Recursos de colección

Archivo Digital UPM (113.270 recursos)

This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Optica

Mostrando recursos 1 - 17 de 17

  1. Color uniformity in spotlights optimized with reflectors and TIR lenses

    Teupner, Anne; Bergenek, Krister; Wirth, Ralph; Benítez, Pablo; Miñano Dominguez, Juan Carlos
    We analyze the color uniformity in the far field of spotlight systems to estimate visual perception with a merit function derived from human factor experiments. A multi-colored light-emitting diode (LED) light engine with different light mixing levels is combined with several reflectors and total internal reflection (TIR) lenses. The optimized systems are analyzed at several color uniformity levels with regard to the efficiency, peak luminous intensity and dimensions. It is shown that these properties cannot all be optimized at the same time. Furthermore, excellent color uniformity can be reached by a light mixing layer in the light engine or by...

  2. Emergence of Small-World Anatomical Networks in Self-Organizing Clustered Neuronal Cultures

    Santos Sierra, Daniel de; Sendiña-Nadal, Irene; Leyva, Inmaculada; Almendral, Juan A.; Anava, Sarit; Ayali, Amir; Papo, David; Boccaletti, Stefano
    In vitro primary cultures of dissociated invertebrate neurons from locust ganglia are used to experimentally investigate the morphological evolution of assemblies of living neurons, as they self-organize from collections of separated cells into elaborated, clustered, networks. At all the different stages of the culture's development, identification of neurons' and neurites' location by means of a dedicated software allows to ultimately extract an adjacency matrix from each image of the culture. In turn, a systematic statistical analysis of a group of topological observables grants us the possibility of quantifying and tracking the progression of the main network's characteristics during the self-organization...

  3. Recent trends in concentrated photovoltaics concentrators' architecture

    Buljan, Marina; Mendes Lopes, Joao; Benitez Gimenez, Pablo; Miñano Dominguez, Juan Carlos
    The field of concentrated photovoltaics (CPV) has met some remarkable advances in recent years. The continuous increase in conversion efficiency of multijunction solar cells and new advancements in optics have led to new demands and opportunities for optical design in CPV. This paper is a mini-review on current requirements for CPV optical design, and it presents some of the main trends in recent years on CPV systems architecture.

  4. Maximizing The Efficiency Of A 4-cell FK Module

    Hernández Sanz, Maikel; Vilaplana, Juan; Mohedano, Rubén; Benitez Gimenez, Pablo; Zamora Herranz, Pablo; Miñano Dominguez, Juan Carlos; Cvetkovic, Aleksandra; Shatford, Will; Sorgato, Simone
    The outdoor measurements of both a single-cell and a 4-cell CPV modules reaching, respectively, maximum peak efficiencies of 36.0% and 34.8% (both corrected @Tcell=25°C) are presented. This is the result of the joint effort by LPI and Solar Junction to demonstrate the potential of combining their respective state-of-the-art concentrator optics and solar cells. The LPI concentrator used is a Fresnel Köhler(FK), which is an advanced nonimaging concentrator using 4-channel Köhler homogenization, based on a primary Fresnel lens and a free-form secondary glass lens. Solar Junction's cell is a triple-junction solar cell with the A-SLAM{trade mark, serif} architecture using dilute-nitrides.

  5. Influence of the characteristics of a light source and target on the Monge-Ampere equation method in freeform optics design

    Wu, Rengmao; Benitez Gimenez, Pablo; Zhang, Yaqin; Miñano Dominguez, Juan Carlos
    It was previously demonstrated in [Opt. Lett. 38, 229 (2013)] that the problem of freeform surface illumination design can be converted into a nonlinear boundary problem for the elliptic Monge–Ampére equation based on the ideal source assumption. But how the Monge–Ampére equation method is affected by the characteristics of the light source and target was not discussed there. This Letter systematically analyzes the influence of discontinuity, nonconvexity, and connectivity of light source and target on the Monge–Ampére equation method and presents some intrinsic features of this design method. These features are applied in practical examples in freeform optics design.

  6. Double surface imaging designs with unconstrained object to image mapping under rotational symmetry

    Liu, Jiayao; Miñano Dominguez, Juan Carlos; Benitez Gimenez, Pablo
    In this work, we present a novel imaging design formed by two optical surfaces with rotational symmetry. In these designs, both object and image shapes are given but mapping from object to image is obtained through the design process. In the examples considered, the image from a planar object surface is virtual and located at infinity and is seen from a known pupil, which can emulate a human eye. The differential equation method is used to provide single optical surface imaging designs by considering the local properties of the imaging surface and the wavefronts. In the first introductory part, both...

  7. Single freeform surface imaging design with unconstrained object to image mapping

    Liu, Jiayao; Benitez Gimenez, Pablo; Miñano Dominguez, Juan Carlos
    An imaging design approach which is free of third-order astigmatism for one freeform optical surface and the image is presented in this paper. A set of differential equations is derived from generalized ray tracing. The solution of the above derived equations provides the anastigmatic freeform optical surface, the image surface and the object to image mapping. The obtained design can be used as a good starting point for optimization. As an example, a reflective freeform surface is designed for a single reflective Head Mounted Display (HMD). This example has a 3 mm pupil, 15mm eye clearance, 24-degree diagonal full field...

  8. Increasing the quantum efficiency of InAs/GaAs QD arrays for solar cells grown by MOVPE without using strain-balance technology

    Kalyuzhnyy, Nikolay A.; Mintairov, Sergey A.; Salii, Roman A.; Nadtochiy, Alexey M.; Payusov, Alexey S.; Brunkov, Pavel M.; Nevedomsky, Vladimir N.; Shvarts, Maxim Z.; Martí Vega, Antonio; Andreev, Viacheslav M.; Luque López, Antonio
    Research into the formation of InAs quantum dots (QDs) in GaAs using the metalorganic vapor phase epitaxy technique ispresented. This technique is deemed to be cheaper than the more often used and studied molecular beam epitaxy. The bestconditions for obtaining a high photoluminescence response, indicating a good material quality, have been found among awide range of possibilities. Solar cells with an excellent quantum ef?ciency have been obtained, with a sub-bandgapphoto-response of 0.07 mA/cm2per QD layer, the highest achieved so far with the InAs/GaAs system, proving the potentialof this technology to be able to increase the ef?ciency of lattice-matched multi-junction solar...

  9. Stopping of α particles from the core in corona plasmas

    Mima, Kunioki; Tajima, Toshiki; Alvarez Ruiz, Jesus; Tanaka, K.A.; Perlado Martín, José Manuel; Nagatomo, H.; Johzaki, T.; Sunahara, A.
    In the laser fusion reactor design, the protection of first wall and the final optics from high energy ions is the key issue. So, it is necessary to predict the precise energy spectra of ions.In the previous reactor designs, the ion energy spectra were provided by the classical ion transport codes. However, this poster shows that the α particle spectrum is significantly modified by the anomalous process in ablated plasmas.

  10. Uncertainty Estimation for Performance Evaluation of a Confocal Microscope as Metrology Equipment

    Guarneros, O.; Vicente Oliva, Jesús de; Maya, M.; Ocaña Moreno, José Luis; Molpeceres Álvarez, Carlos Luis; García-Ballesteros Ramírez, Juan José; Rodríguez, S. R.; Duran, H. M.
    Both in industry and research, the quality control of micrometric manufactured parts is based on the measurement of parameters whose traceability is sometimes difficult to guarantee. In some of these parts, the confocal microscopy shows great aptitudes to characterize a measurand qualitatively and quantitatively. The confocal microscopy allows the acquisition of 2D and 3D images that are easily manipulated. Nowadays, this equipment is manufactured by many different brands, each of them claiming a resolution probably not in accord to their real performance. The Laser Center (Technical University of Madrid) has a confocal microscope to verify the dimensions of the micro mechanizing...

  11. Steady-state thermal analysis of an innovative receiver for linear Fresnel reflectors

    Abbas Cámara, Rubén; Muñoz Antón, Javier; Martínez-Val Peñalosa, José María
    The study of the performance of an innovative receiver for linear Fresnel reflectors is carried out in this paper, and the results are analyzed with a physics perspective of the process. The receiver consists of a bundle of tubes parallel to the mirror arrays, resulting on a smaller cross section for the same receiver width as the number of tubes increases, due to the diminution of their diameter. This implies higher heat carrier fluid speeds, and thus, a more effective heat transfer process, although it conveys higher pumping power as well. Mass flow is optimized for different tubes diameters, different...

  12. In-situ optical reflectance characterization of ion beam irradiation damage on crystalline (quartz) and amorphous (silica) SiO2

    Crespillo Almenara, Miguel; Peña Rodríguez, Ovidio Y.; Manzano Santamaría, Javier; Rivera de Mena, Antonio; Jimenez Rey, D.; Agullo Lopez, Fernando
    Outline: • Motivation, aim • Complement waveguide data on silica • Optical data in quartz • Detailed analysis, i.e. both fluence kinetics and resolution • Efficiency of irradiation and analysis, samples, time... • Experimental set-up description • Reflectance procedure • Options: light source (lasers, white light..), detectors, configurations • Results and discussion • Comparative of amorphous and crystalline phases

  13. Refractive index changes in amorphous SiO2 (silica) by swift ion irradiation

    Peña Rodríguez, Ovidio Y.; Manzano Santamaría, Javier; Olivares, J.; Rivera de Mena, Antonio; Agullo Lopez, Fernando
    The refractive index changes induced by swift ion-beam irradiation in silica have been measured either by spectroscopic ellipsometry or through the effective indices of the optical modes propagating through the irradiated structure. The optical response has been analyzed by considering an effective homogeneous medium to simulate the nanostructured irradiated system consisting of cylindrical tracks, associated to the ion impacts, embedded into a virgin material. The role of both, irradiation fluence and stopping power, has been investigated. Above a certain electronic stopping power threshold (∼2.5 keV/nm), every ion impact creates an axial region around the trajectory with a fixed refractive index...

  14. Avances en la fabricación de células y módulos fotovoltaicos de silicio en capa fina mediante láser

    Fernández Robledo, Susana; Lauzurica Santiago, Sara; García-Ballesteros Ramírez, Juan José; Molpeceres Álvarez, Carlos Luis; Guadaño Ayuso, Gonzalo; Allen-Perkins, F.; Ocaña Moreno, José Luis
    El láser es un instrumento omnipresente en la fabricación de módulos fotovoltaicos. Los láser estándar para la interconexión monolítica de dispositivos de lámina delgada de a-Si son láser de estado sólido bombeados por diodo (DPSS) emitiendo en longitudes IR (λ=1064 nm) y en VIS (λ=532 nm). En este trabajo mostramos estudios de ablación de algunos materiales fotovoltaicos (óxidos conductores transparentes (OCT) y a-Si) con láser emitiendo en UV en el régimen de nanosegundos (ns). La afección térmica resultante en la ablación es menor, y por tanto se reduciría el riesgo de cortocircuitos en la interconexión monolítica, convirtiendo a las fuentes...

  15. Calibración de Microscopios Confocales

    Vicente y Oliva, Jesus de; Molpeceres Álvarez, Carlos Luis; Guarneiros, O.; García-Ballesteros Ramírez, Juan José
    El microscopio confocal ha sido durante mucho tiempo un instrumento de observación tridimensional con múltiples aplicaciones especialmente dentro de la biología. Sin embargo en los últimos años ha comenzado a ser utilizado como instrumento de medida en diferentes áreas de la ingeniería. En la actualidad existen muchas especificaciones de productos (dimensionales, angulares, acabado superficial) en las escalas micrométricas y nanométricas que pueden o podrían ser verificadas utilizando este instrumento. Pero para que esta verificación sea válida dentro de un sistema de calidad el microscopio confocal debe ser trazable. Esta ponencia presenta una solución sencilla a este problema implementada en el...

  16. Micromecanizado Láser de Componentes de Gran calidad de Acabado Superficial

    Molpeceres Álvarez, Carlos Luis; García-Ballesteros Ramírez, Juan José; Lauzurica Santiago, Sara; Vicente y Oliva, Jesus de; Ocaña Moreno, José Luis
    El uso de láseres pulsados con anchos temporales de nanosegundos y longitudes de onda en el rango Ultravioleta, permiten un preciso control del material abferido, convirtiendo dicha técnica en una herramienta fundamental para mecanizados que requieren de una gran calidad y acabado, con relaciones de aspecto muy altas. Este trabajo presenta un análisis paramétrico de la influencia de las distintas variables de proceso para diferentes tipos de materiales (metálicos, dieléctricos, materiales orgánicos, etc) en la calidad y acabado final. The use of nanoseconds U.V. lasers permits a precise control in ablation’s processes. As a result this tool plays a fundamental...

  17. TEMPLUM: A Process Adapted Numerical Simulation Code for The 3D Predictive Assessment of Laser Surface Heat Treatments in Planar Geometry

    García Beltrán, Ángel; Ocaña Moreno, José Luis; Molpeceres Álvarez, Carlos Luis
    A process adapted numerical simulation code for the 3D predictive assessment of laser heat treatment of materials has been developed. Primarily intended for the analysis of the laser transformation hardening of steels, the code has been successfully applied for the predictive characterization of other metallic and non metallic materials posing specific difficulties from the numerical point of view according to their extreme thermal and absorption properties. Initially based on a conventional FEM calculational structure, the developed code (TEMPLUM) reveals itself as an extremely useful prediction tool with specific process adapted features (not usually available in FEM heat transfer codes) in...

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