Person: Álvarez Fernández-Balbuena, Antonio
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First Name
Antonio
Last Name
Álvarez Fernández-Balbuena
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
18 results
Search Results
Now showing 1 - 10 of 18
Item High-efficiency light-emitting diode collimator(Optical Engineering, 2010) Vázquez Molini, Daniel; González Montes, Mario; Álvarez Fernández-Balbuena, Antonio; Bernabeu Martínez, EusebioWe describe an analytical and numerical method to design and optimize LED (light-emitting diode) collimators. The optimization process is confirmed by optical simulations and experimental measurements of a scaled prototype. The collimator's definitive geometry and design parameters rely on the LED's emitting characteristics and the employed collimator material. The resulting parabolic-elliptical-based collimator shows an optimum performance and a compact structure with requirement for mirrored surfaces.Item High efficiency 90° elbow for light guides(Nonimaging Optics and Efficient Illumination Systems V, 2008) Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, Antonio; García Fernández, Berta; Bernabeu Martínez, Eusebio; Winston, Ronald; Koshel, R. JohnTransmission of light through a 90 degrees elbow in a hollow light guide is an important step in the development of natural lighting applications. In this paper we present a new design that has more than 260% higher efficiency in flux transfer than a standard bending system for hollow and aluminum light guides. The clue of this new system is to minimize the light angle at the output of the elbow, in such way that it is possible to guide light at higher distances because of the fewer reflections in the light guide. The system works properly for prismatic light guides but is also suitable for aluminum guides where the reduction of reflections permit the use of cheaper aluminum or the increase in length maintaining flux transfer. Also this reduction of reflections in aluminum light guide derives in less change of chromatic coordinates.Item Light output losses of prism light guides(Optical Systems Design 2012, 2012) García Fernández, Berta; Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; Bernabeu Martínez, EusebioCylindrical prismatic hollow light guides are able to transmit daylight properly into the spaces of a building in which natural light has a difficult access. Transmission through the guide depends on the optical characteristics of the material, the shape of the guide and the fidelity of the geometry in prisms structure. It is important to analyse the micro-structure prism imperfections of the surfaces such as the existence of a curved area on peaks prism which modify the behaviour of the prism film; these imperfections, change the optical path and therefore the rays are directed to other directions instead of undergoing total internal reflections. In this paper, several cylindrical guides made of transparent dielectric material characterized with an absorption factor have been developed. A numerical analysis has been carried out by software tools to analyse the flux distribution in the light guidance system comparing its efficiency by optical analysis in different simulations. These simulations include high reproductively prism related to the light pipe’s material and optical properties including a study of the impact of imperfect geometry which is necessary to allow rigorous comparisons with the experimental simulations. The simulated results have been compared with experimental data obtained through real scale analysis. The experimental measurements have revealed effectiveness of 66.7 % in the aspect ratio of 30.Item Improved spatial integrator with axicon-dioptric elements(Optical Engineering, 2006) Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel; Alda, Javier; Bernabeu Martínez, EusebioThe flux transfer efficiency of an optical array with spatial integration has been improved by adding a new element at the input surface. The optical characteristics of the input surfaces of the individual units do not affect the spatial integration property. We propose to fill this input surface with a nested optical array designed to transfer as much energy as possible to the plane of the synthetic image of the spatial integrator array. Several designs for the individual units of this array are discussed. The most promising design consists of a cylindrical axicon-diopter element. This element has been simulated, fabricated, and tested, showing the expected improvement in performance.Item Beacon system based on light-emitting diode sources for runways lighting(Optical engineering, 2014) González Montes, Mario; Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; Bernabeu Martínez, EusebioNew aeronautical ground lighting techniques are becoming increasingly important to ensure the safety and reduce the maintenance costs of the plane's tracks. Until recently, tracks had embedded lighting systems whose sources were based on incandescent lamps. But incandescent lamps have several disadvantages: high energy consumption and frequent breakdowns that result in high maintenance costs (lamp average life-time is similar to 1500 operating hours) and the lamp's technology has a lack of new lighting functions, such as signal handling and modification. To solve these problems, the industry has developed systems based on light-emitting diode (LED) technology with improved features: (1) LED lighting consumes one tenth the power, (2) it improves preventive maintenance (an LED's lifetime range is between 25,000 and 100,000 hours), and (3) LED lighting technology can be controlled remotely according to the needs of the track configuration. LEDs have been in use for more than three decades, but only recently, around 2002, have they begun to be used as visual aids, representing the greatest potential change for airport lighting since their inception in the 1920s. Currently, embedded LED systems are not being broadly used due to the specific constraints of the rules and regulations of airports (beacon dimensions, power system technology, etc.). The fundamental requirements applied to embedded lighting systems are to be hosted on a volume where the dimensions are usually critical and also to integrate all the essential components for operation. An embedded architecture that meets the lighting regulations for airport runways is presented. The present work is divided into three main tasks: development of an optical system to optimize lighting according to International Civil Aviation Organization, manufacturing prototype, and model validation.Item Louvers design for LED displays for sunny days(Displays, 2007) Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, Antonio; Alda Serrano, Javier; Bernabeu Martínez, EusebioThe use of louvers attached to variable information display needs to be optimized taking into account different intrinsic and extrinsic parameters. The analysis of the performance of the display–louvers system takes into account the location, orientation, and daily and seasonal variations. The observation of the system is divided depending on the distance of observation. The far distance vision performance use the background luminance. The medium distance performance needs the use of the Contrast Sensitivity Function of the eye.Item Horizontal daylighting system for office buildings(Energy and Buildings, 2013) Vázquez Molini, Daniel; González Montes, Mario; Álvarez Fernández-Balbuena, AntonioThis work is focused on a sunlight collection device for solar lighting systems aimed at non-residential buildings. The design takes advantage of solar energy that reaches the facade of the building for lighting purposes, thereby reducing building energy consumption by supplementing it with clean, renewable energy. This daylighting system's structure comprises a light collector located outside the vertical facade of the building, a modular light guide that runs along the horizontal false ceiling and light extractor luminaires strategically positioned along the guide. The system is configured specifically to the particular characteristics of each building (façade orientation, latitude and longitude) to optimize the global performance. The present paper describes in detail the anidolic collecting system as a part of the comprehensive daylighting system. However the entire daylighting system has been completely developed and experimentally tested, and its prototype is currently integrated into Lledó S.A company's facilities.Item Iluminar obras de arte mejorando la conservación. El proyecto Zeus(2015) Benítez, Anton J.; Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, AntonioLa iluminación de obras de arte se enfrenta al reto de resultar adecuada para la exhibición y de minimizar en lo posible los daños a la superficie y los materiales que las componen. En esta encrucijada, en la que la investigación es imprescindible tanto en tecnología como acerca de la recepción por parte del público, el proyecto Zeus trata de obtener una precisa información sobre el color de la obra, y trasladarla a un modelo de iluminación individualizado punto a punto, que permite simular condiciones precisas y compensar efectos indeseables del deterioro, minimizando la luz absorbida por la obra.Item Optical design teaching by computing graphic methods(Proceedings of SPIE, 2012) Vázquez Moliní, Daniel; Muñoz de Luna Clemente, Javier; Álvarez Fernández-Balbuena, Antonio; García Botella, Ángel; Belloni, Paola; Alda, JavierOne of the key challenges in the teaching of Optics is that students need to know not only the math of the optical design, but also, and more important, to grasp and understand the optics in a three-dimensional space. Having a clear image of the problem to solve is the first step in order to begin to solve that problem. Therefore to achieve that the students not only must know the equation of refraction law but they have also to understand how the main parameters of this law are interacting among them. This should be a major goal in the teaching course. Optical graphic methods are a valuable tool in this way since they have the advantage of visual information and the accuracy of a computer calculation.Item Application of dynamic merit function to nonimaging systems optimization(Optical Engineering, 2015) Álvarez Fernández-Balbuena, Antonio; González Montes, Mario; García Botella, Ángel; Vázquez Moliní, DanielAutomatic optimization algorithms have been recently introduced as nonimaging optics design techniques. Unlike optimization of imaging systems, nonsequential ray tracing simulations and complex noncentered systems design must be considered, adding complexity to the problem. The merit function is a key element in the automatic optimization algorithm; nevertheless, the selection of each objective’s weight, {wi}{wi}, inside the merit function needs a prior trial and error process for each optimization. The problem then is to determine appropriate weights’ values for each objective. We propose a new dynamic merit function with variable weight factors {wi(n)}{wi(n)}. The proposed algorithm automatically adapts weight factors during the evolution of the optimization process. This dynamic merit function avoids the previous trial and error procedure by selecting the right merit function and provides better results than conventional merit functions.