High-order adaptive optics system with a high-density spherical membrane deformable mirror

We have designed a new type of curved deformable mirror with 3000 actuators. It will be used at the 6.5 m MMT telescope in an adaptive optics system to correct the wavefront on a scale of 12 cm, for diffraction limited images in visible light and for high contrast imaging with a coronagraph in the near IR. The mirror's 51 cm diameter glass faceplate, 400 microns thick, will be actuated by tubular piezoceramic actuators on 8 mm centers. The mirror is made concave so it can be used in a simple, compact optical relay with no need for large collimator or camera elements. A prototype deformable mirror with 300 elements that test the support and assembly techniques is being built for lab test and will be tested in a closed loop adaptive optics system at the Steward Observatory.