Abstract

Large ground-based telescope projects are currently underway that require primary mirrors as large as 8.4 meters in diameter and as fast as f/1. Since the primary mirrors are concave, they can be interferometrically measured from center of curvature using null correctors. The secondary mirrors for these giant telescopes are often convex, steeply aspheric, and large (up to 1.7 m in diameter) making them much more difficult to measure. To achieve the highest possible image quality, the mirrors must be polished to the correct shape within 20 nm rms, so they should be measured to an accuracy of 10 nm rms.

© 1996 Optical Society of America