6 July 2006 In situ aluminization of the MMT 6.5m primary mirror
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Abstract
In May, 2000 the MMT Conversion was dedicated. Space limitations on the summit of Mt. Hopkins, AZ and limited financial resources dictated in-situ aluminization of the φ 6.5m primary mirror. Some of the attendant challenges successfully addressed in the course of accomplishing that task are described. For example: a 22 metric ton, φ7m vacuum head had to be lifted 25m before being lowered through the horizon-pointing telescope truss (clearing by 16 mm), then secured to the mirror cell that serves as a vacuum vessel; dirty mirror-support hardware integral to the cell required isolation of the process volume operating at 10-6mbar; extensive modeling of source geometry was needed to achieve uniformity goals at very short source-substrate distances; and a cost-effective 75kW DC filament voltage source using commercially-available arc welders was developed that allowed simultaneous firing of 200 evaporation sources. Details of design and construction of the evaporation system are given along with techniques and results of the successful coating in November 2001 and September 2005.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. Clark, W. Kindred, J. T. Williams, "In situ aluminization of the MMT 6.5m primary mirror", Proc. SPIE 6273, Optomechanical Technologies for Astronomy, 627305 (6 July 2006); doi: 10.1117/12.672492; https://doi.org/10.1117/12.672492
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