Gai, MarioMarioGai0000-0002-6928-8589Riva, AlbertoAlbertoRiva0000-0001-9008-134XBusonero, DeborahDeborahBusonero0000-0001-8244-9749Vecchiato, AlbertoAlbertoVecchiato0000-0002-3903-7076Landini, FedericoFedericoLandini0000-0003-1399-55562024-12-092024-12-092024http://hdl.handle.net/20.500.12386/40629The CEntral (field) Three-mirror Anastigmat (CETA) telescope is designed on the specifications of the proposed Theia mission, aiming at high precision differential astrometry over a large field, for exo-planetary system characterization and dark matter /dark energy search through the dynamics of star clusters. Usually, Three Mirror Anastigmat designs are either off-axis in terms of field, or decentered in terms of pupil. We propose a family of solutions using fully centred optics and a large on-axis field, at the expense of a non negligible central obscuration. We analyse in particular a 1 m class compact telescope, with 15 m effective focal length, i.e. suited to small pixel (4-6 μm) CMOS detectors operating in the visible and near IR. Due to the underlying symmetry, the resulting optical response is quite good over a 14 arcmin radius field, and it is of special interest to astrometry applications. Also, manufacturing, alignment and calibration can be expected to benefit significantly; some basic aspects are preliminarily considered.inproceedings10.1117/12.30189662024SPIE13092E..34G