Design Of The Apache Point Observatory 3.5m Telescope II. Deformation Analysis Of The Primary Mirror

Walter A. Siegmund; Edward J. Mannery; James Radochia; Paul E. Gillett

doi:10.1117/12.963554

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20 August 1986 Design Of The Apache Point Observatory 3.5m Telescope II. Deformation Analysis Of The Primary Mirror

Walter A. Siegmund, Edward J. Mannery, James Radochia, Paul E. Gillett

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Proceedings Volume 0628, Advanced Technology Optical Telescopes III; (1986) https://doi.org/10.1117/12.963554
Event: 1986 Astronomy Conferences, 1986, Tucson, United States

Abstract

We have calculated the deflection of the surface of a 3.5 meter diameter borosilicate mirror using the finite element method. The mirror is a 0.46 m thick honeycomb structure with 25 mm thick face plates and 13 mm ribs. The cell spacing is 0.192 m and is regular except near the inner and outer perimeters. Axial support for the mirror will be provided by 48 air pistons. The air pressure in the pistons will be regulated to balance the axial component of the mirror weight. The axial air pistons are located near nodes in the rib pattern of the honeycomb thereby facilitating access to the interior of the mirror for ventilation and transverse support. A simple wind loading case was examined and the resulting deflections are shown to be small. The effects of thickness variations in fabrication of the mirror are presented and are small for the magnitudes of the variations expected. Several thermal load cases are described.

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Walter A. Siegmund, Edward J. Mannery, James Radochia, and Paul E. Gillett "Design Of The Apache Point Observatory 3.5m Telescope II. Deformation Analysis Of The Primary Mirror", Proc. SPIE 0628, Advanced Technology Optical Telescopes III, (20 August 1986); https://doi.org/10.1117/12.963554

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