Profiles of nighttime turbulence above Mauna Kea and isoplanatism extension in adaptive optics

Rene Racine; Brent L. Ellerbroek

doi:10.1117/12.217743

25 August 1995 Profiles of nighttime turbulence above Mauna Kea and isoplanatism extension in adaptive optics

Rene Racine, Brent L. Ellerbroek

Proceedings Volume 2534, Adaptive Optical Systems and Applications; (1995) https://doi.org/10.1117/12.217743
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

We use 414 turbulence profiles obtained by scidar over 20 nights to characterize the structure of the nighttime free atmosphere above Mauna Kea, Hawaii and to examine the isoplanatic patch enlargement that can be achieved in adaptive optics by conjugating the deformable mirror (DM) to the seeing layers. It is found that the typical night-time profile is composed of an underlying background of turbulence upon which are often superposed only one or two thin dominant layers. Low level turbulence is weak at the site. The turbulence structure is such that conjugation of a DM to turbulence rather than to the telescope entrance pupil increases the size of the isoplanatic patch by a factor of two (median); much larger gains are occasionally possible. When a single dominant layer is present, which occurs some 60 percent of the time, conjugation of the DM to that thin layer would typically reduce the seeing spread angle by a factor of two over a field of view of many arcmins. These results should be useful in the design and evaluation of AO systems for the site.

Citation Download Citation

Rene Racine and Brent L. Ellerbroek "Profiles of nighttime turbulence above Mauna Kea and isoplanatism extension in adaptive optics", Proc. SPIE 2534, Adaptive Optical Systems and Applications, (25 August 1995); https://doi.org/10.1117/12.217743

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