Metrology requirements for the serial production of ELT primary mirror segments

Paul C. T. Rees; Caroline Gray

doi:10.1117/12.2189783

27 August 2015 Metrology requirements for the serial production of ELT primary mirror segments

Paul C. T. Rees, Caroline Gray

Proceedings Volume 9575, Optical Manufacturing and Testing XI; 957508 (2015) https://doi.org/10.1117/12.2189783
Event: SPIE Optical Engineering + Applications, 2015, San Diego, California, United States

Abstract

The manufacture of the next generation of large astronomical telescopes, the extremely large telescopes (ELT), requires the rapid manufacture of greater than 500 1.44m hexagonal segments for the primary mirror of each telescope. Both leading projects, the Thirty Meter Telescope (TMT) and the European Extremely Large Telescope (E-ELT), have set highly demanding technical requirements for each fabricated segment. These technical requirements, when combined with the anticipated construction schedule for each telescope, suggest that more than one optical fabricator will be involved in the delivery of the primary mirror segments in order to meet the project schedule. For one supplier, the technical specification is challenging and requires highly consistent control of metrology in close coordination with the polishing technologies used in order to optimize production rates. For production using multiple suppliers, however the supply chain is structured, consistent control of metrology along the supply chain will be required. This requires a broader pattern of independent verification than is the case of a single supplier. This paper outlines the metrology requirements for a single supplier throughout all stages of the fabrication process. We identify and outline those areas where metrology accuracy and duration have a significant impact on production efficiency. We use the challenging ESO E-ELT technical specification as an example of our treatment, including actual process data. We further develop this model for the case of a supply chain consisting of multiple suppliers. Here, we emphasize the need to control metrology throughout the supply chain in order to optimize net production efficiency.

Citation Download Citation

Paul C. T. Rees and Caroline Gray "Metrology requirements for the serial production of ELT primary mirror segments", Proc. SPIE 9575, Optical Manufacturing and Testing XI, 957508 (27 August 2015); https://doi.org/10.1117/12.2189783

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