Towards optimization of pulsed sodium laser guide stars

Pulsed sodium laser guide stars (LGS) are useful because they allow for Rayleigh blanking and fratricide avoidance in multiple-LGS systems. Bloch-equation simulations of sodium-light interactions show that these may be able to achieve photon returns nearly equal to, and in some cases greater than, what is seen from continuous-wave (CW) excitation. In this work, we study the time-dependent characteristics of sodium fluorescence, and investigate the optimal format for the new fiber laser LGS that will be part of the upgraded adaptive optics (AO) system on the Shane telescope at Mt. Hamilton. Results of this analysis are examined in the context of their general applicability to other LGS systems and the potential benefits of uplink correction are considered. Comparisons of simulation predictions with measurements from existing LGS are also presented and discussed.Comment: 9 pages, 7 figures, accepted by JOSA

Progress report on the ESO 4LGSF

The Four Laser Guide Star Facility (4LGSF) is part of the ESO Adaptive Optics Facility (AOF), in which one of the VLT unit telescopes, UT4, is transformed in an adaptive telescope - equipped with a deformable secondary mirror, two adaptive optics systems at the Nasmyth foci and four laser guide star modular units. In this poster we present the key results of the acceptance tests performed on the 4LGSF in Europe and first commissioning results obtained with the Laser Guide Star Unit #1 in stand-alone operation