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Proceedings Paper

Progress towards tomographic wavefront reconstruction using dynamically refocused Rayleigh laser beacons
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Paper Abstract

Simultaneous wavefront measurements are planned at the 6.5 m MMT telescope of five dynamically refocused Rayleigh laser beacons (RLGS) and a bright natural star to demonstrate tomographic wavefront reconstruction. In this paper, we summarize preliminary data recorded from the five laser beacons during the first telescope run at the MMT in June 2004. Beam projection is from behind the secondary of the MMT to form a regular pentagon of beacons on the sky with a radius of 60 arcseconds around the natural star. Beacon images are recorded over a range gate from 20 to 30 km, with dynamic refocus optics in the focal plane to remove perspective elongation (Stalcup, et. al., these proceedings). Separate externally synchronized Shack-Hartmann sensors record wavefront measurements of the beacons and the star, which will yield the first 33 Zernike modes from each wavefront measurement. A linear tomographic reconstructor, implemented as a matrix multiplication of the combined Zernike modal amplitudes from all five RLGS, has been computed to estimate contributions to the atmospheric aberration in two layers at 0 and 6 km. To validate the tomographic approach, the wavefront of the natural star will be predicted by computing the sum of the aberration in the direction of the star, and the prediction compared to simultaneous measurements recorded from the star directly.

Paper Details

Date Published: 25 October 2004
PDF: 9 pages
Proc. SPIE 5490, Advancements in Adaptive Optics, (25 October 2004); doi: 10.1117/12.552297
Show Author Affiliations
Christoph James Baranec, Steward Observatory/Univ. of Arizona (United States)
Michael Lloyd-Hart, Steward Observatory/Univ. of Arizona (United States)
N. Mark Milton, Steward Observatory/Univ. of Arizona (United States)
Tom E. Stalcup, Steward Observatory/Univ. of Arizona (United States)
James A. Georges, Steward Observatory/Univ. of Arizona (United States)
Miguel Snyder, Steward Observatory/Univ. of Arizona (United States)
Nicole Putnam, Steward Observatory/Univ. of Arizona (United States)
James Roger P. Angel, Steward Observatory/Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 5490:
Advancements in Adaptive Optics
Domenico Bonaccini Calia; Brent L. Ellerbroek; Roberto Ragazzoni, Editor(s)

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