Person:
Álvarez Fernández-Balbuena, Antonio

First Name

Antonio

Last Name

Álvarez Fernández-Balbuena

URI

https://hdl.handle.net/20.500.14352/79920

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Óptica y Optometría

Department

Óptica

Area

Optica

Identifiers

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Now showing 1 - 10 of 18

Analytical method to measure bending deformations in prismatic optical films
(Chinese Optics Letters, 2016) García Fernández, Berta; Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel
The aim of this work is to provide an analytical method based on experimental measurements in order to obtain the prismatic film deformation for different curvatures of Hollow Cylindrical Prismatic Light Guides (CPLG). To conform cylindrical guides is necessary bend the film to guide the light, changes induced by curving the film give rise to deformation shifts. Light losses affected by deformation has been experimentally evaluated and numerically analyzed. The effect of deformation in prism angle is specially increased for CPLG of curvatures higher than 20 m-1. An experimental method for accurate transmittance measurements related to bending is presented.
Horizontal daylighting system for office buildings
(Energy and Buildings, 2013) Vázquez Molini, Daniel; González Montes, Mario; Álvarez Fernández-Balbuena, Antonio
This 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.
High-Dynamic-Range Spectral Reflectance for the Segmentation of Paint Pigment: Application to Dalí’s Oil Painting Dos Figuras (1926)
(Sensors, 2023) Álvarez Fernandez-Balbuena, Antonio; Gómez Manzanares, Ana; Martínez Antón, Juan Carlos; García Gómez-Tejedor, Jorge; Mayorga Pinilla, Santiago; Durán Roque, Humberto; Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, Antonio; Martínez Antón, Juan Carlos; Vázquez Molini, Daniel
Restorers and curators in museums sometimes find it difficult to accurately segment areas of paintings that have been contaminated with other pigments or areas that need to be restored, and work on the painting needs to be carried out with minimum possible damage. It is therefore necessary to develop measurement systems and methods that facilitate this task in the least invasive way possible. The aim of this study was to obtain high-dynamic-range (HDR) spectral reflectance and spatial resolution for Dalí’s painting entitled Two Figures (1926) in order to segment a small area of black and white pigment that was affected by the contact transfer of reddish pigment from another painting. Using Hypermatrixcam to measure the HDR spectral reflectance developed by this research team, an HDR multispectral cube of 12 images was obtained for the band 470–690 nm in steps of 20 nm. With the values obtained for the spectral reflectance of the HDR cube, the colour of the area of paint affected by the transfer was studied by calculating the a*b* components with the CIELab system. These a*b* values were then used to define two methods of segmenting the exact areas in which there was a transfer of reddish pigment. The area studied in the painting was originally black, and the contamination with reddish pigment occupied 13.87% to 32% of the total area depending on the selected method. These different solutions can be explained because the lower limit is segmentation based on pure pigment and the upper limit considers red as an exclusion of non-black pigment. Over- and under-segmentation is a common problem described in the literature related to pigment selection. In this application case, as red pigment is not original and should be removed, curators will choose the method that selects the highest red area.
Optimization of daylight utilization in energy saving application on the library in faculty of architecture, design and built environment, Beirut Arab University
(Alexandria Engineering Journal, 2018) Omar, Osama; García Fernández, Berta; Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel
Considering that reading and research are the main functions of use in libraries of all educational facilities, proper lighting becomes a crucial factor in the overall success of a library design. In this framework, daylight is essential for both energy saving and improvement of the quality of life in newer buildings where visual tasks are more diverse, and technology poses new types of lighting requirements. Furthermore, emphasis on the importance and methods used to utilize energy will be implemented; provided by nature as the first step in achieving optimum energy saving and reducing our dependence on fossil fuels. Thus, this study will examine the conditions of indoor daylight and the library’s energy performance in the faculty of Architecture, Design and Built Environment, Beirut Arab University with various architectural elements including space depth, window size, external obstruction angle, and glazing visible transmittance. This is done by first analysing the existing situations of daylighting (using Autocad Ecotect software), the situation of the artificial lighting inside the space (using Dial DIALux software), and the behavior of the users throughout the day (using Hobo loggers). Then, the outcomes will be analyzed to specify the challenges, therefore providing solutions related to environmental, technological, and energy saving as well as sustainable and green building designs. As a result, daylight designs based on hollow prismatic light guides are proposed. These designs act as luminaires increasing guide efficiency and uniformity distribution of natural light into the library spaces. The proposed designs are configured and analyzed by ray-tracing simulations for achieving high illumination levels and uniform lighting in the working plane of the library.
Smooth light extraction in lighting optical fibre
(Illumination Optics II, 2011) Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel; García Botella, Ángel; Martínez Antón, Juan Carlos; Bernabeu Martínez, Eusebio; Kidger, Tina E.; David, Stuart
Recent advances in LED technology have relegated the use of optical fibre for general lighting, but there are several applications where it can be used as scanners lighting systems, daylight, cultural heritage lighting, sensors, explosion risky spaces, etc. Nowadays the use of high intensity LED to inject light in optical fibre increases the possibility of conjugate fibre + LED for lighting applications. New optical fibres of plastic materials, high core diameter up to 12.6 mm transmit light with little attenuation in the visible spectrum but there is no an efficient and controlled way to extract the light during the fibre path. Side extracting fibres extracts all the light on 2π angle so is not well suited for controlled lighting. In this paper we present an extraction system for mono-filament optical fibre which provides efficient and controlled light distribution. These lighting parameters can be controlled with an algorithm that set the position, depth and shape of the optical extraction system. The extraction system works by total internal reflection in the core of the fibre with high efficiency and low cost. A 10 m length prototype is made with 45° sectional cuts in the fibre core as extraction system. The system is tested with a 1W white LED illuminator in one side.
Optics detailed analysis of an improved collimation system for LED light sources
(Illumination Optics II, 2011) González Montes, Mario; Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; García Botella, Ángel; Bernabeu Martínez, Eusebio; Kidger, Tina E.; David, Stuart
Throughout present study will be discusses the influence of the manufacturing margins, adjustment precision and ray model accuracy of a collimating LED unit in the overall system performance. It will be also analyzed the angular performance and the collimated in relation to the relative position of the LED and the collimator's dimensions. Finally the results will be compared with existing publications in this field.
Hyperparabolic concentrators
(Applied Optics, 2009) García Botella, Ángel; Álvarez Fernández-Balbuena, Antonio; Vázquez Molini, Daniel; Bernabeu Martínez, Eusebio; González Cano, Agustín
We 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.
Project number: 152
Sistemas digitales mediante app y QR aplicados a la enseñanza del Color
(2017) Vázquez Molini, Daniel; García Fernández, Berta; Álvarez Fernández-Balbuena, Antonio; Benítez Iglesias, Antonio Jesús; Solano Ramírez, Jaime; Yepes Rincón, Guillermo; Sydyknazar, Sabina; Bernabeu Martínez, Eusebio
El proyecto consiste en el diseño, elaboración y puesta en marcha de un sistema de información digital que permite la integración de las últimas tecnologías de comunicación por medio del móvil en los sistemas de enseñanza prácticos de materias relativas a las medidas colorimétricas.
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.
Improved and customized secondary optics for photo-voltaic concentrators
(Proceedings of SPIE, Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XII, 2015) Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; García Botella, Ángel; Alda, Javier
In this contribution the line flow method is applied to an optimized secondary optics in a photovoltaic concentration system where the primary optics is already defined and characterized. This method is a particular application of photic field theory. This method uses the parameterization of a given primary optics, including actual tolerances of the manufacturing process. The design of the secondary optics is constrained by the selection of primary optics and maximizes the concentration at a previously specified collection area. The geometry of the secondary element is calculated by using a virtual source, which sends light in a first concentration step. This allows us to calculate the line flow for this specific case. This concept allows designing more compact and efficient secondary optics of photovoltaic systems.