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Proceedings Paper

Real-time phase slopes calculations by correlations using FPGAs
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Paper Abstract

ELT laser guide star wavefront sensors are planned to handle an expected amount of data to be overwhelmingly large (1600×1600 pixels at 700 fps). According to the calculations involved, the solutions must consider to run on specialized hardware as Graphical Processing Units (GPUs) or Field Programmable Gate Arrays (FPGAs), among others. In the case of a Shack-Hartmann wavefront sensor is finally selected, the wavefront slopes can be computed using centroid or correlation algorithms. Most of the developments are designed using centroid algorithms, but precision ought to be taken in account too, and then correlation algorithms are really competitive. This paper presents an FPGA-based wavefront slope implementation, capable of handling the sensor output stream in a massively parallel approach, using a correlation algorithm previously tested and compared to the centroid algorithm. Time processing results are shown, and they demonstrate the ability of the FPGA integer arithmetic in the resolution of AO problems. The selected architecture is based in today's commercially available FPGAs which have a very limited amount of internal memory. This limits the dimensions used in our implementation, but this also means that there is a lot of margin to move real-time algorithms from the conventional processors to the future FPGAs, obtaining benefits from its flexibility, speed and intrinsically parallel architecture.

Paper Details

Date Published: 11 July 2008
PDF: 8 pages
Proc. SPIE 7015, Adaptive Optics Systems, 70153B (11 July 2008); doi: 10.1117/12.789492
Show Author Affiliations
J. Trujillo Sevilla, Univ. de La Laguna (Spain)
M. R. Valido, Univ. de La Laguna (Spain)
L. F. Rodríguez Ramos, Instituto de Astrofísica de Canarias (Spain)
E. Boemo, Univ. Autónoma de Madrid (Spain)
F. Rosa, Univ. de La Laguna (Spain)
J. M. Rodríguez Ramos, Univ. de La Laguna (Spain)

Published in SPIE Proceedings Vol. 7015:
Adaptive Optics Systems
Norbert Hubin; Claire E. Max; Peter L. Wizinowich, Editor(s)

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