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MULTIPLE OBJECT ADAPTIVE OPTICS

MULTIPLE OBJECT ADAPTIVE OPTICS. Mixed NGS/LGS Tomography Tim Morris (Durham University, UK) and

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MULTIPLE OBJECT ADAPTIVE OPTICS

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  1. MULTIPLE OBJECT ADAPTIVE OPTICS Mixed NGS/LGS Tomography Tim Morris (Durham University, UK) and Eric Gendron, Alastair Basden, Olivier Martin, David Henry, Zoltan Hubert, Gaetano Sivo, Damien Gratadour, Fanny Chemla, Arnaud Sevin, Matthieu Cohen, Eddy Younger, Fabrice Vidal, James Osborn, Richard Wilson, Tim Butterley, Urban Bitenc, Dani Guzman, Javier de Cos Juez, Andrew Reeves, NazimBharmal, Henri-Francois Raynaud, Caroline Kulcsar, Jean-Marc Conan, Jean-Michel Huet, Denis Perret, Colin Dickson, David Atkinson, Tom Baillie, Andy Longmore, Stephen Todd, David Anderson, Colin Bradley, Olivier Lardiere, Gordon Talbot, Simon Morris, Richard Myers and Gerard Rousset

  2. Overview • MOAO instrumentation • CANARY Status • CANARY Results • SCAO, GLAO, MOAO, LTAO • Bench and on-sky • CANARY development

  3. MOAO instrumentation • First on-sky open-loop AO systems used on-axis guide star to control a single on-axis DM • ViLLaGeS1 and VOLT2 demonstrated open-loop AO on-sky in 2007 & 2008 respectively • Proved that open-loop control of AO systems was feasible • Laboratory test benches were developed that were capable of investigating wavefront tomography and control • UCO/LAO tomographic AO testbench3at UCSC • SESAME at the Observatoire de Paris • Combining open-loop control with wavefront tomography gave rise to instrument concepts such as FALCON and EAGLE • Gavel et al, Proc. SPIE Vol. 6888, p688804 (2008) • Andersen et al, Proc. SPIE Vol. 7015, p70150H (2008) Ammons et al, Proc. SPIE Vol. 6272, p627202 (2006)

  4. RAVEN • RAVEN is a 2-channel MOAO system being built for the Subaru telescope. • Feeds existing slit-based spectrograph • Uses 3 off-axis NGS within a 3.5’ FOV • 15th magnitude NGS goal • Can also use Subaru’s on-axis sodium LGS • First light planned for May 2014

  5. RAVEN • Currently assembled in the UVic AO lab and undergoing initial laboratory AO testing • SCAO > MOAO > GLAO • For more information see posters by: • Olivier Lardière (RAVEN status) • Kate Jackson (RAVEN tomography) Science camera images (l=1.0-1.7mm) after 1s of turbulence history. NGS asterism radius = 40 arcsec.

  6. CANARY • An open-loop tomographic AO demonstrator on the 4.2m William Herschel Telescope in La Palma • Split into 3 phases of increasing complexity • Phase A: NGS-only open-loop tomographic AO (2008-2010) • Phase B: Mixed NGS and LGS open-loop tomographic AO (2010-2013) • B1: Single LGS • B2: Multiple LGS • Phase C: Mixed NGS and LGS open-loop tomographic AO with a closed-loop GLAO/LTAO DM (2014+) 3’ derotated technical field of view 3 off-axis open-loop NGS up to Mv ~ 11-12 On-axis corrected science/verification path

  7. CANARY so far... • Phase A (NGS only) completed 2010 • Seeing-limited (NoAO) (SR=1%) • GLAO (SR=9%) • MOAO (SR=19.4%) • SCAO (SR=23.8%) Asterism 47 and Phase A AO performance at 1.53μm • Phase B1 (3 NGS + 1 LGS) commissioned June 2012 • Almost identical to RAVEN configuration (except on a 4m telescope with a Rayleigh LGS) • Phase B2 (3 NGS + 4 LGS) first on-sky commissioning run finished yesterday morning

  8. CANARY Phase B1 • Single LGS that could be positioned anywhere within a ~1’ FOV • In practice, LGS remained on-axis • LGS altitude was fixed at 13.5km • Provided photon return ‘safety margin’ 13.5km distant LGS WFS image 750m range gate ~4” per subaperture

  9. CANARY Phase B2: 4LGS WFS Pyramid Field Stop Acquisition camera Lenslet LGS WFS • 3 nights on-sky with the Phase B2 system from 23rd to 25th May • 6 nights scheduled in July • New for Phase B2: 4LGS WFS • 128 x 128 pixel camera from MIT-LL/Scimeasure • >1000:1 contrast ratio integrated shutter • Pyramid-based asterism selection • 21km central LGS focal distance • 23” radius asterism • 1.5km range gate depth • 1.2” elongation

  10. Rayleigh Fratricide • Laser outputs more light at pulse rates > 10kHz • Minimum laser pulse rate defines maximum altitude • 10kHz allows a maximum LGS focal distance of 15000m • Optical system defines what altitudes can be observed

  11. CANARY Phase B2: Profiling • New Stereo-SCIDAR turbulence profiler in addition to SLODAR and CANARY WFSs • See talk by James Osborn on Wednesday 15:20 SLODAR @ Pt5M SCIDAR @ JKT CANARY @ WHT

  12. Profiling • Stereo-SCIDAR • High vertical resolution • ~200m (at altitudes >0km) • Wind velocities • CANARY Open-loop WFSs • Up to 4 NGS and LGS for multi-baseline SLODAR profiling • Takes telescope time • SLODAR • Up to ~6km using existing binary targets • Total turbulence strength • Monitoring Altitude (m) Relative turbulence strength (%)

  13. CANARY results • Comprehensive analysis of Phase A/B results will be presented in this afternoon’s talk by Olivier Martin (@ 1700) • Results of the LQG on-sky reconstructor are going to be presented by Gaetano Sivo on Friday • Here we present initial results from the Phase B2 run CANARY Phase B2 system at the WHT Nasmyth platform

  14. NGS & LGS MOAO 29.8” 56.6” Altitude (m) • Three star test asterism (Ast T1) • RA: 13 41 38.2, Dec: +07 36 21 • Mb= 10.4, 11, 11.1 • 3-layer tomographic reconstructor fitted • NIR PSFs recorded at 1530nm 22.8” Relative turbulence strength (%) GLAO SCAO NGS + LGS MOAO SR = 21.5% SR = 9.9% SR = 15.2%

  15. NGS & LGS MOAO Results from single dataset taken switching between SCAO, combined NGS & LGS tomography and combined NGS & LGS GLAO SCAO MOAO (4 LGS + 2 NGS) Strehl Ratio at 1.53μm GLAO (4 LGS + 2 NGS) Hour (UT)

  16. NGS & LGS MOAO • A few caveats: • CANARY is a low-order 7x7 system • High frequency errors in the DM surface leave us with a large residual static error • A few obvious points: • SCAO > MOAO > GLAO • GLAO still pretty good! • A few less obvious points: • CANARY data has shown WHT performance dominated by GL turbulence • Quasi-static error term affecting MOAO results • This term is difficult to calibrate and is partially due to varying field aberrations caused by the derotator Strehl Ratio at 1.53μm Atmospheric r0 (m)

  17. Asterism 32 Open-loop LTAO • CANARY LGS asterism diameter has been selected to optimise on-axis performance • Optimal performance is found when LGS are positioned at ~ 1 pupil diameter at altitude • No fundamental difference between CANARY 4 LGS MOAO configuration and optimal LTAO configuration • Open-loop operation vs. Pseudo open-loop 2 Tip-Tilt, 4 LGS LTAO SCAO SR = 21.6% SR = 14.7%

  18. On-sky tomography testing • Have on-sky data for a wide variety of tomographic configurations: • SCAO • Mixed NGS and LGS MOAO • 0 & 4 LGS, 1-3 NGS stars • LGS-only MOAO (Open-loop LTAO) • 4 LGS, 1-3 TT stars • Mixed NGS and LGS GLAO (open-loop) • 4 LGS, 1-3 NGS stars • LGS only GLAO (open-loop) • 4 LGS, 1-3 TT stars • Have taken corrected datasets for both minimum variance and LQG reconstructors for most of these • Bench validation using the CANARY telescope simulator is the first step

  19. Bench tomography testing • Turbulence generatedusingtelescopesimulator, • 2 layersat 0 and 5200m • 70% atground, 30% alt. • r0 = 11 cm, L0≈12 m • Windspeed≈ 6m/s • NGS configured to simulateCANARY asterism A47 NGS1 -43.4 20.4 NGS2 47.3 21.4 NGS3 28.3 -28.8 • Square LGS asterism • 21.6’’ off-axis • Altitude 17000m

  20. 4LGS+2NGS 4LGS+2TT 4LGS+3TT SCAO 4LGS+3NGS 3LGS + 3NGS 3NGS 4LGS+1TT 1LGS+3NGS 4LGS+1NGS Strehl Ratio at 1.55μm GLAO 4LGS+3NGS 2LGS+3NGS Hour (UT)

  21. CANARY: A Flexible Testbench • CANARY doesn’t only demonstrate MOAO! • Reconfigurable optical layout allows many other tests • New WFSs • LGS WFSing with controlled elongation • Linux-based RTCS has been readily adapted as the project has progressed • Many new centroiding techniques • New reconstructors • Several talks/presentations this week about techniques developed and tested/to-be tested on-sky using CANARY

  22. Tomography with Artificial Neural Networks • Using machine learning to generate a robust tomographic reconstructor • Advantages: • Includes non-linear effects difficult to model • Single reconstructor optimal for all turbulence profiles • Disadvantages: • Requires a large amount of training data • Training process can take a long time for large systems • For CANARY: L&A: 1minute, ANN: 10 minutes • Valid only for a given asterism • Good for LGS systems!

  23. ANN Tomography • Trained an ANN reconstructor using CANARY bench measurements • Compared to L&A reconstructor trained on a 2-layer atmosphere (0km and 2.8km) • Reconstructed on-axis WFS slopes whilst changing conjugate altitude of high layer WFS x 3

  24. CANARY future • Phase C1: LTAO (on-sky May/July 2014) • Design review next week • Reorganisation of the bench to place WFSs behind DM • Additional figure sensor for pseudo open-loop operation • Phase C2: E-ELT configuration MOAO (on-sky 2015) • Closed-loop GLAO DM (existing low-order DM) • Open-loop MOAO DM (high-order DM) • High order figure sensor • High order LGS WFSs

  25. Photon return • Defines optimal LTAO error at Phase C1 • Defines how many subapertures we can use at Phase C2 • LGS photon return measured at Phase B1 on a single LGS • Varying RGD makes this easy! • Projected to 4 LGS Phase C1/2

  26. Beyond Phase C • Funding has been secured for further on-sky investigations with CANARY: • Focal plane NIR WFSing • E-ELT scale LGS elongation WFS study • Several ideas have been proposed for later phases: • Open-loop MCAO demonstration • LGS uplink tomography for tip-tilt determination • Additional technology demonstrations planned: • On-sky demonstration of AO-coupled integrated photonic spectrograph • Always open to new collaborations that will benefit from an on-sky test…

  27. Conclusions • CANARY is now almost in its final configuration with a world record (?) 8 full frame rate, high-order wavefront sensors • We have demonstrated mixed NGS and LGS open-loop tomography on-sky • Additional results this afternoon! • LGS MOAO works and can provide much better performance than LGS GLAO • Closed-loop LTAO and high-order MOAO on-sky in 2014/15 repsectively

  28. System Growth • CANARY complexity has increased since initial testing phase in early 2009 • Currently have 8 WFS’s , 25 reference sources and 288 WFS subapertures Number of WFS subapertures Number of WFSs CANARY: ELT-ready by 2019 Number of reference sources

  29. The CANARY team • The CANARY project is supported via the following funding bodies • STFC, UK E-ELT Design Study • EU FP7 Preparatory fund WP9000 • ANR Maui, INSU, Observatoire de Paris • FP7 OPTICON JRA1 CANARY: NGS/LGS MOAO demonstrator

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