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JWST Telescope Optics: Progress Report

JWST Telescope Optics: Progress Report. Mark Clampin Observatory Project Scientist Goddard Space Flight Center 217 th American Astronomical Society Meeting. JWST’s Optical Design. 3 mirror anastigmat Elliptical f/1.2 Primary Mirror (PM)

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JWST Telescope Optics: Progress Report

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  1. JWST Telescope Optics:Progress Report • Mark Clampin • Observatory Project Scientist • Goddard Space Flight Center • 217th American Astronomical Society Meeting

  2. JWST’s Optical Design • 3 mirror anastigmat • Elliptical f/1.2 Primary Mirror(PM) • HyperbolicSecondary Mirror (SM) creates f/9 intermediate image (6 DOF) • EllipticalTertiary Mirror (TM) images pupil at FlatFine Steering Mirror (FSM) • Active Optical System • 18 primary mirror segments • 6 degrees of freedom + ROC • 40 K temperature • Beryllium mirrors • 3 mirror prescriptions

  3. JWST Mirror Fabrication Raw Be billet (two mirrors) • JWST Mirrors made of beryllium • Lightweight and stable at 40 K • Brush-Wellman Primary segment Secondary Tertiary • Machined & lightweighted by Axsys • 92% material is removed • Mirrors polished at Tinsley • Segment cryo-figure: 20 nm Ambient Surface Figure Cryo Surface Figure

  4. What is a Flight Mirror ? • Primary Mirror Segment Assembly (PMSA) = Mirror + Actuators Front Face Rear Face 6 DOF Actuators Radius of Curvature Actuator + Strongback

  5. EDU Flight mirrors Excellent convergence rate on flight mirrors Mirror Polishing Performance • EDU mirror is designated Pathfinder mirror: • EDU allows timely resolution of processing issues, and optimized processing for flight mirrors

  6. Flight Mirror Cryogenic Testing

  7. Flight Mirrors Meeting Specification

  8. Aft-Telescope Optical System

  9. First Gold Coated EDU Primary Mirror

  10. Coating of Flight Mirrors Underway

  11. Gold Coated Mirror Assemblies

  12. Gold Coatings Exceed Requirements

  13. Flight Mirror Cryogenic Testing

  14. Coated Mirror Figures Meet Requirement

  15. Schedule: Acceptance Testing

  16. Predicted Image Quality • JWST optics are designed to be diffraction-limited at a wavelength of 2 μm • Preliminary simulations of the OTE using A4 flight mirror data as a template for the primary mirror • Simulated PSF through NIRCam filters • F444W, F200W, F115W, & F070W • NIRCam pixels are 0.032” (SW) and 0.065” (LW)

  17. Predicted Image Quality: 2 μm & 4 μm

  18. Predicted Image Quality: 0.7 μm & 1 μm

  19. Flight Mirror: Schedule for 2011 • 5 flight primary mirrors completed w/gold coating • Acceptance testing under way (vibe & optical testing) • 13 flight mirrors in final polishing cycle • Flight Secondary in final polishing cycle • Flight mirror fabrication program will be completed during summer 2011, with delivery of all flight mirrors !

  20. Acknowledgements • Chuck Bowers and Kong Ha • Lee Feinberg and OTE team • at GSFC, BATC, NGAS & QCI

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