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adaptative optics

Paolo Pozzi, Oleg Soloviev, Dean Wilding, Gleb Vdovin, Michel Verhaegen
We report on a universal sample-independent sensorless adaptive optics method, based on modal optimization of the second moment of the fluorescence emission from a point-like excitation. Our method employs a sample-independent precalibration, performed only once for the particular system, to establish the direct relation between the image quality and the aberration. The method is potentially applicable to any form of microscopy with epifluorescence detection, including the practically important case of incoherent fluorescence emission from a three dimensional object, through minor hardware modifications...
2018: PloS One
Flavio Esposito, Rajeev Ranjan, Stefania Campopiano, Agostino Iadicicco
In this work, we report about our recent results concerning the fabrication of Long Period Grating (LPG) sensors in several optical fibers, through the Electric Arc Discharge (EAD) technique. In particular, the following silica fibers with both different dopants and geometrical structures are considered: standard Ge-doped, photosensitive B/Ge codoped, P-doped, pure-silica core with F-doped cladding, Panda type Polarization-maintaining, and Hollow core Photonic crystal fiber. An adaptive platform was developed and the appropriate "recipe" was identified for each fiber, in terms of both arc discharge parameters and setup arrangement, for manufacturing LPGs with strong and narrow attenuation bands, low insertion losses, and short length...
March 20, 2018: Sensors
Marc-Olivier Baradez, Daniela Biziato, Enas Hassan, Damian Marshall
Cell therapies offer unquestionable promises for the treatment, and in some cases even the cure, of complex diseases. As we start to see more of these therapies gaining market authorization, attention is turning to the bioprocesses used for their manufacture, in particular the challenge of gaining higher levels of process control to help regulate cell behavior, manage process variability, and deliver product of a consistent quality. Many processes already incorporate the measurement of key markers such as nutrient consumption, metabolite production, and cell concentration, but these are often performed off-line and only at set time points in the process...
2018: Frontiers in Medicine
Pedro Mecê, Jessica Jarosz, Jean-Marc Conan, Cyril Petit, Kate Grieve, Michel Paques, Serge Meimon
To evaluate the contribution of fixational eye movements to dynamic aberration, 50 healthy eyes were examined with an original custom-built Shack-Hartmann aberrometer, running at a temporal frequency of 236Hz, with 22 lenslets across a 5mm pupil, synchronized with a 236Hz pupil tracker. A comparison of the dynamic behavior of the first 21 Zernike modes (starting from defocus) with and without digital pupil stabilization, on a 3.4s sequence between blinks, showed that the contribution of fixational eye movements to dynamic aberration is negligible...
February 1, 2018: Biomedical Optics Express
David Alonso-Caneiro, Danuta M Sampson, Avenell L Chew, Michael J Collins, Fred K Chen
Adaptive optics flood illumination ophthalmoscopy (AO-FIO) allows imaging of the cone photoreceptor in the living human retina. However, clinical interpretation of the AO-FIO image remains challenging due to suboptimal quality arising from residual uncorrected wavefront aberrations and rapid eye motion. An objective method of assessing image quality is necessary to determine whether an AO-FIO image is suitable for grading and diagnostic purpose. In this work, we explore the use of focus measure operators as a surrogate measure of AO-FIO image quality...
February 1, 2018: Biomedical Optics Express
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
Fernanda Ferruzzi Lima, Constantino Fernandes Neto, José H Rubo, Gildo Coelho Santos, Maria Jacinta Moraes Coelho Santos
STATEMENT OF PROBLEM: Factors that may affect the marginal adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) restorations include preparation design, impression technique, and CAD-CAM system. The influence of impression technique and preparation design on CAD-CAM partial coverage restorations has not been fully addressed. PURPOSE: The purpose of this in vitro study was to investigate the influence of direct and indirect digital impression techniques and 2 preparation designs on the marginal adaptation of CAD-CAM onlays...
March 15, 2018: Journal of Prosthetic Dentistry
Jianjun Meng, Zhong Li, Hongjian Li, Jianbin Zhu, Hongbo Yu
Cortices are non-uniform in their capacity for adaptive changes. In cat area 17, pinwheel centers of the orientation map demonstrated much greater selectivity shifts after the orientation adaptation than the iso-orientation domains (Dragoi et al., 2001a). However, whether this heterogeneity exists in other visual cortical regions remains unclear. Similar to area 17, area 21a neurons in cats are well known to be functionally clustered according to their orientation preference in iso-orientation domains that converge at pinwheel centers but with a higher pinwheel density (Huang et al...
March 14, 2018: Neuroscience
Ryutaro Tomita, Tetsuju Sekiryu, Hiroaki Shintake, Kuniharu Saito
PURPOSE: To report a 67-year-old woman with polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome, showing bilateral serous retinal detachment. The retinal lesion was evaluated by multimodal imaging using spectral domain optical coherence tomography and an adaptive optics (AO) camera. METHODS: A case report. RESULTS: Optical coherence tomography showed hyperreflective foci mainly in the inner retina in both eyes...
March 15, 2018: Retinal Cases & Brief Reports
Mathias Reisbeck, Lukas Richter, Michael Johannes Helou, Stephan Arlinghaus, Birgit Anton, Ignas van Dommelen, Mario Nitzsche, Michael Baßler, Barbara Kappes, Oliver Friedrich, Oliver Hayden
Time-of-flight (TOF) magnetic sensing of rolling immunomagnetically-labeled cells offers great potential for single cell function analysis at the bedside in even optically opaque media, such as whole blood. However, due to the spatial resolution of the sensor and the low flow rate regime required to observe the behavior of rolling cells, the concentration range of such a workflow is limited. Potential clinical applications, such as testing of leukocyte function, require a cytometer which can cover a cell concentration range of several orders of magnitude...
March 12, 2018: Biosensors & Bioelectronics
David L Georgeson, Byron H Christiansen
Idaho National Laboratory transitioned from an external dosimetry system reliant on thermoluminescent dosimeters to one that uses optically stimulated luminescence dosimeters in 2010. This change not only affected the dosimeters worn by personnel, but those found in the nuclear-accident dosimeters used across Idaho National Laboratory. The elimination of on-site use and processing of thermoluminescent dosimeters impacted Idaho National Laboratory's ability to process nuclear-accident dosimeters in a timely manner...
March 14, 2018: Health Physics
Rihui Wu, Adrian Jarabo, Jinli Suo, Feng Dai, Yongdong Zhang, Qionghai Dai, Diego Gutierrez
Introducing polarization into transient imaging improves depth estimation in participating media, by discriminating reflective from scattered light transport and calculating depth from the former component only. Previous works have leveraged this approach under the assumption of uniform polarization properties. However, the orientation and intensity of polarization inside scattering media is nonuniform, both in the spatial and temporal domains. As a result of this simplifying assumption, the accuracy of the estimated depth worsens significantly as the optical thickness of the medium increases...
March 15, 2018: Optics Letters
Michael Hart
Daytime use of adaptive optics (AO) at large telescopes is hampered by shot noise from the bright sky background. Wave-front sensing may use a sodium laser guide star observed through a magneto-optical filter to suppress the background, but the laser beacon is not sensitive to overall image motion. To estimate that, laser-guided AO systems generally rely on light from the object itself, collected through the full aperture of the telescope. Daylight sets a lower limit to the brightness of an object that may be tracked at rates sufficient to overcome the image jitter...
March 15, 2018: Optics Letters
A V Dolzhich, S E Avetisov
PURPOSE: to assess the neurophysiological effect and clinical effectiveness of transcranial direct current stimulation in combination with drug therapy in amblyopic children. MATERIAL AND METHODS: The study involved 32 healthy children in the age of 5-12 years and 97 patients of the same age with refractive strabismic amblyopia. All study subjects underwent standard examination including ophthalmological (visometry, refractometry in normal conditions and in cycloplegia, biomicroscopy, ophthalmoscopy, type of vision), neurophysiological methods (determination of retinal electric sensitivity threshold, electric lability of optic nerve, amplitude and latency period of visual evoked potentials, electroencephalogram wave amplitudes, localization of peak electrical activity area of the cerebral cortex), assessment of neuropsychic development and estimation of mental development coefficient with age tests...
2018: Vestnik Oftalmologii
Anna C Tasolamprou, Thomas Koschny, Maria Kafesaki, Costas M Soukoulis
We present the design of a dielectric inverse photonic crystal structure that couples line-defect waveguide propagating modes into highly directional beams of controllable directionality. The structure utilizes a triangular lattice made of air holes drilled in an infinitely thick Si slab, and it is designed for operation in the near-infrared and optical regime. The structure operation is based on the excitation and manipulation of dark dielectric surface states, in particular on the tailoring of the dark states' coupling to outgoing radiation...
November 15, 2017: ACS Photonics
Kaitlyn A Sapoznik, Ting Luo, Alberto de Castro, Lucie Sawides, Raymond L Warner, Stephen A Burns
In adaptive optics scanning laser ophthalmoscope (AOSLO) systems, capturing multiply scattered light can increase the contrast of the retinal microvasculature structure, cone inner segments, and retinal ganglion cells. Current systems generally use either a split detector or offset aperture approach to collect this light. We tested the ability of a spatial light modulator (SLM) as a rapidly configurable aperture to use more complex shapes to enhance the contrast of retinal structure. Particularly, we varied the orientation of a split detector aperture and explored the use of a more complex shape, the half annulus, to enhance the contrast of the retinal vasculature...
March 1, 2018: Biomedical Optics Express
Kai Yu, Fei Shi, Enting Gao, Weifang Zhu, Haoyu Chen, Xinjian Chen
Optic nerve head (ONH) is a crucial region for glaucoma detection and tracking based on spectral domain optical coherence tomography (SD-OCT) images. In this region, the existence of a "hole" structure makes retinal layer segmentation and analysis very challenging. To improve retinal layer segmentation, we propose a 3D method for ONH centered SD-OCT image segmentation, which is based on a modified graph search algorithm with a shared-hole and locally adaptive constraints. With the proposed method, both the optic disc boundary and nine retinal surfaces can be accurately segmented in SD-OCT images...
March 1, 2018: Biomedical Optics Express
Pengyu Guan, Francesco Da Ros, Mads Lillieholm, Niels-Kristian Kjøller, Hao Hu, Kasper Meldgaard Røge, Michael Galili, Toshio Morioka, Leif Katsuo Oxenløwe
Optical data regeneration is attractive, due to its potential to increase transmission reach and data throughput in communication systems, and several interesting proposals have been made. However, efficient and scalable solutions for regeneration of multiple parallel wavelength channels have been elusive, constituting a key challenge, which must be overcome for optical regeneration to have any prospect of being adapted in actual communication systems. Here we report a scalable wavelength-division multiplexing (WDM) regeneration scheme for phase only regeneration, which satisfies the multichannel requirement, using a set of optical time-lens-based Fourier processors combined with a single phase-sensitive amplifier (PSA)...
March 13, 2018: Nature Communications
Yi Liu, Peng He, Yang Zhang, Xiangyu Zhang, Jun Liu, Yuguo Du
An effective one-pot procedure for enantiomerical synthesis of thiazole-containing amino acid (TCAA) has been established via a cascade disulfide cleavage / thiocarbonylation / intramolecular Staudinger Reduction / aza-Wittig / oxidation reaction. Starting from the commercially available amino acid building blocks, a number of TCAAs were prepared in good yields and in excellent optical purities. This method bears features of mild reaction conditions, wide substrate adaptability, and good functional group tolerance...
March 13, 2018: Journal of Organic Chemistry
John Quan Minh Nguyen, Melanie McWade, Giju Thomas, Bryce T Beddard, Jennifer L Herington, Bibhash C Paria, Herbert S Schwartz, Jennifer L Halpern, Ginger E Holt, Anita Mahadevan-Jansen
Fluorescence imaging is a well-established optical modality that has been used to localize and track fluorophores in vivo and has demonstrated great potential for surgical guidance. Despite the variety of fluorophores currently being researched, many existing intraoperative fluorescence imaging systems are specifically designed for a limited number of applications. We present a modular wide-field fluorescence overlay tissue imaging system for intraoperative surgical guidance that is comprised of commercially available standardized components...
April 2018: Journal of Medical Imaging
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