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

2 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 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.

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

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

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

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

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

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

9 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 The Earth’s Atmosphere - Structure D n : Index Structure Function C n 2 : Index Structure Coefficient Kolmogorov law of turbulence: n: refractive index r: 3D position  : 3D separation : ensemble average

10 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 The Earth’s Atmosphere - Parameters / 1 Fried parameter r 0 characterizes the Seeing at a particular wavelength: Seeing ~ FWHM ~ / r 0 Seeing in V-band (550 nm) = 1’’ -> r 0 = 8.8 cm r 0 scales with the 6/5 power of wavelength -> r 0 at 2.2  m = 46 cm -> Seeing in K-band = 0.76’’ (Seeing scales with the 1/5 power of wavelength) r 0 scales with the -3/5 power of airmass (D/ r 0 ) 2 defines the number of sub-apertures for wavefront sensors

11 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 The Earth’s Atmosphere - Parameters / 2 Isoplanatic angle (or patch):  0 = 0.3 r 0 / h eff  0 characterizes the field of view that a classical AO system can compensate. Greenwood time delay (Taylor approximation): t 0 = 0.3 r 0 / v eff

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

 h d 1 =  ( h + h gs ) h gs 1 Scintillation Measuring C n 2 (h) with SCIDAR d 2 =  h gs 2 Autocorrelation d 2 d 1 B ** (x) =  K ( x, h+h gs ) C n 2 (h) dh + N(x) Rocca et al. 1974, Tallon 1989, Avila et al Inversion Cn2(h)Cn2(h) C N 2 (h) ( m -2/3 ) Altitude above sea level (km) Avila et al. 1998

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

15 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 Current restrictions of AO systems: Sky coverage Requirement: bright guide star within isoplanatic angle. Example: ALFA‘s current limit: m V =14.5 (20´´) => Sky coverage ~ 0.01 Solutions: Infrared Wavefront Sensor (Infrared AO!) Sky coverage ~ 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’

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

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

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

19 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 Current restrictions of AO systems: Sky coverage Requirement: bright guide star within isoplanatic angle. Example: ALFA‘s current limit: m V =14.5 (20´´) => Sky coverage ~ 0.01 Solutions: Infrared Wavefront Sensor (Infrared AO!) Sky coverage ~ 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’

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

21 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 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 VLT Laser Guide Star Facility ESO, MPE, MPIA

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

23 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 Allows diffraction limited beam relay Flexible, compact, better than mirrors Non linear effects due to high power densities (up to 25 MW/cm 2 ) Input beam matching and alignment critical, servoed Laser Beam Relay using a single mode fiber module

24 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 PARSEC Laser Choice P aranal A rtificial R eference S ource for E xtended C overage  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!

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

26 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 Current restrictions of AO systems: Sky coverage Requirement: bright guide star within isoplanatic angle. Example: ALFA‘s current limit: m V =14.5 (20´´) => Sky coverage ~ 0.01 Solutions: Infrared Wavefront Sensor (Infrared AO!) Sky coverage ~ 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’

27 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 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.

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

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

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

31 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 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 actuators, e.g. MEMS micro mirrors. cophasing of 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. MPIA’s role in the AO-ELT network

32 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 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€. Members of the AO-ELT network

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