GMT Laser Guide Star Facility

The Giant Magellan Telescope (GMT) Adaptive Optics (AO) System includes a Laser Guide Star Facility capable of projecting six sodium Laser Guide Stars (LGS) for use in the Laser Tomography AO (LTAO) and Laser Ground Layer AO (LGLAO) modes of operation. The laser beams are projected from the edge of the GMT primary mirror to form a one- (LTAO) or seven- (LGLAO) arcminute diameter circular asterism. The LGSF is made of six identical LGS Units, each containing a Laser System, a Beam Conditioning and Diagnostic System (BCDS), a Laser Launch Telescope (LLT) and their associated Laser Interlock System (LIS). This paper provides an overview of the GMT LGSF requirements, error budgets and preliminary design at the system, subsystem and component level. The LGSF operational model and its interactions with LTAO and LGLAO are also discussed.