LGS AO photon return simulations and laser requirements for the Gemini LGS AO program

Laser Guide Star Adaptive Optics system operation at an 8-m class telescope like Gemini North and Gemini South require minimum laser output power in the 10 W range. Since each additional Watt of laser power increases the laser purchase and operational costs, it is highly desirable to understand how laser parameters can be optimized in order to decrease the total laser power requirement. This paper provides some tools to calculate the output power requirement of a candidate laser system and its optimized parameters in the case of continuous wave lasers and high repetition rate pulsed lasers. Laser power requirements for Gemini North and Gemini South are given as examples of this calculation.