Laser guide star conventional and multiconjugate adaptive optics at the Gemini Observatory: from one sodium laser beacon to five

High resolution imaging with Adaptive Optics (AO) is one of the main scientific drivers for the twin infra-red optimized 8m telescopes of the Gemini Observatory. The "conventional" Laser Guide Star system will use a single 10W-class laser beacon, enabling good AO correction on-axis only. Widening the AO-corrected field-of-view from a radius of few arc seconds to a radius of one arc minute will take place as a next step at the Gemini South telescope where a Multi-Conjugate Adaptive Optics (MCAO) system is planned. Although MCAO will use five laser beacons instead of one, all LGS subsystems are fairly similar in design to their ALTAIR counterparts. For a single laser guidestar adaptive optics system such as ALTAIR, the CW mode-locked scheme is attractive. Five identical nonlinear stages would be implemented to produce the five 10W-class laser beams for MCAO.