Adaptive secondary mirror demonstrator: design and simulation

Atmospheric turbulence distorts the wavefront of the incoming light from an astronomical object and so limits the ability of a telescope to form perfe ct images. Adaptive optics is a combination of technologies that enable the correction of the wavefront distortion in real time. Conventional adaptive optics operate like auxiliary instruments and use additional relay optics, which reduce total throughput and introduce extra IR emissivity and polari zation. Adaptive secondary mirrors avoid additional optical surfaces by pro viding the optical correction at an existing telescope surface (the seconda ry mirror). Previous studies have demonstrated the optical efficacy and mec hanical feasibility of performing the adaptive correction in this way. A te chnique demonstrator is being developed to explore features and capabilitie s applicable to a large adaptive secondary mirror and to explore manufactur ing, assembly/disassembly, calibration, and measurement techniques. The pap er describes the design of the demonstrator and its predicted performance. (C) 1999 Society of Photo-Optical instrumentation Engineers. [S0091-3286(99 )00809-0].