The shipment of TMT’s first meniscus-shaped primary mirror segment to the Indian Institute of Astrophysics (IIA) in Bengaluru (Bangalore) has just been completed. This initial piece of glass will be used by IIA for testing and development purposes.
The CLEARCERAM®-Z special glass ceramic for the mirror segment was cast by Ohara Inc. Subsequently, Okamoto Optics Works, Inc. generated the substrate to the required shape, under contract to Canon Inc.
The Indian TMT Coordination Center (ITCC), which manages all TMT technical development and production in India, received this glass courtesy of the National Astronomical Observatory of Japan, which contracted with Japanese industry, and then provided the glass to India.
NAOJ will send many similar blanks in the months to come, as part of Japan's contribution to the TMT International Partnership. The blanks will go through the same steps of primary mirror segment production: grinding, polishing, hexagonal cutting and support assembly mounting. All mirrors will be processed in a new optics facility, still under construction, located 35 km to the northeast of Bengaluru at the Centre for Research and Education in Science and Technology (CREST).
Ultimately, all segments from India and TMT’s other partners will be sent to a manufacturer in the United States for final surface finishing and optical testing. When completed, the 492 hexagonal mirror segments will be combined to form TMT’s 30-meter diameter primary mirror.