Atmospheric turbulence profiling using multiple laser star wavefront sensors
Article first published online: 20 NOV 2012
© 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS
Monthly Notices of the Royal Astronomical Society
Volume 427, Issue 3, pages 2089–2099, 11 December 2012
How to Cite
Cortés, A., Neichel, B., Guesalaga, A., Osborn, J., Rigaut, F. and Guzman, D. (2012), Atmospheric turbulence profiling using multiple laser star wavefront sensors. Monthly Notices of the Royal Astronomical Society, 427: 2089–2099. doi: 10.1111/j.1365-2966.2012.22076.x
- Issue published online: 20 NOV 2012
- Article first published online: 20 NOV 2012
- Manuscript Accepted: 6 SEP 2012
- Manuscript Received: 6 SEP 2012
- atmospheric effects;
- instrumentation: adaptive optics;
- methods: data analysis;
- site testing
This paper describes the data pre-processing and reduction methods together with SLOpe Detection And Ranging (SLODAR) analysis and wind profiling techniques for the Gemini South Multi-Conjugate Adaptive Optics System (GeMS).
The wavefront gradient measurements of the five GeMS Shack–Hartmann sensors, each pointing to a laser guide star, are combined with the deformable mirror (DM) commands sent to three DMs optically conjugated at 0, 4.5 and 9 km in order to reconstruct pseudo-open loop slopes.
These pseudo-open loop slopes are then used to reconstruct atmospheric turbulence profiles, based on the SLODAR and wind-profiling methods. We introduce the SLODAR method, and how it has been adapted to work in a closed-loop, multi-laser guide star system. We show that our method allows characterizing the turbulence of up to 16 layers for altitudes spanning from 0 to 19 km. The data pre-processing and reduction methods are described, and results obtained from observations made in 2011 are presented. The wind profiling analysis is shown to be a powerful technique not only for characterizing the turbulence intensity, wind direction and speed, but also as it can provide a verification tool for SLODAR results. Finally, problems such as the fratricide effect in multiple laser systems due to Rayleigh scattering, centroid gain variations, and limitations of the method are also addressed.