SIRTF-CTA optical performance test

This paper describes the "End to End" optical test conducted on the Space InfraRed Telescope Facility (SIRTF) Cryogenic Telescope Assembly (CTA) in 2001. It was critical to verify SIRTF's optical functionality and quality under optical and thermal conditions that as much as possible simulated the flight environment. The Liquid Nitrogen cooled "Brutus" chamber at Ball Aerospace was the test facility. Flight-like self cooling, thermal blanketing, and auxiliary cooling loops allowed the assembly to reach temperatures close to orbital conditions. (25-5K) Introducing optical sources at the SIRTF focal plane allowed the telescope to perform as the collimating source. A motorized and cryogenically characterized reflection flat was used to direct the refocused images of test sources to visible and IR focal planes in SIRTF's Multi-Instrument Chamber. A sequence of tests was performed to gather data on system focus position, image stability, telescope wavefront and instrument assembly confocality.