Examinando por Autor "Restrepo, R."

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Restringido
A far infrared spectrometer for SPICA mission: optical E2E of SAFARI
(SPIE Digital Library, 2020-12-13) Fernández, María Manuela; Arrazola Pérez, D.; Jellema, W.; González, Luis M.; García, R.; Belenguer Dávila, T.; Torres Redondo, J.; Restrepo, R.; Eggens, M.; Evers, J.; Dieleman, P.; Agencia Estatal de Investigación (AEI)
This paper describes the end-to-end opto-mechanical design of the SAFARI instrument on SPICA and the analysis of the spectrometer optical performances. SAFARI instrument is a high sensitivity grating-based spectrometer operating in the 34-230 μm wavelength range. The scientific drivers lead to the implementation of two modes of operation. The Low- Resolution (LR) or nominal mode (R~300) and the High-Resolution (HR), that implies to include a Martin-Puplett Fourier Transform Spectrometer (MP-FTS) to achieve the required spectral resolution (R~2000-11000). The optical system is all-reflective and consists of three main modules. The input optics module (IOM) is an unobscured reflective Offner relay. In the IOM a Beam Steering Mirror (BSM) is included for spatial modulation and to allow efficient sky mapping. The Band and Mode Distributing Optics (BMDO) module splits the radiation band into the four different spectral bands and includes the MP-FTS. The field image existing at the output of the BMDO constitutes the entrance to the Grating Module Optics (GM). These modules provide spectral dispersion by means of linear and reflective diffraction gratings and the final image onto the detectors. Performances of the GMs are high demanding with a detector divided into 2 sub-bands with a different pixel size for each sub-band.
Acceso Abierto
Field aberrations in terms of the Q-polynomial basis and its relationship to the Zernike basis
(Optica Publishing Group, 2021-02-01) García Moreno, A.; Restrepo, R.; Belenguer Dávila, T.; González Fernández, M.; Instituto Nacional de Técnica Aeroespacial (INTA)
The aberrations generated at the image plane of an optical system that includes freeform surfaces described through Q-polynomials can be calculated using nodal aberration theory. By analyzing the definition of each Q-polynomial, they can be compared with Zernike polynomials allowing a relationship between the two bases. This relationship is neither simple nor direct, so a fitting must be made. Once established, the contribution to the aberration field map generated by each surface described through the Q-polynomial can be calculated for any surface that is not at the stop of the system. The Q-polynomials are characterized by their orthogonality in the gradient instead of the surface, which represents an opportunity to restrict the changes in the slope in a simple way and facilitate the manufacturing process. The knowledge of the field aberrations generated by each Q-polynomial allows selecting that which of them are necessary to be introduced as variables in the optimization process for an efficient optimization.
Restringido
Imaging polarimeters based on liquid crystal variable retarders: an emergent technology for space instrumentation
(SPIE Optical Engineering Applications, 2011-09-09) Álvarez Herrero, A.; Uribe Patarroyo, N.; García Parejo, P.; Vargas, J.; López Heredero, R.; Restrepo, R.; Martínez Pillet, V.; Del Toro Iniesta, J. C.; López, A.; Fineschi, S.; Capobianco, G.; Georges, M.; López, M.; Boer, G.; Manolis, I.; López Heredero, R. [0000-0002-2197-8388]; Vargas, J. [0000-0001-7519-6106]; García Parejo, P. [0000-0003-1556-9411]; López Jiménez, A. [0000-0002-6297-0681]; Del Toro Iniesta, J. A. [0000-0002-3387-026X]; Álvarez Herrero, A. [0000-0001-9228-3412]; Capobianco, G. [0000-0003-0520-2528]; Restrepo Gómez, R. [0000-0002-3874-3032]; Georges, M. [0000-0002-0460-3912]; Martínez Pillet, V. [0000-0001-7764-6895]
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).
Restringido
Space-qualified liquid-crystal variable retarders for wide-field-of-view coronagraphs
(SPIE Optical Engineering Applications, 2011-10-06) Uribe Patarroyo, N.; Álvarez Herrero, A.; 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.; Álvarez Herrero, A. [0000-0001-9228-3412]; Del Toro Iniesta, J. C. [0000-0002-3387-026X]; López Heredero, R. [0000-0002-2197-8388]; Vargas, J. [0000-0001-7519-6106]; López Jiménez, A. [0000-0002-6297-0681]; García Parejo, P. [0000-0003-1556-9411]; Capobianco, G. [0000-0003-0520-2528]; Georges, M. [0000-0002-0460-3912]; Restrepo Gómez, R. [0000-0002-3874-3032]; Martínez Pillet, V. [0000-0001-7764-6895]
Liquid-crystal variable retarders (LCVRs) are an emergent technology for space-based polarimeters, following its success as polarization modulators in ground-based polarimeters and ellipsometers. Wide-field double nematic LCVRs address the high angular sensitivity of nematic LCVRs at some voltage regimes. We present a work in which wide-field LCVRs were designed and built, which are suitable for wide-field-of-view instruments such as polarimetric coronagraphs. A detailed model of their angular acceptance was made, and we validated this technology for space environmental conditions, including a campaign studying the effects of gamma, proton irradiation, vibration and shock, thermo-vacuum and ultraviolet radiation.