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Ítem Application software for teaching the polarization ellipse(Sociedad Espanola de Optica, 2018-09-01) Cano, Camilo; Echeverri-Chacon, Santiago; Cuartas-Velez, Carlos; Angel, Luciano; Restrepo, Rene; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThis paper describes the development of a computational application that calculates the configuration of a polarization state generator, according to the parameters of a desired polarization ellipse. The most general way to describe the polarization state of light is an ellipse, however, it is rarely used in practical courses in which applications are limited to the case of linear or circular polarization. To generate a desired polarization ellipse, a polarizer and a pair of retarders of ?/2 and ?/4 can be used, the problem is to determine the angle of rotation of the retarders. We present an open source algorithm to calculate these angles by using a minimization method applied to the Jones calculus description of polarizing elements. This development aims to help research and education activities to promote a more practical understanding of the polarimetric properties of light. © Sociedad Española de óptica.En este trabajo se presenta el desarrollo de una aplicación computacional que permite determinar la configuración de un generador de estados de polarización en función de los parámetros de una elipse de polarización deseada. La manera más general de describir la polarización de la luz es una elipse, sin embargo, este estado rara vez se aborda en un curso práctico en los cuales las aplicaciones se limitan al caso de la polarización lineal o circular. Para generar una elipse de polarización deseada se puede utilizar un polarizador y un par de retardadores de ?/2 y ?/4, el problema está en determinar a qué ángulo deben estar ubicados los retardadores. Se presenta un algoritmo de acceso libre que calcula estos ángulos mediante un método de minimización aplicado al cálculo de Jones. Este desarrollo va dirigido a actividades de investigación y educación, para promover una comprensión práctica de las propiedades polarimétricas de la luz. © Sociedad Española de óptica.Ítem Characterization of SrTiO3 thin films at microwave frequencies using coplanar waveguide linear resonator method(John Wiley & Sons Inc., 2011-07-01) Marulanda, José Ignacio; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaÍtem Chromatic aberration compensation in numerical reconstruction of digital holograms by Fresnel-Bluestein propagation(OSA - The Optical Society, 2017-12-15) Hincapie D.; Velasquez D.; Garcia-Sucerquia J.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this Letter, we present a method for chromatic compensation in numerical reconstruction of digitally recorded holograms based on Fresnel-Bluestein propagation. The proposed technique is applied to correct the chromatic aberration that arises in the reconstruction of RGB holograms of both millimeter-and micrometer-sized objects. The results show the feasibility of this strategy to remove the wavelength dependence of the size of the numerically propagated wavefields. (C) 2017 Optical Society of AmericaÍtem Dielectric properties characterization of high dielectric constant thick films(John Wiley & Sons, 2010-10-01) Demenicis, Luciene S.; J. I. Marulanda; Lima, Rodolfo A. A.; Carvalho, Maria Cristina R.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaA technique for the characterization of microwave dielectric properties of high dielectric constant thick films at room temperature is proposed, using multilayered coplanar waveguide transmission lines with high dielectric constant thick films depositÍtem Diffraction Efficiency Adjustment to Record High Quality Color Holograms.(Fondo Editorial Universidad EAFIT, 2014-06-04) D. Velásquez; Giraldo, Leidy; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this article, we report the experimental values of required exposure to obtain the maximum diffraction efficiencies in PFG-03C Slavich film on independent recordings and RGB multiplexed recordings. Also, color adjustments by modifying wavelength...Ítem Digital lensless holographic microscopy: numerical simulation and reconstruction with ImageJ(OPTICAL SOC AMER, 2020-07-01) Trujillo, Carlos; Piedrahita-Quintero, Pablo; Garcia-Sucerquia, Jorge; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe description and validation of an ImageJ open-source plugin to numerically simulate and reconstruct digital lensless holographic microscopy (DLHM) holograms are presented. Two modules compose the presented plugin: the simulation module implements a discrete version of the Rayleigh-Somerfield diffraction formula, which allows the user to directly build a simulated hologram from a known phase and/or amplitude object by just introducing the geometry parameters of the simulated setup; the plugin's reconstruction module implements a discrete version of the Kirchhoff-Helmholtz diffraction integral, thus allowing the user to reconstruct DLHM holograms by introducing the parameters of the acquisition setup and the desired reconstruction distance. The plugin offers the two said modules within the robust environment provided by a complete set of built-in tools for image processing available in ImageJ. While the simulation module has been validated through the evaluation of the forecasted lateral resolution of a DLHM setup in terms of the numerical aperture, the reconstruction module is tested by means of reconstructing experimental DLHM holograms of biological samples. (C) 2020 Optical Society of AmericaÍtem Double exposure specklegrams obtained by using scaled aperture pupils(SPIE-INT SOC OPTICAL ENGINEERING, 2001-01-01) Angel, L; Tebaldi, M; Trivi, M; Bolognini, N; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn speckle photography the pupil aperture is usually not modified between exposures. In our work, the change of the pupil aperture scale between exposures is analysed on the basis of double-exposed image speckle, before and after a diffuser inplane displacement is done. The apertures have the same shape but its scale is modified between exposures. Note that the relative position of the aperture is maintained. In particular, we analyse a simple case that uses a circular aperture whose diameter is modified for recording each image. The intensities in the image plane and the fringe visibility are evaluated, in terms of the geometric characteristics of the pupils. © 2001 SPIE · 0277-786X/01/$15.00.Ítem Dynamic tracking with simultaneous edge enhancement(ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2017-01-01) Sierra-Sosa D.; Isaza-Monsalve M.; Angel-Toro L.; Tebaldi M.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaDue to the isotropic edge enhancement, the vortex phase filters are of commonly used in spatial filtering. In general, these filters employ a spiral phase mask on the Fourier plane, the square modulo from this convolution is the edge enhanced image. Nonetheless, several digital filtering applications based on vortex phase filters leave aside the complex-valued information. This complex-valued field is obtained from the Laguerre-Gauss transform application over static or dynamic events, namely single images or frames in a video. We propose the usage of complex field to locate and track phase singularities in dynamic events. In this sense, not only each object edges in a given scene are enhanced, but also phase singularities related to each object. This imprints a characteristic marker given by the assignation of optical vortex to objects with unique core structure properties, allowing for tracking a particular object in dynamic events. © 2017 Elsevier GmbHÍtem Electronic speckle pattern interferometry using vortex beams(OSA - The Optical Society, 2011-11-01) Restrepo, Rene; Uribe, Néstor; Belenguer, Tomás; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaÍtem EMIR mechanical design status(SPIE-INT SOC OPTICAL ENGINEERING, 2004-09-01) Fuentes, F. J; Sánchez, Vicente; Barrera, Sonia; Correa, Santiago; Pérez, Jaime; Redondo, Pablo; R. Restrepo; Tenegi, Fabio; Villegas, Alejandro; Patrón, Jesus; Garzón, Francisco; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaEMIR is the NIR multi-object imager and spectrograph for the GTC (Gran Telescopio Canarias). The instrument PDR phase was held successfully in March 2003, and we are at present in the middle of the ADR (Advanced Design Phase) during which a number of mechÍtem EMIR optomechanics(SPIE-INT SOC OPTICAL ENGINEERING, 2004-09-01) Barrera, Sonia; Villegas, Alejandro; Fuentes, Javier; Correa, Santiago; Pérez, Jaime; Redondo, Pablo; R. Restrepo; Sánchez, Vicente; Tenegi, Fabio; Garzón, Francisco; Patrón, Jesus; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaEMIR is a NIR multiobject spectrograph with imaging capabilities to be used at the GTC. A general description of instrument performances, as well as the updated optical and mechanical layouts, can be found elsewhere on these proceedings.Ítem EMIR: the GTC NIR multi-object imager spectrograph(SPIE-INT SOC OPTICAL ENGINEERING, 2004-09-01) Garzón, Francisco; Abreu, David; Barrera, Sonia; Correa, Santiago; Díaz, Jose; Fragoso, Ana; Fuentes, F.J; Gago, Fernando; Gonzalez, Carlos; López, Pablo; Manescau, Antonio; Patrón, Jesus; Pérez, Jaime; Redondo, Pablo; R. Restrepo; Sánchez, Vicente; Villegas, Alejandro; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaWe present the final global design and performances of EMIR, the NIR multi-object spectrograph of the GTC, as well as the plan for its early scientific exploitation.Ítem Evaluation between methods for the color measurement in holograms by using a CMOS-RGB camera and a spectrometer.(SPIE-INT SOC OPTICAL ENGINEERING, 2013-07-01) Velásquez, Daniel Ignacio; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaÍtem Evaluation of a liquid crystal based polarization modulator for a space mission thermal environment(Elsevier B.V., 2017-10-15) Silva-López M.; Bastide L.; Restrepo R.; García Parejo P.; Álvarez-Herrero A.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe Multi Element Telescope for Imaging and Spectroscopy (METIS) is one of the remote sensing instruments to be onboard the future NASA/ESA Solar Orbiter mission. The science nominal mission orbit will take the spacecraft from 0.28 to 0.95 astronomical units from the Sun, setting challenging and variable thermal conditions to its payload. METIS is an inverted-occultation coronagraph that will image the solar corona in the visible and UV wavelength range. In the visible light path a Polarization Modulation Package (PMP) performs a polarimetric analysis of the incoming solar light. This PMP is based on liquid crystal variable retarders (LCVR) and works under a temporal modulation scheme. The LCVRs behavior has a dependence on temperature and, as a consequence, it is critical to guarantee the PMP performance in the mission thermal environment. Key system specifications are the optical quality and the optical retardance homogeneity. Moreover, the thermally induced elastic deformations of the mechanical mounts and the LCVRs shall not produce any performance degradation. A suitable thermal control is hence required to maintain the system within its allowed limits at any time. The PMP shall also be able to reach specific set-points with the power budget allocated. Consequently, and in order to verify the PMP thermal design, we have experimentally reproduced the expected thermal flight environment. Specifically, a thermal vacuum cycle test campaign is run at the different mission operational conditions. The purpose is both to check the stability of the thermal conditions and to study the optical quality evolution/degradation. Within this test transmitted wavefront measurements and functional verification tests have been carried out. To do that we adapted an optical interrogation scheme, based on a phase shifting interferometric technique, that allows for inspection of the PMP optical aperture. Finally, measurements obtained at nonoperational temperature conditions are also shown. These results demonstrate that the device meets the specifications required to perform its operational role in the space mission environment. (C) 2017 The. Authors. Published by Elsevier B.V.Ítem Experimentos en el aula de clase para enseñanza de la física(Sociedad Colombiana de Física, 2006-01-01) J. I. Marulanda; Gómez, Luis A.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaConsiderando la importancia de los aspectos fenomenológicos como motivación para elaborar modelos formales en la enseñanza de la física, la experimentación se convierte en un recurso didáctico valioso en este proceso.Ítem Fringe visibility analysis with different scale apertures in speckle photography(TAYLOR & FRANCIS LTD, 2001-09-15) Angel, L; Tebaldi, M; Trivi, M; Bolognini, N; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe use of different scale aperture pupils for image recording in speckle photography is analysed. In particular a double-exposure specklegram is considered. The ensemble-average intensity in the Fourier plane is analytically derived and fringe visibility is investigated. The theoretical results are verified by in-plane displacement translation experiments.Ítem High dynamic range imaging method for interferometry(ELSEVIER SCIENCE BV, 2011-01-01) Vargas, J.; Restrepo, R.; Quiroga, J.A.; Belenguer, T.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaWe demonstrate a method to easily and quickly extend the dynamic range imaging capabilities of the camera in a typical interferometric approach. The camera dynamic range is usually low and limited to 256 gray levels. Also, it is well known that one may have over or under-exposed regions in the interferogram (due to non-uniform illumination) which makes these image regions not reliable. In our proposed method it is not necessary to obtain or use the non-linear camera response curve in order to extend the camera dynamic range. We obtain a sequence of differently exposed interferograms, typically five or six; after that, we compute the corresponding normalized fringe patterns and modulation maps using a typical normalization method. These normalized patterns are combined through a temporal weighted average using as weights the corresponding modulation maps. We show a set of experimental results that prove the effectiveness of the proposed method. © 2011 Elsevier B.V. All rights reserved.Ítem Holoprinter: study and development of a direct write synthetic full parallax holographic system(Sociedad Espanola de Optica, 2018-12-01) Madrid-Sanchez, A; Velasquez-Prieto, D; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaHoloprinters based on holographic stereograms (HS) have been developed to synthesize holograms by using 2D images with perspective information of 3D objects. The objects can be real or computer generated. HS has been applied to different fields such as engineering, medicine and military because the high visual impact of the tridimensional and multi-view images it presents. To implement a Holoprinter requires development of three components: i) 2D images generation, ii) optical system design for HS recording and iii) mechanical and control implementation. Therefore, we design and develop each of the components, which integrated compose a holoprinter to synthesize full parallax HS. This paper studies basis for production of this kind of holograms and describes the computational and opto-mechanical design and implementation that we have made. Experimental HS were obtained to validate the system.Ítem Hygroscopic growth study in the framework of EARLINET during the SLOPE i campaign: Synergy of remote sensing and in situ instrumentation(Copernicus GmbH, 2018-05-18) Bedoya-Velásquez A.E.; Navas-Guzmán F.; Granados-Muñoz M.J.; Titos G.; Román R.; Andrés Casquero-Vera J.; Ortiz-Amezcua P.; Antonio Benavent-Oltra J.; De Arruda Moreira G.; Montilla-Rosero E.; Hoyos C.D.; Artiñano B.; Coz E.; Olmo-Reyes F.J.; Alados-Arboledas L.; Guerrero-Rascado J.L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThis study focuses on the analysis of aerosol hygroscopic growth during the Sierra Nevada Lidar AerOsol Profiling Experiment (SLOPE I) campaign by using the synergy of active and passive remote sensors at the ACTRIS Granada station and in situ instrumentation at a mountain station (Sierra Nevada, SNS). To this end, a methodology based on simultaneous measurements of aerosol profiles from an EARLINET multi-wavelength Raman lidar (RL) and relative humidity (RH) profiles obtained from a multi-instrumental approach is used. This approach is based on the combination of calibrated water vapor mixing ratio (r) profiles from RL and continuous temperature profiles from a microwave radiometer (MWR) for obtaining RH profiles with a reasonable vertical and temporal resolution. This methodology is validated against the traditional one that uses RH from co-located radiosounding (RS) measurements, obtaining differences in the hygroscopic growth parameter (?) lower than 5% between the methodology based on RS and the one presented here. Additionally, during the SLOPE I campaign the remote sensing methodology used for aerosol hygroscopic growth studies has been checked against Mie calculations of aerosol hygroscopic growth using in situ measurements of particle number size distribution and submicron chemical composition measured at SNS. The hygroscopic case observed during SLOPE I showed an increase in the particle backscatter coefficient at 355 and 532nm with relative humidity (RH ranged between 78 and 98%), but also a decrease in the backscatter-related Ångström exponent (AE) and particle linear depolarization ratio (PLDR), indicating that the particles became larger and more spherical due to hygroscopic processes. Vertical and horizontal wind analysis is performed by means of a co-located Doppler lidar system, in order to evaluate the horizontal and vertical dynamics of the air masses. Finally, the Hänel parameterization is applied to experimental data for both stations, and we found good agreement on ? measured with remote sensing (?532 0.48 ± 0.01 and ?355 0.40 ± 0.01) with respect to the values calculated using Mie theory (?532 0.53 ± 0.02 and ?355 0.45 ± 0.02), with relative differences between measurements and simulations lower than 9% at 532nm and 11% at 355nm. © Author(s) 2018.Ítem Improvement of the signal-to-noise ratio in digital holography(Sociedad Mexicana de Física, 2005-02) Velásquez-Prieto, Daniel; Herrera Ramírez, Jorge Alexis; García Sucerquia, Jorge Iván; Velásquez-Prieto, Daniel; Herrera Ramírez, Jorge Alexis; García Sucerquia, Jorge Iván; Universidad EAFIT. Departamento de Ciencias Básicas; dvelas@eafit.edu.co; Óptica AplicadaA fundamental problem in optical and digital holography is the presence of speckle noise in the reconstruction process, which essentially diminishes the signal to noise ratio (SNR). For many applications, that reduction of the SNR makes the digital holography impractical, so great number of approaches have been carried out in order to overcome such a problem. They range from modifying the spatial coherence of the illumination to the application of image processing techniques. In this paper we propose the merged use of digital image processing techniques in order to increase this SNR by reducing the speckle noise in the digital reconstruction of optically recorded Fresnel’s holograms. The proposed techniques are illustrated with experimental results.