Examinando por Autor "Restrepo R."

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    Design of a linear in wavenumber spectrometer
    (OSA - The Optical Society, 2018-01-01) Ruiz-Lopera S.; Restrepo R.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    We describe the optical design of a linear in wavenumber spectrometer that combines a grating and a prism. OpticStudio software was used to validate the performance of the design. High lineartiy in k-space was achived. © 2018 The Author (s)
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    Ítem
    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 Aplicada
    The 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.
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    Ítem
    Monoscopic multifocus in polarization images for biological samples segmentation
    (OSA - The Optical Society, 2018-01-01) Cano C.; Restrepo R.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    We present an implementation based on polarization images acquisition for different focus planes in a microscope, allowing the volumetric segmentation of structured biological samples like onion cellular walls. © 2018 The Author (s)
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    Ítem
    Multi-plane phase retrieval methods to recover free-aberrations object complex field via SLM
    (Sociedad Espanola de Optica, 2017-12-01) Restrepo R.; Belenguer T.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    This paper explains two iterative phase recovery methods where the goal of each one is different. The Phase Diversity method is used to recover the wavefront aberrations in optical incoherent imaging systems when an extended object is illuminated. The purpose of the Multi-plane Phase Retrieval method is recovering the object complex field seen from the image plane, therefore the object has to be illuminated with coherent light. Both methods are simultaneously used to pick out the aberrations and free aberrations object phase. The use of both methods is proposed as a methodology for the integration of optical instruments.