Progress towards tomographic wavefront reconstruction using dynamically refocused Rayleigh laser beacons

Christoph J. Baranec, Michael Lloyd-Hart, N. Mark Milton, Thomas Stalcup, James A. Georges, Miguel Snyder, Nicole Putnam, Roger Angel

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations


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.

Original languageEnglish (US)
Article number122
Pages (from-to)1129-1137
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue numberPART 3
StatePublished - 2004
EventAdvancements in Adaptive Optics - Glasgow, United Kingdom
Duration: Jun 21 2004Jun 25 2004


  • Adaptive optics
  • Multi-conjugate adaptive optics
  • Tomography
  • Wavefront sensors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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