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Proceedings Paper

Modeling temperature-induced surface distortions in the MMTO 6.5 meter primary mirror
Author(s): T. E. Pickering
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Paper Abstract

We have performed finite element thermal analysis of our 6.5 meter primary mirror in the hopes of improving the accuracy of our open loop models and reducing the need to interrupt science observations to tune our optics. In the analysis we apply temperature variations to the front, back, and middle of the mirror to correspond to the locations of installed thermocouples. The input temperature variations and the predicted steady-state surface distortions are modeled as Zernike polynomials. The most significant effect we find is the focus error generated by a temperature gradient between the front and back of the mirror. Comparison with wavefront sensor data shows that we can get reasonably good agreement between predicted and measured focus errors. However, we do not yet get good agreement for other, higher order terms. There is also poorer agreement when conditions are changing rapidly.

Paper Details

Date Published: 11 July 2008
PDF: 11 pages
Proc. SPIE 7017, Modeling, Systems Engineering, and Project Management for Astronomy III, 701718 (11 July 2008); doi: 10.1117/12.788581
Show Author Affiliations
T. E. Pickering, MMT Observatory (United States)


Published in SPIE Proceedings Vol. 7017:
Modeling, Systems Engineering, and Project Management for Astronomy III
George Z. Angeli; Martin J. Cullum, Editor(s)

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