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

2. JWST JWST’s Optical Design ➡ 3 mirror anastigmat ➡ Elliptical f/1.2 Primary Mirror (PM) ➡ Hyperbolic Secondary Mirror (SM) creates f/9 intermediate image (6 DOF) ➡ Elliptical Tertiary Mirror (TM) images pupil at Flat Fine 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 JWST Mirror Fabrication JWST Mirrors made of beryllium Lightweight and stable at 40 K Brush-Wellman Machined & lightweighted by Axsys 92% material is removed Raw Be billet (two mirrors) Primary segment Tertiary Secondary Mirrors polished at Tinsley Segment cryo-figure: 20 nm Ambient Surface Figure Cryo Surface Figure

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

6. JWST Flight Mirror Cryogenic Testing

7. JWST Flight Mirrors Meeting Specification

8. JWST Aft-Telescope Optical System

9. JWST First Gold Coated EDU Primary Mirror

10. JWST Coating of Flight Mirrors Underway

11. JWST Gold Coated Mirror Assemblies

12. JWST Gold Coatings Exceed Requirements

13. JWST Flight Mirror Cryogenic Testing

14. JWST Coated Mirror Figures Meet Requirement

15. JWST Schedule: Acceptance Testing

16. JWST 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. JWST Predicted Image Quality: 2 μm & 4 μm

18. JWST Predicted Image Quality: 0.7 μm & 1 μm

19. JWST 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. JWST Acknowledgements ➡ Chuck Bowers and Kong Ha ➡ Lee Feinberg and OTE team ➡ at GSFC, BATC, NGAS & QCI