Microroughness measurements and EUV calibration of the solar ultraviolet imager multilayer-coated mirrors

Abstract

The Solar Ultraviolet Imager (SUVI) is one of several instruments that will fly on board the next generation of Geostationary Operational Environmental Satellites (GOES) -R and -S platforms, as part of NOAA'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. Once operational, over the mission lifetime expected to last up to 10 years, SUVI will record full disk, EUV 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 herein will touch upon general aspects of the SUVI optical design, as well as the fabrication, super polishing and metrology of the fabricated mirrors, including measured EUV spectral performance.

Triple-wavelength, narrowband Mg/SiC multilayers with corrosion barriers and high peak reflectance in the 25-80 nm wavelength region

“…Moreover, this approach requires the use of a hardware mask placed on top of the mirror during multilayer deposition, which involves additional complexities and risks due to the proximity of the mask to the area being coated. "Shadowing" effects between the edges of the mask and the sector being coated diminish the multilayer performance and reduce the overall effective area of the mirror [14][15][16]. Multiple telescopes often need to be employed in a given mission in order to achieve the number of EUV channels required to accomplish the science objectives [13].…”

Multisegmented, multilayer-coated mirrors for the Solar Ultraviolet Imager

“…3 (see Ref. 16 for more details). We note that fewer "spot" measurements were taken across the optic at LLNL than at Tinsley: i.e., two to five measurement locations in contrast to a dozen locations, respectively, thus yielding better statistics for the Tinsley measurements.…”

“…The shaping, figuring, and polishing of all the SUVI mirrors were carried out at SSG-Tinsley (Tinsley, hereafter). Herein, we focus more on the mid-and high-spatial frequency microroughness surface analyses; for more details regarding all test setups and equipment used, we refer the reader to Martínez-Galarce et al 16 …”