Introduction to the 30m Ringy Interferometric Telescope

In order to meet the demands of exploring extra-terrestrial planets,black holes and other astronomical utmost observation in the near infrared and optical regions,several extremely large telescopes(optical and infrared) with the aperture diameter larger than 30m and the long baseline optical synthetic aperture imaging arrays have been proposed.We advise to build a ringy shape telescope with a large primary mirror,and the telescope with such formation is called Ringy Interferometric Telescope-RIT.The form of the RIT is between the forms of a traditional ELT and an interferometric array.The paper also shows our research results about the ringy aperture.An optical parameter WRR is introduced in this paper,it is the ratio of effective ring width to the aperture outer radius.The normalized modulation transfer function(MTF) of the ringy aperture is uniquely decided by the WRR.The MTF of the ringy aperture has the characteristic of experiencing a comparatively flat area in the middle-frequency region and a short raise in the high-frequency region when WRR < 0.54;and when WRR > 0.54,the MTF is more approximately to that of a full circular aperture.Obviously,the ringy aperture has the characteristic of covering the spatial frequencies fully and integrally,even if in the case of a very small WRR.Filling factor can be expressed quantificationally by WRR.We also have done several observational experiments with the ringy aperture for astronomical objects using the 1m optical telescope in Yunnan Observatory.We have used a ringy mask whose outer diameter is 1m and WRR is 0.2,and we have got the high resolution reconstruction image of an object under observation by ISA^9,10.On the foundation of these research results,we propose to build a segmented RIT with outer diameter 30m and effective ring width 1m.Because of the whole spatial-frequency coverage characteristic,images photographed by RIT can have the same spatial resolution with a 30m full aperture telescope,need only some simple processes.The resolution(FWHM) of RIT can reach to 0.003 arcsec,its light-gathering area equivalent to that of a 10m full aperture telescope.Since its simple configuration,the cost of building the 30m RIT will not exceed that of a 10m segmented telescope a lot.