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27 June 2006 Tomographic reconstruction of stellar wavefronts from multiple laser guide stars
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Experiments have been carried out at the MMT telescope in June 2005 and again in April 2006 to validate open loop tomographic wavefront reconstruction using five dynamically refocused Rayleigh laser beacons (RLGS) and multiple tilt natural guide stars (NGS). Wavefront sensing in this manner is recognized as a critical precursor to the development of adaptive optics for Extremely Large Telescopes. At the MMT, wavefronts from the laser beacons are recorded by five 60-element Shack-Hartmann sensors implemented on a single CCD. A wide-field camera measures image motion from multiple field stars to calculate global tilt and distinguish effects of contributions to second order aberrations from low and high altitude turbulence. Together, the signals from these sensors are used to estimate the first 45 Zernike modes in the wavefront of a star within the LGS constellation. The reconstruction is compared off line to simultaneous wavefront measurements made of the star with a separate Shack-Hartmann sensor. We will present the results in this paper and quantify the wavefront improvement expected from tomographic adaptive optics correction.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christoph Baranec, Michael Lloyd-Hart, N. Mark Milton, Thomas Stalcup, Miguel Snyder, and Roger Angel "Tomographic reconstruction of stellar wavefronts from multiple laser guide stars", Proc. SPIE 6272, Advances in Adaptive Optics II, 627203 (27 June 2006);

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