Optical design of glancing incidence extreme ultraviolet telescopes.

Glancing incidence telescope designs employing surfaces of revolution and of the same geometry as the Wolter type 2 telescope (a concave paraboloid followed by a confocal convex hyperboloid) are investigated for primarily solar physics applications in the spectral region greater than 100 A. The optical properties of the telescopes are evaluated in terms of minimum spot size and flattened focal surface as a function of optical acceptance (throughput) and folding ratio (physical length of the telescope/effective focal length). One meter focal length systems with full fields of 0.8 deg, throughputs of 15 x 10(-4) sr and 30 x 10(-4) sr, and maximum grazing angles of 13 deg are shown to exhibit optimum imaging properties for a folding ratio on the order of 0.85.