SOLARNET has 3 Gregory telescopes of Ø350 mm diameter (f=1050 mm). For each telescope, the secondary is Ø70 mm (f=210 mm). A tertiary plane mirror helps to select a 5 arcmin field on the Sun and to deflect the rest of the solar field to the pointing system (made on the solar limb: precision expected is a few mas). The forth mirror is the "Active Steering Mirror" that folds the beam to a retroreflector that controls the Optical Path Delay (OPD) between the three beams of the SOLARNET interferometer. Following the retroreflectors, the three beams are focused by the recombination mirror (Ø190 mm) on the Double Monochromator (DM). On the entrance slight of the DM where the image is formed, a field of 40" is selected while the rest of the 5 arcmin field-of-view is directed towards the Cophasing System, a set of three reference White Light Interferometers which make an absolute measure of the phases (by double synchronous detection) and control the Delay Lines (the retroreflectors).
3D View of SOLARNET Concept