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GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer Adaptive Optics, N. HubinGround Layer Adaptive Optics, N. Hubin
Ground Layer Adaptive OpticsGround Layer Adaptive OpticsStatus and strategy at ESOStatus and strategy at ESO
Norbert HubinNorbert HubinEuropean Southern ObservatoryEuropean Southern Observatory
With contributions from:With contributions from:R. Conzelman, B. Delabre, M. Le Louarn, S. R. Conzelman, B. Delabre, M. Le Louarn, S.
Stroebele, R. Stuik, E. VernetStroebele, R. Stuik, E. Vernet
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
SCOPESCOPE
Is there a Ground Layer Adaptive Optics?Is there a Ground Layer Adaptive Optics? FAQ about GLAO and astronomical interestFAQ about GLAO and astronomical interest VLT GLAOs: GALACSI and GRAAL projectsVLT GLAOs: GALACSI and GRAAL projects Adaptive secondary: an essential element of GLAOAdaptive secondary: an essential element of GLAO Laser requirements, R&D status and issuesLaser requirements, R&D status and issues Optimization, calibration and testing of GLAOOptimization, calibration and testing of GLAO Minimizing telescope down time during GLAO-DSM Minimizing telescope down time during GLAO-DSM
commissioning?commissioning?
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
WHAT IS GROUND LAYER AO?WHAT IS GROUND LAYER AO?
WFSs
Reference Stars
Telescope
High Altitude Layer
Ground Layer
DM conjugatedTelescope pupil Real Time Computer
Averaged WF..Ground Layer
AltitudeLayers
Laserbeams
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. HubinEx: 50% of the time there is 55% OR LESS turbulence in the 1st 500mMore measurements are being carried out (M. Sarazin)
Does a ground layer exist?Does a ground layer exist?
PARANAL OBSERVATORY
Courtesy: M. Sarazin
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Turbulence Profile and ground layerTurbulence Profile and ground layer
Mauna Kea, October 22/23, 2002: G-scidarMauna Kea, October 22/23, 2002: G-scidar
0km
5km
10km
15km
Data: J.Vernin, A.Ziad
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Turbulence profile investigation toolsTurbulence profile investigation tools
Courtesy: M. Sarazin
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Turbulence Profile and ground layerTurbulence Profile and ground layer
CERRO TOLOLO OBSERVATORY
Courtesy: M. SarazinR. Wilson
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Turbulence Profile and ground layerTurbulence Profile and ground layer
CERRO TOLOLO OBSERVATORY
Courtesy: M. Sarazin
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Investigation of Ground layer at ParanalInvestigation of Ground layer at Paranal
Multi Aperture Scintillation Sensor MASS + DIMM: Cn2 profileMulti Aperture Scintillation Sensor MASS + DIMM: Cn2 profile SLODAR: Slope Detection and ranging: Higher resolution of SLODAR: Slope Detection and ranging: Higher resolution of
ground layerground layer
Courtesy: R. Wilson
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO as seeing reducer?GLAO as seeing reducer?
VIS TT NGSAcquisition FoV
7.5 arc-minutes
13,2 arc-minutes
15,2 arc-minutes
VIS TTNGS
LGS
LGS LGS
LGS
IR TTNGS
Pupil Rotation
Field Rotation
7.8 arc-minutes
Improved seeing, Sr(K) ~ 4% 8’ FOV
Seeing PSF on-axis PSF off-axis
Seeing reducer
Reduced exposure & Telescope time
Better light concentration
Reduced confusion in Stellar populations & Cluster fields
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO as seeing reducer? VLT-GRAALGLAO as seeing reducer? VLT-GRAAL
K Band, gain: 100% FWHM
Y Band,Gain: 30%
Seeing
With AO
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO improves Ensquared Energy? VLT GRAALGLAO improves Ensquared Energy? VLT GRAAL
Y Band,gain: 50%
K Band, EE doubled
With AO
Seeing
Pixel: 0.1”
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO reduces confusion?: VLT GRAALGLAO reduces confusion?: VLT GRAAL
K Band, gain: 40%
Y Band,Gain: 30%
Seeing
With AO
Yes but more difficult!
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO and full sky coverage?GLAO and full sky coverage?
Need Laser artificial stars for WFS tomography because of:Need Laser artificial stars for WFS tomography because of: Median to bad seeing conditions assumptionsMedian to bad seeing conditions assumptions Science performed down to short Science performed down to short λλ
Require Natural Guide Star for Tip-tilt correctionRequire Natural Guide Star for Tip-tilt correction
Tip-tilt limiting magnitude (R-Band)Probability for (top to bottom) 1,2,3 TT NGS
In 1arcmin annular FOV
Tip-tilt limiting magnitude (R-Band)Probability for (top to bottom) 1,2,3 TT NGS
In 2 arcmin annular FOV
1 VIS NGS
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO in the visible?: VLT GALACSIGLAO in the visible?: VLT GALACSI
@750nm; FOV=1’
GLAO
Seeing
Science 1’ FOV
4’ FOV
4 Sodium LGSsØ120”
Faint vis. TT-NGS
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO: useful for most astronomical programsGLAO: useful for most astronomical programs
Ground Layer Adaptive Optics = Seeing reducerGround Layer Adaptive Optics = Seeing reducer Reduced Seeing => reduced exposure & telescope timesReduced Seeing => reduced exposure & telescope times Reduced seeing => Reduced confusion in Stellar Reduced seeing => Reduced confusion in Stellar
populations & Cluster fieldspopulations & Cluster fields Ground Layer Adaptive Optics = Seeing “stabilizer”Ground Layer Adaptive Optics = Seeing “stabilizer” Seeing stabilizer => better percentile seeing for your site!Seeing stabilizer => better percentile seeing for your site! Seeing reducer is “easily” achievable at all Seeing reducer is “easily” achievable at all λλss (down to vis.) (down to vis.) High Sky coverage GLAO systems will benefit most High Sky coverage GLAO systems will benefit most
astronomical programsastronomical programs Seeing reducer = light concentration: Sufficient for distant Seeing reducer = light concentration: Sufficient for distant
(“small”) galaxies with low surface brightness (0.2-0.1” (“small”) galaxies with low surface brightness (0.2-0.1” pixel enough)pixel enough)
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
VLT GLAO Top Level RequirementsVLT GLAO Top Level Requirements
GALACSI: VLT-GLAO for a Visible 3D Spectro (MUSE):GALACSI: VLT-GLAO for a Visible 3D Spectro (MUSE): Very deep exposures (80 h) =>NGSs in Scientific FOV forbidden !Very deep exposures (80 h) =>NGSs in Scientific FOV forbidden ! Statistically BAD seeing (1.1’’)Statistically BAD seeing (1.1’’) High sky coverage requiredHigh sky coverage required Provide factor 2 EE improvement (0.2”) over 1’ FOV in [450-930]Provide factor 2 EE improvement (0.2”) over 1’ FOV in [450-930] Diffraction limited @ 750 nm over ~10’’ FOV=> Diffraction limited @ 750 nm over ~10’’ FOV=> LTAO!LTAO!
GRAAL: VLT-GLAO for an NIR Imager (HAWK-I)GRAAL: VLT-GLAO for an NIR Imager (HAWK-I) reduce by 15-30 % in Y-Ks bands the diameter collecting 50% of reduce by 15-30 % in Y-Ks bands the diameter collecting 50% of
the encircled energy (for seeing 1”) over 8’ FOVthe encircled energy (for seeing 1”) over 8’ FOV
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GALACSI: Baseline conceptGALACSI: Baseline concept
Wavefront tomography using 4 sodium LGSsWavefront tomography using 4 sodium LGSs Four 32x32 subapertures Shack Hartmann WFSFour 32x32 subapertures Shack Hartmann WFS Ground layer correction: one Deformable MirrorGround layer correction: one Deformable Mirror Sodium notch filter to block the laser Rayleigh lightSodium notch filter to block the laser Rayleigh light Off-axis visible tip-tilt NGS for Wide Field ModeOff-axis visible tip-tilt NGS for Wide Field Mode On-axis NIR tip-tilt NGS for Narrow Field ModeOn-axis NIR tip-tilt NGS for Narrow Field Mode
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GALACSI Narrow Field ModeGALACSI Narrow Field ModeSr(R)~10%Sr(R)~10%
4 Sodium LGSsØ30”
Faint NIR TT-NGSScience
7.5”FOV
GALACSI Wide Field ModeGALACSI Wide Field ModeEEx2 in 0.2”EEx2 in 0.2”
Science 1’ FOV
4’ FOV
4 Sodium LGSsØ120”
Faint vis. TT-NGS
From GLAO to LTAO: Laser Tomography AOFrom GLAO to LTAO: Laser Tomography AO
LTAO essentially correct for Laser cone effect within small FOV
LYON, January 18/19th 2005LYON, January 18/19th 2005
EuropeanSouthernObservatory
EuropeanSouthernObservatory
© ESO 2005© ESO 2005Page 20Page 20 AO DepartmentAO Department
Reimaging lens F/4.0
Field separator
Nasm
yth
Adap
tor
flang
e
4’ Field selector
VisibleTT
Sensor
1’ Optics free Scientific Field
LGS WFS
LGS WFS
LGS Focus compensation
500 mm BFD500 mm BFD
180mm defocused Laser beam
1.45 arc min
Hole
FIELD SEPARATOR
4 a
rc m
in
GALACSI: Ground Atmospheric Layer Adaptive Corrector for Spectroscopic Imaging
Exchangeable unit for NFMExchangeable unit for NFM
See S. Stroebele talk`
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GALACSI mechanical conceptGALACSI mechanical concept
See S. Stroebele talk`
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO: Practical implementationsGLAO: Practical implementationsGRAAL: GRAAL: GRGRound layer ound layer AAO O AAssisted by ssisted by LLaseraser
Goal: Goal: reduce by 15 % in Y and 30% in Ks band the diameter reduce by 15 % in Y and 30% in Ks band the diameter collecting 50% of the encircled energy (for 1”) over 7.5’ FOVcollecting 50% of the encircled energy (for 1”) over 7.5’ FOV
HAWK-I camera size: 4kHAWK-I camera size: 4k×4k×4k, 7.5, 7.5×7.5 arcmin, 0.1063 arcsec/pixel×7.5 arcmin, 0.1063 arcsec/pixel Wavefront tomography using 4 sodium LGSsWavefront tomography using 4 sodium LGSs Four Shack-Hartmann WFS for LGSsFour Shack-Hartmann WFS for LGSs Ground layer correction: one Deformable Secondary Mirror (only Ground layer correction: one Deformable Secondary Mirror (only
solution!)solution!) On-axis NIR tip-tilt NGS using the HAWK-I detectorOn-axis NIR tip-tilt NGS using the HAWK-I detector As alternative, off-axis visible tip-tilt NGSAs alternative, off-axis visible tip-tilt NGS One NGS WFS for DSM commissioning & maintenanceOne NGS WFS for DSM commissioning & maintenance
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GRAAL on-sky guide stars geometryGRAAL on-sky guide stars geometry
VIS TT NGSAcquisition FoV
7.5 arc-minutes
13,2 arc-minutes
15,2 arc-minutes
VIS TTNGS
LGS
LGS LGS
LGS
IR TTNGS
Pupil Rotation
Field Rotation
7.8 arc-minutes
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GRAAL Functional Block DiagramGRAAL Functional Block Diagram
WFS Calibration
IR NGS TT
Sensing
Off-axis Vis NGS
TT Sensor
VLT
ADAPTER
4 LGS Wavefront
sensors withLGS focus
System
HAWK-I
HAWK-I Calibration
7.5’ FOV
Pupil
LGSs
VLT M1
M2 +DM
Laser LaunchTelescopesPosition 1
Pupil
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
CCD VIS TT Sensor
Four 32x32 LGS WFSs
40x40 VIS NGS WFS
DSM comm lenses unit
Calibration fiber
GRAAL: Opto-mechanical DesignGRAAL: Opto-mechanical Design
Rotating Structure to follow pupil rotation
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Lenses DSM comm
40x40 VIS NGS WFS
32x32 LGS WFS
VIS TT Sensor
SKY HAWK-I
Calibration fiber
GRAAL Opto-mechanical DesignGRAAL Opto-mechanical Design
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
DSM commissioning & maintenance modeDSM commissioning & maintenance mode
40x40 subapertures Shack-Hartmann WFS40x40 subapertures Shack-Hartmann WFS 6x6 pixels per subaperture6x6 pixels per subaperture, pixel scale: 0.3 arcsec/pix, pixel scale: 0.3 arcsec/pix 1.8 arcsec FOV per sub-aperture1.8 arcsec FOV per sub-aperture Focal Elongator in front of HAWK-IFocal Elongator in front of HAWK-I Pixel scale up to Pixel scale up to
10 milli arcsec/pixel 10 milli arcsec/pixel
on a 10’’ FoVon a 10’’ FoV
15:29:24
Scale: 0.80 26-Oct-04
31.25 MM
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Large FOV GLAO: The essential DSMLarge FOV GLAO: The essential DSM
VLT-Deformable Secondary MirrorVLT-Deformable Secondary MirrorFull replacement unitFull replacement unitØ Ø 1.1m with 1170 act.1.1m with 1170 act. 29 mm pitch29 mm pitch 1 ms response1 ms responseTotal actuator stroke: ±40-50µm P-VTotal actuator stroke: ±40-50µm P-VTotal inter-actuator stroke: 1.3 µm P-Total inter-actuator stroke: 1.3 µm P-V (goal 1.5V (goal 1.5m PV)m PV)Stroke resolution: 5 nmStroke resolution: 5 nm
VLT-DSMVLT-DSM
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
ACTUATORS SEPARATION
28.5 < Dist. < 29.6
VLT DSM Actuator PatternVLT DSM Actuator Pattern
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Large Deformable mirror designLarge Deformable mirror design
Reference plateHeat-sink and act.support plate
Electronics boxes
deformable shell: 2mm!
Central membranefor lateral support
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Laser Guide Star RequirementsLaser Guide Star Requirements
Photon flux: at least Photon flux: at least 1.5x101.5x1066 Na photons/m Na photons/m22/s (goal 2.5x10/s (goal 2.5x1066) ) LGS pointing range up to 5.5 arcmin / VLT optical axisLGS pointing range up to 5.5 arcmin / VLT optical axis Max. spot size of 1.25arcsec FWHM at 45 degrees from Max. spot size of 1.25arcsec FWHM at 45 degrees from
ZenithZenith Absolute LGS pointing precision in open loop: 1.1” (goal Absolute LGS pointing precision in open loop: 1.1” (goal
0.5”)0.5”) Total residual jitter smaller than 50 mas rmsTotal residual jitter smaller than 50 mas rms Output power stability: Output power stability: <1 % on a 10 ms time scale, <15 % <1 % on a 10 ms time scale, <15 %
on longer time scales (days)on longer time scales (days)
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
ESO’s fibre laser programme
• For next generation LGS-AO systems and MCAO, ESO’s strategy is to develop ~1 GHz 15 W CW*) fiber lasers at 589 nm, together with industry
• This strategy has created a collaboration agreement with LLNL to develop a sum-frequency fiber laser and an internal effort on fiber Raman laser/amplifier for which we ask support to the EU funding schemes*)The design also allows a pulsed laser output format if needed
Courtesy: D. Bonaccini W. Hackenberg
Ground Layer AO, N. HubinGround Layer AO, N. Hubin 3333
ESO Fibre Raman laser demonstrator setup
1178 nm, 0.75 GHzfibre Raman
seed laser
Fibre Ramanpre-amplifier
Fibre Ramanbooster amplifier
Diode-pumped 1121-nm Yb-doped fibre pump laser
Bulk 2nd-harmonic generation in periodically-poled KTP crystal
589 nm, 1.5 GHz
Courtesy: D. Bonaccini W. Hackenberg
Ground Layer AO, N. HubinGround Layer AO, N. Hubin 3344
First 589-nm light with the frequency-doubled fibre Raman laser demonstrator in Oct ‘04
• achieved 150 mW CW at 589-
nm
• diffraction-limited output
beam
• 1.5 GHz linewidthPPKTP, 30mm long used for SHG from 1178 to 589nm
Courtesy: D. Bonaccini W. Hackenberg
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Rayleigh scattering and “Fratricide” effectRayleigh scattering and “Fratricide” effect
-80 -60 -40 -20 0 20 40 60 80
-80
-60
-40
-20
0
20
40
60
80
field position ["]
field
pos
ition
["]
View of 1 subap. "Big WFS" Simulated for large fieldWFS cut a small section4 LGSLaunch behind M2Pointing 60“ off axisSubaperture pos. (0, -1) [m]
View of one individual sub aperture
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
Optimization and calibration aspectsOptimization and calibration aspects
10 20 30 40 50 60
10
20
30
40
50
6010 20 30 40 50 60
10
20
30
40
50
60
IM on beacon IM on sky
Interaction matrices measured on MACAO UT4with a membrane stroke of 10% and a DM stroke of 4%On sky, the seeing was 0.63" and the T0 2.3 ms
• Optimization of WFS square –DSM circular geometry• Influence functions optimization• Synthetic versus on-sky interaction matrix?•
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO-DSM laboratory testing facilityGLAO-DSM laboratory testing facility
3D Turbulence generator
2’ FOVOpticalcorrector
~1.7 m Spherical mirror
1.1m Adaptive secondary
4’ Field selector
VisibleTT
Sensor
LGS WFS
LGS WFS
Full testing of DSM and GLAO facilitybefore installation at the VLT!!GALACSI
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
GLAO as 1GLAO as 1stst stage for FALCON-MCAO stage for FALCON-MCAO
multi-IFUs
3WFS/IFU
GLAO as a first stage for FALCON-MOAO concept Correct ground layer over a large FOV ~ concept of Woofer DM Reduce stroke requirements for the local corrector (MEMS) Optimum use of the numerous WFSs needed for multi-IFU
GLAO is a natural 1st stage for MCAO system
GLAO Workshop, Leiden; April 26GLAO Workshop, Leiden; April 26thth 2005 2005 Ground Layer AO, N. HubinGround Layer AO, N. Hubin
ConclusionsConclusions
GLAO is:GLAO is: a seeing reducer & stabilizer at all a seeing reducer & stabilizer at all λλ and essentially gives access to a better site and essentially gives access to a better site improves Ensquared Energy, reduce confusion and reduce telescope timeimproves Ensquared Energy, reduce confusion and reduce telescope time if designed for full sky coverage will impact most of astronomical fieldsif designed for full sky coverage will impact most of astronomical fields
GRAAL for large FOV in NIRGRAAL for large FOV in NIR GALACSI for 1’ FOV correction in the visibleGALACSI for 1’ FOV correction in the visible GALACSI with Laser reconfiguration provides LTAO correction GALACSI with Laser reconfiguration provides LTAO correction Large DM and LGSs are essential for GLAOLarge DM and LGSs are essential for GLAO Intensive calibration & testing essential for on-site robust operationIntensive calibration & testing essential for on-site robust operation GLAO is an important 1GLAO is an important 1stst stage corrector for FALCON or MCAO stage corrector for FALCON or MCAO GRAAL-GALACSI-DSM-LGSF4: a VLT Facility? GRAAL-GALACSI-DSM-LGSF4: a VLT Facility?
=> ESO Facility design review: end 05=> ESO Facility design review: end 05