Fabrication and metrology study for M3M of TMT

The M3M (Mirror 3 Mirror) of TMT (Thirty Meter Telescope) project is a3.5m×2.5m solid flat elliptical mirror. CIOMP is responsible for the fabrication of the M3M. A primary study on the fabrication and metrology is done in the past 2 years, and this paper introduces our work on the project. The fabrication strategy is based on large orbital tools and a plan combining with multiple measure methods is developed based on the requirement of M3M. A concept of dualsupporting system is also studied in the program to reduce the effect of gravity deformation.