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Tsukasa Hirayama, Yuka Aizawa, Kazuo Yamamoto, Takeshi Sato, Hidekazu Murata, Ryuji Yoshida, Craig A J Fisher, Takehisa Kato, Yasutoshi Iriyama
Advanced techniques for overcoming problems encountered during in situ electron holography experiments in which a voltage is applied to an ionic conductor are reported. The three major problems encountered were 1) electric-field leakage from the specimen and its effect on phase images, 2) high electron conductivity of damage layers formed by the focused ion beam method, and 3) chemical reaction of the specimen with air. The first problem was overcome by comparing experimental phase distributions with simulated images in which three-dimensional leakage fields were taken into account, the second by removing the damage layers using a low-energy narrow Ar ion beam, and the third by developing an air-tight biasing specimen holder...
March 15, 2017: Ultramicroscopy
Francesco Merola, Álvaro Barroso, Lisa Miccio, Pasquale Memmolo, Martina Mugnano, Pietro Ferraro, Cornelia Denz
In this work, the optical behavior of Red Blood Cells (RBCs) under an optically-induced mechanical stress was studied. Exploiting the new findings concerning the optical lens-like behavior of RBCs, the variations of the wavefront refracted by optically-deformed RBCs were further investigated. Experimental analysis have been performed through the combination of digital holography and numerical analysis based on Zernike polynomials, while the biological lens is deformed under the action of multiple dynamic optical tweezers...
March 13, 2017: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
Mohamed Haouat, Jorge Garcia-Sucerquia, Abdelhamid Kellou, Pascal Picart
This Letter presents an easy, fast, and efficient single-shot method to reduce speckle noise in digital Fresnel holography. In this method, several images from a single hologram are reconstructed by introducing spatial displacements in the Fresnel kernel. Spatial jitters produce images with different speckle positions. Averaging the set of numerically produced images leads to a strong reduction of speckle noise in both amplitude and phase difference images. The experimental results show the suitability of the proposed approach and confirm its applicability to digital holographic interferometry...
March 15, 2017: Optics Letters
Felix Willems, Clemens von Korff Schmising, David Weder, Christian M Günther, Michael Schneider, Bastian Pfau, Sven Meise, Erik Guehrs, Jan Geilhufe, Alaa El Din Merhe, Emmanuelle Jal, Boris Vodungbo, Jan Lüning, Benoit Mahieu, Flavio Capotondi, Emanuele Pedersoli, David Gauthier, Michele Manfredda, Stefan Eisebitt
We present an element specific and spatially resolved view of magnetic domains in Co/Pt heterostructures in the extreme ultraviolet spectral range. Resonant small-angle scattering and coherent imaging with Fourier-transform holography reveal nanoscale magnetic domain networks via magnetic dichroism of Co at the M2,3 edges as well as via strong dichroic signals at the O2,3 and N6,7 edges of Pt. We demonstrate for the first time simultaneous, two-color coherent imaging at a free-electron laser facility paving the way for a direct real space access to ultrafast magnetization dynamics in complex multicomponent material systems...
January 2017: Structural Dynamics (Melville, N.Y.)
S Borghardt, F Winkler, Z Zanolli, M J Verstraete, J Barthel, A H Tavabi, R E Dunin-Borkowski, B E Kardynal
The quantitative analysis of electron-optical phase images recorded using off-axis electron holography often relies on the use of computer simulations of electron propagation through a sample. However, simulations that make use of the independent atom approximation are known to overestimate experimental phase shifts by approximately 10%, as they neglect bonding effects. Here, we compare experimental and simulated phase images for few-layer WSe_{2}. We show that a combination of pseudopotentials and all-electron density functional theory calculations can be used to obtain accurate mean electron phases, as well as improved atomic-resolution spatial distribution of the electron phase...
February 24, 2017: Physical Review Letters
K Shibata, A Kovács, N S Kiselev, N Kanazawa, R E Dunin-Borkowski, Y Tokura
The internal and lattice structures of magnetic Skyrmions in B20-type FeGe are investigated using off-axis electron holography. The temperature, magnetic field, and angular dependence of the magnetic moments of individual Skyrmions are analyzed. The internal Skyrmion shape is found to vary with applied magnetic field. In contrast, the inter-Skyrmion distance remains almost unchanged in the lattice phase over the studied range of applied field. The amplitude of the local magnetic moment is found to vary with temperature, while the Skyrmion shape does not change significantly...
February 24, 2017: Physical Review Letters
Christophe Gatel, Xiaoxiao Fu, Virginie Serin, Mahmoud Eddrief, Victor Etgens, Benedicte Warot-Fonrose
Most studies on MnAs material in its bulk form have been focused on its temperature dependent structural phase transition accompanied by a magnetic one. Magnetostructural phase transition parameters in thin MnAs films grown on GaAs substrate present however some differences from the bulk behavior, and local studies become mandatory for a deeper understanding of the mechanisms involved within the transition. Up to now, only surface techniques have been carried on, while the transition is a three dimensional phenomenon...
March 9, 2017: Nano Letters
Chih-Hao Liu, Alexander Schill, Raksha Raghunathan, Chen Wu, Manmohan Singh, Zhaolong Han, Achuth Nair, Kirill V Larin
Optical coherence elastography (OCE) is an emerging technique for quantifying tissue biomechanical properties. Generally, OCE relies on point-by-point scanning. However, long acquisition times make point-by-point scanning unfeasible for clinical use. Here we demonstrate a noncontact single shot line-field low coherence holography system utilizing an automatic Hilbert transform analysis based on a spatial phase shifting technique. Spatio-temporal maps of elastic wave propagation were acquired with only one air-pulse excitation and used to quantify wave velocity and sample mechanical properties at a line rate of 200 kHz...
February 1, 2017: Biomedical Optics Express
Dhananjay Kumar Singh, Caroline C Ahrens, Wei Li, Siva A Vanapalli
Large-scale and label-free phenotyping of cells holds great promise in medicine, especially in cancer diagnostics and prognosis. Here, we introduce inline digital holography microscopy for volumetric imaging of cells in bulk flow and fingerprinting of flowing tumor cells based on two metrics, in-focus scattered intensity and cell diameter. Using planar distribution of immobilized particles, we identify the optimal recording distance and microscope objective magnification that minimizes the error in measurement of particle position, size and scattered intensity...
February 1, 2017: Biomedical Optics Express
Guoli Ping, Zhigang Chu, Zhongming Xu, Linbang Shen
This paper is concerned with acoustical engineering and mathematical physics problem for the near-field acoustical holography based on equivalent source method (ESM-based NAH). An important mathematical physics problem in ESM-based NAH is to solve the equivalent source strength, which has multiple solving algorithms, such as Tikhonov regularization ESM (TRESM), iterative weighted ESM (IWESM) and steepest descent iteration ESM (SDIESM). To explore a new solving algorithm which can achieve better reconstruction performance in wide frequency band, a refined wideband acoustical holography (RWAH) is proposed...
March 7, 2017: Scientific Reports
F-R Chen, C Kisielowski, D Van Dyck
It is now established that the 3D structure of homogeneous nanocrystals can be recovered from in-line hologram of single projections. The method builds on a quantitative contrast interpretation of electron exit wave functions. Since simulated exit wave functions of single and bilayers of graphene reveal the atomic structure of carbon-based materials with sufficient resolution, we explore theoretically how the approach can be expanded beyond periodic carbon-based materials to include non-periodic molecular structures...
2017: Advanced Structural and Chemical Imaging
Nisan Siegel, Vladimir Lupashin, Brian Storrie, Gary Brooker
Fresnel incoherent correlation holography (FINCH) microscopy is a promising approach for high-resolution biological imaging but has so far been limited to use with low-magnification, low-numerical-aperture configurations. We report the use of in-line incoherent interferometers made from uniaxial birefringent α-barium borate (α-BBO) or calcite crystals that overcome the aberrations and distortions present with previous implementations that employed spatial light modulators or gradient refractive index lenses...
December 2016: Nature Photonics
Jean-Michel Attendu, Annie Ross
Nearfield acoustical holography can be used to visualize time domain evolution of non-stationary sound fields. It requires sampling of the pressure field with a microphone array to calculate the sound field on other parallel surfaces, either toward the source or farther away from it. This paper focuses on forward propagation of fields sampled with a planar array. Several formulations exist to perform such calculation; however, despite being mathematically well-posed, they generate significant errors, especially for larger propagation distances...
February 2017: Journal of the Acoustical Society of America
Rajib Ahmed, Ali K Yetisen, Haider Butt
Flexible imprinted photonic nanostructures that are able to diffract/focus narrow-band light have potential applications in optical lenses, filters, tunable lasers, displays, and biosensing. Nanophotonic structures through holography and roll-to-roll printing may reduce fabrication complexities and expenses and enable mass production. Here, 3D photonic nanostructures of a stacked ring array were imprinted on acrylate polymer (AP) over poly(ethylene terephthalate) (PET) substrate through holography and lift-off processes to create a microlens array (MLA)...
March 28, 2017: ACS Nano
Tatiana A Vovk, Nikolay V Petrov
We propose a new express method of the correlation characterization of the particles suspended in the volume of optically transparent medium. It utilizes inline digital holography technique for obtaining two images of the adjacent layers from the investigated volume with subsequent matching of the cross-correlation function peak-to-basement ratio calculated for these images. After preliminary calibration via numerical simulation, the proposed method allows one to quickly distinguish parameters of the particle distribution and evaluate their concentration...
March 2, 2017: Scientific Reports
A Krynkin, G Dolcetti, S Hunting
Accurate reconstruction of the surface roughness is of high importance to various areas of science and engineering. One important application of this technology is for remote monitoring of open channel flows through observing its dynamic surface roughness. In this paper a novel airborne acoustic method of roughness reconstruction is proposed and tested with a static rigid rough surface. This method is based on the acoustic holography principle and Kirchhoff approximation which make use of acoustic pressure data collected at multiple receiver points spread along an arch...
February 2017: Review of Scientific Instruments
M Gross
Ultrasound-modulated optical tomography (UOT) is a technique that images optical contrast deep inside scattering media. Heterodyne holography is a promising tool that is able to detect UOT-tagged photons with high efficiency. In this work, we describe theoretically the detection of the tagged photon in heterodyne holography-based UOT, show how to filter the untagged photon, and discuss the effect of shot noise. The discussion also considers speckle decorrelation. We show that optimal detection sensitivity can be reached, if the frame exposure time of the camera used to perform the holographic detection is on the order of the decorrelation time...
March 1, 2017: Applied Optics
Matthew J Berg, Nava R Subedi, Peter A Anderson
Through simulations and experiment, this Letter shows how a particle's extinction cross section can be extracted from a digital hologram. Spherical and nonspherical particles are considered covering a range of cross-sectional values of nearly five orders of magnitude. The extracted cross sections are typically less than 10% in error from the true values. It is also shown that holograms encompassing a sufficiently large angular range of scattered light yield an estimate for the absorption cross section.
March 1, 2017: Optics Letters
A Vijayakumar, Joseph Rosen
In this Letter, we present an advanced optical configuration of coded aperture correlation holography (COACH) with a diffractive objective lens. Four-dimensional imaging of objects at the three spatial dimensions and with an additional spectral dimension is demonstrated. A hologram of three-dimensional objects illuminated by different wavelengths was recorded by the interference of light diffracted from the objects with the light diffracted from the same objects, but through a random-like coded phase mask (CPM)...
March 1, 2017: Optics Letters
Aya Nozaki, Masaya Mitobe, Fumio Okuyama, Yuji Sakamoto
Electro-holography can display images without inducing fatigue and three-dimensional (3D) sickness, i.e., visual discomfort due to viewing a stereoscopic display. Thus, this technology is expected to be applied to 3D media. However, there are no studies that have shown the agreement between the dynamic responses of accommodation and vergence to the reconstructed images of electro-holography and those to the real targets. This paper describes the measurement results of these responses using a developed system that can simultaneously measure the dynamic responses of accommodation and vergence...
February 20, 2017: Optics Express
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