A. Álvarez‐Herrero
A5005664146- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Optical Polarization and Ellipsometry
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Liquid Crystal Research Advancements
- Solar Radiation and Photovoltaics
- Photonic and Optical Devices
- Spacecraft Design and Technology
- Advanced Fiber Optic Sensors
- Leaf Properties and Growth Measurement
- Calibration and Measurement Techniques
- Photonic Crystals and Applications
- Optical measurement and interference techniques
- Photochemistry and Electron Transfer Studies
- Geophysics and Gravity Measurements
- Photorefractive and Nonlinear Optics
- Optical Wireless Communication Technologies
- Inertial Sensor and Navigation
- Space Satellite Systems and Control
- Semiconductor Lasers and Optical Devices
- Orbital Angular Momentum in Optics
- Luminescence and Fluorescent Materials
- CCD and CMOS Imaging Sensors
Instituto Nacional de Técnica Aeroespacial
2014-2024
École Polytechnique
2019
Centre National de la Recherche Scientifique
2019
Laboratoire de Physique des Interfaces et des Couches Minces
2019
Universidad Complutense de Madrid
2019
Osservatorio Astrofisico di Torino
2018
Instituto de Ciencia de Materiales de Sevilla
2008
Unidades Centrales Científico-Técnicas
2001-2004
Consejo Superior de Investigaciones Científicas
2001-2004
This paper describes the Polarimetric and Helioseismic Imager on Solar Orbiter mission (SO/PHI), first magnetograph helioseismology instrument to observe Sun from outside Sun-Earth line. It is key meant address top-level science question: How does solar dynamo work drive connections between heliosphere? SO/PHI will also play an important role in answering other questions of Orbiter, as well hosting potential a rich return further science. measures Zeeman effect Doppler shift FeI 617.3nm...
Metis is the first solar coronagraph designed for a space mission capable of performing simultaneous imaging off-limb corona in both visible and UV light. The observations obtained with aboard Solar Orbiter ESA-NASA observatory will enable us to diagnose, unprecedented temporal coverage spatial resolution, structures dynamics full from 1.7 $R_\odot$ about 9 $R_\odot$. Due uniqueness profile, be able observe close vantage point (down 0.28 AU), achieving out-of-ecliptic views increase orbit...
The first science flight of the balloon-borne \Sunrise telescope took place in June 2009 from ESRANGE (near Kiruna/Sweden) to Somerset Island northern Canada. We describe scientific aims and mission concept project give an overview a description various hardware components: 1-m main with its postfocus instruments (the UV filter imager SuFI imaging vector magnetograph IMaX) support (image stabilizing light distribution system ISLiD correlating wavefront sensor CWS), optomechanical structure...
The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by four institutions in Spain that flew on board the Sunrise balloon-borne telesocope June 2009 for almost six days over Arctic Circle. As polarimeter IMaX uses fast polarization modulation (based use of two liquid crystal retarders), real-time image accumulation, and dual beam polarimetry to reach sensitivities 0.1%. spectrograph, instrument LiNbO3 etalon double pass narrow band pre-filter achieve spectral resolution...
The SUNRISE balloon-borne solar observatory, consisting of a 1~m aperture telescope that provided stabilized image to UV filter imager and an imaging vector polarimeter, carried out its second science flight in June 2013. It observations parts active regions at high spatial resolution, including the first high-resolution images Mg~{\sc ii}~k line. obtained data are very quality, with best reaching diffraction limit 3000~\AA\ after Multi-Frame Blind Deconvolution reconstruction accounting for...
This paper describes the wave-front correction system developed for Sunrise balloon telescope, and provides information about its in-flight performance. For of low-order aberrations, a Correlating Wave-Front Sensor (CWS) was used. It consisted six-element Shack-Hartmann sensor (WFS), fast tip-tilt mirror compensation image motion, an active telescope secondary focus correction. The CWS delivered stabilized with precision 0.04 arcsec (rms), whenever coarse pointing better than 90...
Abstract This paper describes the innovative optical design of Metis coronagraph for Solar Orbiter ESA-NASA mission. is a multi-wavelength, externally occulted telescope imaging solar corona in both visible and ultraviolet wavelength ranges. adopts novel occultation scheme disk, that we named “inverse external occulter”, reducing extremely high thermal load on instrument at spacecraft perihelion. The core an aplanatic Gregorian common to channels. A suitable dichroic beam-splitter, optimized...
The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter (SO) spacecraft observed small extreme ultraviolet (EUV) bursts, termed campfires, that have been proposed to be brightenings near apexes of low-lying loops in quiet-Sun atmosphere. underlying magnetic processes driving these campfires are not understood. During cruise phase SO and at a distance 0.523\,AU from Sun, Polarimetric Helioseismic (SO/PHI) region jointly with SO/EUI, offering possibility investigate surface field...
A low relative humidity (RH) sensor based on overlay side-polished fiber is presented. The evanescent field from a single-mode optical coupled to TiO/sub 2/ waveguide overlay. transmission response exhibits sharp resonances whose central wavelengths are linearly shifted with RH. This behavior due the porous columnar nanostructure of film. water adsorbed in pores changing refractive index layer and causing shift wavelength resonances. determined by shape size pores. developed has linear high...
The application of Optical Wireless Links to intra- Spacecraft communications (OWLS) is presented here. This work summarizes ten years developments, ranging from basic optoelectronic parts and front-end electronics, different inorbit demonstrations. Several wireless applications were carried out in representative environments at ground level, on in-flight experiments. A completely satellite will be launched the beginning 2010. benefits replacing standard data wires connectors with systems...
In July 2024, Sunrise completed its third successful science flight. The III observatory had been upgraded significantly after the two previous flights in 2009 and 2013. Three completely new instruments focus on small-scale physical processes their complex interaction from deepest observable layers photosphere up to chromospheric heights. Previously poorly explored spectral regions lines are exploited paint a three-dimensional picture of solar atmosphere with unprecedented completeness level...
We present the optical effects of different tests that simulate aerospace environment on liquid-crystal variable retarders (LCVRs) used in Imaging Magnetograph eXperiment postfocal instrument SUNRISE payload within NASA Long Duration Balloon program. Analysis influence vacuum, temperature, vibration, and gamma ultraviolet radiation is performed by measuring these retardance, response time, wavefront distortion, transmittance, including some situ measurements. Outgassing measurements parts...
We briefly outline the scientific and instrumental aspects of ESA's Solar Orbiter mission. Special emphasis is given to Polarimetric Helioseismic Imager, instrument with highest relevance for helioseismology applications, which will observe gas motions vector magnetic field in photosphere at high spatial temporal resolution.
The High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager on board Solar Orbiter spacecraft (SO/PHI) Magnetic (HMI) Dynamics Observatory (SDO) both infer photospheric magnetic field from polarised light images. SO/PHI is first magnetograph to move out Sun--Earth line will provide unprecedented access Sun's poles. This provides excellent opportunities for new research wherein maps instruments are used simultaneously. We aim compare these two discuss any possible...
Aims. We use wavefront sensing to characterise the image quality of High Resolution Telescope (HRT) Polarimetric and Helioseismic Imager (SO/PHI) data products during second remote window Solar Orbiter (SO) nominal mission phase. Our ultimate aims are reconstruct HRT by deconvolving with point spread function (PSF) correct for effects optical aberrations on data. Methods. a pair focused–defocused images compute error derive PSF means phase diversity (PD) analysis. Results. The depends...
This work reports about the preparation of plasma polymerized thin films perylene with thicknesses ∼30−150 nm and their characterization by different methods analysis optical properties. Highly absorbent fluorescent have been obtained this method that combines sublimation molecules controlled polymerization interaction remote Ar plasma. The polymeric are very flat a root mean square (rms) roughness in range 0.3−0.4 nm. In contrast sublimated layers present high scattering light, depict...
The use of Liquid Crystal Variable Retarders (LCVRs) as polarization modulators are envisaged a promising novel technique for space instrumentation due to the inherent advantage eliminating need conventional rotary polarizing optics hence mechanisms. LCVRs is mature technology ground applications; they wellknow, already used in polarimeters, and during last ten years have undergone an important development, driven by fast expansion commercial Displays. In this work brief review state art...
Earth-side observations of solar p modes can be used to image and monitor magnetic activity on the Sun's far side. Here we use magnetograms side obtained by Polarimetric Helioseismic Imager (PHI) onboard Solar Orbiter (SO) directly assess -- for first time validity far-side helioseismic holography. We wish co-locate positions active regions in images magnetograms, calibrate measurements terms field strength. identify three 18 November 2020, 3 October 2021, February 2022 displaying a total...
We report the correction of shrinkage observed during UV postrecording curing in a holographic solgel material that was recently achieved by use various chemical formulations for composition hybrid supporting matrix. found modification matrix noticeably attenuates (from 1.3% to 0.4% material's initial thickness with inclusion just 20% tetramethylorthosilicate), providing improved stability permanent data storage applications. The properties samples different binders are also reported. In...
Context. The orbital angular momentum (OAM) of the photon is a property light from astronomical objects that has not yet been measured. We propose method measuring OAM spectrum an extended natural source, Sun. Relating different solar areas to its structures could lead novel remote sensing technique.
The presence of uncontrolled mechanical vibrations is typically the main precision-limiting factor a phase-shifting interferometer. We present method that instead trying to insolate vibrations; it takes advantage their produce different phase-steps. based on spatial and time domain processing techniques compute first unknown phase-steps then reconstruct phase from these tilt-shifted interferograms. In order compensate camera movement, needed perform an affine registration process between...
The usage of QKD protocols through the current terrestrial infrastructure is limited to a hundred kilometers due attenuation problems with fiber. This implies that satellite will be necessary for transmission quantum keys in order avoid these limitations. Therefore, debate does not lie need but rather what type best suited, and specifically GEO vs LEO satellites. analysis trivial should consider only link budgets physical layer as it has been done up date. It also even more important...
Context. Traditionally, the observation time needed to build synoptic maps of solar magnetic field is bound 27 days a full Carrington rotation due single viewpoint from Earth. Aims. Our aim reduce this 13.5 by combining magnetograms two vantage points, 180° apart in longitude ideal case. Methods. We combined observations taken Polarimetric and Helioseismic Imager (SO/PHI) during superior conjunction Solar Orbiter February 2021 with data Magnetic (SDO/HMI) constructed map line-of-sight CR...
A temperature sensor based on overlay side-polished fibers is presented. It works the basis of evanescent field coupling between a single-mode optical fiber and dielectric waveguide overlay. The spectrum white light beam transmitted through former system exhibit sharp deep regularly spaced resonances whose central wavelenths are linearly shifted with temperature. has wavelength sensitivity /spl sim/1 nm//spl deg/C, which one order magnitude better than that obtained Bragg sensors.