Wide field four mirror telescope using off-axis aspherical mirrors

A telescope comprising:

• an entrance pupil region;
• a first concave mirror (M1) belonging to a first imaginary axially symmetric aspheric surface and reflecting light passing through said entrance pupil region;
• a second convex mirror (M2) belonging to a second imaginary axially symmetric aspheric surface and reflecting light reflected by said first mirror;
• a third convex mirror (M3) belonging to a third imaginary aspheric surface axially symmetric about a symmetry axis z and reflecting light reflected by said second mirror;
• a fourth concave mirror (M4) belonging to a fourth imaginary axially symmetric aspheric surface and reflecting light reflected by said third mirror and passing through an exit pupil;
• wherein said third mirror is axially symmetric about the symmetry axis z, and
• said first, second, third and fourth axially symmetric aspheric surfaces being centered on the symmetry axis z of the third mirror, said first, second and fourth mirrors being centered about a first plane formed by said symmetric axis z and a first direction perpendicular to said symmetry axis z and off-centered in a second plane perpendicular to said first plane along said symmetry axis z.