Design of the laser beam transfer system for the new Gemini North adaptive optics laser guide star

In 2018 the Gemini Observatory was awarded by the NSF a large grant for the Gemini in the Era of Multi Messenger Astronomy (GEMMA) project to build the next generation laser AO system from Gemini North. This new system is tentatively called Gemini North Adaptive Optics (GNAO) and will be a flexible AO system that can run multiple types of AO correction and serve as a facility capable of feeding multiple science cameras. As part of this new system the Laser Guide Star Facility (LGSF) of Gemini North is being completely redesigned from a single laser single Laser Guide Star (LGS) beacon facility into a multi-laser multi LGS beacon facility. It will be able to generate from 0-4 LGS on sky to feed not only GNAO but potential future systems as well. The LGSF consists of 3 main components, 589 nm sodium lasers, a set of free space beam transfer optics, and Laser Launch Telescopes (LLT). The sodium lasers and the LLT are contracted out to external vendors while the beam transfer optics are being designed and built in house. The new beam transfer optics are called the Beam Expander and Control Node (BEaCoN) and function as the link between the two contracted products. Within the BEaCoN the laser beam is split, expanded, and steered before being injected into the LLT. This report covers the design and analysis of the BEaCoN optical bench.