Material characteristics of CLEARCERAM-Z HS 1.5m diameter mirror blanks for the TMT M1 segment blanks

Within the Astronomical community there is growing interest in the development and use of very large aperture telescopes which will incorporate the latest advancements in optical materials. One of the most notable of these large size telescope projects, the Thirty Meter Telescope (TMT), will use mirror segments in the actively controlled primary mirrors and Ohara is a supplier of the near zero expansion mirror blanks. In this paper we present the measurement and inspection results on the initial 60 pieces of Ohara CLEARCERAM-Z HS 1.5m diameter blanks, which will be used for the TMT M1 Segment Blanks, including data on the Coefficient of Thermal Expansion (CTE), CTE uniformity, residual stress, bubbles and inclusions.