Share Email Print

Proceedings Paper

Full-aperture interferometric test of convex secondary mirrors using holographic test plates
Author(s): James H. Burge; David S. Anderson
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

Convex secondary mirrors are notoriously difficult to fabricate because of the tremendous cost and difficulty of making accurate measurements of the optical surfaces. The new 6.5- and 8-m-class telescopes require secondary mirrors that are larger, more aspheric, and more accurately figured than those for existing telescopes. The challenge of measuring these giant optics has spurred the development of a new measurement technique using holographic test plates. This test uses a full-aperture test plate with a computer-generated hologram fabricated onto the spherical reference surface. When supported a few millimeters from the secondary and properly illuminated with laser light, an interference pattern is formed that shows the secondary surface errors. The hologram consists of annular rings of metal drawn onto the curved test plate surface using a custom-built writing machine. The accuracy of the surface measurement using this technique is expected to be 35 nm P-V and 6 nm rms for a 1.65-m secondary mirror for the MMT. Considerably higher accuracy is expected for less aspheric surfaces.

Paper Details

Date Published: 1 June 1994
PDF: 12 pages
Proc. SPIE 2199, Advanced Technology Optical Telescopes V, (1 June 1994); doi: 10.1117/12.176188
Show Author Affiliations
James H. Burge, Univ. of Arizona Steward Observatory (United States)
David S. Anderson, Univ. of Arizona Steward Observatory (United States)

Published in SPIE Proceedings Vol. 2199:
Advanced Technology Optical Telescopes V
Larry M. Stepp, Editor(s)

© SPIE. Terms of Use
Back to Top