Abstract

Advances in casting and polishing technology at the Steward Observatory Mirror Laboratory enable the production of astronomical mirrors of unprecedented size and focal ratio. The null correctors required for the interferometric center-of-curvature test of such large optics must also be of unprecedented proportions. To correct for the enormous departure of the mirrors from spherical (5.7 mm from the vertex-matching sphere for 8.4-m f/1.14 Columbus telescope primary) several extreme null lens designs are considered.

© 1991 Optical Society of America