The advent of large telescopes for remote sensing presents special challenges for optical testing, particularly for verifying focal plane array alignment. If testing in air, the large well-enclosed telescope cavity can create air stagnation or thermal gradient effects that can distort the optical wavefront unpredictably, resulting in noisy and inaccurate measurements. Testing in vacuum presents instrumentation challenges but eliminates the air effects and provides excellent data. This paper describes the experimental setups and compares through-focus test results for a large remote sensing telescope when tested in both air and in a vacuum.

Date Published: 26 September 2007
PDF: 8 pages
Proc. SPIE 6677, Earth Observing Systems XII, 66770B (26 September 2007); doi: 10.1117/12.732189

Published in SPIE Proceedings Vol. 6677:
Earth Observing Systems XII
James J. Butler; Jack Xiong, Editor(s)