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
8 results
Search Results
Now showing 1 - 8 of 8
Item Hyperparabolic concentrators(Applied Optics, 2009) García Botella, Ángel; Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel; Bernabeu Martínez, Eusebio; González Cano, AgustínWe present a family of three-dimensional concentrators constructed from the photic field generated by a Lambertian emitter. The profile of these concentrators is obtained from the field lines for a two-dimensional truncated wedge and is based on the union between a hyperbola and a tilted parabola. By revolution of this profile, we obtain hyperparabolic concentrators (HPCs). In the limiting case when the focal length of the hyperbola becomes the radius of the exit aperture, the HPC becomes the well-known compound parabolic concentrator. On the other hand, when the focal length of the hyperbola becomes infinite, the HPC achieves the thermodynamic limit of concentration.Item Skylight: a hollow prismatic CPC(Proceedings of the SPIE, 2009) García Fernández, Berta; García Botella, Angel; Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel; Bernabéu Martínez, Eusebio; Winston, Roland; Gordon, Jeffrey M.Many applications involve the use of a compound parabolic concentrator (CPC) like, natural lighting, thermal applications, optics for illuminators, optical fibre coupling and solar energy. The use of a CPC in reverse mode for natural lighting gives the chance to use it as a lighting skylight in ceilings because light output is controlled inside the design angle, on the contrary having a low flux transfer ratio because of the reduced area of the entrance pupil regarding exit pupil. The authors propose an innovative 3D hollow prismatic CPC (HPCPC) made of a dielectric material, which has a high efficiency comparing it with aluminium CPC. The basic idea is to use a hollow prismatic light guide with CPC shape. This paper reports 2D, 3D design and numerical analysis by raytracing software, also experimental results are shown. The system works almost like a true CPC when light enters through standard entrance pupil and also collect light that enters outside entrance pupil. Performance and efficiency of the prismatic CPC is in average 300% higher than standard aluminium CPC for collimated light in a range from 0º to 85º. A prototype has been developed and tested.Item Chromatic perception of non-invasive lighting of cave paintings(Proceedings of SPIE, 2009) Zoido Chamorro, Jesús Manuel; Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, Antonio; Bernabeu Martínez, Eusebio; García Botella, Ángel; Herráenz Ferreiro, Juan Antonio; Egido Rodríguez, Marian, delThis work is intended to deal with the problems which arise when illuminanting Paleolithic cave paintings. We have carried out the spectral and colorimetric characterization of some paintings located in the Murcielagos (bats) cave (Zuheros, Córdoba, Spain). From this characterization, the chromatic changes produced under different lighting conditions are analysed. The damage function is also computed for the different illuminants used. From the results obtained, it is proposed an illuminant whose spectral distribution diminishes the damage by minimizing the absorption of radiation and optimises the color perception of the paintings in this cave. The procedure followed in this study can be applied to optimise the lighting systems used when illuminating any other art work.Item Ideal 3D asymmetric concentrator(Solar Energy, 2009) García Botella, Ángel; Álvarez Fernández-Balbuena, Antonio; Vázquez Moliní, Daniel; Bernabeu Martínez, EusebioNonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used for producing reflective and refractive optical devices, including reverse engineering techniques. In this paper we apply photometric field theory and elliptic ray bundles method to study 3D asymmetric – without rotational or translational symmetry – concentrators, which can be useful components for nontracking solar applications. We study the one-sheet hyperbolic concentrator and we demonstrate its behaviour as ideal 3D asymmetric concentrator.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 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 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 Experimental study of filtered light effect in the retina. Its aplication for car windows.(2007) Sánchez Ramos, Celia; Vega, J.A.; Ochoa Erena, F.J.; Moral Martínez, M.I.; Álvarez Fernández-Balbuena, AntonioPurpose: exposure ot light seems to be the triggering factor for some age-related retinal diseases, although the portion of the visual spectrum responsible for damage to the retina is as yet unknown. The present study was designed to investigate the role of circadian exposure to white, blue and yellow light on the retina Materials and methods: Adult albino rats were exposed to white, yellos or blue light for 15 days. The animals were sacrificed and the eyes removed and processed for light microscopy. Results: Exposure to white light does not modify the structure of the retina. The retinas of the rats exposed to yellow liht showe a thinner outer plexiform layer, reduced cell numbers in the inner and outer granular layers, and occasionally a lack of photoreceptor external segment of the photoreceptors was absent, and the density of cells severely reduced. Further, most of the animals showed enlarged and dilated choroidal blood vessels. Results were confirmed by quantitative histological techniques. Conclusions: Light exposure induces several retinal changes, with blue light inducing the most remarkable changes. Car windscreens could be a goo support system for the use of filters to block blue light.