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International Journal of Optics
Volume 2010, Article ID 201305, 10 pages
http://dx.doi.org/10.1155/2010/201305
Research Article

Mirror Prescription Regression: A Differential Interferometric Technique

Center for Applied Optics, University of Alabama in Huntsville, 301 Sparkman Drive Huntsville, AL 35899, USA

Received 9 September 2010; Accepted 21 November 2010

Academic Editor: A. Beléndez

Copyright © 2010 Brian M. Robinson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We present a remote, differential method for measuring the prescription of aspheric mirrors using null interferometry in the center-of-curvature configuration. The method requires no equipment beyond that used in a basic interferometery setup (i.e., there are no shearing elements or absolute distance meters). We chose this configuration because of its widespread use. However, the method is generalizable to other configurations with an adjustment of the governing equation. The method involves taking a series of interferograms before and after small, known misalignments are applied to the mirror in the interferometry setup and calculating the prescription (e.g., radius of curvature and conic constant) of the mirror, based on these differential measurements, using a nonlinear regression. We apply this method successfully to the testing of a Space Optics Research Lab off-axis parabola with a known focal length of 152.4 mm, a diameter of 76.2 mm, and an off-axis angle of 12°.