Share Email Print
cover

Proceedings Paper

Planning The National New Technology Telescope (NNTT): III. Primary Optics - Tests On A 1.8-M Borosilicate Glass Honeycomb Mirror
Author(s): E. Pearson; L. Stepp; W-Y . Wong; J. Fox; D. Morse; J. Richardson; S. Eisenberg
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Materials for large primary mirrors should have low density, high elastic modulus, low coefficient of thermal expansion, dimensional stability over time, favorable polishing characteristics and affordable cost. The mirror's structural shape can contribute to high stiffness, low weight and a short thermal time constant. These characteristics can be provided by cast honeycomb borosilicate glass mirrors, but the coefficient of thermal expansion is high enough to require thermal control to achieve images at the 1/4-arcsecond level. This paper describes a series of tests performed on a 1.8-meter cast honeycomb mirror with an integral ventilation system for temperature control. Surface distortions have been related to the pattern of temperatures present, and the effect of ventilation on the thermal time constant has been explored. The results are extrapolated to larger size mirrors using finite-element analysis.

Paper Details

Date Published: 20 August 1986
PDF: 11 pages
Proc. SPIE 0628, Advanced Technology Optical Telescopes III, (20 August 1986); doi: 10.1117/12.963515
Show Author Affiliations
E. Pearson, National Optical Astronomy Observatories (United States)
L. Stepp, National Optical Astronomy Observatories (United States)
W-Y . Wong, National Optical Astronomy Observatories (United States)
J. Fox, National Optical Astronomy Observatories (United States)
D. Morse, National Optical Astronomy Observatories (United States)
J. Richardson, National Optical Astronomy Observatories (United States)
S. Eisenberg, National Optical Astronomy Observatories (United States)


Published in SPIE Proceedings Vol. 0628:
Advanced Technology Optical Telescopes III
Lawrence D. Barr, Editor(s)

© SPIE. Terms of Use
Back to Top