Easily fabricated wide-angle telescope

A novel configuration for a wide angle flat field all reflective unobscured telescope using two figured surfaces which are easily fabricated and aligned is described. DESCRIPTION OF TELESCOPE This paper describes an easily fabricated telescope which forms a high quality image of an extremely wide angle object field on a flat image surface. The telescope uses only reflectors and thus has no chromatic aberrations. An eccentric portion of the rotationally symmetrical field of the telescope is used such that no part of the aperture is obscured. The mirrors are surfsces of revolution described exclusively as flats spheres or conic sections all of which are easily tested and verified in manufacwre using well-known conventional null tests. Each mirror shares a common axis of rotational symmetry facilitating telescope alignment. One mirror is used twice providing the function of a secondary and tertiary mirror while eliminating the need to fabricate and align a separate tertiary mirror. The current design evolved from a form pcpularly known as the WALRUS'' a three mirr rotationally symmetric flat field unobscured design arranged in a " Z" configuration with an aperture stop between the secondary and tertiary mirrors (figure 1). In the WALRUS patent the two concave mirrors are specified as an effipsoid (secondary mirror) and a sphere (tertiary mirror) while the convex (primary) mirror is a sphere. The base curvatures of the three powered mirrors are chosen such