1. 1 Guidestar Laser Requirements for ELTs Brent Ellerbroek (with thanks to Norbert Hubin and Michael Lloyd-Hart) 2007 CfAO Fall Retreat Lake Arrowhead November 2, 2007 TMT.AOS.PRE.07.xxx.REL01

2. 2 TMT.AOS.PRE.07.040.REL01 The information contained herein is subject to the restrictions contained on the cover page of this document. Early Light Laser Requirements Summary ProjectE-ELTGMTTMT Early light LGS AO modes LTAO, GLAO MCAO (Follow-on LGS AO modes) MCAO, MOAO GLAO, MOAO RMS WFE, nm ~220~200~190 Subap. width, cm 50 Frame rate, Hz 1000 800 # of LGS 666 CW LGS power estim., W 40 (baseline)30 (baseline)25 (baseline) Pulsed LGS power estim., W 15-2010-12?10-12 Laser Mass/Volume Constraints ?Dedicated room 7x2x2m 3x Gemini- South laser Changing g vector? yesnoyes

3. 3 TMT.AOS.PRE.07.040.REL01 The information contained herein is subject to the restrictions contained on the cover page of this document. Goals and Upgrade Paths Goals –Pulsed lasers Dynamic refocusing Rayleigh backscatter gating Both? –Compatible with fiber beam transport –As small and as light as possible Upgrade Paths –Higher powers (e.g., 4-5x) for reduced RMS WFE –Additional guidestars for MOAO and enlarged FoVs