Search results for "òptica"
showing 10 items of 205 documents
Facultat de Física i Optometria
2008
La Universitat de València t'obri les seues portes. En les seues Facultats i Escoles Universitàries descobriràs una àmplia oferta d'estudis, equipament docent d'última tecnologia, instal·lacions esportives i culturals i una completa xarxa de biblioteques. Tot el que necessites per a accedir a una formació integral que garantisca el teu futur professional.
Robust Light Field Watermarking by 4D Wavelet Transform
2020
Unlike common 2D images, the light field representation of a scene delivers spatial and angular description which is of paramount importance for 3D reconstruction. Despite the numerous methods proposed for 2D image watermarking, such methods do not address the angular information of the light field. Hence the exploitation of such methods may cause severe destruction of the angular information. In this paper, we propose a novel method for light field watermarking with extensive consideration of the spatial and angular information. Considering the 4D innate of the light field, the proposed method incorporates 4D wavelet for the purpose of watermarking and converts the heavily-correlated chann…
Validation of a set of compact and low-cost Stokes lenses aimed at refractive astigmatism measurement for optometric practice
2022
We describe the construction and characterization of three Stokes lenses that can be used in optometric practice to measure different ranges of refractive astigmatism using subjective routines. The proposed set of Stokes lenses is assembled from Risley prism mounts coming from a Nidek phoropter in which the optical prisms are replaced by three different sets of cylindrical lenses ( ± 0.75, ± 1.25, and ± 1.75 D) coming from a trial lens case to cover a different astigmatism range (1.5, 2.5, and 3.5 D in modulus, respectively). We present the experimental characterization of the three Stokes lenses with the power vector notation and use an automatic lensmeter (Topcon CL-300) for dioptric powe…
Power-dependent effective reflection of fiber Bragg grating as output coupler of Ytterbium-doped fiber laser
2022
In this paper, we discuss the effective reflection of a fiber Bragg grating and its dependence on laser power when it is used as an output coupler of an ytterbium-doped fiber laser (here the effective reflection is considered to be a part of intracavity laser power reflected by the grating back to the laser cavity). We propose and discuss an experimental technique based on spectral and power analysis and derive simple formulae that permits one to obtain the intra-cavity power and the grating effective reflection. We show that, due to spectral broadening, the effective reflection dramatically decreases with increasing laser power, the effect precisely fitted using the derived formulae descri…
Compensación de la vista en España hasta la mitad del siglo XVIII
2016
Tal como indica Mary Beard, premio Princesa de Asturias 2016, "entender la antigüedad ayuda a entendernos hoy". La óptica y la optometría en España, no es una excepción, se pueden considerar tres etapas temporales importantes para su desarrollo, desde el origen hasta la mitad del siglo XVIII, (correspondiendo al inicio y establecimiento de la actividad artesanal), desde la segunda mitad del siglo XVIII hasta la primera mitad del siglo XX, (que es la consolidación de la actividad profesional), y desde la segunda mitad del siglo XX hasta la actualidad, (siendo la evolución de la profesión reglada académicamente, y con sus funciones dentro de la rama sanitaria).
Fabricación y venta de gafas en España en la segunda mitad del siglo XVIII
2017
A partir de la segunda mitad del siglo XVIII, se empieza a producir un incremento de los artesanos dedicados a la óptica en España. En gran parte este aumento se debe a su paso previo y consecuente aprendizaje laboral en la Real Fábrica de Cristales. Este centro formador de futuras generaciones de ópticos, se nutre inicialmente de los conocimientos de maestros expertos extranjeros, generalmente franceses, siendo su misión enseñar a operarios y aprendices a que adquieran la suficiente experiencia para realizar un producto correcto y de calidad
Transición en la fabricación, venta y adaptación de gafas en España a partir del siglo XVIII
2019
Las gafas hasta el siglo XIX se pueden considerar un producto con un uso minoritario asociado a tener, o para simular tener, un nivel cultural. A partir de entonces es cuando se produce el cambio pasando de estar asociado el uso de los anteojos a una demanda de un determinado nivel de instrucción. Esta difusión, y el incremento de la necesidad del uso de las gafas, hace que se produzca una evolución en el sector profesional, debiendo tener más gente preparada en el quehacer. En este articulo se muestra la evolución en la fabricación, venta y adaptación de gafas en España a partir del siglo XVIII hasta el siglo XX
Roadmap on 3D integral imaging: Sensing, processing, and display
2020
This Roadmap article on three-dimensional integral imaging provides an overview of some of the research activities in the field of integral imaging. The article discusses various aspects of the field including sensing of 3D scenes, processing of captured information, and 3D display and visualization of information. The paper consists of a series of 15 sections from the experts presenting various aspects of the field on sensing, processing, displays, augmented reality, microscopy, object recognition, and other applications. Each section represents the vision of its author to describe the progress, potential, vision, and challenging issues in this field.
Analysis of an interferometric optical fibre detection technique applied to silicon vibrating sensors
1987
A simple and accurate analysis of a single-mode optical fibre interferometric displacement detection technique is resented. This analysis is in good agreement with experimental measurements, and shows that angular alignment between the fibre and the sensor is the most critical parameter.
An overview of head tracking integral imaging three-dimensional display using smart pseudoscopic-to-orthoscopic conversion
2017
We overview a previously reported head tracking integral imaging three-dimensional (3D) display to extend viewing angle accommodated to a viewer's position without the crosstalk phenomenon. A head detection system is applied to obtain the head position and rotation of a viewer, and a new set of elemental images is then computed using the smart pseudoscopic-to-orthoscopic conversion (SPOC) method for head tracking 3D display. Experimental results validate the proposed method for high quality 3D display with large viewing angle.