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JWST Optical Telescope Element Center of Curvature TestThe James Webb Space Telescope (JWST) Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) completed element level integration and test programs and were integrated to the next level of assembly called OTE/ISIM (OTIS) at Goddard Space Flight Center (GSFC) in Greenbelt, Maryland in 2016. Before shipping the OTIS to Johnson Space Center (JSC) for optical test at cryogenic temperature a series of vibration and acoustic tests were performed. To help ensure that the OTIS was ready to be shipped to JSC an optical center of curvature (CoC) test was performed to measure changes in the mirror's optical performance to verify that the telescope's primary mirror was not adversely impacted by the environmental testing and help us in understanding potential anomalies identified during the JSC tests. The primary is a 6.5 meter diameter mirror consisting of 18 individual hexagonal segments. Each segment is an off-axis asphere. There are a total of three prescriptions repeated six times each. As part of the CoC test each segment was individually measured using a high-speed interferometer (HSI) designed and built specifically for this test. This interferometer is capable of characterizing both static and dynamic characteristics of the mirrors. The latter capability was used, with the aid of a vibration stinger applying a low-level input force, to measure the dynamic characteristic changes of the PM backplane structure. This paper describes the CoC test setup and both static and dynamic test results.
Document ID
20180004906
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Saif, Babak (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Keski-Kuha, Ritva (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Chaney, David (Ball Aerospace and Technologies Corp. Boulder, CO, United States)
Greenfield, Perry (Space Telescope Science Inst. Baltimore, MD, United States)
Van Gorkom, Kyle (Space Telescope Science Inst. Baltimore, MD, United States)
Brooks, Keira (Space Telescope Science Inst. Baltimore, MD, United States)
Hack, Warren (Space Telescope Science Inst. Baltimore, MD, United States)
Bluth, Marcel (SGT, Inc. Greenbelt, MD, United States)
Bluth, Josh (SGT, Inc. Greenbelt, MD, United States)
Sanders, James (Vantage Systems, Inc. Lanham, MD, United States)
Smith, Koby (Ball Aerospace and Technologies Corp. Boulder, CO, United States)
Carey, Larkin (Ball Aerospace and Technologies Corp. Boulder, CO, United States)
Chaung, Sze (ATK Space Systems, Inc. San Diego, CA, United States)
Feinberg, Lee (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Tournois, Severine (Sigma Space Corp. Lanham, MD, United States)
Smith, W. Scott (NASA Marshall Space Flight Center Huntsville, AL, United States)
Kradinov, Vladimir (Smithsonian Astrophysical Observatory Cambridge, MA, United States)
Date Acquired
September 5, 2018
Publication Date
June 10, 2018
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN57827
Meeting Information
Meeting: Astronomical Telescopes + Instrumentation
Location: Austin, TX
Country: United States
Start Date: June 10, 2018
End Date: June 15, 2018
Sponsors: International Society for Optical Engineering
Funding Number(s)
CONTRACT_GRANT: NAS5-03127
CONTRACT_GRANT: NNG13FB20C
CONTRACT_GRANT: NAS5-02200
CONTRACT_GRANT: NNX13AI83A
CONTRACT_GRANT: NNG15CR64C
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
interferometer
optical testing
JWST

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