Keck Adaptive Optics: Test of a Deformable Mirror in a Freezing Environment

The W. M. Keck Observatory and Lawrence Livermore National Labs are currently developing an adaptive optics system for use on Keck II--a 10.8-meter segmented telescope. This AO system will make use of a 349-actuator deformable mirror (DM). The Keck II telescope sits atop Hawaii’s Mauna Kea, where the ambient nighttime temperature varies between -5 and 5 degrees C. In order to reduce dome seeing, and to minimize the thermal emissivity, the AO system (and hence the DM) will be cooled to the ambient temperature of the outside air. Therefore, we are motivated to use actuators in the DM that are optimized for operation at 0 degrees C.