The work on the secondary mirror polishing for the Thirty Meter Telescope (TMT) has begun. Following an extensive Request for Proposal process, the TMT International Observatory (TIO) is pleased to announce the selection of the University of Arizona College of Optical Sciences (COS) for the precise and delicate work required for the metrology and polishing of the TMT secondary mirror (M2).
The M2 is one of the largest convex mirrors ever created and is a key component of the Thirty Meter Telescope (TMT). M2 has an impressive diameter of 3.13 m (10.3 ft; see the figure above) and weighs in at 2000 kg (4410 lb). And yet this convex aspheric mirror must have an extremely precise optical surface for the telescope to achieve its groundbreaking performance. State-of-the-art metrology to measure the optical surface and accurate knowledge of the mechanical system used to support M2 during fabrication are critical ingredients in polishing the M2 optical surface.
A realistic simulation of the Thirty Meter Telescope's Secondary Mirror System. The secondary mirror reflects the light from the primary mirror and converts it to the beam for the science instruments. Image credit: TMT International Observatory
The full M2 Metrology and Polishing program (M2POL) consists of two phases of work:
“We are excited to partner with COS on the full polishing program for TMT’s secondary mirror, which is a critical piece of our telescope,” said TIO Lead Contracts Specialist Pratheep Eamranond. “Their experience in polishing and metrology of very large, high-accuracy mirrors for ground-based telescopes will serve our project well.”
A kick-off meeting was recently held at the University of Arizona with TIO staff members on site together with key members of the team from COS. The meeting marked a successful beginning to the M2 Metrology and Polishing program.
The meeting began with introductions from both teams, followed by a comprehensive presentation by COS that provided insight into their conceptual design for the M2POL program. COS demonstrated their remarkable expertise and heritage in optical metrology and polishing of large optics, identified design driving requirements and trade studies to drive this project forward. Both TIO and the COS are thrilled and privileged to join forces in this important project.
Ben Gallagher, TIO Optics Group Lead, said "Our M2POL kickoff meeting is an important milestone in our journey to polish the M2 mirror. The thorough analysis and design of the metrology system conducted in this initial phase of the work provides the foundation for the remainder of the M2POL program. We are confident that the collective expertise of our combined COS-TIO team will pave the way for successful completion of M2 mirror polishing."
Photo of the combined M2 Metrology & Polishing team at the Kick-Off meeting.
The polished M2 will be integrated into its Support System and Positioner Assembly (M2SSP) to form the complete M2 System of the telescope. The M2SSP has been designed by TIO contractor Advanced Mechanical and Optical Systems (AMOS), in Liège, Belgium and recently passed Final Design Review (FDR) - a major milestone for TMT. Read more about the M2SSP FDR here.
The work outlined in this contract is supported by funding from the National Science Foundation (NSF), which was granted to TIO for design and development purposes.
With members from the US, Canada, India and Japan, TIO is a non-profit organization established to carry out the construction and operation phases of the TMT Project. More information on TMT: https://www.tmt.org/
This material is based upon work supported by the National Science Foundation under Cooperative Agreement No. 2437863. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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