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Laurin Ginner, Tilman Schmoll, Abhishek Kumar, Matthias Salas, Nastassia Pricoupenko, Lara M Wurster, Rainer A Leitgeb
We demonstrate a high-resolution line field en-face time domain optical coherence tomography (OCT) system using an off-axis holography configuration. Line field en-face OCT produces high speed en-face images at rates of up to 100 Hz. The high frame rate favors good phase stability across the lateral field-of-view which is indispensable for digital adaptive optics (DAO). Human retinal structures are acquired in-vivo with a broadband light source at 840 nm, and line rates of 10 kHz to 100 kHz. Structures of different retinal layers, such as photoreceptors, capillaries, and nerve fibers are visualized with high resolution of 2...
February 1, 2018: Biomedical Optics Express
Hidehito Adaniya, Martin Cheung, Cathal Cassidy, Masao Yamashita, Tsumoru Shintake
A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests...
March 6, 2018: Ultramicroscopy
Nebile Isik, Elisabetta Maria Fiordaliso, Ray R LaPierre
Semiconductor nanowires (NWs) are a candidate technology for future optoelectronic devices. One of the critical issues in NWs is the control of impurity doping for the formation of p-n junctions. In this study, beryllium (p-type dopant) and tellurium (n-type dopant) in self-assisted GaAs NWs was studied. The GaAs NWs were grown on (111) Si by molecular beam epitaxy (MBE) using the self-assisted method. The dopant incorporation in the self-assisted GaAs NWs was investigated using Raman spectroscopy, photoluminescence, secondary ion mass spectrometry and electron holography...
March 15, 2018: Nanotechnology
Longchao Yao, Jun Chen, Paul E Sojka, Xuecheng Wu, Kefa Cen
Dynamic stringy objects such as liquid rims and ligaments are frequently observed in important applications such as the multiphase breakup of fuel droplets. We develop a new method based on digital in-line holography to automatically measure complicated stringy objects. A static spring mounted on a rotator is measured to validate the effectiveness and accuracy of the method. The sections are extracted along the skeleton of the spring in a depth-of-field extended image and then sized and located as individual particles using a hybrid method...
March 15, 2018: Optics Letters
Karl Landsteiner, Esperanza Lopez, Guillermo Milans Del Bosch
In the presence of a gravitational contribution to the chiral anomaly, the chiral magnetic effect induces an energy current proportional to the square of the temperature in equilibrium. In holography the thermal state corresponds to a black hole. We numerically study holographic quenches in which a planar shell of scalar matter falls into a black hole and raises its temperature. During the process the momentum density (energy current) is conserved. The energy current has two components, a nondissipative one induced by the anomaly and a dissipative flow component...
February 16, 2018: Physical Review Letters
Angelo Forli, Dania Vecchia, Noemi Binini, Francesca Succol, Serena Bovetti, Claudio Moretti, Francesco Nespoli, Mathias Mahn, Christopher A Baker, McLean M Bolton, Ofer Yizhar, Tommaso Fellin
Sensory information is encoded within the brain in distributed spatiotemporal patterns of neuronal activity. Understanding how these patterns influence behavior requires a method to measure and to bidirectionally perturb with high spatial resolution the activity of the multiple neuronal cell types engaged in sensory processing. Here, we combined two-photon holography to stimulate neurons expressing blue light-sensitive opsins (ChR2 and GtACR2) with two-photon imaging of the red-shifted indicator jRCaMP1a in the mouse neocortex in vivo...
March 13, 2018: Cell Reports
Zhijie Ma, Yi Li, Yang Li, Yandong Gong, Stefan A Maier, Minghui Hong
Planar optical chirality of a metasurface measures its differential response between left and right circularly polarized (CP) lights and governs the asymmetric transmission of CP lights. In 2D ultra-thin plasmonic structures the circular dichroism is limited to 25% in theory and it requires high absorption loss. Here we propose and numerically demonstrate a planar chiral all-dielectric metasurface that exhibits giant circular dichroism and transmission asymmetry over 0.8 for circularly polarized lights with negligible loss, without bringing in bianisotropy or violating reciprocity...
March 5, 2018: Optics Express
Jose Luis Martínez Fuentes, Ignacio Moreno
A new technique for encoding the amplitude and phase of diffracted fields in digital holography is proposed. It is based on a random spatial multiplexing of two phase-only diffractive patterns. The first one is the phase information of the intended pattern, while the second one is a diverging optical element whose purpose is the control of the amplitude. A random number determines the choice between these two diffractive patterns at each pixel, and the amplitude information of the desired field governs its discrimination threshold...
March 5, 2018: Optics Express
Xianfeng Xu, Zhiwei Zhang, Zecheng Wang, Jing Wang, Kaiyun Zhan, Yulei Jia, Zhiyong Jiao
A robust digital holography recording design is presented to complete the work of switching between in-line and off-axis recording methods. We precisely supervise the off-axis angle in off-axis holography, so that the original reconstructed image can be separated by a minimum off-axis angle. In the design, we can also monitor and remove the negative effects of the reference tilt error in phase-shifting digital holography. Compared with the conventional digital holographic recording configuration, a supervising unit is introduced to control and to monitor the angle between the reference beam and object beam...
March 1, 2018: Applied Optics
Mani Ratnam Rai, A Vijayakumar, Joseph Rosen
Interferenceless coded aperture correlation holography (I-COACH) is an incoherent digital holography technique developed to record and reconstruct 3D images of objects without two-wave interference. Herein, we introduce a novel technique to extend the field of view (FOV) of I-COACH beyond the limit imposed by the ratio between the finite area of the image sensor and the magnification of the optical system. Light diffracted from a point object located on the optical axis is modulated by a pseudorandom coded phase mask, and the central part of the point spread hologram (PSH) on the image sensor is recorded...
March 1, 2018: Optics Letters
Ji-Young Kim, Myung-Geun Han, Miao-Bin Lien, Sergei Magonov, Yimei Zhu, Heather George, Theodore B Norris, Nicholas A Kotov
The symmetry of metallic nanocolloids, typically envisaged as simple geometrical shapes, is rarely questioned. However, the symmetry considerations are so essential for understanding their electronic structure, optical properties, and biological effects that it is important to reexamine these foundational assumptions for nanocolloids. Gold nanorods (AuNRs) are generally presumed to have nearly perfect geometry of a cylinder and therefore are centrosymmetric. We show that AuNRs, in fact, have a built-in electrostatic potential gradient on their surface and behave as noncentrosymmetric particles...
February 2018: Science Advances
Yuta Goto, Atsushi Okamoto, Atsushi Shibukawa, Kazuhisa Ogawa, Akihisa Tomita
We propose a virtual phase conjugation (VPC) based optical tomography (VPC-OT) for realizing single-shot optical tomographic imaging systems. Using a computer-based numerical beam propagation, the VPC combines pre-modulation and post-demodulation of the probe beam's wavefront, which provides an optical sectioning capability for resolving the depth coordinates. In VPC-OT, the physical optical microscope system and VPC are coupled using digital holography. Therefore, in contrast to conventional optical tomographic imaging (OTI) systems, this method does not require additional elements such as low-coherence light sources or confocal pinholes...
February 19, 2018: Optics Express
Gili Dardikman, Gyanendra Singh, Natan T Shaked
We present a new four-dimensional phase unwrapping approach for time-lapse quantitative phase microscopy, which allows reconstruction of optically thick objects that are optically thin in a certain temporal point and angular view. We thus use all four dimensions of the dynamic quantitative phase profile acquired, including the angular dimension and the temporal dimension, in addition to the x-y dimensions. We first demonstrate the capabilities of this algorithm on simulative data, enabling the quantification of the reconstruction quality relative to both the ground truth and existing unwrapping approaches...
February 19, 2018: Optics Express
Haiyan Ou, Yong Wu, Edmund Y Lam, Bing-Zhong Wang
This paper presents a method to identify the axial location of targets in an optical scanning holography (OSH) system. By combining time reversal (TR) technique with the multiple signal classification (MUSIC) method in OSH, axial location can be detected with high resolution. Both simulation and experimental work have been carried out to verify the feasibility of the proposed work.
February 19, 2018: Optics Express
Yifeng Shao, Xingyuan Lu, Sander Konijnenberg, Chengliang Zhao, Yangjian Cai, H Paul Urbach
The complete characterization of spatial coherence is extremely difficult because the mutual coherence function (MCF) is a complex-valued function of four independent Cartesian coordinates. This difficulty limits the ability to control and to optimize the spatial coherence in a broad range of key applications. Here we propose an efficient and robust scheme for measuring the complete MCF of an arbitrary partially coherent beam using self-referencing holography, which does not require any prior knowledge or making any assumptions about the MCF...
February 19, 2018: Optics Express
Argha Mondal, Aaron Yevick, Lauren C Blackburn, Nikitas Kanellakopoulos, David G Grier
We introduce intermediate-plane holography, which substantially improves the ability of holographic trapping systems to project propagation-invariant modes of light using phase-only diffractive optical elements. Translating the mode-forming hologram to an intermediate plane in the optical train can reduce the need to encode amplitude variations in the field, and therefore complements well-established techniques for encoding complex-valued transfer functions into phase-only holograms. Compared to standard holographic trapping implementations, intermediate-plane holograms greatly improve diffraction efficiency and mode purity of propagation-invariant modes, and so increase their useful non-diffracting range...
February 19, 2018: Optics Express
Tatsuki Tahara, Xiangyu Quan, Reo Otani, Yasuhiro Takaki, Osamu Matoba
In this review, we introduce digital holographic techniques and recent progress in multidimensional sensing by using digital holography. Digital holography is an interferometric imaging technique that does not require an imaging lens and can be used to perform simultaneous imaging of multidimensional information, such as three-dimensional structure, dynamics, quantitative phase, multiple wavelengths and polarization state of light. The technique can also obtain a holographic image of nonlinear light and a three-dimensional image of incoherent light with a single-shot exposure...
February 17, 2018: Microscopy
Cuong M Nguyen, Dilband Muhammad, Hyuk-Sang Kwon
We describe a new method for recording spatially incoherent common-path off-axis color digital holograms. We present the theoretical and experimental evidence to demonstrate an incoherent common-path off-axis color digital holographic (ICOCH) system capable of capturing information from three-dimensional color objects under incoherent illumination, both in transmission and reflection modes. Fresnel incoherent correlation holography (FINCH), a common-path system, is a frequently used incoherent holography technique...
February 20, 2018: Applied Optics
Zhujun Shi, Mohammadreza Khorasaninejad, Yao-Wei Huang, Charles Roques-Carmes, Alexander Yutong Zhu, Wei Ting Chen, Vyshakh Sanjeev, Zhaowei Ding, Michele Tamagnone, Kundan Chaudhary, Robert Charles Devlin, Chengwei Qiu, Federico Capasso
In this paper, we report dispersion-engineered metasurfaces with distinct functionalities controlled by wavelength. Unlike previous approaches based on spatial multiplexing or vertical stacking of metasurfaces, we utilize a single phase profile with wavelength dependence encoded in the phase shifters' dispersion. We designed and fabricated a multiwavelength achromatic metalens (MAM) with achromatic focusing for blue (B), green (G), yellow (Y), and red (R) light; and two wavelength-controlled beam generators (WCBG): one focuses light with orbital angular momentum (OAM) states (l = 0,1,2) corresponding to three primary colors; the other produces ordinary focal spots (l = 0) for red and green light, while generating a vortex beam (l = 1) in the blue...
February 20, 2018: Nano Letters
Dakui Lin, Huoyao Chen, Zhengkun Liu, Kay Dietrich, Stefanie Kroker, Thomas Kaesebier, Ying Liu, Ernst-Bernhard Kley, Yilin Hong
Near-field holography (NFH) combined with electron beam lithography (EBL)-written phase masks is a promising method for the rapid realization of diffraction gratings with high resolution and high accuracy in line density distribution. We demonstrate a dynamic exposure method in which the grating substrate is shifted during pattern transfer. This reduces the effects of stitching errors, resulting in the decreased intensity of the optical stray light (i.e., Rowland ghosts). We demonstrate the intensity suppression of ghosts by 60%...
February 15, 2018: Optics Letters
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