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Gemini ExAOC kickoff

Join us for the Gemini eXtreme Coronagraph (GeXCo) conference kick-off meeting on Monday. The agenda includes discussions on science cases, project structure, lessons from other systems, ExAO system overview, science instruments, technology development, Error budget, and tech development areas.

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Gemini ExAOC kickoff

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  1. Gemini ExAOC kickoff

  2. Monday Agenda • 8:30-9:30: Coffee, CfAO lobby. • 9:30 start • Introduction: Bruce (10 min+20 min introduction) • 10:00 • Science case: James (20 min+25 min discussion) (Moderator: Bruce) • Key science questions for instrument design • 10:45-11:00: Break • 11:00 • Introduction to Gemini instruments and environment: Les (30 min) (Moderator: Dave) • overview of Gemini instrument environment • outline of Gemini committee structure (Rene Doyon) • 11:30 • Project structure, plan and timetable: Dave Palmer (15 min+15 min discussion) (Moderator: Les) • project deliverables and timetable

  3. Monday Agenda 1:00 Lessons from other systems: (60 min) (Moderator: Bruce) -discuss broad lessons from previous projects -Altair (Jean-Pierre) (10-20 min) -Lick , Keck, OSIRIS, Trident, etc. 2:00: ExAO System overview and error budget: Bruce (20 min+40 min discussion) (Moderator: James Graham) -discussion of error budget -key technology choices to be made 3:00-3:25 break 3:25-4:10 Science Instrument (moderator: James Graham) • Differential imaging principals and concepts: Rene (20) • Integral field unit/OSIRIS: James (10) • Science instrument concepts discussion (15) 4:10-4:45: Technology development and verification (Bruce) (moderator: Dave Palmer) 4:45-5:30 Wrapup and discussion of ExAO concepts: -calibration outline (Wallace) -alternative nuller concepts (Shao) -why we should build this at the south pole using non-redundant aperture masking (Jamie) 5:30-7:30 Barbeque dinner, CfAO patio area (bring a jacket or sweater!)

  4. Generalized PSF noise expansion • Error power spectra can be evaluated analytically or in small simulations • This assumes that all error sources are uncorrelated • This also neglects the fourth-order term • A useful approach because end-to-end simulations are prohibitive; some noise terms only begin to dominate in 60 minute exposures!

  5. Error terms: atmospheric fitting 5 second monochromatic image

  6. Aliasing error 5 second monochromatic image

  7. Temporal bandwidth 5 second monochromatic image

  8. WFS measurement noise 5 second monochromatic image

  9. XAOPI 0 nm static errors, 5 MJ/500 MYr planet, 15 minute integration

  10. XAOPI 1 nm static errors, 5 MJ/500 MYr planet, 15 minute integration

  11. XAOPI 2 nm static errors, 5 MJ/500 MYr planet, 15 minute integration

  12. XAOPI 5 nm static errors, 5 MJ/500 MYr planet, 15 minute integration

  13. Error budget

  14. Relative weight of error terms

  15. Error budget w. 90% PSF subtraction

  16. Error budget: missing terms • Chromaticism: • Atmospheric dispersion (with/without correction?) • Beam displacement errors • Scintillation • Very preliminary calculations indicate this doesn’t dominate at 10-7 • Optics surface roughness • Optical properties as input rather than spec • Post-coronagraph error leakage • Coronagraph properties

  17. Error budget: refinement • Speckle lifetime modelling (by SPIE?) • Better power spectrum modeling (PAOLA) • PSF differencing modeling • Fourth-order terms • Verification through simulation

  18. Tech development areas • AO: MEMS • AO: CCD • Coronagraph: masks and apodizers • Dichroic? • Others”

  19. PSDI Front End Short temporal coherence laser Lens and Aperture Stop Optical MEMS Device Variable neutral density filter Diffraction aperture Half-wave retardation plate Variable delay path Polarizers Diffraction aperture (for PSDI mode) Optical fibers Testbed Area Polarization beam splitter Quarter-wave retardation plates Interferometer CCD camera Piezoelectric phase shifter Image CCD replaces Diffraction aperture for Far-Field mode. Computer system ExAO testbed

  20. MEMS measurements

  21. Testbed plans • June: Flatten MEMS, demonstrate high-contrast PSF • Summer: exercise MEMS, test other MEMS • Fall: demonstrate SFWFS • Correct phase errors (plates?) • 2005: Design integrated white-light testbed • 2006: Test • Other goals? Algorithm tests?

  22. We need an better name! Gemini eXtreme Coronagraph GeXCo

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