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Proceedings Paper

Results of the NFIRAOS RTC trade study
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Paper Abstract

With two large deformable mirrors with a total of more than 7000 actuators that need to be driven from the measurements of six 60x60 LGS WFSs (total 1.23Mpixels) at 800Hz with a latency of less than one frame, NFIRAOS presents an interesting real-time computing challenge. This paper reports on a recent trade study to evaluate which current technology could meet this challenge, with the plan to select a baseline architecture by the beginning of NFIRAOS construction in 2014. We have evaluated a number of architectures, ranging from very specialized layouts with custom boards to more generic architectures made from commercial off-the-shelf units (CPUs with or without accelerator boards). For each architecture, we have found the most suitable algorithm, mapped it onto the hardware and evaluated the performance through benchmarking whenever possible. We have evaluated a large number of criteria, including cost, power consumption, reliability and flexibility, and proceeded with scoring each architecture based on these criteria. We have found that, with today’s technology, the NFIRAOS requirements are well within reach of off-the-shelf commercial hardware running a parallel implementation of the straightforward matrix-vector multiply (MVM) algorithm for wave-front reconstruction. Even accelerators such as GPUs and Xeon Phis are no longer necessary. Indeed, we have found that the entire NFIRAOS RTC can be handled by seven 2U high-end PC-servers using 10GbE connectivity. Accelerators are only required for the off-line process of updating the matrix control matrix every ~10s, as observing conditions change.

Paper Details

Date Published: 21 July 2014
PDF: 20 pages
Proc. SPIE 9148, Adaptive Optics Systems IV, 91482F (21 July 2014); doi: 10.1117/12.2057323
Show Author Affiliations
Jean-Pierre Véran, National Research Council Canada (Canada)
Corinne Boyer, Thirty Meter Telescope Observatory Corp. (United States)
Brent L. Ellerbroek, Thirty Meter Telescope Observatory Corp. (United States)
Luc Gilles, Thirty Meter Telescope Observatory Corp. (United States)
Glen Herriot, National Research Council Canada (Canada)
Daniel A. Kerley, National Research Council Canada (Canada)
Zoran Ljusic, National Research Council Canada (Canada)
Eric A. McVeigh, Univ. of Victoria (Canada)
Robert Prior, Univ. of Victoria (Canada)
Malcolm Smith, National Research Council Canada (Canada)
Lianqi Wang, Thirty Meter Telescope Observatory Corp. (United States)

Published in SPIE Proceedings Vol. 9148:
Adaptive Optics Systems IV
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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