Search results for "Optica"
showing 10 items of 7696 documents
Durcissement aux radiations de fibres optiques dopées terres rares et d'amplificateurs 'a fibres optiques
2011
National audience; Cette étude vise à comprendre les effets d'une irradiation Ȗ sur les propriétés optiques et structurales des fibres dopées aux Terres Rares en vue de leur utilisation dans des amplificateurs à fibre réalisés pour des applications spatiales. L'enjeu majeur de durcissement de ces composants est abordé via des techniques telles que le chargement en hydrogène et/ou le co-dopage au Cérium du cœur des fibres optiques. L'identification des centres responsables de l'atténuation induite par irradiation et la compréhension des mécanismes de dégradation mis en jeu sont des étapes indispensables au développement de ces fibres.
HYPERBLEND: SIMULATING SPECTRAL REFLECTANCE AND TRANSMITTANCE OF LEAF TISSUE WITH BLENDER
2022
Abstract. Remotely sensing vegetation condition and health hazards requires modeling the connection of plants’ biophysical and biochemical parameters to their spectral response. Even though many models exist already, the field suffers from lack of access to program code. In this study, we will assess the feasibility of open-source 3D-modeling and rendering software Blender in simulating hyperspectral reflectance and transmittance of leaf tissue to serve as a base for a more advanced large-scale simulator. This is the first phase of a larger HyperBlend project, which will provide a fully open-source, canopy scale leaf optical properties model for simulating remotely sensed hyperspectral imag…
Retinal Vascular Assessment in Psoriasis: A Multicenter Study
2021
PurposeTo investigate the vascular status of the macula in psoriasis patients without history of ocular inflammation by Optical Coherence Tomography Angiography (OCTA).MethodsThis prospective cross-sectional multicenter study included 55 psoriasis patients and 55 control healthy subjects. A complete eye examination and 6 mm × 6 mm OCTA imaging were performed. Retinal vascular status was evaluated by analyzing vascular density (VD) of superficial vascular plexus (superficial wVD) and deep vascular plexuses (deep wVD) in a 6 mm × 6 mm area and in foveal (superficial fVD and deep fVD) and parafoveal sectors (superficial pVD and deep pVD). In addition, foveal thickness (FT) and foveal avascular…
Retinal abnormalities in multiple sclerosis patients with associated chronic cerebrospinal venous insufficiency
2012
Optical coherence tomography (OCT) is a non-invasive method for the assessment of optic nerve fibers and retinal ganglion cells. This study was aimed at the assessment of retinal abnormalities in multiple sclerosis patients in the context of chronic cerebrospinal venous insufficiency using OCT of the retina and the optic nerve. We examined 239 multiple sclerosis (MS) patients, including 220 patients with associated chronic cerebrospinal venous insufficiency and 19 MS patients without venous pathology. The following OCT parameters were assessed: average ganglion cell complex thickness, global loss volume, focal loss volume and average retinal nerve fibre layer thickness. Abnormalities in the…
Macular Structure–Function Relationships of All Retinal Layers in Primary Open-Angle Glaucoma Assessed by Microperimetry and 8 × 8 Posterior Pole Ana…
2021
Purpose: The aim of this study is too correlate the sensitivity and thickness values of intraretinal layers at macula in healthy eyes and primary open-angle glaucoma (POAG) eyes. Methods: The thickness of different intraretinal segmentations was estimated by means of optical coherence tomography (OCT) Spectralis (Heidelberg, Engineering, Inc., Heidelberg, Germany) with the posterior pole analysis program 8 × 8 in 91 eyes from 91 patients (60 with glaucoma and 31 healthy patients). Macular sensitivity was also measured with an MP-1 microperimeter (Nidek Instruments, Inc Padova, Italy) with a customized, 36-stimulus pattern adjusted to an anatomical correspondence with the OCT grid. Correlati…
The Influence of Nanoparticle Shape on Protein Corona Formation
2020
Nanoparticles have become an important utility in many areas of medical treatment such as targeted drug and treatment delivery as well as imaging and diagnostics. These advances require a complete understanding of nanoparticles' fate once placed in the body. Upon exposure to blood, proteins adsorb onto the nanoparticles surface and form a protein corona, which determines the particles' biological fate. This study reports on the protein corona formation from blood serum and plasma on spherical and rod‐shaped nanoparticles. These two types of mesoporous silica nanoparticles have identical chemistry, porosity, surface potential, and size in the y ‐dimension, one being a sphere and the other a …
Room temperature synthesis of lanthanum phosphates with controlled nanotexture as host for Ln(III) through the Epoxide Route
2022
AbstractHerein, the Epoxide Route, a one-pot room temperature alkalinization method based on the reaction between a nucleophile and an epoxide, has been employed to synthesize LaPO4 in the form of a Rhabdophane phase. The intrinsic features of this synthetic approach allow the reaction to be followed by pH monitoring, making possible the identification of the different precipitation steps involved in the formation of the solid. Once demonstrated the effectiveness of this chemical methodology, the size and shape of the LaPO4 particles were controlled by varying the identity and proportion of the organic co-solvents employed to perform the reaction. By these means, crystalline particles with …
FIBRE OPTICAL COUPLER SIMULATION BY COMSOL MULTIPHYSICS SOFTWARE
2022
Funding: The research has been supported by the European Regional Development Fund project No.1.1.1.1/18/A/068. The Institute of Solid State Physics, University of Latvia as a Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.
Photoluminescence properties of point defects in Ge-doped fibers and preforms
2008
International audience; The optical properties of Ge-related point defects are often the most important parameter for the performances of silica based optical fibers. On one side their presence is often detrimental for the light transmission, on the other side some defect typologies exhibit modifications under radiation exposure thus offering the peculiar property of photosensitivity that is exploited to build technologically relevant devices such as fiber Bragg gratings.