Update on the TMT laser guide star facility design

The Thirty Meter Telescope (TMT) will implement a Laser Guide Star Facility (LGSF), which will generate up to nine Na laser beams in at least four distinct asterisms. The TMT LGSF conceptual design is based upon three 50W solid state, continuous wave, sum frequency 589 nm lasers and conventional beam transport optics. In this paper, we provide an update to the TMT LGSF conceptual design. The LGSF top end and the beam transfer optics have been significantly redesigned to compensate for the TMT telescope top end flexure, to adapt for the new TMT Ritchey-Chrétien optical design, to reduce the number of optical surfaces and to reduce the mass and volume. Finally, the laser service enclosure has been relocated within the telescope azimuth structure. This will permit the lasers to operate with a fixed gravity vector, but also requires further changes in the beam transport optical path