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Proceedings Paper

Optical performance prediction of the Thirty Meter Telescope after initial alignment using optical modeling
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Paper Abstract

We present an estimate of the optical performance of the Thirty Meter Telescope (TMT) after execution of the full telescope alignment plan. The TMT alignment is performed by the Global Metrology System (GMS) and the Alignment and Phasing System (APS). The GMS first measures the locations of the telescope optics and instruments as a function of elevation angle. These initial measurements will be used to adjust the optics positions and build initial elevation look-up tables. Then the telescope is aligned using starlight as the input for the APS at multiple elevation angles. APS measurements are used to refine the telescope alignment to build elevation and temperature dependent look-up tables. Due to the number of degrees of freedom in the telescope (over 10,000), the ability of the primary mirror to correct aberrations on other optics, the tight optical performance requirements and the multiple instrument locations, it is challenging to develop, test and validate these alignment procedures. In this paper, we consider several GMS and APS operational scenarios. We apply the alignment procedures to the model-generated TMT, which consists of various quasi-static errors such as polishing errors, passive supports errors, thermal and gravity deformations and installation position errors. Using an integrated optical model and Monte-Carlo framework, we evaluate the TMT's aligned states using optical performance metrics at multiple instrument and field of view locations. The optical performance metrics include the Normalized Point Source Sensitivity (PSSN), RMS wavefront error before and after Adaptive Optics (AO) correction, pupil position change, and plate scale distortion.

Paper Details

Date Published: 10 July 2018
PDF: 17 pages
Proc. SPIE 10705, Modeling, Systems Engineering, and Project Management for Astronomy VIII, 107050T (10 July 2018); doi: 10.1117/12.2314351
Show Author Affiliations
Byoung-Joon Seo, Jet Propulsion Lab. (United States)
Carl Nissly, Jet Propulsion Lab. (United States)
Mark Colavita, Jet Propulsion Lab. (United States)
Mitchell Troy, Jet Propulsion Lab. (United States)
Scott Roberts, Thirty Meter Telescope Observatory (United States)
John Rogers, Thirty Meter Telescope Observatory (United States)

Published in SPIE Proceedings Vol. 10705:
Modeling, Systems Engineering, and Project Management for Astronomy VIII
George Z. Angeli; Philippe Dierickx, Editor(s)

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