The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-fiel
d images of the corona and transition region on the solar disc and up
to 1.5 R. above the solar limb. Its normal incidence multilayer-coated
optics will select spectral emission lines from Fe IX (171 Angstrom),
Fe XII (195 Angstrom), Fe XV (284 Angstrom), and He II (304 Angstrom)
to provide sensitive temperature diagnostics in the range from 6 x 10
(4) K to 3 x 10(6) K. The telescope has a 45 x 45 arcmin field of view
and 2.6 arcsec pixels which will provide approximately 5-arcsec spati
al resolution. The EIT will probe the coronal plasma on a global scale
, as well as the underlying cooler and turbulent atmosphere, providing
the basis for comparative analyses with observations from both the gr
ound and other SOHO instruments. This paper presents details of the EI
T instrumentation, its performance and operating modes.