A telescope has an entrance pupil region; a first concave mirror (M1) belonging to a first rotationally symmetric aspheric surface and reflecting light passing through the entrance pupil region; a second convex mirror (M2) belonging to a second rotationally symmetric aspheric surface and reflecting light reflected by the first mirror; a third convex mirror (M3) belonging to a third rotationally symmetric aspheric surface and reflecting light reflected by the second mirror; a fourth concave mirror belonging to a fourth rotationally symmetric aspheric surface and reflecting light reflected by the second mirror to an exit pupil. The first, second, third and fourth rotationally symmetric aspheric surfaces are centered on the symmetry axis of the third mirror. The first, second and fourth mirrors are centered along the first direction perpendicular to the optical axis and off-centered in a second direction perpendicular to the symmetry axis and to the first direction.