Grazing-incidence imaging spectrograph for solar observations in the extreme-ultraviolet domain

The design of an imaging spectrograph operating at grazing incidence and stigmatic in a large field-of-view is presented. It is realized coupling a double telescope and a spectrometer. The instrument may be used for XUV space observations of extended sources, and is particularized to the Sun observation from the Earth. The performances of a laboratory prototype are presented. This instrument covers the 4-20 nm (310-62 eV) spectral region, with a spectral resolution of 0.1% at 10 nm and a spatial resolution of 3.5 arcsec over a field-of-view of 0.5 deg, within a total envelope of 1.2 m. The design and the characterization of the instrument in the whole spectral region of operation are presented.