title: Equal-curvature grazing-incidence x-ray telescopes.
abstract: We introduce a new type of x-ray telescope design, an equal-curvature telescope. We simply add a second-order axial sag to the base grazing-incidence cone-cone telescope. The radius of curvature of the sag terms is the same on the primary surface and on the secondary surface. The design is optimized such that the on-axis image spot at the focal plane is minimized. The on-axis rms spot diameter of two telescopes that we studied is less than 0.2 arc sec. The off-axis performance is comparable with that of equivalent Wolter type 1 telescopes.
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. timo.saha@gsfc.nasa.gov
authors.forename: Timo T
authors.initials: TT
authors.lastname: Saha
authors.forename: William
authors.initials: W
authors.lastname: Zhang