Examinando por Materia "Space optics"

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    Analyzing Long-Term Availability of Urban Green Space by Socioeconomic Status in Medellin, Colombia, Using Open Data and Tools
    (Institute of Electrical and Electronics Engineers Inc., 2020-01-01) Patino J.E.; Patino J.E.; Universidad EAFIT. Departamento de Ciencias; Research in Spatial Economics (RISE)
    The availability of green spaces is an important issue for urban populations worldwide, given the benefits that the green spaces provide for health, well-being, and quality of life. But urban green spaces are not always distributed equally for different population groups within cities. Latin America is the second most urbanized region of the world, but there are few published studies analysing the green space availability for different urban population groups, and less so analysing the long-term trends. This work presents an analysis of long-term availability of urban green spaces by different socioeconomic status population groups in Medellin city, Colombia, using open geospatial data and open software tools. The results indicate that disparities between different groups have been decreasing in the last years, but there are still efforts to do. Showing this kind of analysis based on open data and tools is essential as it opens the possibility for replicating it in other cities with scarce budgets. © 2020 IEEE.
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    Imaging polarimeters based on liquid crystal variable retarders: An emergent technology for space instrumentation
    (SPIE-INT SOC OPTICAL ENGINEERING, 2011-01-01) Alvarez-Herrero, A.; Uribe-Patarroyo, N.; García Parejo, P.; Vargas, J.; Heredero, R.L.; Restrepo, R.; Martínez-Pillet, V.; Del Toro Iniesta, J.C.; López, A.; Fineschi, S.; Capobianco, G.; Georges, M.; López, M.; Boer, G.; Manolis, I.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    The use of Liquid Crystal Variable Retarders (LCVRs) as polarization modulators are envisaged as a promising novel technique for space instrumentation due to the inherent advantage of eliminating the need for conventional rotary polarizing optics hence the need of mechanisms. LCVRs is a mature technology for ground applications; they are wellknow, already used in polarimeters, and during the last ten years have undergone an important development, driven by the fast expansion of commercial Liquid Crystal Displays. In this work a brief review of the state of the art of imaging polarimeters based on LCVRs is presented. All of them are ground instruments, except the solar magnetograph IMaX which flew in 2009 onboard of a stratospheric balloon as part of the SUNRISE mission payload, since we have no knowledge about other spaceborne polarimeters using liquid crystal up to now. Also the main results of the activity, which was recently completed, with the objective to validate the LCVRs technology for the Solar Orbiter space mission are described. In the aforementioned mission, LCVRs will be utilized in the polarisation modulation package of the instruments SO/PHI (Polarimetric and Helioseismic Imager for Solar Orbiter) and METIS/COR (Multi Element Telescope for Imaging and Spectroscopy, Coronagraph). © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).