2. Gemini AO Program October 21, 1999Gemini Science Committee1 The Gemini Adaptive Optics Program MCAO for Gemini-South Gemini Adaptive Optics Team B. Ellerbroek and F.Rigaut

3. Gemini AO Program October 21, 1999Gemini Science Committee2 Top Level Perf. 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 […]” enable unique NGST-class scienceThe 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.

4. Gemini AO Program October 21, 1999Gemini Science Committee3 AO and Science AO is a rather new domain... –First AO instrument for astro. -> Come-on, ESO 1990 –UH curvature system, Mauna Kea 1992 –1994-1998: Exponential progression of # of systems …but science is already flowing: –Number of Astro paper is growing exponentially –Total of 70+ refereed papers (lost count). Highlights: Discovery of an asteroid satellite, wrap of  Pic disk, Surface and orbital parameters of solar system bodies, YSO disks and outflows (e.g. HL and GG Tau), Stellar motions in GC, Stellar multiplicity surveys, Structure in AGNs, Galaxy dynamic (e.g. CFHT AOSIS), etc...

5. Gemini AO Program October 21, 1999Gemini Science Committee4 1989: First AO images w/ Come-On (OHP & ESO) 110mas A short history of astronomical AO 1992: First Curvature system (UH) 70mas 1996: First Facility system (CFHT AOB)

6. Gemini AO Program October 21, 1999Gemini Science Committee5 CFHT Pueo 1996 Galactic Center 2.2  m FWHM 130 mas

7. Gemini AO Program October 21, 1999Gemini Science Committee6 A short history of astronomical AO 1989: First AO images w/ Come-On (OHP & ESO) 110mas 1992: First Curvature system (UH) 70mas 1996: First Facility system (CFHT AOB) 1996: First compensation in the visible (Mt Wilson) 58mas 1996: First LGS systems 1998: LGS systems getting closing expectations 1999: First h.order system on a large telescope (Keck) 40mas

8. Gemini AO Program October 21, 1999Gemini Science Committee7 Keck AO System 1999 Vesta 1.5  m FWHM <40 mas 1’’

9. Gemini AO Program October 21, 1999Gemini Science Committee8 Gemini’s Dedication Courtesy C.Roddier, UH-IfA

10. Gemini AO Program October 21, 1999Gemini Science Committee9 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.

11. Gemini AO Program October 21, 1999Gemini Science Committee10 Where is AO standing ? AO technology for astronomy is maturing rapidly –Well designed and calibrated NGS AO systems (CFHT Pueo, Hokupa’a, MIT/Lincoln Laboratory, SOR) now closely approach their performance predictions. –Rayleigh beacon LGS AO programs (MIT/LL, SOR) have been technically successful –Astronomical sodium beacon LGS AO systems have progressed from Strehls of 0.03 to 0.30 in two years –Sodium layer variability has been well characterized by numerous LIDAR campaigns

12. Gemini AO Program October 21, 1999Gemini Science Committee11 Proposed Baseline AO Program NORTH SOUTH 199920002001200220032004 SubaruKeckVLTVLT-LGS CP AOS/LGS CP AOS/LGS Altair 10W LGS Hokupa’a3685 2W LGS CP Hokupa’a 85

13. Gemini AO Program October 21, 1999Gemini Science Committee12 Baseline Program: Altair CP AOS/LGS 10W LGS NORTH SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 Altair Progresses well (CDR 02/99) Statement of work for Altair LGS upgrade nearly ready

14. Gemini AO Program October 21, 1999Gemini Science Committee13 Baseline Program: 10W LGS CP AOS/LGS 10W LGS NORTH SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 10W LGS 10 W Laser RFP to go out early October Power requirements vary from 7 to 23W depending on laser pulse format Design of the LLT and BTO underway

15. Gemini AO Program October 21, 1999Gemini Science Committee14 Baseline Program: MK-Hokupa’a CP AOS/LGS 10W LGS NORTH SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85Hokupa’a3685 Hokupa’a-36 installed on the telescope early June this year Images fully compatible with expectations (seeing ok but not exceptional), near diffraction limit in K band w/ Strehl ~ 15-30%. Great tool for telescope engineering 85 Actuators upgrade to be done next year by UH team on UH/NSF internal funds. Small transferred field (30’’) Performance w/ NGS (AO only) (2 fold vs 36 actuators): SeeingStrehl(J)Strehl(K) 0.45’’ 50%80% 0.65’’25%62%

16. Gemini AO Program October 21, 1999Gemini Science Committee15 Cerro Pachon-AOS/LGS Forum April 1999, Review Panel Recommendations 1The IGPO should develop a strategy for its overall adaptive optics program which satisfies the Gemini community. Timing of the program, staff resources, and cost must be addressed. The RP also notes that the experience gained with the Altair AO and Hokupa'a teams are valuable to the overall program and should be folded into the planning. 2The Project should conduct a significant but time-limited study of a multiconjugate adaptive optics system for Cerro Pachon. This would provide an exciting advancement in capabilities but implementing the system should be conditional on "filling" the AO gap on Gemini-South and addressing the requirements of the coronagraphic imager. The study should address the theoretical analysis, science drivers, technical challenges, systems engineering, and programmatics of such an AO system. With the development of a plan, the RP recommends that Gemini adopt as aggressive a schedule as possible to bring this capability to the community. 3The IGPO should lead the conceptual design program of the Gemini-South AO system, including defining the allocation of subsystems across the Gemini Community 4In light of the proposals presented for turn-key laser systems, the RP recommends that the IGPO explore with LiteCycles the manufacture of a Sum Frequency laser. To reduce cost and risk for the laser, procurement through a consortium should be explored, including Keck, and possibly other groups if they can participate on timescales which are consistent with Gemini's schedule for laser deployment. 5The project should avoid relying on major technological developments such as MEMs, liquid crystals, and other 'advanced' DMs for the CP AOS

17. Gemini AO Program October 21, 1999Gemini Science Committee16 Baseline Program: CP-Hokupa’a CP AOS/LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH 2W LGS CP Hokupa’a 85 AO 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): SeeingStrehl(J)Strehl(K) 0.45’’ 50%80% 0.65’’25%62% LGS LGS: Off-the-shelf 2W CW laser. Coherent/Spectra physics CW 10W pump laser + ring dye laser (demonstrated in lab) IR Imager IR Imager: ABU

18. Gemini AO Program October 21, 1999Gemini Science Committee17 Baseline Program: CP-Hokupa’a CP AOS/LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH 2W LGS CP Hokupa’a 85 Rationale: unchallenged AO+LGS capability in the southern hemisphere 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

19. Gemini AO Program October 21, 1999Gemini Science Committee18 Baseline Program: Facility CP AOS CP AOS/LGS 10W LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH Context: Simplest case = duplicate Altair -> No AO facility until late 2002. Other observatories have very capable AOSs in the north (Keck 1999) and in the south (VLT-NAOS 2001) -> Competitiveness issue Rationale: (Why?) 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 CP AOS/LGS CP AOS/LGS

20. Gemini AO Program October 21, 1999Gemini Science Committee19 Baseline Program: Facility CP AOS CP AOS/LGS 10W LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH Proposal:(What?) Proposal: (What?) 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) CP AOS/LGS CP AOS/LGS

21. Gemini AO Program October 21, 1999Gemini Science Committee20 What is Tomography ? 1. Cone effect 90 km

22. Gemini AO Program October 21, 1999Gemini Science Committee21 What is tomography ? 2. Multiple guide star and tomography 90 km

23. Gemini AO Program October 21, 1999Gemini Science Committee22 What is multiconjugate?

24. Gemini AO Program October 21, 1999Gemini Science Committee23 What is multiconjugate?

25. Gemini AO Program October 21, 1999Gemini Science Committee24 What is multiconjugate? Telescope DM1 DM2 Turb. Layers #1 #2 Atmosphere WFS UP

26. Gemini AO Program October 21, 1999Gemini Science Committee25 Baseline Program: Facility CP AOS CP AOS/LGS 10W LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH What does MCAO do that another system wouldn’t ? 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 taken care of Increased field of view (well matched to IRMOS) Uniform PSF across the FoV -> Easier and more accurate Data Reduc. CP AOS/LGS CP AOS/LGS

27. Gemini AO Program October 21, 1999Gemini Science Committee26 Classical AOMCAO No AO 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

28. Gemini AO Program October 21, 1999Gemini Science Committee27 MCAO Performance Summary Early NGS results, MK Profile Classical AO MCAO Guide star location

29. Gemini AO Program October 21, 1999Gemini Science Committee28 Baseline Program: Facility CP AOS CP AOS/LGS 10W LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH Performance Mode %Sky 3 SR J (0’’) SR J (48’’)FOVHardware NGS 1% 0.55 0.0430’’ 1 1DM LGS 17% 0.47 0.0432’’ 1 1DM/1LGS MCAO 34% 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 CP AOS/LGS CP AOS/LGS

30. Gemini AO Program October 21, 1999Gemini Science Committee29 Baseline Program: Facility CP AOS CP AOS/LGS 10W LGS SOUTH 199920002001200220032004 SubaruKeck VLTVLT-LGS Hokupa’a 3685 2W LGS CP Hokupa’a 85 SOUTH Where are we? Feasibility study Feasibility study progressing, including: First pass on the science drivers Theoretical analysis of MCAO control/numerical simulations/Performance assessment A proof-of-concept optical and mechanical layout Assessment of the need in computing issues Management plan including schedule and resource needs CP AOS/LGS CP AOS/LGS

31. Gemini AO Program October 21, 1999Gemini Science Committee30 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 128 2 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

32. Gemini AO Program October 21, 1999Gemini Science Committee31 NGS, LGS, and Multi-conjugate AO System Characteristics Several dim natural stars One dim natural star One bright natural star Tip/tilt beacons Several laser stars One or more laser stars One bright natural star Higher-order wave-front beacons SeveralOne or moreOne Higher-order wave-front sensors SeveralOne Deformable mirrors MCAOLGS AONGS AO

33. Gemini AO Program October 21, 1999Gemini Science Committee32 NGS, LGS, and Multi-conjugate AO Performance Characteristics T/T guide star brightness (relaxed) TBD (new inverse problem) T/T guide star brightness (relaxed) Tilt anisoplanatism Cone effect Guide star brightness Common anisoplanatism Fundamental limits 1-2’ (Nearly uniform) 20-40” (Nonuniform) 20-40” (Nonuniform) Compensated field-of-view Further improved (~34% at galactic pole) Good (~17% at galactic pole, SR=0.6 in H) Poor (0.1-2%)Sky coverage MCAOLGS AONGS AO Sky coverage and field-of-view are for J, H, K bands with 0.5 arc second seeing

34. Gemini AO Program October 21, 1999Gemini Science Committee33 Analysis and Simulation Models Two approaches available for more detailed modeling of MCAO –Upgraded simulation –Statistical analysis based opon turbulence statistics, MCAO system parameters Both approaches treat laser- and natural guide stars, WFS/DM geometries, CP turbulence profiles –Analysis derives “optimal” wave front reconstructors –Simulation more efficient for standard least-squares approach Both approaches extendable to model WFS noise, servo lag, telescope/instrument aberrations –Simulation can potentially model wave optics effects in wave front sensors and the atmosphere

35. Gemini AO Program October 21, 1999Gemini Science Committee34 MCAO Parameters for Gemini-CP 4 or 5 laser guide stars –30 to 60” (48”) offset from optical axis –10 to 20 Watts CW equivalent power, 1.5 XDL 4 or 5 LGS wave front sensors –12 by 12 or 16 by 16 subapertures –80 by 80 to 128 by 128 pixels –5 to 10 read noise electrons, 500 to 1000 Hz sampling 2 or 3 deformable mirrors –13 or 17 actuators across beamprint –Conjugate ranges of 0, 4-4.5, 8-9 km 3-4 T/T or T/T/F natural guide stars, 1 T/T mirror (Parameters Used for Following Sample Results) (Parameters not Yet Modeled)

36. Gemini AO Program October 21, 1999Gemini Science Committee35 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

37. Gemini AO Program October 21, 1999Gemini Science Committee36 Sample Numerical Results Variation with Seeing and Zenith Angle 0 Degree Zenith45 Degree Zenith 12 by 12 NGS (black), 12 by 12 MCAO (red), and 16 by 16 MCAO (blue) I, J, H, and K spectral bands

38. Gemini AO Program October 21, 1999Gemini Science Committee37 Sample Results Slit Coupling Efficiency at 0 Degrees Zenith 16 by 16 MCAO, I, J, H, and K spectral bands Horizontal and vertical 0.1 arc second slits

39. Gemini AO Program October 21, 1999Gemini Science Committee38 Why Multiple Tip/Tilt NGS’s? –Consider a turbulence profile with a focus aberrations at two ranges (blue) –LGS measurements (yellow) cannot determine range of the aberration Tip/tilt information lost Equal focus measurement from each LGS, regardless of aberration range –Tip/tilt NGS measurements can determine range from the differential tilt between stars –Three tip/tilt NGS’s needed for all three quadratic modes –Alternate approaches: Rayleigh LGS’s, or a solution to the LGS tilt indeterminacy problem  r)=ar 2  r)=a(cr+d) 2 =ac 2 r 2 +2acdr+ad 2 ~ ac 2 r 2 After tilt removal

40. Gemini AO Program October 21, 1999Gemini Science Committee39 MCAO Sky Coverage with Multiple Tip/Tilt NGS Quantitative sky coverage calculations more complex than for conventional AO, but some initial estimates are possible –Only one NGS need be sufficiently bright for correction of high-bandwidth, wind-shake induced tip/tilt jitter –The atmospheric modes corrected by remaining reference stars are lower frequency, allowing lower control bandwidths and dimmer stars (e.g. 30Hz sampling rate) –Preliminary calculation for the galactic pole: LGS AO sky coverage for 60% Strehl in H: 17% MCAO coverage with 1 m=18 star and 2 m=20 stars within 1’ radius: 34%

41. Gemini AO Program October 21, 1999Gemini Science Committee40 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 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

42. Gemini AO Program October 21, 1999Gemini Science Committee41 MCAO Science Optical Path 3 DM’s at R=0, 4, and 8 km3 DM’s at R=0, 4, and 8 km 13 actuators across beamprint13 actuators across beamprint 4 folds, 2 off-axis parabolas,4 folds, 2 off-axis parabolas, 1 dichroic beamsplitter (not shown) 1 dichroic beamsplitter (not shown) - Near-minimum number of surfaces for - Near-minimum number of surfaces for facility MCAO facility MCAO f/30 output focus f/30 output focus

43. Gemini AO Program October 21, 1999Gemini Science Committee42 MCAO LGS Optical Path 4 LGS’s sensed with 1 WFS CCD ZEMAX optical schematic Outgoing: Single launch telescope for all guide stars Return: One WFS camera for all guide stars

44. Gemini AO Program October 21, 1999Gemini Science Committee43 WFS Camera Options Supports 5 LGS, 16 by 16 SA 1000+6-10128 by 128 MIT/LL CCD 1-2 Cameras for 4-5 LGS, 12 by 12 SA 1000580 by 80 EEV CCD 500- 1000 5-10 80 by 80 to 128 by 128 Requirement Comments Frame rate, Hz Read noise electrons Pixels MIT/LL read noise level is new information since feasibility study

45. Gemini AO Program October 21, 1999Gemini Science Committee44 Approach to Multiple Tip/Tilt NGS WFS’s X stage Y stage 200mm To APDs X stage Focal plane Fiber-fed APD quadrant detectors 2 or 3 T/T WFS’s in AO instrument package One additional T/T/F WFS in each facility instrument, for a total of 3-4 sensors

46. Gemini AO Program October 21, 1999Gemini Science Committee45 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)

47. Gemini AO Program October 21, 1999Gemini Science Committee46 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

48. Gemini AO Program October 21, 1999Gemini Science Committee47 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. Outsourcing of work expected after CoDR.