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The Gemini Adaptive Optics ProgramMCAO for Gemini-South : 

The Gemini Adaptive Optics Program MCAO for Gemini-South F.Rigaut and B.Ellerbroek 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

Gemini’s Dedication: 

Gemini’s Dedication

Gemini Top Level Performance Requirement #2: 

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 report need 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

Proposed Baseline AO Program: 

Proposed Baseline AO Program NORTH SOUTH

Baseline Program: Facility CP AOS: 

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

Baseline Program: Facility CP AOS: 

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)

What is Tomography ?1. Cone effect: 

What is Tomography ? 1. Cone effect

What is Tomography ?2. Multiple guide star and tomography: 

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

What is multiconjugate?: 

What is multiconjugate? Deformable mirror

What is multiconjugate?: 

What is multiconjugate?

Effectiveness of MCAO: 

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

MCAO Performance SummaryEarly NGS results, MK Profile: 

165’’ MCAO Performance Summary Early NGS results, MK Profile 2 DMs / 5 NGS 320 stars / K band / 0.7’’ seeing 1 DM / 1 NGS Stars magnified for clarity

Sample Numerical Results: 

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

Baseline Program: Facility CP AOS: 

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

MCAO Implementation-Feasibility study conclusions:: 

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

MCAO Science Optical Path: 

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

Laser Issues: 

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)

Baseline Schedule: 

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

MCAO Budget Estimate (Part I): 

MCAO Budget Estimate (Part I)

MCAO Budget Estimate (Part II): 

MCAO Budget Estimate (Part II)

Labor Requirements by Year: 

Labor Requirements by Year

Gemini AO Program: Division of Work within Partnership: 

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.

Recent Progress: 

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

MCAO—A Step Beyond…: 

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

MCAO for Gemini-SouthPerformance, Feasibility, and Schedule: 

MCAO for Gemini-South Performance, Feasibility, and Schedule A multi-conjugate AO system for Gemini-south can theoretically provide highly uniform turbulence compensation over a 1-2’ diameter field-of-view System can be implemented with largely existing hardware and technology Fully acceptable deformable mirrors, tip/tilt mirrors, and wave front reconstructs have been demonstrated Most recent high-speed 1282 CD's meet wave front sensor requirements with margin Significant improvements still required in sodium laser power and reliability Comparable with conventional LGS AO on a per beacon basis Estimated schedule for science handover is spring 2004

Baseline Program: CP-Hokupa’a: 

Baseline Program: CP-Hokupa’a CP AOS/LGS SOUTH 1999 2000 2001 2002 2003 2004 Subaru Keck VLT VLT-LGS Hokupa’a 36 85 2W LGS CP Hokupa’a 85 SOUTH AO: Duplicate of the MK upgrade of Hokupa’a to 85 actuators. UH AO Team. Proposal submitted to NSF 08/99. Optomechanical upgrades (FoV 60’’) + LGS compatible Performance w/ NGS (AO only): Seeing Strehl(J) Strehl(K) 0.45’’ 50% 80% 0.65’’ 25% 62% LGS: Off-the-shelf 2W CW laser. Coherent/Spectra physics CW 10W pump laser + ring dye laser (demonstrated in lab) IR Imager: ABU

Baseline Program: CP-Hokupa’a: 

Baseline Program: CP-Hokupa’a CP AOS/LGS SOUTH 1999 2000 2001 2002 2003 2004 Subaru Keck VLT VLT-LGS Hokupa’a 36 85 2W LGS CP Hokupa’a 85 SOUTH Rationale: Gives us a 2+ year window of unchallenged AO+LGS capability in the southern hemisphere (comp. NAOS) w/ Adequate JHK performance. Build expertise on LGS by stepping up gradually (Laser Launch Telescope + Beam Transfer Optics) Getting AO on CP as soon as possible relieves pressure, allowing us to avoid the rush and do a better job on the final CP system

MCAO Performance SummaryEarly NGS results, MK Profile: 

MCAO Performance Summary Early NGS results, MK Profile Classical AO MCAO Guide star location

Baseline Program: Facility CP AOS: 

Baseline Program: Facility CP AOS CP AOS/LGS 10W LGS SOUTH 1999 2000 2001 2002 2003 2004 Subaru Keck VLT VLT-LGS Hokupa’a 36 85 2W LGS CP Hokupa’a 85 SOUTH Performance Mode %Sky3 SRJ(0’’) SRJ(48’’) FOV Hardware NGS 1% 0.55 0.04 30’’ 1 1DM LGS 17% 0.47 0.04 32’’ 1 1DM/1LGS MCAO 30% 0.54 0.35 2’ 2 3DM/5LGS 1 50% Strehl ratio attenuation 2 limited by the AO-Fold aperture 3 Sky coverage at galactic pole

ALFA AO Results(18 Modes, 0.9-1.0’’ seeing, K band): 

ALFA AO Results (18 Modes, 0.9-1.0’’ seeing, K band) NGS AO 0.42 Strehl 0.53 predicted Open loop Loop closed with LGS AO 4 W dye laser 0.23 Strehl FWHM dif-fraction limited.

What is multiconjugate?: 

What is multiconjugate? Telescope DM1 DM2 Turb. Layers #1 #2 Atmosphere WFS UP

Sample Numerical Results: 

Sample Numerical Results 0 degree zenith 50% seeing 12 by 12 NGS (black) 12 by 12 MCAO (red) 16 by 16 MCAO (blue) I, J, H, and K bands K H J I