Translator Disclaimer
22 July 2010 Fabrication of 4-meter class astronomical optics
Author Affiliations +
Abstract
The 8-meter mirror production capacity at the University of Arizona is well known. As the Arizona Stadium facility is occupied with giant mirrors, we have developed capability for grinding, polishing, and testing 4-m mirrors in the large optics shop in the College of Optical Sciences. Several outstanding capabilities for optics up to 4.3 meters in diameter are in place: A 4.3-m computer controlled grinding and polishing machine allows efficient figuring of steeply aspheric and nonaxisymmetric surfaces. Interferometry (IR and visible wavelengths) and surface profilometry making novel use of a laser tracker allows quick, accurate in-process measurements from a movable platform on a 30-m vertical tower. A 2-meter class flat measured with a 1-m vibration insensitive Fizeau interferometer and scanning pentaprism system; stitching of 1-m sub-apertures provides complete surface data with the technology ready for extension to the 4 m level. These methods were proven successful by completion of several optics including the 4.3-m Discovery Channel Telescope primary mirror. The 10 cm thick ULE substrate was ground and polished to 16 nm rms accuracy, corresponding to 80% encircled energy in 0.073 arc-second, after removing low order bending modes. The successful completion of the DCT mirror demonstrates the engineering and performance of the support system, ability to finish large aspheric surfaces using computer controlled polishing, and accuracy verification of surface measurements. In addition to the DCT mirror, a 2-meter class flat was produced to an unprecedented accuracy of <10 nm-rms, demonstrating the combined 1-m Fizeau interferometer and scanning pentaprism measurement techniques.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. J. Valente, D. W. Kim, C. J. Oh, M. J. Novak, and J. H. Burge "Fabrication of 4-meter class astronomical optics", Proc. SPIE 7739, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation, 77392D (22 July 2010); https://doi.org/10.1117/12.861979
PROCEEDINGS
13 PAGES


SHARE
Advertisement
Advertisement
RELATED CONTENT

Research on fabrication of mirror segments for E-ELT
Proceedings of SPIE (October 16 2012)
Fabrication of freeform optics
Proceedings of SPIE (August 27 2015)
Machining of paraboloidal mirrors
Proceedings of SPIE (May 14 2007)
Long-Wavelength Interferometer In The Optical Shop
Proceedings of SPIE (December 25 1979)

Back to Top