keyword
MENU ▼
Read by QxMD icon Read
search

WaveFront

keyword
https://www.readbyqxmd.com/read/28332611/visible-light-focusing-flat-lenses-based-on-hybrid-dielectric-metal-metasurface-reflector-arrays
#1
Qingbin Fan, Pengcheng Huo, Daopeng Wang, Yuzhang Liang, Feng Yan, Ting Xu
Conventional metasurface reflector-arrays based on metallic resonant nanoantenna to control the wavefront of light for focusing always suffer from strong ohmic loss at optical frequencies. Here, we overcome this challenge by constructing a non-resonant, hybrid dielectric-metal configuration consisting of TiO2 nanofins associated with an Ag reflector substrate that provides a broadband response and high polarization conversion efficiency in the visible range. A reflective flat lens based on this configuration shows an excellent focusing performance with the spot size close to the diffraction limit...
March 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28324609/optical-coherence-microscopy
#2
Rainer A Leitgeb
The present chapter aims at demonstrating the capabilities of optical coherence microscopy (OCM) for applications in biomedical imaging. We furthermore review the functional imaging capabilities of OCM focusing on lable-free optical angiography. We conclude with a section on digital wavefront control and a short outlook on future developments, in particular for contrast enhancement techniques.
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28324117/accommodation-responds-to-optical-vergence-and-not-defocus-blur-alone
#3
Antonio J Del Águila-Carrasco, Iván Marín-Franch, Paula Bernal-Molina, José J Esteve-Taboada, Philip B Kruger, Robert Montés-Micó, Norberto López-Gil
Purpose: To determine whether changes in wavefront spherical curvature (optical vergence) are a directional cue for accommodation. Methods: Nine subjects participated in this experiment. The accommodation response to a monochromatic target was measured continuously with a custom-made adaptive optics system while astigmatism and higher-order aberrations were corrected in real time. There were two experimental open-loop conditions: vergence-driven condition, where the deformable mirror provided sinusoidal changes in defocus at the retina between -1 and +1 diopters (D) at 0...
March 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28323304/characterization-of-wavefront-errors-in-mouse-cranial-bone-using-second-harmonic-generation
#4
Kayvan Forouhesh Tehrani, Peter Kner, Luke J Mortensen
No abstract text is available yet for this article.
March 1, 2017: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/28322268/universal-sensitivity-of-speckle-intensity-correlations-to-wavefront-change-in-light-diffusers
#5
KyungDuk Kim, Hyeonseung Yu, KyeoReh Lee, YongKeun Park
Here, we present a concept based on the realization that a complex medium can be used as a simple interferometer. Changes in the wavefront of an incident coherent beam can be retrieved by analyzing changes in speckle patterns when the beam passes through a light diffuser. We demonstrate that the spatial intensity correlations of the speckle patterns are independent of the light diffusers, and are solely determined by the phase changes of an incident beam. With numerical simulations using the random matrix theory, and an experimental pressure-driven wavefront-deforming setup using a microfluidic channel, we theoretically and experimentally confirm the universal sensitivity of speckle intensity correlations, which is attributed to the conservation of optical field correlation despite multiple light scattering...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28321943/development-of-3d-intramural-and-surface-potentials-in-the-lv-microstructural-basis-of-preferential-transmural-conduction
#6
Bryan J Caldwell, Mark L Trew, Ian J Legrice, Bruce H Smaill
INTRODUCTION: Extracellular potentials measured on the heart surfaces are used to infer events that originate deep within the heart wall. We have reconstructed intramural potentials in three dimensions for the first time, and compare these with epicardial and endocardial surface potentials and cardiac microstructure. METHODS AND RESULTS: Extracellular potentials from intramural point stimulation were measured from a high density 3D electrode array in the in vivo pig LV...
March 21, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28317927/observation-of-acoustic-dirac-like-cone-and-double-zero-refractive-index
#7
Marc Dubois, Chengzhi Shi, Xuefeng Zhu, Yuan Wang, Xiang Zhang
Zero index materials where sound propagates without phase variation, holds a great potential for wavefront and dispersion engineering. Recently explored electromagnetic double zero index metamaterials consist of periodic scatterers whose refractive index is significantly larger than that of the surrounding medium. This requirement is fundamentally challenging for airborne acoustics because the sound speed (inversely proportional to the refractive index) in air is among the slowest. Here, we report the first experimental realization of an impedance matched acoustic double zero refractive index metamaterial induced by a Dirac-like cone at the Brillouin zone centre...
March 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28317683/new-technique-for-femtosecond-laser-creation-of-clear-corneal-incisions-for-cataract-surgery
#8
Sebastiano Serrao, Daniela Giannini, Domenico Schiano-Lomoriello, Giuseppe Lombardo, Marco Lombardo
PURPOSE: To evaluate the changes in corneal topography and corneal higher-order wavefront aberrations with the use of a new technique in which clear corneal incisions (CCIs) for cataract surgery are created with a femtosecond laser. SETTING: IRCCS Fondazione G.B. Bietti, Rome, Italy. DESIGN: Prospective randomized case series. METHODS: Cataract surgery patients were randomized into 2 groups. In the study group, a 3-plane CCI was created with a femtosecond laser...
January 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28317678/quality-of-vision-after-wavefront-guided-laser-in-situ-keratomileusis-or-photorefractive-keratectomy-contralateral-eye-evaluation
#9
Michele D Lee, Edward E Manche
PURPOSE: To compare quality of vision between laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). SETTING: Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California, USA. DESIGN: Prospective randomized case series. METHODS: Patients had refractive surgery, with 1 eye treated with LASIK and the other with PRK. Eyes were randomized for dominance. The patients completed a questionnaire assessing quality of vision in each eye at the initial visit and 1, 3, 6, and 12 months postoperatively...
January 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28303580/synteyes-ktc-higher-order-statistical-eye-model-for-developing-keratoconus
#10
Jos J Rozema, Pablo Rodriguez, Irene Ruiz Hidalgo, Rafael Navarro, Marie-José Tassignon, Carina Koppen
PURPOSE: To present and validate a stochastic eye model for developing keratoconus to e.g. improve optical corrective strategies. This could be particularly useful for researchers that do not have access to original keratoconic data. METHODS: The Scheimpflug tomography, ocular biometry and wavefront of 145 keratoconic right eyes were collected. These data were processed using principal component analysis for parameter reduction, followed by a multivariate Gaussian fit that produces a stochastic model for keratoconus (SyntEyes KTC)...
March 17, 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28302854/revealing-the-subfemtosecond-dynamics-of-orbital-angular-momentum-in-nanoplasmonic-vortices
#11
G Spektor, D Kilbane, A K Mahro, B Frank, S Ristok, L Gal, P Kahl, D Podbiel, S Mathias, H Giessen, F-J Meyer Zu Heringdorf, M Orenstein, M Aeschlimann
The ability of light to carry and deliver orbital angular momentum (OAM) in the form of optical vortices has attracted much interest. The physical properties of light with a helical wavefront can be confined onto two-dimensional surfaces with subwavelength dimensions in the form of plasmonic vortices, opening avenues for thus far unknown light-matter interactions. Because of their extreme rotational velocity, the ultrafast dynamics of such vortices remained unexplored. Here we show the detailed spatiotemporal evolution of nanovortices using time-resolved two-photon photoemission electron microscopy...
March 17, 2017: Science
https://www.readbyqxmd.com/read/28296044/biolens-behavior-of-rbcs-under-optically-induced-mechanical-stress
#12
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
https://www.readbyqxmd.com/read/28295087/high-numerical-aperture-na%C3%A2-%C3%A2-0-92-objective-lens-for-imaging-and-addressing-of-cold-atoms
#13
Carsten Robens, Stefan Brakhane, Wolfgang Alt, Felix Kleißler, Dieter Meschede, Geol Moon, Gautam Ramola, Andrea Alberti
We have designed, built, and characterized a high-resolution objective lens that is compatible with an ultrahigh vacuum environment. The lens system exploits the principle of the Weierstrass sphere solid immersion lens to reach a numerical aperture (NA) of 0.92. Tailored to the requirements of optical lattice experiments, the objective lens features a relatively long working distance of 150 μm. Our two-lens design is remarkably insensitive to mechanical tolerances in spite of the large NA. Additionally, we demonstrate the application of a tapered optical fiber tip, as used in scanning near-field optical microscopy, to measure the point spread function (PSF) of a high NA optical system...
March 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28295068/two-photon-shack-hartmann-wavefront-sensor
#14
Fei Xia, David Sinefeld, Bo Li, Chris Xu
We introduce a simple wavefront sensing scheme for aberration measurement of pulsed laser beams in near-infrared wavelengths (<2200  nm), where detectors are not always available or are very expensive. The method is based on two-photon absorption in a silicon detector array for longer wavelengths detection. We demonstrate the simplicity of such implementations with a commercially available Shack-Hartmann wavefront sensor and discuss the detection sensitivity of this method.
March 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28285388/effect-of-iris-registration-on-visual-outcome-in-wavefront-guided-lasek-for-myopic-astigmatism
#15
Jong Joo Lee, Mee Kum Kim, Won Ryang Wee
PURPOSE: This study aimed to investigate the effect of iris registration (IR) on visual outcomes in wavefront-guided LASEK for myopic astigmatism. METHODS: The retrospective chart review was performed for wavefront-guided LASEK using VISX Star S4 in patients with myopic astigmatism (cylinder ≥ 1.00 diopter[D]). Eyes were divided into IR group (LASEK with IR at the time of surgery) and Non-IR group (LASEK without IR system + failed-IR engagement during LASEK)...
March 11, 2017: International Ophthalmology
https://www.readbyqxmd.com/read/28282592/development-of-an-automaton-model-of-rotational-activity-driving-atrial-fibrillation
#16
E J Ciaccio, A B Biviano, E Y Wan, N S Peters, H Garan
BACKGROUND: Atrial fibrillation (AF) is difficult to treat effectively, owing to uncertainty in where to best ablate to eliminate arrhythmogenic substrate. A model providing insight into the electrical activation events would be useful to guide catheter ablation strategy. Method A two-dimensional, 576×576 node automaton was developed to simulate atrial electrical activity. The substrate field was altered by the presence of differing refractory period at varying locations. Fibrosis was added in the form of short, randomly positioned lines of conduction block...
March 2, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28281302/compensation-of-corneal-oblique-astigmatism-by-internal-optics-a-theoretical-analysis
#17
Tao Liu, Larry N Thibos
PURPOSE: Oblique astigmatism is a prominent optical aberration of peripheral vision caused by oblique incidence of rays striking the refracting surfaces of the cornea and crystalline lens. We inquired whether oblique astigmatism from these two sources should be expected, theoretically, to have the same or opposite signs across the visual field at various states of accommodation. METHODS: Oblique astigmatism was computed across the central visual field for a rotationally-symmetric schematic-eye using optical design software...
March 9, 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28271004/influence-of-wave-front-sampling-in-adaptive-optics-retinal-imaging
#18
Marie Laslandes, Matthias Salas, Christoph K Hitzenberger, Michael Pircher
A wide range of sampling densities of the wave-front has been used in retinal adaptive optics (AO) instruments, compared to the number of corrector elements. We developed a model in order to characterize the link between number of actuators, number of wave-front sampling points and AO correction performance. Based on available data from aberration measurements in the human eye, 1000 wave-fronts were generated for the simulations. The AO correction performance in the presence of these representative aberrations was simulated for different deformable mirror and Shack Hartmann wave-front sensor combinations...
February 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28268888/detection-of-the-propagating-direction-of-electrical-wavefront-in-atrial-fibrillation
#19
Dongping Du, Yuncheng Du
Atrial Fibrillation (AF) is one of the most common sustained arrhythmia, which can increase the risk of heart failure and stroke. Understanding the complex electrical dynamics of AF and correctly targeting AF sources for ablation therapies remain challenging in clinical practice. This is due to the incapability to reconstruct the electrical dynamic of AF, and lack of efficient approach for AF source identification. This paper builds a multi-sale framework for modeling of the abnormal electrical propagation in AF initiated by triggers from Pulmonary Veins (PVs)...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268887/maximum-likelihood-cardiac-conduction-velocity-estimation-from-sequential-mapping-in-the-presence-of-activation-time-noise-with-unknown-variances
#20
Mohammad Hassan Shariat, Saeed Gazor, Damian Redfearn
The cardiac conduction velocity (CV) can be estimated by analysing the activation times (ATs) and the locations of the electrodes that are used for the intracardiac electrogram (IEGM) recording. Here, we study the problem of the CV estimation in sequential mapping without using any independent electrogram as a time alignment reference. We assume that the IEGMs are sequentially recorded from several sites, where at each site, at least two of the catheter's electrodes are in contact with the cardiac tissue. We consider the planar wavefront with stable CV that propagates within the recording sites throughout our data collection period...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
keyword
keyword
104439
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"