Solar Orbiter EUI

(started in 2006 and has been selected in 2010 in the ESA Comic Vision program)

The EUI (Extreme Ultraviolet Imagers) instrument suite onboard the ESA Cosmic Vision Class-M Solar Orbiter candidate mission is composed of two high resolution imagers (HRI), one at Lyman α and one dual band at the two 17,4 and 33,5 nm EUV pass bands in the extreme UV, and one dual band full-sun imager (FSI) working alternatively at the two 17,4 and 30,4 nm EUV pass bands. In all the units, the image is produced by a mirror-telescope, working in nearly normal incidence. The EUV reflectivity of the optical surfaces is obtained with specific EUV multilayered coatings, providing also the spectral selection of the EUV units. The spectral selection is complemented with very thin filters rejecting the visible and IR radiation. Due to its orbit, EUI / Solar Orbiter will be irradiated to 20 solar constants and an entrance baffle to limit the solar heat input into EUI is needed. The CSL is the PI Institute of the EUI Consortium including members from Belgium, France, Germany and United Kingdom. Solar Orbiter launch is planned in 2017/2018.

solar orbiter 1

The optical design of the High Resolution Imager is performed by the CSL optical design workshop. This telescope makes an image of a portion of the sun. One pixel sees a surface of sun equal to 85 x 85 km².The main activity was a tradeoff between different designs depending on the minimum distance to the sun; between 0.2 and 0.3 AU :

  •  modification of the focal length,
  •  increase of the entrance pupil diameter.


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