Abstract

The building blocks for fabricating the 8.3-m Subaru primary mirror blank are ultralow-expansin solid hexagonal units that were subjected to rigorous ultrasonic examination to establish thermal expansion characterization as reported by Hagy [Appl. Opt. 12, 1440 (1973)]. Following assembly of the mirror by fusion and fine annealing, photoelastic analyses at hex-to-hex seals were used to calculate thermal expansion differences. These differences are found to be in excellent agreement with the ultrasonically established differences.

© 1996 Optical Society of America

High Precision Photoelastic and Ultrasonic Techniques for Determining Absolute and Differential Thermal Expansion of Titania–Silica Glasses

Henry E. Hagy
Appl. Opt. 12(7) 1440-1446 (1973)

Determination of the coefficient of thermal expansion of ultra-low-expansion glass using an ultrasonic immersion testing method

Wenqing Wei, Xue Qi, Hu Deng, Liping Shang, Yuanyuan Zhang, and Hong Liu
Appl. Opt. 62(13) 3347-3356 (2023)

A New Ultralow-Expansion, Modified Fused-Silica Glass

C. L. Rathmann, G. H. Mann, and M. E. Nordberg
Appl. Opt. 7(5) 819-823 (1968)

Determining absolute thermal expansion of titania–silica glasses: a refined ultrasonic method

H. E. Hagy and W. D. Shirkey
Appl. Opt. 14(9) 2099-2103 (1975)

Evaluation of a Large Glass–Ceramic Mirror Blank

D. R. Stewart and W. L. Davis
Appl. Opt. 9(4) 938-941 (1970)