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The Gemini Adaptive Optics Program MCAO for Gemini-South

The Gemini Adaptive Optics Program MCAO for Gemini-South. Presentation Overview: Dedication success The Gemini Adaptive Optics Program Revisited Multi-Conjugate Adaptive Optics: A Science Opportunity: Context and rationale Principles and performance Feasibility Cost and Schedule.

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The Gemini Adaptive Optics Program MCAO for Gemini-South

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  1. The Gemini Adaptive Optics ProgramMCAO for Gemini-South • Presentation Overview: • Dedication success • The Gemini Adaptive Optics Program Revisited • Multi-Conjugate Adaptive Optics: • A Science Opportunity: Context and rationale • Principles and performance • Feasibility • Cost and Schedule F.Rigaut and B.Ellerbroek Gemini Board

  2. BD30: Courtesy C.Roddier, UH-IfA Gemini’s Dedication Gemini Board

  3. Gemini Top Level Performance Requirement #2 “ Image quality of better than 0.1 arcsec with AO: Achievement of outstanding image quality will have the highest scientific priority for the project […]” • 85% of the science topics in the Abingdon reportneed AO to be “effectively addressed” • The proposed evolution of the program at CP will enable unique NGST-class science 4 years ahead of NGST launch. It will keep Gemini competitive during the NGST era Gemini Board

  4. Doing AO Since 1989 (Come-On, ESO 3.6-m) • Facility VLT AO : NAOS+Conica • AO/Integral field unit: MACAO • 4 AO systems for the VLTI 1999 2000 2001 2002 2003 2004 Altair 10W LGS Hokupa’a 36 Keck Subaru VLT-LGS CP AOS/LGS CP Hokupa’a 1’’ 85 85 3 Years Gap 2W LGS VLT Vesta 1.5 m FWHM<40mas Proposed Baseline AO Program NORTH SOUTH Gemini Board

  5. CP AOS/LGS Baseline Program: Facility CP AOS 1999 2000 2001 2002 2003 2004 SOUTH • Context: • The Gemini science mission relies heavily on high angular resolution • Other observatories have “high performance” AOSs in the north (Keck 1999) and in the south (VLT 2001) -> Competitiveness issue • Rationale: • Provide the Gemini community with NGST-like capabilities (spatial res. and field), matching the Gemini science goals and instrumentation • Sets up Gemini to be a lead ground-based facility in the NGST era with matching resolution and similar field of view • Future ELTs require “wide” field of view AO Gemini Board

  6. CP AOS/LGS Baseline Program: Facility CP AOS 1999 2000 2001 2002 2003 2004 SOUTH • Proposal: • Build a high performance, 2 arcminutes field of view AOS with homogeneous PSF quality over the entire field of view, with very high sky coverage • How ? • Using Multi-Conjugate AO, i.e. 4-5 LGSs and wavefront sensors to measure the turbulence in 3D and 2-3 deformable mirrors to correct it • This uses currently available technology. NO hardware development required other than lasers (same as MK-LGS) Gemini Board

  7. 90 km “Missing” Data What is Tomography ?1. Cone effect Gemini Board

  8. What is Tomography ?2. Multiple guide star and tomography 90 km Gemini Board

  9. Turbulence Layers What is multiconjugate? Deformable mirror Gemini Board

  10. Deformable mirrors Turbulence Layers What is multiconjugate? Gemini Board

  11. Effectiveness of MCAO Numerical simulations: • 5 Natural guide stars • 5 Wavefront sensors • 2 mirrors • 8 turbulence layers • MK turbulence profile • Field of view ~ 1.2’ • H band Gemini Board

  12. Classical AO MCAO No AO MCAO Performance SummaryEarly NGS results, MK Profile 2 DMs / 5 NGS 1 DM / 1 NGS 165’’ 320 stars / K band / 0.7’’ seeing Stars magnified for clarity Gemini Board

  13. Sample Numerical Results • 0 degree zenith • 50% seeing • CP turbulence profile • K band • 12x12 subapertures • NGS-AO (triangles) • MCAO with 5 LGSs and 3 Tip-tilt NGS (crosses) K H J I Gemini Board

  14. CP AOS/LGS Baseline Program: Facility CP AOS 1999 2000 2001 2002 2003 2004 SOUTH • Advantages of MCAO versus Classical AO : • Sky coverage (50%) increased (50-500x) w/ respect to a NGS system • Increased performance on axis w/ respect to a LGS system because the cone effect is compensated • Increased field of view (well matched to IRMOS) • Uniform PSF across the FoV -> Easier and more accurate Data Reduction Gemini Board

  15. MCAO Implementation-Feasibility study conclusions: • Optics and optics bench • Mass, volume similar to Altair • Wave front sensor camera • Goal of a single camera for all laser guide stars • 80 by 80 to 128 by 128 pixels, 5 to 10 read noise electrons • Deformable mirrors and tip/tilt mirror • Number of actuators, other parameters demonstrated • Wave front reconstruction electronics • Frame rate, number of inputs/outputs demonstrated • Flexible algorithms and architectures necessary for NGS tip/tilt measurements • Tip/tilt sensors, laser transfer optics and launch telescope • Appear straightforward, feasibility designs in progress • 2-3 T/T sensors + 1 more provided by OIWFS • Laser(s): Technology and engineering development required Gemini Board

  16. MCAO Science Optical Path • 3 DM’s at R=0, 4, and 8 km • 13 actuators across beamprint • 4 folds, 2 off-axis parabolas, • 1 dichroic beamsplitter (not shown) • - Near-minimum number of surfaces for • facility MCAO • f/30 output focus Gemini Board

  17. Laser Issues • Power requirement: • Equivalent to conventional LGS AO on a per beacon basis • 20-40 Watts per LGS, 80-200 Watts total for short pulse, flashlamp+Nd:YAG-pumped dye lasers (LLNL) • ~20 Watts demonstrated • Scaling a cost/engineering issue (electrical power, heat dissipation, flammable dye) • 7-12 Watts per LGS, 28-60 Watts total for diode-pumped, Nd:YAG sum frequency lasers (MIT/LL and others) • ~5 Watts demonstrated • Scaling a technical issue (Nd:YAG beam quality and sum frequency feasibility at higher powers) Gemini Board

  18. Baseline Schedule • Conceptual design review: 3/00 • Preliminary design reviews: 12/00 • Critical design reviews: 12/01 • Subsystems complete: 6/03 • System integration and test: 10/03 • Science handover: 3/04 Gemini Board

  19. MCAO Budget Estimate (Part I) Gemini Board

  20. MCAO Budget Estimate (Part II) Gemini Board

  21. Labor Requirements by Year Gemini Board

  22. Gemini AO Program: Division of Work within Partnership Gemini AO program ambitious, but IGPO is not proceeding alone • Partnership Workload (including vendors): • Hokupa’a-85 for Gemini-North: UH • Hokupa’a-85 for Gemini-South: • WFS and DM: UH • Commercially supplied dye laser • Altair: HIA • Altair LGS: • WFS upgrades: HIA • Laser source: Contract • Coronograph AO: Instrument supplier • Common infrastructure (IGPO): LGS transfer optics, launch telescope, and safety system • MCAO is the focus of IGPO efforts. Significant outsourcing of work expected after CoDR. Gemini Board

  23. Recent Progress • Overall roadmap to CoDR drafted • Science requirements, system requirements, system design, cost, labor, and schedule • System analysis street map drafted • LGS power requirements, NGS magnitude limits and sky coverage, instrument performance, comparison with LGS • Coordination with Gemini partners and community underway • HIA (10/23), CfAO (11/2), NOAO (11/4) • LGS development meeting planned with CfAO for 12/7 • Meeting at Durham (and possibly ATC) planned for 12/9-10 • Launch telescope and transfer optics design in progress • Conversations with component vendors continue • System modeling, algorithm development continues Gemini Board

  24. MCAO—A Step Beyond… • Using the same components as other planned LGS AO systems, MCAO on Gemini-South will go a step beyond… • Enabling NGST-class observations for the Gemini Community Classical AO MCAO Gemini Board

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