Read by QxMD icon Read

adaptative optics

Atanu Ghosh, Len Zheleznyak, Antoine Barbot, HaeWon Jung, Geunyoung Yoon
In the presence of optical blur at the fovea, blur adaptation can improve visual acuity (VA) and perceived image quality over time. However, little is known regarding blur adaptation in the peripheral retina. Here, we examined neural adaptation to myopic defocus at the fovea and parafovea (10° temporal retina) in both emmetropes and myopes. During the 60-min adaptation period, subjects (3 emmetropes and 3 myopes) watched movies with +2 diopters of defocus blur through a 6-mm artificial pupil in two separate, counter balanced sessions for each retinal location...
December 2, 2016: Vision Research
Thomas G Bifano, Joel A Kubby, Sylvain Gigan
No abstract text is available yet for this article.
December 1, 2016: Journal of Biomedical Optics
Zachary M Dong, Gadi Wollstein, Bo Wang, Joel S Schuman
Since the introduction of commercial optical coherence tomography (OCT) systems, the ophthalmic imaging modality has rapidly expanded and it has since changed the paradigm of visualization of the retina and revolutionized the management and diagnosis of neuro-retinal diseases, including glaucoma. OCT remains a dynamic and evolving imaging modality, growing from time-domain OCT to the improved spectral-domain OCT, adapting novel image analysis and processing methods, and onto the newer swept-source OCT and the implementation of adaptive optics (AO) into OCT...
December 1, 2016: Progress in Retinal and Eye Research
M L Cowan, J H Page, T Norisuye, D A Weitz
Dynamic sound scattering (DSS) is a powerful acoustic technique for investigating the motion of particles or other inclusions inside an evolving medium. In DSS, this dynamic information is obtained by measuring the field autocorrelation function of the temporal fluctuations of singly scattered acoustic waves. The technique was initially introduced 15 years ago, but its technical aspects were not adequately discussed then. This paper addresses the need for a more complete account of the method by describing in detail two different implementations of this sound scattering technique, one of which is specifically adapted to a common experimental situation in ultrasonics...
September 2016: Journal of the Acoustical Society of America
Shigeta Arichika, Akihito Uji, Tomoaki Murakami, Kiyoshi Suzuma, Norimoto Gotoh, Nagahisa Yoshimura
AIMS: To evaluate retinal arterial wall thickness (WT) using high-resolution retinal imaging in patients with type 2 diabetes and assess its correlation with risk factors for arteriosclerosis. METHODS: Outer diameter, inner diameter and WT of the retinal artery were measured using adaptive optics scanning laser ophthalmoscopy in 28 patients with type 2 diabetes without clinically apparent diabetic retinopathy and normal volunteers. Laboratory values and intima-media thickness (IMT) in the common carotid artery were measured...
December 2, 2016: British Journal of Ophthalmology
Peter J E M van der Linden, Marco Moretti Sala, Christian Henriquet, Matteo Rossi, Kenya Ohgushi, François Fauth, Laura Simonelli, Carlo Marini, Edmundo Fraga, Claire Murray, Jonathan Potter, Michael Krisch
We have developed a helium gas flow cryostat for use on synchrotron tender to hard X-ray beamlines. Very efficient sample cooling is achieved because the sample is placed directly in the cooling helium flow on a removable sample holder. The cryostat is compact and easy to operate; samples can be changed in less than 5 min at any temperature. The cryostat has a temperature range of 2.5-325 K with temperature stability better than 0.1 K. The very wide optical angle and the ability to operate in any orientation mean that the cryostat can easily be adapted for different X-ray techniques...
November 2016: Review of Scientific Instruments
O Meyer, O M Jones, J C Giacalone, J Y Pascal, D Raulin, H Xu, M H Aumeunier, R Baude, A Escarguel, C Gil, J H Harris, J-C Hatchressian, C C Klepper, S Larroque, Ph Lotte, Ph Moreau, B Pégourié, S Vartanian
The present work concerns the development of a W sources assessment system in the framework of the tungsten-W environment in steady state tokamak project that aims at equipping the existing Tore Supra device with a tungsten divertor in order to test actively cooled tungsten Plasma Facing Components (PFCs) in view of preparing ITER operation. The goal is to assess W sources and D recycling with spectral, spatial, and temporal resolution adapted to the PFCs observed. The originality of the system is that all optical elements are installed in the vacuum vessel and compatible with steady state operation...
November 2016: Review of Scientific Instruments
Lingjie Wu, Zuohua Tang, Xiaoyuan Feng, Xinghuai Sun, Wen Qian, Jie Wang, Lixin Jin, Jingxuan Jiang, Yufeng Zhong
The metabolic changes accompanied with adaptive plasticity in the visual cortex after early monocular visual loss were unclear. In this study, we detected the metabolic changes in bilateral visual cortex of normal (group A) and monocular blind macaque (group B) for studying the adaptive plasticity using multi-voxel proton magnetic resonance spectroscopy ((1)H-MRS) at 32 months after right optic nerve transection. Then, we compared the N-Acetyl aspartate (NAA)/Creatine (Cr), myoinositol (Ins)/Cr, choline (Cho)/Cr and Glx (Glutamate + glutamine)/Cr ratios in the visual cortex between two groups, as well as between the left and right visual cortex of group A and B...
December 1, 2016: Neurochemical Research
E Racine, G Hautvast, D Binnekamp, L Beaulieu
PURPOSE: To describe the principles and report on the performance of a novel real-time electromagnetic (EM) seed drop detection technology for permanent implants brachytherapy procedures. METHODS: A novel EM hollow needle prototype was recently developed by Philips. It possesses standard 3D tracking capability as well as a seed drop detection mechanism, both performed from a single custom built EM sensor. The detection mechanism is based on the magnetic permeability changes in the sensor as the seeds pass through...
December 2016: Medical Physics
Yeong-Min Ji, Hanju- Yeom, Jae-Hyeung Park
We propose a method that achieves efficient texture mapping in fully-analytic computer generated holograms based on triangular meshes. In computer graphics, the texture mapping is commonly used to represent the details of objects without increasing the number of the triangular meshes. In fully-analytic triangular-mesh-based computer generated holograms, however, those methods cannot be directly applied because each mesh cannot have arbitrary amplitude distribution inside the triangular mesh area in order to keep the analytic representation...
November 28, 2016: Optics Express
Gaël Nardin, Tristan Colomb, Yves Emery, Christophe Moser
We demonstrate the potential of spatial light modulators for the spectral control of a broadband source in digital holographic microscopy. Used in a 'pulse-shaping' geometry, the spatial light modulator provides a versatile control over the bandwidth and wavelength of the light source. The control of these properties enables adaptation to various experimental conditions. As a first application, we show that the source bandwidth can be adapted to the off-axis geometry to provide quantitative phase imaging over the whole field of view...
November 28, 2016: Optics Express
Fei Sun, Zhaoliang Cao, Yukun Wang, Caihua Zhang, Xingyun Zhang, Yong Liu, Quanquan Mu, Li Xuan
Almost all the deformable mirror (DM) based adaptive optics systems (AOSs) used on large aperture telescopes work at the infrared waveband due to the limitation of the number of actuators. To extend the imaging waveband to the visible, we propose a DM and Liquid crystal wavefront corrector (DM/LCWFC) combination AOS. The LCWFC is used to correct the high frequency aberration corresponding to the visible waveband and the aberrations of the infrared are corrected by the DM. The calculated results show that, to a 10 m telescope, DM/LCWFC AOS which contains a 1538 actuators DM and a 404 × 404 pixels LCWFC is equivalent to a DM based AOS with 4057 actuators...
November 28, 2016: Optics Express
Lei Huang, Heejoo Choi, Wenchuan Zhao, Logan R Graves, Dae Wook Kim
We report an adaptive interferometric null testing method for overcoming the dynamic range limitations of conventional null testing approaches during unknown freeform optics metrology or optics manufacturing processes that require not-yet-completed surface measurements to guide the next fabrication process. In the presented adaptive method, a deformable mirror functions as an adaptable null component for an unknown optical surface. The optimal deformable mirror's shape is determined by the stochastic parallel gradient descent algorithm and controlled by a deflectometry system...
December 1, 2016: Optics Letters
Sarang Pendharker, Swapnali Shende, Ward Newman, Stephen Ogg, Neda Nazemifard, Zubin Jacob
Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave...
December 1, 2016: Optics Letters
Erik P Schartner, Matthew R Henderson, Malcolm Purdey, Deepak Dhatrak, Tanya M Monro, P Grantley Gill, David F Callen
Intraoperative detection of tumorous tissue is an important unresolved issue for cancer surgery. Difficulty in differentiating between tissue types commonly results in the requirement for additional surgeries to excise unremoved cancer tissue or alternatively in the removal of excess amounts of healthy tissue. Although pathologic methods exist to determine tissue type during surgery, these methods can compromise postoperative pathology, have a lag of minutes to hours before the surgeon receives the results of the tissue analysis, and are restricted to excised tissue...
December 1, 2016: Cancer Research
Xiangmin Fu, Yongze Wang, Jinhua Wang, Erin Garza, Ryan Manow, Shengde Zhou
D(-)-lactic acid is needed for manufacturing of stereo-complex poly-lactic acid polymer. Large scale D-lactic acid fermentation, however, has yet to be demonstrated. A genetically engineered Escherichia coli strain, HBUT-D, was adaptively evolved in a 15% calcium lactate medium for improved lactate tolerance. The resulting strain, HBUT-D15, was tested at a lab scale (7 L) by fed-batch fermentation with up to 200 g L(-1) of glucose, producing 184-191 g L(-1) of D-lactic acid, with a volumetric productivity of 4...
November 29, 2016: Journal of Industrial Microbiology & Biotechnology
K V Jovan Jose, Krishnan Raghavachari
The molecules-in-molecules (MIM) fragment-based method has recently been adapted to evaluate the chiroptical (vibrational circular dichroism [VCD] and Raman optical activity [ROA]) spectra of large molecules such as peptides. In the MIM-VCD and MIM-ROA methods, the relevant higher energy derivatives of the parent molecule are assembled from the corresponding derivatives of smaller fragment subsystems. In addition, the missing long-range interfragment interactions are accounted at a computationally less expensive level of theory (MIM2)...
December 2016: Chirality
Shaozhen Song, Jingjiang Xu, Ruikang K Wang
Current optical coherence tomography (OCT) imaging suffers from short ranging distance and narrow imaging field of view (FOV). There is growing interest in searching for solutions to these limitations in order to expand further in vivo OCT applications. This paper describes a solution where we utilize an akinetic swept source for OCT implementation to enable ~10 cm ranging distance, associated with the use of a wide-angle camera lens in the sample arm to provide a FOV of ~20 x 20 cm(2). The akinetic swept source operates at 1300 nm central wavelength with a bandwidth of 100 nm...
November 1, 2016: Biomedical Optics Express
Junlei Zhao, Fei Xiao, Jian Kang, Haoxin Zhao, Yun Dai, Yudong Zhang
Measurement of the double-pass (DP) point-spread function (PSF) can provide an objective and non-invasive method for estimating intraocular scatter in the human eye. The objective scatter index (OSI), which is calculated from the DP PSF images, is commonly used to quantify intraocular scatter. In this article, we simulated the effect of higher-order ocular aberrations on OSI, and the results showed that higher-order ocular aberrations had a significant influence on OSI. Then we developed an adaptive optics DP PSF measurement system (AO-DPPMS) which was capable of correcting ocular aberrations up to eighth-order radial Zernike modes over a 6...
November 1, 2016: Biomedical Optics Express
Omer P Kocaoglu, Zhuolin Liu, Furu Zhang, Kazuhiro Kurokawa, Ravi S Jonnal, Donald T Miller
Cone photoreceptors undergo a daily cycle of renewal and shedding of membranous discs in their outer segments (OS), the portion responsible for light capture. These physiological processes are fundamental to maintaining photoreceptor health, and their dysfunction is associated with numerous retinal diseases. While both processes have been extensively studied in animal models and postmortem eyes, little is known about them in the living eye, in particular human. In this study, we report discovery of the optical signature associated with disc shedding using a method based on adaptive optics optical coherence tomography (AO-OCT) in conjunction with post-processing methods to track and monitor individual cone cells in 4D...
November 1, 2016: Biomedical Optics Express
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"