For the instrument of Pleiades, THALES ALENIA SPACE confided (entrusted) to Thales SESO the realization of all the mirrors of the telescope with their interfaces of fixation. The optical set is constituted by 4 mirrors among which aspheric 3 including an off-axis mirror.
All these mirrors are very relieved (in better than 50 kg / m2), satisfy a severe vibratory environment (compatible of the launcher Soyouz) and of difficult thermal vacuum, while keeping qualities of excellent surface. So the primary mirror 660 mm in diameter has a surface in better than 15 nm and the aspheric tertiary off-axis mirror has flatness for all its sub-pupils better than 6 nm rms, what is exceptional towards its big opening (F/1). The total optical quality of 4 mirrors gives performances instrument limited by the diffraction.