Search results for "òptica"
showing 10 items of 205 documents
Òptica Fisiològica : Temari Òptica Fisiològica
2017
El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València Temari de l'assignatura de primer del Grau d'Òptica i Optometria de la Universitat de València Content of the Phisiologycal Optics subject. In the first year of the Degree of Optics and Optometry at University od Valencia
Indoor free space optics link under the weak turbulence regime: Measurements and model validation
2015
In this study, the authors present the measurements performed on a free space optics (FSO) communications link using an indoor atmospheric chamber. In particular, the authors have generated several different optical turbulence conditions, demonstrating how even the weak turbulence regime can strongly affect the FSO link performance. The authors have carried out an in-depth analysis of the data collected during the measurements, and calculated the turbulence strength (i.e. scintillation index and Rytov variance) and the important performance metrics (i.e. the Q-factor and bit error rate) to evaluate the FSO link quality. Moreover, the authors have tested, for the first time, an appositely de…
Refractometric sensor based on whispering-gallery modes of thin capillarie.
2009
Whispering-gallery modes resonances of submicron wall thickness capillaries exhibit very large wavelength shifts as a function of the refractive index of the medium that fills the inside. The sensitivity to refractive index changes is larger than in other optical microcavities as microspheres, microdisks and microrings. The outer surface where total internal reflection takes place remains always in air, enabling the measure of refractive index values higher than the refractive index of the capillary material. The fabrication of capillaries with submicron wall thickness has required the development of a specific technique. A refractometer with a response higher than 390 nm per refractive ind…
Apunts de teoria de Física II. Òptica geomètrica
2014
El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València. Aquest material docent son apunts de teoria que hem preparat per a l'assignatura obligatòria "Física II. Òptica Geomètrica", impartida en el Grau d'Òptica i Optometria. This theory notes have been prepared for the subject "Physics II. Geometrical Optics," included in the Degree in Optics and Optometry.
Presbyopia and the aging eye: Existing refractive approaches and their potential impact on dry eye signs and symptoms.
2020
Every part of the human body is subject to aging, including the eye. Increased prevalence of dry eye disease with age is widely acknowledged: aging threatens ocular surface homeostasis, altering the normal functioning of the lacrimal functional unit and potentially leading to signs and symptoms of dry eye. Parallelly, two additional degenerative processes take place within the crystalline lens, leading to presbyopia and cataractogenesis. With continuously increasing life expectancies both conditions are expected to impact society further. Correction strategies for presbyopia and cataracts either directly or indirectly challenge ocular surface additionally. On one hand, contact lens presbyop…
De la necesidad de diseñar pruebas optométricas adaptadas para el seguimiento visual en patologías
2019
Objetivo Valorar si las pruebas convencionales de análisis de la visión del color son válidas en pacientes con ataxia telangiectasia (AT). Metodología Se evaluó la visión cromática en el ojo dominante de 6 pacientes con AT, y de 10 pacientes de grupo control. En todos ellos se usó para ello el test de Farnsworth-Munsell de 100 tonos. Se analizaron los parámetros TES y PTES, así como el tiempo necesario empleado para realizar las pruebas. En tres pacientes con AT se midieron ambos ojos para valorar los efectos de aprendizaje y fatiga. Resultados En los pacientes con AT, se observaron anomalías en la visión cromática generalizadas comparadas con el grupo normal, más marcadas en el canal azul-…
Analysis of the depth of field of integral imaging displays based on wave optics.
2013
In this paper, we analyze the depth of field (DOF) of integral imaging displays based on wave optics. With considering the diffraction effect, we analyze the intensity distribution of light with multiple micro-lenses and derive a DOF calculation formula for integral imaging display system. We study the variations of DOF values with different system parameters. Experimental results are provided to verify the accuracy of the theoretical analysis. The analyses and experimental results presented in this paper could be beneficial for better understanding and designing of integral imaging displays.
Evaluation of the use of wavefront encoding to reduce depth-induced aberration in structured-illumination microscopy
2018
Three-dimensional imaging is affected by depth-induced spherical aberration (SA) when imaging deep into an optically thick sample. In this work, we evaluate the impact of SA on the performance of incoherent grating-projection structured illumination microscopy (SIM). In particular, we analyze the reduction of the contrast in the structured pattern and compare the reconstructed SIM images for different amounts of SA. In order to mitigate the impact of SA, we implement and evaluate in SIM a wavefront encoded imaging system using a square cubic (SQUBIC) phase mask, an approach shown previously to be successful in conventional microscopy.
Cylindrical metal-coated optical fibre devices for filters and sensors
1996
Novel fibre-optic components suitable for sensor applications and wavelength filters are reported. The devices consist of a tapered fibre whose uniform waist has been coated with a thin layer of gold. The operation principle is the resonant excitation of a surface plasma mode of the metal film.
Experimental characterization and mitigation of turbulence induced signal fades within an ad hoc FSO network
2014
Optical beams propagating through the turbulent atmospheric channel suffer from both the attenuation and phase distortion. Since future wireless networks are envisaged to be deployed in the ad hoc mesh topology, this paper presents the experimental laboratory characterization of mitigation of turbulence induced signal fades for two ad hoc scenarios. Results from measurements of the thermal structure constant along the propagation channels, changes of the coherence lengths for different turbulence regimes and the eye diagrams for partially correlated turbulences in free space optical channels are discussed. Based on these results future deployment of optical ad hoc networks can be more strai…