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Marine Blondeau, Yohan Guyodo, François Guyot, Christophe Gatel, Nicolas Menguy, Imène Chebbi, Bernard Haye, Mickaël Durand-Dubief, Edouard Alphandery, Roberta Brayner, Thibaud Coradin
Understanding the biological processes enabling magnetotactic bacteria to maintain oriented chains of magnetic iron-bearing nanoparticles called magnetosomes is a major challenge. The study aimed to constrain the role of an external applied magnetic field on the alignment of magnetosome chains in Magnetospirillum magneticum AMB-1 magnetotactic bacteria immobilized within a hydrated silica matrix. A deviation of the chain orientation was evidenced, without significant impact on cell viability, which was preserved after the field was turned-off...
May 16, 2018: Scientific Reports
Luciana Vidas, Christian Guenther, Timothy Miller, Bastian Pfau, Daniel Perez, Elias Martinez, Michael Schneider, Erik Guehrs, Robert E Marvel, Kent Hallman, Richard F Haglund, Stefan Eisebitt, Simon Wall
We use resonant soft X-ray holography to image the insulator-metal phase transition in vanadium dioxide with element and polarization specificity and nanometer spatial resolution. We observe that nanoscale inhomogenity in the film results in spatial-dependent transition pathways between the insulating and metallic states. Additional nanoscale phases form in the vicinity of defects which are not apparent in the initial or final states of the system, which would be missed in area-integrated X-ray absorption measurements...
May 16, 2018: Nano Letters
Honggu Choi, Zhe Li, Hao Sun, Dan Merrill, John Turek, Michael Childress, David Nolte
Biodynamic digital holography was used to obtain phenotypic profiles of canine non-Hodgkin B-cell lymphoma biopsies treated with standard-of-care chemotherapy. Biodynamic signatures from the living 3D tissues were extracted using fluctuation spectroscopy from intracellular Doppler light scattering in response to the molecular mechanisms of action of therapeutic drugs that modify a range of internal cellular motions. The standard-of-care to treat B-cell lymphoma in both humans and dogs is a combination CHOP therapy that consists of doxorubicin, prednisolone, cyclophosphamide and vincristine...
May 1, 2018: Biomedical Optics Express
Dongsheng Song, Zi-An Li, Jan Caron, András Kovács, Huanfang Tian, Chiming Jin, Haifeng Du, Mingliang Tian, Jianqi Li, Jing Zhu, Rafal E Dunin-Borkowski
Whereas theoretical investigations have revealed the significant influence of magnetic surface and edge states on Skyrmonic spin texture in chiral magnets, experimental studies of such chiral states remain elusive. Here, we study chiral edge states in an FeGe nanostripe experimentally using off-axis electron holography. Our results reveal the magnetic-field-driven formation of chiral edge states and their penetration lengths at 95 and 240 K. We determine values of saturation magnetization M_{S} by analyzing the projected in-plane magnetization distributions of helices and Skyrmions...
April 20, 2018: Physical Review Letters
Florian Winkler, Juri Barthel, Amir H Tavabi, Sven Borghardt, Beata E Kardynal, Rafal E Dunin-Borkowski
An absolute scale match between experiment and simulation in atomic-resolution off-axis electron holography is demonstrated, with unknown experimental parameters determined directly from the recorded electron wave function using an automated numerical algorithm. We show that the local thickness and tilt of a pristine thin WSe_{2} flake can be measured uniquely, whereas some electron optical aberrations cannot be determined unambiguously for a periodic object. The ability to determine local specimen and imaging parameters directly from electron wave functions is of great importance for quantitative studies of electrostatic potentials in nanoscale materials, in particular when performing in situ experiments and considering that aberrations change over time...
April 13, 2018: Physical Review Letters
Hao-Bo Jiang, Yu-Qing Liu, Yong-Lai Zhang, Yan Liu, Xiu-Yan Fu, Dong-Dong Han, Yun-Yun Song, Luquan Ren, Hong-Bo Sun
Controlling the wettability of graphene and graphene derivatives is critical for broader applications. However, the dynamic dewetting performance of graphene is usually overlooked. Currently, superhydrophobic graphene with an anisotropic wettability is rare. Inspired by natural reed leaves, we report an ingenious fabrication process combining photolithography and laser holography technologies to create biomimetic graphene surfaces that demonstrate anisotropic wettability along two directions of grooved hierarchical structures, which are similar to reed leaf veins...
May 3, 2018: ACS Applied Materials & Interfaces
Federico Venturi, Gian Carlo Gazzadi, Amir H Tavabi, Alberto Rota, Rafal E Dunin-Borkowski, Stefano Frabboni
The magnetic properties of nanowires (NWs) and square nanorings, which were deposited by focused electron beam induced deposition (FEBID) of a Co carbonyl precursor, are studied using off-axis electron holography (EH), Lorentz transmission electron microscopy (L-TEM) and magnetic force microscopy (MFM). EH shows that NWs deposited using beam energies of 5 and 15 keV have the characteristics of magnetic dipoles, with larger magnetic moments observed for NWs deposited at lower energy. L-TEM is used to image magnetic domain walls in NWs and nanorings and their motion as a function of applied magnetic field...
2018: Beilstein Journal of Nanotechnology
Tomasz Kozacki, Maksymilian Chlipala, Piotr L Makowski
We present an end-to-end full color Fourier holographic imaging approach, which involves standard holographic recording with three wavelengths and an improved LED-driven display. It provides almost undistorted orthoscopic reconstruction of large objects in full color, which can be viewed with a naked eye. High quality reconstruction is preserved across large object depths, measured in meters, as shown theoretically and experimentally. Our imaging approach is based on capture, processing and display of the object wave fields without spherical phase factors...
April 30, 2018: Optics Express
F F Qin, Z Z Liu, Z Zhang, Q Zhang, J J Xiao
Due to the abilities of manipulating the wavefront of light with well-controlled amplitude, and phase and polarization, optical metasurfaces are very suitable for optical holography, enabling applications with multiple functionalities and high data capacity. Here, we demonstrate encoding two- and three-dimensional full-color holographic images by an ultrathin metasurface hologram whose unit cells are subwavelength nanoslits with spatially varying orientations. We further show that it is possible to achieve full-color holographic multiplexing with such kind of geometric metasurfaces, realized by a synthetic spectrum holographic algorithm...
April 30, 2018: Optics Express
Darshika Singh, Rakesh Kumar Singh
The recording and reconstruction of the Stokes parameter is of paramount importance for the description of the vectorial interference of light. Polarization holography provides a complete vectorial wavefront, however, direct recording and reconstruction of the hologram is not possible in a situation where the object is located behind the random scattering layer. The Stokes holography plays an important role in such situations and makes use of the Fourier transform relation between the Stokes parameters (SPs) at the scattering plane and the generalized Stokes parameters (GSPs) of the random field...
April 16, 2018: Optics Express
Athanasia Symeonidou, David Blinder, Peter Schelkens
A technique integrating the bidirectional reflectance distribution function (BRDF) is proposed to generate realistic high-quality colour computer-generated holograms (CGHs). We build on prior work, namely a fast computer-generated holography method for point clouds that handles occlusions. We extend the method by integrating the Phong illumination model so that the properties of the objects' surfaces are taken into account to achieve natural light phenomena such as reflections and shadows. Our experiments show that rendering holograms with the proposed algorithm provides realistic looking objects without any noteworthy increase to the computational cost...
April 16, 2018: Optics Express
Frédéric Jolivet, Fabien Momey, Loïc Denis, Loïc Méès, Nicolas Faure, Nathalie Grosjean, Frédéric Pinston, Jean-Louis Marié, Corinne Fournier
Reconstruction of phase objects is a central problem in digital holography, whose various applications include microscopy, biomedical imaging, and fluid mechanics. Starting from a single in-line hologram, there is no direct way to recover the phase of the diffracted wave in the hologram plane. The reconstruction of absorbing and phase objects therefore requires the inversion of the non-linear hologram formation model. We propose a regularized reconstruction method that includes several physically-grounded constraints such as bounds on transmittance values, maximum/minimum phase, spatial smoothness or the absence of any object in parts of the field of view...
April 2, 2018: Optics Express
Haiyan Ou, Yong Wu, Edmund Y Lam, Bing-Zhong Wang
In this Letter, we propose a new method for auto-focusing and reconstruction without defocus noise in optical scanning holography. By using a connected domain (CD) to calculate the area of different domains, which are labeled by a connected component, the focus distance can be found via the smallest area of each CD. Meanwhile, the sectional images without defocus noise can also be reconstructed based on the labeled domains. The effectiveness of this method has been verified with a simulation and experiments...
May 1, 2018: Optics Letters
Chih-Hao Liu, Dmitry Nevozhay, Alexander Schill, Manmohan Singh, Susobhan Das, Achuth Nair, Zhaolong Han, Salavat Aglyamov, Kirill V Larin, Konstantin V Sokolov
Wave-based optical elastography is rapidly emerging as a powerful technique for quantifying tissue biomechanical properties due to its noninvasive nature and high displacement sensitivity. However, current approaches are limited in their ability to produce high-frequency waves and highly localized mechanical stress. In this Letter, we demonstrate that the rapid liquid-to-gas phase transition of dye-loaded perfluorocarbon nanodroplets ("nanobombs") initiated by a pulsed laser can produce highly localized, high-frequency, and broadband elastic waves...
May 1, 2018: Optics Letters
Leo Puyo, Jean-Pierre Huignard, Michael Atlan
We report on an optical imaging design based on common-path off-axis digital holography, using a multiplexed volume Bragg grating. In the reported method, a reference optical wave is made by deflection and spatial filtering through a volume Bragg grating. This design has several advantages, including simplicity, stability, and robustness against misalignment.
April 20, 2018: Applied Optics
Miguel León-Rodríguez, Juan A Rayas, Raúl R Cordero, Amalia Martínez-García, Adrián Martínez-Gonzalez, Alejandro Téllez-Quiñones, Pedro Yañez-Contreras, Orlando Medina-Cázares
In order to recover the holographic object information, a method based on the recording of two digital holograms, not only at different planes but also in a slightly off-axis scheme, is presented. By introducing a π -phase shift in the reference wave, the zero-order diffracted term and the twin image are removed in the frequency domain during the processing of the recorded holograms. We show that the zero-order elimination by the phase-shifted holograms is better than working with weak-order beam and average intensity removal methods...
April 1, 2018: Applied Optics
Dahi Ghareab Abdelsalam Ibrahim
In this paper, we enhance the steepness of film thickness edge in terahertz off-axis digital holography by employing a reconstruction method based on a direct Fourier and Hermite polynomial function. The method is applied to samples of 110 μm and 80 μm step heights to extract the phase images in real time. Use of this method reduces the resolution factor by around one half, representing around a 50% decrease in critical dimension as compared with conventional measurements. The method is very promising and opens the route to potential applications in the fields of microlithography...
April 1, 2018: Applied Optics
Mingrui He, Yang Li, Yueming Zhou, Min Li, Wei Cao, Peixiang Lu
Watching the valence electron move in molecules on its intrinsic timescale has been one of the central goals of attosecond science and it requires measurements with subatomic spatial and attosecond temporal resolutions. The time-resolved photoelectron holography in strong-field tunneling ionization holds the promise to access this realm. However, it remains to be a challenging task hitherto. Here we reveal how the information of valence electron motion is encoded in the hologram of the photoelectron momentum distribution (PEMD) and develop a novel approach of retrieval...
March 30, 2018: Physical Review Letters
Wenwei Liu, Zhancheng Li, Hua Cheng, Chengchun Tang, Junjie Li, Shuang Zhang, Shuqi Chen, Jianguo Tian
Fourier optics, the principle of using Fourier transformation to understand the functionalities of optical elements, lies at the heart of modern optics, and it has been widely applied to optical information processing, imaging, holography, etc. While a simple thin lens is capable of resolving Fourier components of an arbitrary optical wavefront, its operation is limited to near normal light incidence, i.e., the paraxial approximation, which puts a severe constraint on the resolvable Fourier domain. As a result, high-order Fourier components are lost, resulting in extinction of high-resolution information of an image...
April 19, 2018: Advanced Materials
Livia Angeloni, Melania Reggente, Daniele Passeri, Marco Natali, Marco Rossi
Identification of nanoparticles and nanosystems into cells and biological matrices is a hot research topic in nanobiotechnologies. Because of their capability to map physical properties (mechanical, electric, magnetic, chemical, or optical), several scanning probe microscopy based techniques have been proposed for the subsurface detection of nanomaterials in biological systems. In particular, atomic force microscopy (AFM) can be used to reveal stiff nanoparticles in cells and other soft biomaterials by probing the sample mechanical properties through the acquisition of local indentation curves or through the combination of ultrasound-based methods, like contact resonance AFM (CR-AFM) or scanning near field ultrasound holography...
April 17, 2018: Wiley Interdisciplinary Reviews. Nanomedicine and Nanobiotechnology
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