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Manuel Bedrossian, Casey Barr, Chris A Lindensmith, Kenneth Nealson, Jay L Nadeau
Accurately detecting and counting sparse bacterial samples has many applications in the food, beverage, and pharmaceutical processing industries, in medical diagnostics, and for life detection by robotic missions to other planets and moons of the solar system. Currently, sparse bacterial samples are counted by culture plating or epifluorescence microscopy. Culture plates require long incubation times (days to weeks), and epifluorescence microscopy requires extensive staining and concentration of the sample...
November 1, 2017: Journal of Visualized Experiments: JoVE
Pieter G G Muyshondt, Raf Claes, Peter Aerts, Joris J J Dirckx
The nature of the movement of the columellar footplate (CFP) in birds is still a matter of ongoing debate. Some sources claim that rocking motion is dominant, while others propose a largely piston-like motion. In this study, motions of the CFP are experimentally investigated in the ostrich using a post-mortem approach. For quasi-static loads, micro-CT scans of ostrich heads were made under positive and negative middle-ear pressures of 1 kPa. For dynamic loads, laser Doppler vibrometry was used to measure the velocity on multiple locations of the CFP as a function of excitation frequency from 0...
November 9, 2017: Hearing Research
Kazuo Tsutsui, Tomohiro Matsushita, Kotaro Natori, Takayuki Muro, Yoshitada Morikawa, Takuya Hoshii, Kuniyuki Kakushima, Hitoshi Wakabayashi, Kouichi Hayashi, Fumihiko Matsui, Toyohiko Kinoshita
The atomic scale characterization of dopant atoms in semiconductor devices to establish correlations with the electrical activation of these atoms is the essential to the advancement of contemporary semiconductor process technology. Spectro-photoelectron holography combined with first-principles simulations can determine the local three-dimensional atomic structures of dopant elements, which in turn affect their electronic states. In the work reported herein, this technique was used to examine arsenic (As) atoms doped into a silicon (Si) crystal...
November 17, 2017: Nano Letters
Sudheesh K Rajput, Osamu Matoba
We propose an optical voice encryption scheme based on digital holography (DH). An off-axis DH is employed to acquire voice information by obtaining phase retardation occurring in the object wave due to sound wave propagation. The acquired hologram, including voice information, is encrypted using optical image encryption. The DH reconstruction and decryption with all the correct parameters can retrieve an original voice. The scheme has the capability to record the human voice in holograms and encrypt it directly...
November 15, 2017: Optics Letters
Moran Rubin, Gili Dardikman, Simcha K Mirsky, Nir A Turko, Natan T Shaked
We present a new holographic concept, named six-pack holography (6PH), in which we compress six off-axis holograms into a single multiplexed off-axis hologram without loss of magnification or resolution. The multiplexed hologram contains straight off-axis fringes with six different orientations, and can be generated optically or digitally. We show that since the six different complex wavefronts do not overlap in the spatial frequency domain, they can be fully reconstructed. 6PH allows more than 50% improvement in the spatial bandwidth consumption when compared to the best multiplexing method proposed so far...
November 15, 2017: Optics Letters
Jaime Sánchez-Barriga, Ilya I Ogorodnikov, Mikhail V Kuznetsov, Andrey A Volykhov, Fumihiko Matsui, Carolien Callaert, Joke Hadermann, Nikolay I Verbitskiy, Roland J Koch, Andrei Varykhalov, Oliver Rader, Lada V Yashina
To realize spintronic devices based on topological insulators (TIs), well-defined interfaces between magnetic metals and TIs are required. Here, we characterize atomically precisely the interface between the 3d transition metal Fe and the TI Bi2Te3 at different stages of its formation. Using photoelectron diffraction and holography, we show that after deposition of up to 3 monolayers Fe on Bi2Te3 at room temperature, the Fe atoms are ordered at the interface despite the surface disorder revealed by our scanning-tunneling microscopy images...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
Julian Sonner, Benjamin Withers
We describe a large family of nonequilibrium steady states (NESS) corresponding to forced flows over obstacles. The spatial structure at large distances from the obstacle is shown to be universal, and can be quantitatively characterized in terms of certain collective modes of the strongly coupled many body system, which we define in this work. In holography, these modes are spatial analogues of quasinormal modes, which are known to be responsible for universal aspects of relaxation of time dependent systems...
October 20, 2017: Physical Review Letters
Manuel Fohler, Stefanie Frömmel, Michael Schneider, Bastian Pfau, Christian M Günther, Martin Hennecke, Erik Guehrs, Laura Shemilt, Durgamadhab Mishra, Dirk Berger, Sören Selve, Dmitriy Mitin, Manfred Albrecht, Stefan Eisebitt
We present a general approach to thin bulk samples to transparency for experiments in the soft x-ray and extreme ultraviolet spectral range. The method relies on mechanical grinding followed by focused-ion-beam milling. It results in a uniformly thin area of high surface quality, suitable for nanoscale imaging in transmission. In a proof-of-principle experiment, nanoscale magnetic bits on a commercial hard drive glass disk are imaged with a spatial resolution below 30 nm by soft x-ray spectro-holography. Furthermore, we demonstrate imaging of a lithographically patterned test object via absorption contrast...
October 2017: Review of Scientific Instruments
Dierck Hillmann, Hendrik Spahr, Helge Sudkamp, Carola Hain, Laura Hinkel, Gesa Franke, Gereon Hüttmann
In numerous applications, Fourier-domain optical coherence tomography (FD-OCT) suffers from a limited imaging depth due to signal roll-off, a limited focal range, and autocorrelation noise. Here, we propose a parallel full-field FD-OCT imaging method that uses a swept laser source and an area camera in combination with an off-axis reference, which is incident on the camera at a small angle. As in digital off-axis holography, this angle separates autocorrelation signals and the complex conjugated mirror image from the actual signal in Fourier space...
October 30, 2017: Optics Express
Soraya Sangiao, César Magén, Darius Mofakhami, Grégoire de Loubens, José María De Teresa
In this work, we present a detailed investigation of the magnetic properties of cobalt nanospheres grown on cantilever tips by focused electron beam induced deposition (FEBID). The cantilevers are extremely soft and the cobalt nanospheres are optimized for magnetic resonance force microscopy (MRFM) experiments, which implies that the cobalt nanospheres must be as small as possible while bearing high saturation magnetization. It was found that the cobalt content and the corresponding saturation magnetization of the nanospheres decrease for nanosphere diameters less than 300 nm...
2017: Beilstein Journal of Nanotechnology
Nicolas C Pégard, Alan R Mardinly, Ian Antón Oldenburg, Savitha Sridharan, Laura Waller, Hillel Adesnik
Optical methods capable of manipulating neural activity with cellular resolution and millisecond precision in three dimensions will accelerate the pace of neuroscience research. Existing approaches for targeting individual neurons, however, fall short of these requirements. Here we present a new multiphoton photo-excitation method, termed three-dimensional scanless holographic optogenetics with temporal focusing (3D-SHOT), which allows precise, simultaneous photo-activation of arbitrary sets of neurons anywhere within the addressable volume of a microscope...
October 31, 2017: Nature Communications
Junior Arroyo, Benjamin Castaneda
Mechanical properties of soft human tissue are linked to their pathological state. One way to assess these properties is through the Young modulus measurement, which is related to the shear wave speed in the medium when considering tissues as nearly incompressible. In order to characterize its elastic properties using sonoelastography, we introduce a new technique for shear wave estimation from a static interference pattern based on Shear Wave Holography. A relation between the mathematical representation of the interference pattern and the local shear speed is derived using the Phase Derivative approach...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Glen Evenbly
We propose a new class of tensor network state as a model for the AdS/CFT correspondence and holography. This class is demonstrated to retain key features of the multiscale entanglement renormalization ansatz (MERA), in that they describe quantum states with algebraic correlation functions, have free variational parameters, and are efficiently contractible. Yet, unlike the MERA, they are built according to a uniform tiling of hyperbolic space, without inherent directionality or preferred locations in the holographic bulk, and thus circumvent key arguments made against the MERA as a model for AdS/CFT...
October 6, 2017: Physical Review Letters
Rachit Saluja, G R K S Subrahmanyam, Deepak Mishra, R V Vinu, Rakesh Kumar Singh
We propose and demonstrate a compressive sensing (CS) framework for correlation holography. This is accomplished by adopting the principle of compressive sensing and thresholding in the two-point intensity correlation. The measurement matrix and the sensing matrix that are required for applying the CS framework here are systematically extracted from the random illuminations of the laser speckle data. Reconstruction results using CS, CS with thresholding, and intensity correlation are compared. Our study reveals that liminal CS requires far fewer samples for the reconstruction of the hologram and has wide application in image reconstruction...
August 20, 2017: Applied Optics
Takanori Nomura, Kazuma Shinomura
A generalized sequential four-step phase-shifting color digital holography is proposed. As an arbitrary phase-shift quantity is independent from wavelengths, it can be used for four-step phase-shifting color digital holography. Furthermore, no constraint on the phase-shifting quantities or statistical property on the hologram is required in the proposed method. Experimental results using a reflective object are shown to confirm the proposed phase-shifting digital holography.
August 20, 2017: Applied Optics
Joseph van Rooij, Jeroen Kalkman
We present sub-millimeter full-field depth from focus digital holography of surface topography of rough objects. For each pixel, the depth of the object is calculated from the variance of the intensity image over a set of reconstruction distances. First, we theoretically describe the axial resolution of this method and show that sub-millimeter resolution is feasible. Second, using a digital holography setup without magnifying optics or lateral scanning we experimentally demonstrate 100 μm axial resolution depth ranging and surface topography imaging...
September 1, 2017: Applied Optics
Juan Martinez-Carranza, Konstantinos Falaggis, Tomasz Kozacki
The phase information of a complex field is routinely obtained using coherent measurement techniques as, e.g., interferometry or holography. The obtained measurement result is subject to a 2π ambiguity and is often referred to as wrapped phase. Phase-unwrapping algorithms (PUAs) are commonly employed to remove this ambiguity and, hence, obtain the absolute phase. However, implementing PUAs can be computationally intensive, and the accuracy of those algorithms may be low. Recently, the transport of intensity equation (TIE) has been proposed as a simple and practical alternative for obtaining the absolute phase map...
September 1, 2017: Applied Optics
Takaaki Shiratori, Keisuke Kasai, Nobukazu Yoshikawa
We propose a color-image reconstruction method for two-wavelength digital holography using generalized phase-shifting digital holography (GPSDH). In this method, color interference fringes are captured by a digital camera with a Bayer array color filter, and phase shifting is simultaneously performed for all wavelengths. Color interference fringes are separated into three monochromatic interference fringes using a color-separation method that suppresses the color-filter crosstalk. The object wave is extracted from each monochromatic interference fringe using GPSDH, which prevents problems due to the phase shift wavelength dependence...
August 10, 2017: Applied Optics
Wei-Na Li, Sang-Min Lee, Sang Keun Gil, Nam Kim
We propose a multiple-3D-object decryption scheme based on one interference using two beams that are from two different phase-only functions. It takes advantage of off-axis digital holography to extract the optical fields of multiple 3D objects, and respectively utilize single different decryption keys to decrypt multiple 3D objects in the decryption procedure. The advantages of the proposed scheme include the following: each 3D object can be decrypted discretionarily without decrypting a series of other objects earlier; no iterative algorithm is involved; and the decrypted image of each object can be successfully clearly distinguished...
August 1, 2017: Applied Optics
Vít Lédl, Pavel Psota, František Kaván, Ondřej Matoušek, Pavel Mokrý
High-precision measurements of mechanical parts' surface topography represent an essential task in many industry sectors. Examples of such tasks are, e.g., precise alignments of opto-mechanical systems, large object deformation measurements, evaluation of object shape, and many others. Today, the standard method used for such measurements is based on use of coordinate measuring machines (CMMs). Unfortunately, CMMs have severe shortcomings: low measurement point density, long measurement time, risk of surface damage, etc...
October 1, 2017: Applied Optics
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