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
12 results
Search Results
Now showing 1 - 10 of 12
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”.- Project number: 54
Item Desarrollo de material docente audiovisual online de apoyo para la asignatura: dispositivos de instrumentación óptica(2023) Vargas Balbuena, Javier; Diez Garrote, Francisco; Quiroga Mellado, Juan Antonio; Canabal Boutureira, Héctor Alfonso; Boiso Calero, AntonioEn este proyecto de innovación docente se han desarrollado una serie de videos cortos para fijar visualmente conceptos clave sobre instrumentación óptica. Estos videos están enfocados en la mejora de la compresión y análisis de los estudiantes de la asignatura Dispositivos de Instrumentación Óptica de cuarto curso del Grado en Físicas. Es decir, nuestro objetivo es proporcionar a los estudiantes con experiencias virtuales de laboratorio que les permitan entender de forma sencilla y rápida conceptos esenciales de la asignatura. También estos videos serán utilizados en el aula por los profesores como material docente de apoyo. 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 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.Item Laser beam deflectometry based on a subpixel resolution algorithm(Optical Engineering, 2001) Canabal Boutureira, Héctor Alfonso; Alonso Fernández, José; Bernabéu Martínez, EusebioA deflectometric method for the characterization of optical systems is presented. It is based on the use of a CCD camera and a subpixel resolution algorithm for the measurement of the deflection of a laser beam that propagates through the system. To obtain accurate results, three different algorithms for measuring the position of the deflected beam are tested and compared. Based on this comparison, an algorithm based on the calculation of the phase of the fast Fourier transform (FFT) is selected, and an accuracy of 0.024 pixels is obtained on the determination of the beam position in our setup. Using an XY scanning stage, the proposed method is completely automated and applied for the characterization of ophthalmic lenses. In this application, the gradients of the wavefront refracted by the lens are measured directly, and from them, the thickness and the local power of the lens are computed.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.- Project number: 49
Item Ampliación y actualización de las prácticas del laboratorio de Instrumentación Biomédica buscando un aprendizaje y evaluación centrados en el estudiante(2020) Chevalier Del Río, Margarita; Alieva Krasheninnikova, Tatiana; Martínez Matos, Óscar; Rodrigo Martín Romo, José Augusto; Canabal Boutureira, Héctor Alfonso; Comas Renfigo, María Dolores; Soto Rueda, Juan Manuel; Angulo Curto, Mercedes; Castillo García, MaríaEl objetivo del proyecto es el diseño de las prácticas de laboratorio para la asignatura Instrumentación Biomédica del Master de Física Biomédica. Se pretende mejorar el aprendizaje potenciando la participación activa y autonomía de los estudiantes. La falta de financiación económica se ha traducido en obtener como resultado del proyecto la redacción de guiones de prácticas que posibiliten el trabajo individual del alumno fuera del laboratorio dado el alto número de alumnos por puesto para llevar a cabo las prácticas. Estos guiones se han complementado con scripts en MatLab para analizar y procesar los datos obtenidos en el laboratorio así como datos obtenidos en diversas bases. Esta propuesta dió información sobre el progreso de los estudiantes en el aprendizaje cuando se utilizó el sistema de rúbricas tambien resultado de este proyecto. - 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 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 In-line detection and evaluation of surface defects on thin metallic wires(Optical Measurement Systems for Industrial Inspection II: Applications in Production Engineering, 2001) Martínez Antón, Juan Carlos; Siegmann, Philip; Sánchez Brea, Luis Miguel; Gómez Pedrero, José Antonio; Canabal Boutureira, Héctor Alfonso; Bernabéu Martínez, Eusebio; Hoefling, Roland; Jueptner, Werner P. O.; Kujawinska, MalgorzataWe have developed a prototype for in-line detection of surface defects in metallic wires, specially for scratches. A simple geometrical relationship between surface topography and conical reflection, permits to correlate the defects with intensity patterns in a simple way. The presented apparatus consists basically in a grating-divided laser beam incident on angular equidistant points. A CCD and an associated optics capture the information of the whole wire perimeter at once. Analytic rudiments are provided in agreement with the experimental results.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.