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TMT roundels conformance review group photo, April 27, 2021 - NAOJ delivered eight additional roundels produced by Canon Inc. in Utsunomiya, Japan. Image credit: TMT International Observatory

Progress made on TMT mirror production

Pasadena, CA - TIO recently celebrated the completion of another eight newly polished roundels produced for the TMT primary mirror by Canon in Japan. The TIO and NAOJ teams responsible for the mirror polishing held a face-to-face meeting virtually on April 27, 2021 to confirm that the polishing results met the demanding requirements for these parts. The optical glass used for manufacturing TMT segments, is made of Ohara's CLEARCERAM-Z ultra-low expansion glass-ceramic.


During the meeting, team members discussed the conformance of the polished roundels based on the measurements and inspections carried out beforehand. The technical information, inspection and verification reports, and certifications of conformance were approved and, as a result, all of the submitted roundels met the conformance criteria.


Congratulations to the TMT-Japan team for ensuring the successful continued production with Roundels SN024-SN025, SN027-SN031, and SN061. TMT now has 11 accepted polished roundels - only 563 to go (including the 82 spare segments)!

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