We believe that an optical Arecibo telescope with an effective aperture diameter of 10 to 25 meters has considerable merit as a Next Generation Telescope design because of the outstanding economy inherent in its stationary mosaic spherical primary mirror. Although the aspheric secondary mirror corrects the spherical aberration of the primary mirror, the telescope itself has a useful field of view, limited by coma, of less than 1 arc second. Recognizing this deficiency, we have designed a field corrector assembly which will provide well-corrected extended images over a 1 arc minute flat field at a focal ratio of f/4.4. The extended field capability ought to significantly enhance the overall acceptability of the Arecibo design.
Paul N. Robb,
"Improvements For An Arecibo Style Next Generation Telescope (NGT)", Proc. SPIE 0172, Instrumentation in Astronomy III, (3 May 1979); doi: 10.1117/12.957061; https://doi.org/10.1117/12.957061