Person: Martínez Antón, Juan Carlos
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First Name
Juan Carlos
Last Name
Martínez Antón
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
13 results
Search Results
Now showing 1 - 10 of 13
Item Improvement of driver night vision in foggy environments by structured light projection.(Heliyon, 2022) Quintana Benito, Jaime; Álvarez Fernández-Balbuena, Antonio; Martínez Antón, Juan Carlos; Vázquez Moliní, DanielNowadays, fog is still a natural phenomenon that hinders our ability to detect targets, particularly in the field of driving where accidents are increasing. In the literature we find different studies determining the range of visibility, improving the quality of an image, determining the characteristics of fog, etc. In this work we propose the possibility of using a structured lighting system, on which we project the light towards the target, limiting the field lighting. We have developed a scattering light propagation model to simulate and subsequently study the veil luminance, generated by backscattering, to predict the decrease in visibility. This simulation considers the type of fog, the relative orientation of various elements (observer, light source and targets). We have built a fog chamber to validate the experimental params of the described system. The results obtained from both the simulation and the experimental measurements demonstrate that it is possible to obtain a high contrast enhancement for viewing a target when illuminated as described. Clearly, this kind of lighting technology will improve the road safety in foggy night environments. The results of this work can also be extrapolated to any situation in which the visibility of an observer is compromised by the environment, such as heavy rain, smoke from fires, among others.Item 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, DanielRestorers 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.Item PhDAY 2020 -FOO (Facultad de Óptica y Optometría)(2020) Pintor Just, Jesús Jerónimo; Carpena Torres, Carlos; Peral Cerda, María Asunción; Pérez de Lara, María Jesús; Toral, Fernando; Crooke Álvarez, Almudena; Pastrana Robles, Cristina; Carracedo Rodríguez, Juan Gonzalo; Cayuela López, Ana; Sorzano Sánchez, Óscar; Charbel, Carla; Garzón Jiménez, Nuria; Carballo Álvarez, Jesús; Diz Arias, Elena; Fernández Jiménez, Elena; Lledó Mayans, Victoria Eugenia; Gómez Pedrero, José Antonio; Durán Prieto, Elena; López Alonso, José Manuel; Fernández Torres, Miguel Ángel; Guzmán Aránguez, Ana Isabel; Gómez Manzanares, Ángela; Vázquez Molini, Daniel; Martínez Antón, Juan Carlos; Bernárdez Vilaboa, Ricardo; Mayorga Pinilla, Santiago; Álvarez Fernández-Balbuena, Antonio; Benítez, AntoJ.; Igalla El-Youssfi, Asmae; León Álvarez, Alejandro; Palomo Álvarez, Catalina; Awad Alkozi, Hanan; Sánchez Naves, Juan; Martínez Alberquilla, Irene; García Montero, María; Ruiz Alcocer, Javier; Madrid Costa, David; Martínez Florentín, Gema; Papas, Eric B.; Medrano Muñoz, Sandra Milena; Molina, Nancy; Jurado, Sandra; Oliveiros López, Juan; Platero Alvarado, Nadiuska Cristine; Garrido Mercado, Rafaela; Pérez Garmendia, Carlos; Antona Peñalba, Beatriz; Barrio De Santos, Ana Rosa; González Pérez, Mariano; Pérez Garmendia, Carlos; Serramito Blanco, María; Privado Aroco, Ana; Almalki, Wael; Bodas Romero, Julia; Ouzzani, Mohamed; Paune, Jaume; Calderón García, Raquel; Pitarch Velasco, Aída; Cebrián, José Luis; Sánchez Pérez, María Isabel; García Rojo, Marta María; Bonnin Arias, Cristina Natalia; Sánchez Ramos, Celia; Gutiérrez Jorrín, Sara Carmen; Rodríguez Alonso, Xabier; Laucirica Sáenz, Gorka; Arranz Márquez, Esther; Alonso Castellanos, Miriam; Teus Guezala, Miguel Ángel; Hernández Verdejo, José Luis; Mármol Errasti, Esther; Martín García, Beatriz; Arriola Villalobos, Pedro; Gómez De Liaño Sánchez, María Rosario; Mínguez Caro, N; Orduña Azcona, Javier; Navarro Gil, Francisco Javier; Huete Toral, Fernando; Rodríguez Pomar, Candela; Martínez Águila, Alejandro; Martín Gil, Alba; Tomé de la Torre, Miguel ÁngelPor cuarto año consecutivo los doctorandos de la Facultad de Óptica y Optometría de la Universidad Complutense de Madrid cuentan con un congreso propio organizado por y para ellos, el 4º PhDAY- FOO. Se trata de un congreso gratuito abierto en la que estos jóvenes científicos podrán presentar sus investigaciones al resto de sus compañeros predoctorales y a toda la comunidad universitaria que quiera disfrutar de este evento. Apunta en tu agenda: el 15 de octubre de 2020. En esta ocasión será un Congreso On-line para evitar que la incertidumbre asociada a la pandemia Covid-19 pudiera condicionar su celebración.Item Measuring High Dynamic Range Spectral Reflectance of Artworks through an Image Capture Matrix Hyperspectral Camera(Sensors, 2022) Gómez Manzanares, Ángela; Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, Antonio; Mayorga Pinilla, Santiago; Martínez Antón, Juan CarlosCommercial hyperspectral imaging systems typically use CCD or CMOS sensors. These types of sensors have a limited dynamic range and non-linear response. This means that when evaluating an artwork under uncontrolled lighting conditions and with light and dark areas in the same scene, hyperspectral images with underexposed or saturated areas would be obtained at low or high exposure times, respectively. To overcome this problem, this article presents a system for capturing hyperspectral images consisting of a matrix of twelve spectral filters placed in twelve cameras, which, after processing these images, makes it possible to obtain the high dynamic range image to measure the spectral reflectance of the work of art being evaluated. We show the developed system and describe all its components, calibration processes, and the algorithm implemented to obtain the high dynamic range spectral reflectance measurement. In order to validate the system, high dynamic range spectral reflectance measurements from Labsphere’s Spectralon Reflectance Standards were performed and compared with the same reflectance measurements but using low dynamic range images. High dynamic range hyperspectral imaging improves the colorimetric accuracy and decreases the uncertainty of the spectral reflectance measurement based on low dynamic range imaging.Item Improvement of driver night vision in foggy environments by structured light projection(Heliyon, 2022) Quintana Benito, Jaime; Álvarez Fernández-Balbuena, Antonio; Martínez Antón, Juan Carlos; Vázquez Moliní, DanielNowadays, fog is still a natural phenomenon that hinders our ability to detect targets, particularly in the field of driving where accidents are increasing. In the literature we find different studies determining the range of visibility, improving the quality of an image, determining the characteristics of fog, etc. In this work we propose the possibility of using a structured lighting system, on which we project the light towards the target, limiting the field lighting. We have developed a scattering light propagation model to simulate and subsequently study the veil luminance, generated by backscattering, to predict the decrease in visibility. This simulation considers the type of fog, the relative orientation of various elements (observer, light source and targets). We have built a fog chamber to validate the experimental params of the described system. The results obtained from both the simulation and the experimental measurements demonstrate that it is possible to obtain a high contrast enhancement for viewing a target when illuminated as described. Clearly, this kind of lighting technology will improve the road safety in foggy night environments. The results of this work can also be extrapolated to any situation in which the visibility of an observer is compromised by the environment, such as heavy rain, smoke from fires, among others.Item Geometrical limits for UV-C inactivation of pathogens(Optik, 2022) Quintana Benito, Jaime; Álvarez Fernández-Balbuena, Antonio; Martínez Antón, Juan Carlos; Vázquez Moliní, Daniel; Prada, Luis; Estrada, Luis; Alda Serrano, JavierThe inactivation of pathogens through the irradiation of ultraviolet light depends on how light propagates within the medium where the microorganism is immersed. A simple geometrical optics analysis, and a fluence evaluation reveal some reservoirs where the pathogen may hide and be weakly exposed to the incoming radiation. This geometrical hide-outs also generate a tail in the plot of the total inactivation plot vs. the incoming fluence. We have analyzed these facts using geometrical optics principles and illumination engineering computational packages. The results obtained from previous biomedical measurements involving SARS-CoV-2 have been used to evaluate the inactivation degree for an spherical geometry applicable to airborne pathogens, and for an spherical cap geometry similar to that used in biomedical experiments. The case presented here can be seen as the worst-case scenario applicable under collimated illumination.Item Reflectance Measurements on Cultural Heritage(Heritage - New Paradigm [Working Title], 2021) Álvarez Fernández-Balbuena, Antonio; Vázquez Moliní, Daniel; Gómez Manzanares, Ángela; Martínez Antón, Juan Carlos; Mayorga Pinilla, SantiagoCultural heritage is a valuable and characteristic symbol of every country. It should be handled with care and it must be exhaustively investigated and measured with non-destructive techniques. In this chapter, we will talk about different reflectance measurement techniques to obtain the conservation state of the artwork. With this reflectance characterization, conservators, and curators could soon determine the best maintenance procedures for restoration purposes. Also, a new technique for lighting will be discussed, where the artwork can be also photonically restored illuminating with the correct light in the desired area of the artwork using a spectrally selective projection system.Item Method for the characterization of Fresnel lens flux transfer performance(Proceedings of SPIE, 2011) Martínez Antón, Juan Carlos; Vázquez Moliní, Daniel; Muñóz de la Luna, Javier; Gómez Pedrero, José Antonio; Álvarez Fernández-Balbuena, AntonioFresnel lenses and other faceted or micro-optic devices are increasingly used in multiple applications like solar light concentrators and illumination devices, just to name some representative. However, it seems to be a certain lack of adequate techniques for the assessment of the performance of final fabricated devices. As applications are more exigent this characterization is a must. We provide a technique to characterize the performance of Fresnel lenses, as light collection devices. The basis for the method is a configuration where a camera images the Fresnel lens aperture. The entrance pupil of the camera is situated at the focal spot or the conjugate of a simulated solar source. In this manner, detailed maps of the performance of different Fresnel lenses are obtained for different acceptance angles.Item Achromatic Fresnel Lens with Improved Efficiency for PV Systems(International Journal of Photoenergy, 2014) González Montes, Mario; Martínez Antón, Juan Carlos; Vázquez Molini, Daniel; Álvarez Fernández-Balbuena, Antonio; Bernabeu Martínez, EusebioThis work is aimed to design and evaluate different achromatic Fresnel lens solutions capable of operating as concentrators aimed at photovoltaic cells systems. Throughout this study, the theoretical parametric design of the achromatic lens will be shown together with a series of simulations to verify the performance of each lens topology. The results will be compared with a standard Fresnel lens to ascertain the validity and effectiveness of the obtained design. Finally, a novel kind of hybrid lens is proposed, which combines the advantages of each type of lens (standard and Fresnel) according to the optimal operating region of each design. Efficiency and concentration ratios of each particular lens are shown, regarding lens dimension, light’s incidence angle, or wavelength. Through this innovative achromatic design concentration ratios above 1000 suns, which hardly reach standard Fresnel lenses. Furthermore chromatic dispersion is minimized and the efficiency rate is over 85% of efficiency for a wide spectral range (from 350 nm to 1100 nm).Item Light losses in hollow, prismatic light guides related to prim defects: a transmittance model(Chinese Optics Letters, 2015) García Fernández, Berta; Vázquez Moliní, Daniel; Álvarez Fernández-Balbuena, Antonio; García Botella, Ángel; Martínez Antón, Juan CarlosHollow, cylindrical, prismatic light guides (CPLGs) are optical components that, using total internal reflection (TIR), are able to transmit high-diameter light beams in daylight and artificial lighting applications without relevant losses. It is necessary to study the prism defects of their surfaces to quantify the behavior of these optical components. In this Letter, we analyze a CPLG made of a transparent dielectric material. Scanning electron microscopy (SEM) and the topographic optical profilometry by absorption in fluids (TOPAF) imaging technique are conducted to determine if there are defects in the corners of the prisms. A model for light guide transmittance that is dependent on prism defects is proposed. Finally, a simulation and an experimental study are carried out to check the validity of the proposed model.