Search results for "Glasse"
showing 10 items of 88 documents
Anisometropia of spherical equivalent and astigmatism among myopes: a 23-year follow-up study of prevalence and changes from childhood to adulthood.
2017
Purpose To study anisometropia of spherical equivalent and astigmatism from the onset of myopia at school age to adulthood. Methods A total of 240 myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983–1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Examinations with subjective cyclopedic refraction were repeated 3 years later (follow-up 1) for 238 subjects and thereafter at the mean ages of 23.2 (follow-up 2) and 33.9 years (follow-up 3) for 178 and 134 subjects. After exclusions, the 102 subjects who attended all three follow-ups were included in the analyses. Corneal refractive power and astigmatism and anterior cha…
Refractive Lens Exchange with Foldable Toric Intraocular Lens
2009
To assess visual and refractive outcomes, and rotational stability after refractive lens exchange (RLE) with toric intraocular lens (IOL) implantation to correct ametropia and preexisting astigmatism.Prospective, nonrandomized, observational case series (self-controlled).This prospective, nonrandomized, and self-controlled study included 32 eyes of 19 consecutive patients with more than 1.00 diopter (D) of preexisting corneal astigmatism having RLE with AcrySof Toric IOL implantation (Alcon Laboratories Inc, Fort Worth, Texas, USA). Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refractive sphere, and keratometric and refractive cylinder were recorded preoperatively …
Astigmatism among myopics and its changes from childhood to adult age: a 23‐year follow‐up study
2014
Purpose To study the prevalence of and changes in astigmatism from the onset of myopia at school age. Methods Two hundred and forty myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983–1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Three annual examinations with subjective cycloplegic refraction were performed for 237–238 subjects. Subsequent examinations were performed at the mean ages of 23.2 and 33.9 years for 178 and 163 subjects, and the last examination, including data from prescriptions of different ophthalmologists, for 32 subjects. Corneal topography was studied at baseline, at the 3-year follow-up and at t…
Er3+-doped GeGaSbS glasses for mid-IR fibre laser application: Synthesis and rare earth spectroscopy
2008
International audience; With an infrared transparency extended to 10 µm, low multiphonon relaxation rates and suitable rare earth solubility, sulphide glasses in the Ge-Ga-Sb-S system allow radiative emission from rare earth ions in the mid-IR range. The Er3+ ion, widely studied in glass fibres for optical amplification at 1.5 µm, presents an interesting transition for mid-IR applications around 4.5 µm (4I9/2→ 4I11/2). Thus, the aim of this work is to evaluate the Er3+-doped Ge20Ga5Sb10S65 glass as a potential fibre laser source operating in the 3-5 µm mid-IR spectral region. For that purpose, absorption and emission spectra were recorded from visible to mid-IR and the radiative lifetimes o…
Photosensitivity and second harmonic generation in chalcogenide arsenic sulfide poled glasses
2011
International audience; The present work investigates the photoinduced Second Harmonic Generation processes in thermally poled arsenic sulfide glasses. SHG Maker fringes patterns associated to SHG kinetic measurements about illumination and Raman spectroscopy have been conducted in order to bring new information which confirm the combined influence of charge carriers and mid-range glass structural modification on the poling and the photodarkening mechanisms.
Chalcogenide Glasses Based on Germanium Disulfide for Second Harmonic Generation
2007
International audience; High second-order susceptibilities are created by thermal poling in bulk germanium disulfide based chalcogenide glasses. Experimental conditions of the poling treatment (temperature, voltage, time) were optimized for each glass composition. The second-order nonlinear signals were recorded by using the Maker fringes experiment and a second-order coefficient χ(2) up to 8 pm V-1 was measured in the Ge25Sb10S65 glass. This value is obtained using a simulation based on accurate knowledge of the thickness of the nonlinear layer. Two mechanisms are proposed to explain the creation of a nonlinear layer under the anode: the formation and the migration of charged defects towar…
Active shape correction of a thin glass/plastic x-ray mirror
2015
Optics for future X-ray telescopes will be characterized by very large aperture and focal length, and will be made of lightweight materials like glass or plastic in order to keep the total mass within acceptable limits. Optics based on thin slumped glass foils are currently in use in the NuSTAR telescope and are being developed at various institutes like INAF/OAB, aiming at improving the angular resolution to a few arcsec HEW. Another possibility would be the use of thin plastic foils, being developed at SAO and the Palermo University. Even if relevant progresses in the achieved angular resolution were recently made, a viable possibility to further improve the mirror figure would be the app…
From equilibrium to steady state: The transient dynamics of colloidal liquids under shear
2008
We investigate stresses and particle motion during the start up of flow in a colloidal dispersion close to arrest into a glassy state. A combination of molecular dynamics simulation, mode coupling theory and confocal microscopy experiment is used to investigate the origins of the widely observed stress overshoot and (previously not reported) super-diffusive motion in the transient dynamics. A link between the macro-rheological stress versus strain curves and the microscopic particle motion is established. Negative correlations in the transient auto-correlation function of the potential stresses are found responsible for both phenomena, and arise even for homogeneous flows and almost Gaussia…
Wave-Vector Dependence of the Dynamics in Supercooled Metallic Liquids
2020
Physical review letters 125(5), 055701 (2020). doi:10.1103/PhysRevLett.125.055701
Chalcogenide Microstructured Fibers for Infrared Systems, Elaboration, Modelization, and Characterization
2009
special issue " Fiber Optic Research in France " (Part III of III); International audience; Chalcogenide fibers present numerous possible applications in the IR field. For many applications, single mode fibers must be obtained. An original way is the realization of microstructured optical fibers (MOFs) with solid core. These fibers present a broad range of optical properties thanks to the high number of freedom degrees of their geometrical structure. In this context, we have developed MOFs for near and mid IR transmission with different geometries and properties such as multimode or endless single-mode operation, small or large mode area fibers. We have also investigated numerically the mai…