (CPM) is used as a coded aperture. Even though the CPM is optimized to reduce background noise, there is still a substantial amount of noise, mitigating the performance of COACH. In order to reduce the noise, we first modify the hologram reconstruction method. Instead of computing the correlation between a complex hologram of the entire object and a hologram of a source point, in this study the numerical correlation is performed with a phase-only filter...
May 1, 2017: Applied Optics
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