Adaptive Optics at the Max Planck Institute for

Adaptive Optics at the Max Planck Institute for Astronomy September 1993 Trapezium with MAGIC and CHARM. M. Mc. Caughrean 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 Germany Adaptive Optics at MPIA, Heidelberg, 26 January 2001 1

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

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 3

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

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

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

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

The Principle of Adaptive Optics - Summary Turbulence Phase Distortions 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 8

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

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 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 10

The Earth’s Atmosphere - Parameters / 2 Isoplanatic angle (or patch): 0 = 0. 3 r 0 / heff 0 characterizes the field of view that a classical AO system can compensate. Greenwood time delay (Taylor approximation): t 0 = 0. 3 r 0 / veff Adaptive Optics at MPIA, Heidelberg, 26 January 2001 11

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

Measuring Cn 2(h) with SCIDAR Rocca et al. 1974, Tallon 1989, Avila et al. 1997 1 2 B**(x)= K(x, h+hgs) Cn 2(h) dh + N(x) Inversion hgs d 1 Autocorrelation 15 10 5 d 2 Avila et al. 1998 0 Scintillation Altitude above sea level (km) d 1= ( h + hgs ) Cn 2(h) d 2= hgs CN 2(h) ( m-2/3 ) h Adaptive Optics at MPIA, Heidelberg, 26 January 2001 13

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

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 ~ 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 15

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

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

Good IR-WFS target: S 106 ALFA in active optics mode! Resolution: 0. 35” m. V=21 m. K=5. 5 Adaptive Optics at MPIA, Heidelberg, 26 January 2001 18

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 ~ 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 19

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

VLT Laser Guide Star Facility ESO, MPE, MPIA Mission: give the ESO AO systems (NAOS+CONICA, SINFONI) on UT 4 an artificial laser guide star (LGS), to boost their sky coverage and science throughput. Present: LGS-AO is being implemented on all large ( 8 m) 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 21

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 22

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/cm 2) • Input beam matching and alignment critical, servoed Adaptive Optics at MPIA, Heidelberg, 26 January 2001 23

PARSEC Laser Choice Paranal Artificial Reference Source for Extended Coverage è Original ESO proposal was to combine two 6. 5 W CW laser modules. ESO Messenger No. 99, December 1999 è This concept (backup solution) is an ALFA modification tested at Calar Alto. ESO Messenger No. 100, July 2000 è ESO concept moved to backup solution. è MPE/MPIA propose new MOPA (Master Oscillator Power Amplifier) laser concept, better performing, more stable CW dye laser (October 2000). è MPE/MPIA PARSEC HAS BEEN ADOPTED AS BASELINE CHOICE >10 W CW output power (goal 15 W), solid state pump lasers. è MPIA contribution: 600 TDM, 2 man-years; return: 8 nights with LGS-AO instruments! Adaptive Optics at MPIA, Heidelberg, 26 January 2001 24

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

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 ~ 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 26

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 27

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 each single turbulent layer. Adaptive Optics at MPIA, Heidelberg, 26 January 2001 28

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 (Mc. Donald Observatory) • Swedish 50 -m Telescope (Lund Observatory) • 100 m OWL (ESO Overwhelmingly Large Telescope) èHigh angular resolution (V-band: 1. 4 mas). èHuge photon gathering capability (V~38). Adaptive Optics at MPIA, Heidelberg, 26 January 2001 29

0. 6 arcsec Resolution Comparison Adaptive Optics at MPIA, Heidelberg, 26 January 2001 30

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 31

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 32

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