Multisegmented, multilayer-coated mirrors for the Solar Ultraviolet Imager

Abstract. The Solar Ultraviolet Imager (SUVI) is one of the several instruments that will fly on board the next generation of Geostationary Operational Environmental Satellites R-U platforms, as part of the National Oceanic and Atmospheric Administration’s space weather monitoring fleet. SUVI is a generalized Cassegrain telescope that employs multilayer-coated optics that operate in six extreme ultraviolet (EUV) narrow bandpasses centered at 93.9, 131.2, 171.1, 195.1, 284.2 and 303.8 Å. The innovation of the design is that SUVI is the first EUV solar telescope that has six different wavelength channels accommodated on each mirror. And despite having six segmented multilayer-coatings, shadowing (due to the mask) is minimized allowing SUVI to exceed its effective area specifications. Once operational, SUVI will record full-disk, spectroheliograms every few minutes, where this data will be used to better understand the effects of solar produced EUV radiation on Earth and the near-Earth environment. The material presented discusses general aspects of the SUVI optical design, mirror fabrication, super polishing, and metrology carried out to verify optical surface quality and in-band, EUV reflectivity performance of the multilayer coatings. The power spectral density and EUV measurements are shown to exceed performance requirements and are critical for the overall calibration and monitoring of SUVI’s throughput and imaging performance, once operational.