Optics Block Diagram of the Full Disc Telescope path. L1 and L2 are lens 1 and lens 2; FL is the field lens; LC1 and LC2 are the liquid crystal cells; T1, T2 and T3 are the triplet lenses 1, 2 and 3 respectively; M5, M3 and M4 are the folding mirrors; the Filtergraph oven includes the two lenses FG1 and FG2, the two components of the prefilter (PF1 and PF2), and the etalon; finally, the camera lenses (C1, C2 and C3) provide the image at the scientific focal plane.