Person: Canabal Boutureira, Héctor Alfonso
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First Name
Héctor Alfonso
Last Name
Canabal Boutureira
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Automatic processing in Moiré deflectometry by local fringe direction calculation(Applied Optics, 1998) Canabal Boutureira, Héctor Alfonso; Quiroga Mellado, Juan Antonio; Bernabéu Martínez, EusebioAn algorithm for accurately extracting the local fringe direction is presented. The algorithm estimates, in the neighborhood of n × n points, the direction of the gradient that points normal to the local fringe direction. The performance of four different derivative kernels is also compared. Since this method is sensitive to noise and variations in background and amplitude, a preprocessing step is used to limit these error sources. The method has been applied to the moiré deflectogram of a spherical and a progressive addition ophthalmic lens, resulting in a map of the refractive power of these lenses. The results are compared with the data obtained with a commercial focimeter. This technique is useful for analyzing the fringe patterns where the fringe direction is variable and must be obtained locally.Item Enhancement of surface inspection by Moiré interferometry using flexible reference gratings(Optics Express, 2001) Quiroga Mellado, Juan Antonio; Martínez Antón, Juan Carlos; Canabal Boutureira, Héctor Alfonso; Bernabéu Martínez, Eusebio; Álvaro Labajo, M.; Cortés Testillano, V.We have extended the use of shadow Moiré technique to be implemented in simple curved surfaces by using a flexible grating. Dynamic visual inspection of surface micro-damages is significantly favored by the use of well adapted pliable gratings compared to the use of flat reference gratings. The experimental set-up consists of a plastic foil with a printed Ronchi grating stretched between three points which adapts to any cylindrical or conical convex surface independently of the relative orientation grating/surface. Static quantification of defects profiles is also possible with an attached CCD camera. Visual detection of defects in the range of ~30 μm in depth is obtainable.Item Energy optimization of a light projection system for buildings that virtually restores artworks(Digital Applications in Archaeology and Cultural Heritage, 2019) Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; Canabal Boutureira, Héctor Alfonso; Muro, Carmen; Durmus, D.; Davis, W.; Benítez Iglesias, Antonio Jesús; Mayorga Pinilla, SantiagoThe need to achieve energy efficiency standards in the lighting systems of buildings makes it necessary to optimize all aspects of them. Here, the development of a light projection system that achieves this goal by studying and modifying the spectral output, compared to conventional illumination, is described. A lighting system that estimates the reflectance characteristics of artwork and emits optimized lighting can reduce light absorption. A damage-minimizing point-by-point light projection system is developed using an optimization algorithm, to improve the appearance of the surfaces of artworks whose color has faded. In this case, a simulation of an aged oil painting was made by manipulating the original photograph, which was printed and to which the proposed system was applied. The results show that, when the aged printed image is illuminated with the optimized light source, it appears indistinguishable from the non-aged oil painting.Item A generalization of Prentice's law for lenses with arbitrary refracting surfaces(Ophthalmic & Physiological Optics (OPO), 1998) Canabal Boutureira, Héctor Alfonso; Gómez Pedrero, José Antonio; Alonso Fernández, José; Bernabéu Martínez, EusebioA generalization of the Prentice's law is presented in this paper. The idea consists of removing some (but not all) of the approximations that comprise the paraxial approach. In that way, we obtain a new formulation that permits us to compute the prismatic power of a lens made up of arbitrary refracting surfaces, and to improve the precision obtained by Prentice's law when applied to monofocal lenses. The resulting formalism is simple and manageable and its derivation leads us to a precise definition of the local dioptric power matrix, introduced in a previous paper, as well as a better understanding of the same.Item Improved Phase-Shifting Method for Automatic Processing of Moiré Deflectograms(Applied Optics, 1998) Canabal Boutureira, Héctor Alfonso; Quiroga Mellado, Juan Antonio; Bernabéu Martínez, EusebioAn improved moiré deflectometry phase-shifting technique is presented. A squared grating is used to multiplex the information of the deflections in two orthogonal directions in one image. This procedure avoids the need to rotate the gratings to obtain complete deflection information. However, the use of these gratings makes impossible the application of standard phase-shifting algorithms. Specifically, the problems associated with the nonsinusoidal profile of the moiré fringes and the low-modulation areas produced by the square gratings are solved. A modified moiré deflectometry phase-shifting method is designed to deal with these problems. In addition, a method to obtain the zero order of the prismatic effect is developed. The technique configures a complete and automatic method of mapping ray deflections. From them the refractive power maps can be derived. Experimental results obtained with a progressive-addition lens are shown.- Project number: 136
Item Estrategias de iniciación a la experimentación en laboratorios de las enseñanzas en Óptica(2015) Martínez Matos, Óscar; Alieva Krasheninnikova, Tatiana; Canabal Boutureira, Héctor Alfonso; Navarrete Fernández, María de la Cruz; Gonzalo Fonrodona, Isabel; Herrera Fernández, José María; Irigoyen Irigoyen, Maite; Luis Aina, Alfredo; Piquero Sanz, Gemma María; Rodrigo Martín Romo, José Augusto; Sánchez Brea, Luis Miguel; Sánchez Martín, José Antonio; Serna Galán, Julio; Tercero Gómez, José Luis; Torcal Milla, Francisco José; Vilas Prieto, José Luis; Weigand Talavera, Rosa MaríaSe propone un cambio en la metodología docente de la asignatura Laboratorio de Física III del Grado en Física, para hacerla más dinámica y potenciar la participación e iniciativas de los estudiantes, adecuándola al espíritu de Bolonia Item Point to point multispectral light projection applied to cultural heritage(Proceedings of SPIE, 2017) Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; Canabal Boutureira, Héctor Alfonso; García Botella, Ángel; Mayorga Pinilla, Santiago; Muro, Carmen; Galán Cañestro, María TeresaUse of new of light sources based on LED technology should allow the develop of systems that combine conservation and exhibition requirements and allow to make these art goods available to the next generations according to sustainability principles. The goal of this work is to develop light systems and sources with an optimized spectral distribution for each specific point of the art piece. This optimization process implies to maximize the color fidelity reproduction and the same time to minimize the photochemical damage. Perceived color under these sources will be similar (metameric) to technical requirements given by the restoration team uncharged of the conservation and exhibition of the goods of art. Depending of the fragility of the exposed art objects (i.e. spectral responsivity of the material) the irradiance must be kept under a critical level. Therefore, it is necessary to develop a mathematical model that simulates with enough accuracy both the visual effect of the illumination and the photochemical impact of the radiation. Spectral reflectance of a reference painting The mathematical model is based on a merit function that optimized the individual intensity of the LED-light sources taking into account the damage function of the material and color space coordinates. Moreover the algorithm used weights for damage and color fidelity in order to adapt the model to a specific museal application. In this work we show a sample of this technology applied to a picture of Sorolla (1863-1923) an important Spanish painter title “woman walking at the beach”.