Wide-angle flat field telescope

An all-reflective wide-angle unvignetted flat-field telescopic imaging system, comprising:

• baffle means for defining a predetermined relatively wide-angled field of view;
• primary mirror means comprising a segment of a first spherical mirror and having a convex spherical reflecting surface positioned relative to said baffle means to receive and reflect input light beams received from a remote source;
• secondary mirror means comprising a segment of an ellipsoidal mirror having a concave ellipsoidal reflecting surface positioned relative to said primary mirror means to receive and reflect light beams from said convex spherical reflecting surface of said first spherical mirror;
• tertiary mirror means comprising a segment of a second spherical mirror and being positioned relative to said secondary mirror means to receive light from said concave ellipsoidal reflecting surface thereof and reflect said light beams to a planar focal surface;
• aperture stop means located intermediate said secondary and tertiary mirror means;
• said segments of said primary, secondary and tertiary mirror means being positioned offset from a common optical axis in a first direction and in alignment therewith in a second direction, and wherein the centers of said first and second spherical mirrors, the foci of said ellipsoidal mirror and the center of said aperture stop means are substantially coincident with said optical axis, whereby said light beams pass through the system unobscured by any of said mirror segments;
• and
• light detector means being positioned in front of the concave spherical reflecting surface of said tertiary mirror means at the location of said planar focal surface and clear of light being received by said tertiary mirror means from said secondary mirror means.