Adaptive Optics for Extremely Large Telescopes 4 – Conference Proceedings

Stereo-SCIDAR is a generalised-SCIDAR instrument which is used to characterise the atmospheric optical turbu- lence in terms of strength (Cn2) and wind velocity profile using the triangulation technique and an optical binary star. Stereo-SCIDAR differs from most other SCIDAR instruments in that, instead of overlapping pupil images on a single detector, the image of each star is recorded on a separate EMCCD. Separating the pupil images in this way leads to several advantages, including better signal to noise ratios, larger useable magnitude difference of the target stars and reliable automated wind velocity measurements. The data is analysed and made available to observatory systems in real-time. Here we review the Stereo-SCIDAR technique and present recent results from the instrument on the Isaac Newton Telescope, La Palma.