Colibrì has an array of seven telescopes operating in parallel. Each telescope has a focal length of 4.5 m and an outermost mirror shell of diameter 327 mm (hence f/15). The innermost shell has a diameter of 155 mm.
The Colibrì mirrors are optimized for throughout. The average glancing angle off of the first parabolic mirror is the same as the angle off of the second hyperbolic mirror. This geometry maximizes the fraction of the radiation that reaches the detector at the expense of image quality away from the optical axis. This combination gives Colibrì large collecting area over a wide range of photon energies from 0.1 to over 10 keV.