25 August 1995 Techniques for optical fabrication of a 2-mm-thick adaptive secondary mirror
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Abstract
We describe the development of techniques for the optical fabrication of the adaptive secondary mirror for the 6.5-m MMT Conversion Project. The f/15 secondary is 640 mm in diameter and consists of a 2-mm-thick convex mirror supported on 320 actuators. This mirror will be polished using the stressed lap method and measured using the holographic test plate system developed at the Mirror Lab, but it presents unique challenges because of its flexibility. During fabrication, the support of the thin mirror must be uniform and stiff enough to keep it from bending significantly under polishing forces which are 25 - 50 times the weight of the mirror. We plan to support the thin mirror by attaching it to a rigid glass substrate, and are pursuing two experimental approaches to the attachment: optical contact and blocking with pitch. The experiments are being performed by fabricating 200-mm concave prototypes of the secondary mirror.
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Hubert M. Martin, David S. Anderson, "Techniques for optical fabrication of a 2-mm-thick adaptive secondary mirror", Proc. SPIE 2534, Adaptive Optical Systems and Applications, (25 August 1995); doi: 10.1117/12.217732; https://doi.org/10.1117/12.217732
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