25 October 2004 A method for high-resolution C2N profiling in the first few hundred meters
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We present the concept of an instrument for the monitoring of the optical turbulence in the first 300 meters above the ground with an altitude resolution of 10 meters approximately. The method is based on a modified version of the generalized scidar. It could be implemented with the use of a 40-cm telescope, a 1376x1040 pixels CCD detector with low readout noise at 20 frames per second, a fast commercial personal computer and a colimating optics. The ideal light source is a bright double star with an angular separation of 180". The principal difference from a conventional generalized scidar is that the scintillation images produced by each star would be fully separated on the detector, whereas in a generalized scidar, the images overlap over a certain region. The image processing consists of selecting on the detector two subframes containing each the scintillation image of one of the stellar component, recenter each image on the corresponding subframe (to correct for telescope missguiding and shaking), and compute the spatial correlation of the two subframes. This procedure is to be repeated several thousand times and the output is the mean correlation. The data reduction would be very similar to that of the generalized scidar, which consists of the inversion of a Fredholm integral equation. This method is particularly interesting to study the turbulence above locations that are a few hundred meters below a given site summit.
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Remy Avila, Remy Avila, Mark R. Chun, Mark R. Chun, } "A method for high-resolution C2N profiling in the first few hundred meters", Proc. SPIE 5490, Advancements in Adaptive Optics, (25 October 2004); doi: 10.1117/12.552465; https://doi.org/10.1117/12.552465

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