Daylight operation of a sodium laser guide star

Michael Hart; Stuart Jefferies; Neil Murphy

doi:10.1117/12.2235080

27 July 2016 Daylight operation of a sodium laser guide star

Michael Hart, Stuart Jefferies, Neil Murphy

Proceedings Volume 9909, Adaptive Optics Systems V; 99095N (2016) https://doi.org/10.1117/12.2235080
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

Abstract

We report photometric measurements of a sodium resonance guide star against the daylight sky when observed through a tuned magneto-optical filter (MOF). The MOF comprises a sodium vapor cell in a kilogauss-level magnetic field between crossed polarizers and has a very narrow transmission profile at the sodium D₂ resonance of approximately 0.008 nm. Our observations were made with the 1.5 m Kuiper telescope on Mt. Bigelow, AZ, which has a separately mounted guide star laser projecting a circularly polarized single-frequency beam of approximately 6.5 W at 589.16 nm. Both the beam projector and the 1.5 m telescope were pointed close to zenith; the baseline between them is approximately 5 m. Measurements of the guide star were made on the morning of 2016 March 24 using an imaging camera focused on the beacon and looking through the full aperture of the telescope. The guide star flux was estimated at 1.20×10⁶ photon/m²/s while at approximately 45 minutes after sunrise, the sky background through the MOF was 1100 photon/m²/s/arcsec². We interpret our results in terms of thermal infrared observations with adaptive optics on the next generation of extremely large telescopes now being built.

Citation Download Citation

Michael Hart, Stuart Jefferies, and Neil Murphy "Daylight operation of a sodium laser guide star", Proc. SPIE 9909, Adaptive Optics Systems V, 99095N (27 July 2016); https://doi.org/10.1117/12.2235080

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