The lightweight, rigid reference optic for the new deformable secondary mirror at ESO's VLT

This is a view of a backside of a newly completed reference optic for the new deformable secondary mirror system at ESO’s VLT. It shows the remarkable sculpted structure that makes the new element both very light and very rigid. When the new mirror is complete, 1170 actuators working with this reference optic will act on a thin mirror shell to change the shape of its reflecting optical surface to correct for starlight wobbles produced by the Earth’s atmosphere.