Measurement of atmospheric turbulence with a Shack-Hartmann wavefront sensor at the new MMT's prime focus

Patrick C. McGuire, Maud P. Langlois, Michael Lloyd-Hart, Troy A. Rhoadarmer, J. Roger P. Angel

Research output: Contribution to journalConference articlepeer-review


In order to prepare for the adaptive secondary program at the new 6.5 meter MMT, we have begun a campaign to measure atmospheric turbulence with a Shack-Hartmann wavefront sensor (WFS) camera. Our first efforts, prior to second aluminization of the primary, consisted of taking turbulence data with our WFS camera with special coma-correcting optics at the MMT prime focus, without a Cassegrain secondary mirror. Our first measurements consisted of 1000 frames of approximately 10 millisecond duration, taken approximately 3 seconds apart. We measure a 5/3 power law structure function, suggesting Kolmogorov turbulence, with an r0 = 15 cm, but with possible hints of an outer scale and tracking jitter in the structure function. At the end of our data acquisition, we deliberately put 2 μm of astigmatism into the primary mirror with its actuators, and in our analysis, we recover 1.7±0.3 μm of astigmatism. A brief analysis of the low-order modal amplitudes with the 3 second frame delay shows that there are significant self-correlations of the low-order modes even on this long time-scale.

Original languageEnglish (US)
Pages (from-to)II/-
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2000
EventAdaptive Optical Systems Technology - Munich, Ger
Duration: Mar 29 2000Mar 31 2000

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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