The need for both high quality images and light structures is one of the main driver in the conception of space telescopes. An e fficient wave-front control will then become mandatory in the future large observatories, ensuring the optical performance while relaxing the specifications on the global system stability. Consisting in controlling the mirror deformation, active optics techniques can be used to compensate for primary mirror deformation, to allow the use of reconfigurable instruments or to manufacture aspherical mirror with stress polishing. In this manuscript, the conception of active mirrors dedicated to space instrumentation is presented. Firstly, a system compensating for large lightweight mirror deformation in space, is designed and its performance are experimentally demonstrated. With 24 actuators, the MADRAS mirror (Mirror Actively Deformed and Regulated for Applications in Space) will perform an effi cient wave-front correction in the telescope's pupil relay. Secondly, a warping harness for the stress polishing of the 39 m European Extremely Large Telescope segments is presented. The performance of the process is predicted and optimized with Finite Element Analysis and the segments mass production is considered. Thirdly, two original concepts of deformable mirrors with a minimum number of actuators have been developed. The Variable Off -Axis parabola (VOALA) is a 3-actuators system and the Correcting Optimized Mirror with a Single Actuator (COMSA) is a 1-actuator system. The active systems presented in this manuscript off er many advantages for the future large space-borne observatories: limited number of degrees of freedom, compactness, low weight, robustness and reliability. They will allow some technological breakthroughs and lead to innovative telescope architectures.
