Polychromatic laser guide star using a single laser at 330 nm

Jean-Paul Pique; Ioana C. Moldovan; Vincent Fesquet; Hugues Guillet de Chatellus; Fabien Marc

doi:10.1117/12.692350

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28 June 2006 Polychromatic laser guide star using a single laser at 330 nm

Jean-Paul Pique, Ioana C. Moldovan, Vincent Fesquet, Hugues Guillet de Chatellus, Fabien Marc

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Proceedings Volume 6272, Advances in Adaptive Optics II; 62723D (2006) https://doi.org/10.1117/12.692350
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

The differential atmospheric tip-tilt can be measured using a Polychromatic Laser Guide Star. A two photon excitation has been proposed. It consists in exciting the 4D_5/2 level of mesospheric sodium atoms with two identical lasers operating at 589 nm and 569 nm. With two modeless lasers of 2×15W at the mesosphere level, this scheme will produce a returned flux at 330 nm of about 4×10⁴ photons/s/m². Thanks to our modeless laser, we propose a new method which consists in exciting directly the 4P_3/2 sodium level with one photon excitation, using a single laser operating at 330 nm. This solution was previously rejected probably because of strong saturation problems using single longitudinal mode lasers. We show that 1 W modeless laser at 330 nm can produce the same returned flux at 330 nm. This solution will save at least 400 k€ of equipment. Moreover, our new method is very promising in terms of simplicity but also in terms of flux because the returned flux above will probably be not sufficient for getting a good Strehl ratio. We propose very efficient solid state laser systems for the production of tens of watts at 330 nm.

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Jean-Paul Pique, Ioana C. Moldovan, Vincent Fesquet, Hugues Guillet de Chatellus, and Fabien Marc "Polychromatic laser guide star using a single laser at 330 nm", Proc. SPIE 6272, Advances in Adaptive Optics II, 62723D (28 June 2006); https://doi.org/10.1117/12.692350

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