SECCHIinstThe EUVI telescope was developed at (LMSAL). The EUVI mirrors were figured and coated at (IOTA) and calibrated at (IAS), the focal plane assembly was developed at NRL and the University of Birmingham, the camera electronics were developed at RAL, and the aperture door was supplied by (MPS). The EUVI observes the chromosphere and low corona in four different EUV emission lines between 17.1 and 30.4 nm. It is a small, normal-incidence telescope with thin metal filters, multilayer coated mirrors, and a back- thinned CCD detector.

EUV radiation enters the telescope through a thin metal film filter of 150 nm of aluminum. This filter suppresses most of the UV, visible, and IR radiation and keeps the solar heat out of the telescope. Each quadrant of the primary and secondary mirror is coated with a narrow-band, multilayer reflective coating, optimized for one of four EUV lines. After bouncing off the primary and secondary mirror, the radiation continues through a filter wheel that has redundant thin-film aluminum filters to remove the remainder of the visible and IR radiation. A rotating blade shutter controls the exposure time. The image is formed on a CCD detector.

The EUVI uses thin metal film filters at both the entrance aperture and near the focal plane to suppress undesired UV, visible, and IR radiation. Two types of filters are at the entrance of the telescope: an aluminum-on-polyimide foil on a coarse nickel grid for the short wavelength quadrants (17.1 and 19.5 nm), and a single layer aluminum foil on a fine nickel mesh for the long wavelength quadrants (28.4 and 30.4 nm). Both types of filters have been flown on highly successful experiments: EIT used a plastic reinforced aluminum foil on a nearly identical coarse grid for all wavelengths and TRACE used fine mesh supported filters nearly identical to the ones on the EUVI. A detailed review of the EUV instrument is described in the review article of Jean-Pierre Wülser et al. 2003, titled “EUVI: the STEREO-SECCHI extreme ultraviolet imager” (click to open).