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Adaptive Optics at the Max Planck Institute for Astronomy

Adaptive Optics at the Max Planck Institute for Astronomy. September 1993 Trapezium with MAGIC and CHARM. M. McCaughrean and J.R. Stauffer, AJ 108 (1994). Stefan Hippler Markus Feldt Robert Weiß Elena Puga Antolin David Butler Max-Planck- Institut für Astronomie (MPIA) Heidelberg

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Adaptive Optics at the Max Planck Institute for Astronomy

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  1. Adaptive Optics at theMax Planck Institute for Astronomy September 1993 Trapezium with MAGIC and CHARM. M. McCaughrean and J.R. Stauffer, AJ 108 (1994). Stefan HipplerMarkus Feldt Robert Weiß Elena Puga Antolin David Butler Max-Planck- Institut für Astronomie (MPIA) Heidelberg Germany Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  2. Outline of this talk • The principle of Adaptive Optics. • The Earth’s atmosphere. • Current restrictions of Adaptive Optics systems. • New techniques, new ideas. • MPIA’s future contributions. • What’s next. Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  3. The Principle of Adaptive Optics - Basics Plane wavefront Turbulent atmosphere Distorted image Plane wavefront Turbulent atmosphere Deformable mirror compensates the atmosphere “Perfect” image Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  4. The Principle of Adaptive Optics - Example • Closed Loop Open Loop Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  5. The Principle of Adaptive Optics - Sketch Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  6. The Principle of Adaptive Optics - ALFA Bench Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  7. The Principle of Adaptive Optics -ALFA/OMEGA Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  8. The Principle of Adaptive Optics - Summary Turbulence Phase Distortions. Phase Distortions Blurring Blurring Telescope Resolution Order Of Magnitude Worse ... The goal of Adaptive Optics is to overcome these limitations! Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  9. The Earth’s Atmosphere - Structure Kolmogorov law of turbulence: Dn: Index Structure Function Cn2: Index Structure Coefficient n: refractive indexr: 3D position: 3D separation<...>: ensemble average Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  10. The Earth’s Atmosphere - Parameters / 1 Fried parameter r0 characterizes the Seeing at a particular wavelength: Seeing ~ FWHM ~ / r0 Seeing in V-band (550 nm) = 1’’ -> r0 = 8.8 cm r0 scales with the 6/5 power of wavelength -> r0 at 2.2m = 46 cm -> Seeing in K-band = 0.76’’ (Seeing scales with the 1/5 power of wavelength) r0 scales with the -3/5 power of airmass (D/ r0)2defines the number of sub-apertures for wavefront sensors Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  11. The Earth’s Atmosphere - Parameters / 2 Isoplanatic angle (or patch): 0 = 0.3 r0 / heff 0 characterizes the field of view that a classical AO system can compensate. Greenwood time delay (Taylor approximation):t0 = 0.3 r0 / veff Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  12. The Earth’s Atmosphere - Parameters / 2 Calar Alto SCIDAR campaign September 2000 Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  13. B**(x)= K(x, h+hgs)Cn2(h) dh + N(x) 2 Inversion Cn2(h) d2= hgs Avila et al. 1998 15 10 CN2(h) ( m-2/3 ) Altitude above sea level (km) d2 5 Autocorrelation d1 0 Measuring Cn2(h) withSCIDAR  Rocca et al. 1974, Tallon 1989, Avila et al. 1997 1 h hgs d1= (h + hgs) Scintillation

  14. The MPIA-LBTSCIDAR Project • AO Science Data • Processing • Seeing Measurements • Atmosphere Diagnostics • Flexible Scheduling • In-kind contribution, 100 TDM. Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  15. Current restrictions of AO systems: Sky coverage • Requirement:brightguide star within isoplanatic angle. • Example: ALFA‘s current limit: mV=14.5 (20´´) => Sky coverage ~ 0.01 • Solutions: • Infrared Wavefront Sensor (Infrared AO!) • Sky coverage ~ 0.2-0.6 for embedded galactic sources, Star Formation Research! • Artificial guide star • Sky coverage ~ 1.0(without tip-tilt and focus compensation!) • Multi-conjugate (multi layer) AO Sky coverage depends on telescope size, isoplanatic angle up to 3’ Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  16. Pyramid Wavefront Sensor - Sketch Foucault-like Wavefront Sensor Ragazzoni et al. 1995 MPIA: replace CCD by near-infrared detector Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  17. Pyramid Wavefront Sensor - Demo Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  18. Good IR-WFS target: S106 ALFA in active optics mode! Resolution: 0.35” mV=21 mK=5.5 Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  19. Current restrictions of AO systems: Sky coverage • Requirement:brightguide star within isoplanatic angle. • Example: ALFA‘s current limit: mV=14.5 (20´´) => Sky coverage ~ 0.01 • Solutions: • Infrared Wavefront Sensor (Infrared AO!) • Sky coverage ~ 0.2-0.6 for embedded galactic sources, Star Formation Research! • Artificial guide star • Sky coverage ~ 1.0(without tip-tilt and focus compensation!) • Multi-conjugate (multi layer) AO Sky coverage depends on telescope size, isoplanatic angle up to 3’ Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  20. VLT LGSF Overview Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  21. VLT Laser Guide Star FacilityESO, MPE, MPIA • Mission: give the ESO AO systems (NAOS+CONICA, SINFONI) on UT4 an artificial laser guide star (LGS), to boost their sky coverage and science throughput. • Present: LGS-AO is being implemented on all large (8m) telescopes. Keck II is likely to be the first one this year. Gemini, LBT, Subaru to follow. 40% K-Strehl demonstrated at Lick Obs., 20% K-Strehl demonstrated with ALFA. • Future:Multiple LGS: promise “full” sky coverage through Turbulence Tomography Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  22. LGSF on the VLT:Quick Look • 4 subsystems: • Laser and Laser Room • Beam relay (fiber modules) • Launch Telescope + diagnostics • LIDAR Facility(=ALFA/LIDAR) Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  23. Laser Beam Relay using a single mode fiber module • Allows diffraction limited beam relay • Flexible, compact, better than mirrors • Non linear effects due to high power densities (up to 25 MW/cm2) • Input beam matching and alignment critical, servoed Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  24. PARSEC Laser Choice Paranal Artificial Reference Source for Extended Coverage • Original ESO proposal was to combine two 6.5W CW laser modules. ESO Messenger No. 99, December 1999 • This concept (backup solution) is an ALFA modification tested at Calar Alto. ESO Messenger No. 100, July 2000 • ESO concept moved to backup solution. • MPE/MPIA propose new MOPA (Master Oscillator Power Amplifier) laser concept, better performing, more stable CW dye laser (October 2000). • MPE/MPIA PARSEC HAS BEEN ADOPTED AS BASELINE CHOICE >10W CW output power (goal 15 W), solid state pump lasers. • MPIA contribution: 600 TDM, 2 man-years; return: 8 nights with LGS-AO instruments! Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  25. PARSEC - Sketch Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  26. Current restrictions of AO systems: Sky coverage • Requirement:brightguide star within isoplanatic angle. • Example: ALFA‘s current limit: mV=14.5 (20´´) => Sky coverage ~ 0.01 • Solutions: • Infrared Wavefront Sensor (Infrared AO!) • Sky coverage ~ 0.2-0.6 for embedded galactic sources, Star Formation Research! • Artificial guide star • Sky coverage ~ 1.0(without tip-tilt and focus compensation!) • Multi-conjugate (multi layer) AO Sky coverage depends on telescope size, isoplanatic angle up to 3’ Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  27. Current restrictions of AO systems: Compensated Field of View Wish Make Compensated Field of View infinite (get rid of the atmosphere!) Solution Increasing of the isoplanatic angle with Multi-conjugate adaptive optics = Atmospheric Tomography. Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  28. Atmospheric Tomography Ragazzoni et al., Nature 403, 2000 Configuration Pupil images Calculated wavefront map of central star and difference of ref. stars to central star The intensity distribution on each individual defocused pupil is given by a linear combination of the wavefront perturbation contributions of eachsingle turbulent layer. Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  29. AO for ELTs Research and Training Network • Extremely Large Telescope (ELT) Projects: • 30 m CELT (California ELT) • the 30-50 m MAXAT (MAXimum Aperture Telescope) • the 30-m ELT (McDonald Observatory) • Swedish 50-m Telescope (Lund Observatory) • 100 m OWL (ESO Overwhelmingly Large Telescope) • High angular resolution (V-band: 1.4 mas). • Huge photon gathering capability (V~38). Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  30. Resolution Comparison 0.6 arcsec Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  31. MPIA’s role in the AO-ELT network • Primary goal: • investigate Natural Guide Star (NGS) and Laser Guide Star (LGS) tomography methods coupled with multi-conjugate AO. • Technology: • deformable mirrors (DM) with about 500000 actuators, e.g. MEMS micro mirrors. • cophasing of 1000-2000 mirrors with accuracy compatible with AO in the visible. Study of novel techniques of on-sky segment phasing using AO wavefront sensors to minimize the loss of telescope time. • MPIA contribution and funding from EU commission: • Man-power and infrastructure from MPIA, 340 TDM from EU (2 postdocs).Turbulence simulator with ferroelectric LCD spatial light modulator. Simulations to find “best” MCAO configuration for ELTs. • Side project: • MCAO-demonstrator for the VLT. Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  32. Members of the AO-ELT network • European Southern Observatory (ESO), Germany (N. Hubin) • Osservatorio Astrofisico di Arcetri (OAA), Italy (S. Esposito) • Osservatorio Astronomico di Padova (OADP), Italy (R. Ragazzoni) • Office National d’Etudes et de Recherches Aerospatiales (ONERA), France (G. Rousset) • MPIA (S. Hippler) • Observatoire de Marseille (OM), France (M. Ferrari) • Gran Telescopio Canarias (GRANTECAN), Spain (N. Devaney) • Associated partner:Lund Observatoy Sweden • Total Network Budget from EU commission: 1.4 M€. Adaptive Optics at MPIA, Heidelberg, 26 January 2001

  33. What’s next? Adaptive Optics at MPIA, Heidelberg, 26 January 2001

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