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The center of curvature optical assembly for the JWST primary mirror cryogenic optical test: optical verification

2010; SPIE; Volume: 7790; Linguagem: Inglês

10.1117/12.861874

1996-756X

Conrad Wells, Gene Olczak, Cormic Merle, Tom Dey, Mark Waldman, Tony Whitman, Eric Wick, Aaron Peer,

Advanced optical system design

The James Webb Space Telescope (JWST) Optical Telescope Element (OTE) consists of a 6.6 m clear aperture, allreflective, three-mirror anastigmat. The 18-segment primary mirror (PM) presents unique and challenging assembly, integration, alignment and testing requirements. A full aperture center of curvature optical test is performed in cryogenic vacuum conditions at the integrated observatory level to verify PM performance requirements. The Center of Curvature Optical Assembly (CoCOA), designed and being built by ITT satisfies the requirements for this test. The CoCOA contains a multi wave interferometer, patented reflective null lens, actuation for alignment, full in situ calibration capability, coarse and fine alignment sensing systems, as well as a system for monitoring changes in the PM to CoCOA distance. Two wave front calibration tests are utilized to verify the low and Mid/High spatial frequencies, overcoming the limitations of the standard null/hologram configuration in its ability to resolve mid and high spatial frequencies. This paper will introduce the systems level architecture and optical test layout for the CoCOA.