© 2017 The Authors. Published by Elsevier B.V.Silva-López, ManuelBastide, L.Restrepo, R.García Parejo, PilarÁlvarez-Herrrero, Alberto2026-01-212026-01-212017-09-21Sensors and Actuators A: Physical 266: 247-2570924-4247https://www.sciencedirect.com/science/article/pii/S0924424717305630https://hdl.handle.net/20.500.12666/1635Highlights Liquid crystal polarization modulator designed for a space mission environment Thermal simulation performed to evaluate suitability of the power budget allocated. Thermal test campaign with a set-up for optical quality characterization. Transmitted wavefront measurements repeatable and within specifications required. Optical tests performed at non-operational conditions reveal no device degradation.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 non-operational 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.Manuel Silva-López graduated in Physics at the Sevilla University in Spain in 2002. He then moved to Edinburgh, United Kingdom, where he obtained his Ph.D. in optics in 2007 at Heriot-Watt University. After a period working as researcher at different universities, he joined the National Institute of Aerospace Technology (INTA) at Madrid, Spain, in 2013. At INTA he is working in the development of optical based instrumentation for space. Laurent Bastide graduated in 2006 as an Aerospace Engineer at the IPSA School in Paris. He has then several experiences in companies of the European space sector such as Thales Alenia Space and Airbus Defence and Space before joining INTA in 2009 as a thermal engineer to design space payloads for scientific missions. René Restrepo is a Mechanical Engineer at EAFIT University, Medellín, Colombia, DEA (MSc) in Physics and Computer Science at the University of La Laguna (ULL), Tenerife, Canary Islands – Spain. Ph.D. in Physics at the Complutense University of Madrid (UCM), Spain. He was a researcher at INTA and worked as an engineer at the Instituto de Astrofísica de Canarias (IAC) and at the Gran Telescopio de Canarias, Tenerife, Canary Islands – Spain. Currently, he is the Head of Applied Optics Group at EAFIT University. Pilar García Parejo graduated in Chemistry at the Universidad Autonóma de Madrid (UAM), Spain, in 2003. She was awarded with the Ph.D. from the UAM, researching on the preparation and characterization of sol–gel coatings for optical applications. Currently, she works in the space instrumentation area of INTA, Madrid. Her research interests are focused on the development and characterization of materials and optical devices to be used in payloads for space missions. Alberto Álvarez-Herrero received the degree in fundamental physics and the Ph.D. from the Complutense University of Madrid (UCM), Spain in 1994 and 2002, respectively. He has been at INTA since 1994 working in the development of space optical instrumentation. His research is aimed at new technologies, techniques, materials and devices to be used in payloads for space missions. Ellipsometry and polarimetry are his main areas of expertise. Currently he is focused on liquid crystal devices, nanostructured coatings and effects of the space environment on the optical properties of materials.engAttribution-NonCommercial-ShareAlike 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-sa/4.0/info:eu-repo/semantics/article10.1016/j.sna.2017.09.0330924-4247info:eu-repo/semantics/openAccess