Adaptive optics bender with sub-nanometer correction and stability

We present an adaptive mirror system capable of controlling the figure of the mirror surface with resolution and stability below one nanometer, and in operation conditions. This allows correcting wavefront deformations caused by static or dynamic sources, like thermal bump on optics, gravity sag, or clamping effects, to the level of the highest quality figure errors. The bender system includes the usual torque actuators at the ends of the mirror as well as a number of force correctors along the mirror length, which introduce the desired deformation of the mirror substrate. The deformation of the substrate is stabilized using different strategies: for the bending actuators, load cells are used to provide feedback of the applied force. For the corrector actuators, which require a considerably lower force, the system is stabilized by combining springs and magnets to apply a force with independence of mechanical drifts of the mirror.