Na variability and LGS elongation: impact on wavefront error

Katharine J. Jones

doi:10.1117/12.890296

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16 September 2011 Na variability and LGS elongation: impact on wavefront error

Katharine J. Jones

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Proceedings Volume 8149, Astronomical Adaptive Optics Systems and Applications IV; 81490E (2011) https://doi.org/10.1117/12.890296
Event: SPIE Optical Engineering + Applications, 2011, San Diego, California, United States

Abstract

Variation in density structure and altitude of mesospheric sodium impacts the performance of Adaptive Optics (AO). With large entrance apertures, Laser Guide Stars (LGS) are seen as cylinders with an intensity structure that reflects the density structure of the sodium layers. Such elongation spreads the sodium light over more WaveFront Sensor (WFS) pixels and reduces the signal to noise ratios. This effect is proportional to the square of the telescope diameter: 30 m for TMT and 42 m for E-ELT. NA variability is examined and the resulting elongation analyzed for impact on WaveFront Error. TMT and E-ELT will be compared for methods being applied to mitigate LGS elongation to reduce resulting WaveFront Error.

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Katharine J. Jones "Na variability and LGS elongation: impact on wavefront error", Proc. SPIE 8149, Astronomical Adaptive Optics Systems and Applications IV, 81490E (16 September 2011); https://doi.org/10.1117/12.890296

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