In this work we propose a multiprocessor architecture to reach high performance in floating point operations by using radiation tolerant FPGA devices, and under narrow time and power constraints. This architecture is used in the PHI instrument that carries out the scientific analysis aboard the ESA’s Solar Orbiter mission. The proposed architecture, in a SIMD flavor, is aimed to be an accelerator within the Data Processing Unit (it is composed by a main Leon processor and two FPGAs) for carrying out the RTE inversion on board the spacecraft using a relatively slow FPGA device – Xilinx XQR4VSX55–. The proposed architecture squeezes the FPGA resources in order to reach the computational requirements and improves the ground-based system performance based on commercial CPUs regarding time and power consumption. In this work we demonstrate the feasibility of using this FPGA devices embedded in the SO/PHI instrument. With that goal in mind, we perform tests to evaluate the scientific results and to measure the processing time and power consumption for carrying out the RTE inversion.
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.
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).
In this work, it is described the Imaging Magnetograph eXperiment, IMaX, one of the three postfocal instruments of
the Sunrise mission. The Sunrise project consists on a stratospheric balloon with a 1 m aperture telescope, which will fly
from the Antarctica within the NASA Long Duration Balloon Program.
IMaX will provide vector magnetograms of the solar surface with a spatial resolution of 70 m. This data is relevant
for understanding how the magnetic fields emerge in the solar surface, how they couple the photospheric base with the
million degrees of temperature of the solar corona and which are the processes that are responsible of the generation of
such an immense temperatures.
To meet this goal IMaX should work as a high sensitivity polarimeter, high resolution spectrometer and a near
diffraction limited imager. Liquid Crystal Variable Retarders will be used as polarization modulators taking advantage of
the optical retardation induced by application of low electric fields and avoiding mechanical mechanisms. Therefore, the
interest of these devices for aerospace applications is envisaged. The spectral resolution required will be achieved by
using a LiNbO3 Fabry-Perot etalon in double pass configuration as spectral filter before the two CCDs detectors. As well
phase-diversity techniques will be implemented in order to improve the image quality.
Nowadays, IMaX project is in the detailed design phase before fabrication, integration, assembly and verification.
This paper briefly describes the current status of the instrument and the technical solutions developed to fulfil the
The SUNRISE balloon project is a high-resolution mission to study solar magnetic fields able to resolve the critical scale of 100 km in the solar photosphere, or about one photon mean free path. The Imaging Magnetograph eXperiment (IMaX) is one of the three instruments that will fly in the balloon and will receive light from the 1m aperture telescope of the mission. IMaX should take advantage of the 15 days of uninterrupted solar observations and the exceptional resolution to help clarifying our understanding of the
small-scale magnetic concentrations that pervade the solar surface. For this, IMaX should act as a diffraction limited imager able to carry out spectroscopic analysis with resolutions in the 50.000-100.000 range and capable to perform polarization measurements. The solutions adopted by the project to achieve all these three demanding goals are explained in this article. They include the use of Liquid Crystal Variable Retarders for the polarization modulation, one
LiNbO3 etalon in double pass and two modern CCD detectors that allow for the application of phase diversity techniques by slightly changing the focus of one of the CCDs.
The description of the Imaging Magnetograph eXperiment
(IMaX) is presented in this contribution. This is a magnetograph
which will fly by the end of 2006 on a stratospheric balloon,
together with other instruments (to be described elsewhere).
Especial emphasis is put on the scientific requirements to
obtain diffraction-limited visible magnetograms, on the optical
design and several constraining characteristics, such as the
wavelength tuning or the crosstalk between the Stokes