Roger B. Bagwell

Performance of a precision high-density deformable mirror for extremely high contrast imaging astronomy from space

Active wavefront correction of a space telescope provides a technology path for extremely high contrast imaging astronomy at levels well beyond the capabilities of current telescope systems. A precision deformable mirror technology intended specifically for wavefront correction in a visible/near-infrared space telescope has been developed at Xinetics and extensively tested at JPL over the past several years. Active wavefront phase correction has been demonstrated to 1 Angstrom rms over the spatial frequency range accessible to a mirror with an array of actuators on a 1 mm pitch. It is based on a modular electroceramic design that is scalable to 1000s of actuator elements coupled to the surface of a thin mirror facesheet. It is controlled by a low-power multiplexed driver system. Demonstrated surface figure control, high actuator density, and low power dissipation are described. Performance specifications are discussed in the context of the Eclipse point design for a coronagraphic space telescope.

Cryogenic Cofired Multilayer Actuator Development for a Deformable Mirror in the Next Generation Space Telescope

Xinetics is working with NASA to develop a cryogenic deformable mirror technology to meet the specific needs of the Next Generation Space Telescope. One of the critical technical issues is the development of a cryogenic actuator with sufficient displacement and temperature stability. This paper discusses the two year effort to achieve a cofired electroceramic multilayered cryogenic actuator. The development began by testing materials from 300 to 35 K via a cut and bond actuator technology that led to a cryogenic electroceramic material down selection. After selecting a doped SrTiO3, a cofired actuator process specific to the cryogenic ceramic was developed. The assembled cryogenic actuators achieved the 3 μm displacement (stroke) between 35 and 65 K required by the deformable mirror design. The discrete cryogenic actuators were assembled into an engineering model cryogenic 349-channel deformable mirror that was delivered to NASA in October 2001.