Transcript NAOS-CONICA (a.k.a NACO) for the VLT Thierry Fusco Gérard Rousset NACO History ESO, 27/11/2009 CFT for the VLT Coude AO feasibility study: Feb.

NAOS-CONICA (a.k.a NACO)
for the VLT
Thierry Fusco
Gérard Rousset
NACO History
ESO, 27/11/2009
CFT for the VLT Coude AO feasibility study: Feb. 91
CONICA contract signed with MPIA et al: 1991
VLT Coude AO feasibility study: Matra-Marconi-Space in 92-93
VLT Coude AO project (4 AO systems) cancelled: Council Dec 93
NAOS concept is proposed by ESO to STC-FC-Council:  end 1994
CONICA is redesigned by MPIA et al.:  end 1994
NAOS Preliminary Inquiry & CFT: Dec. 94- March 96
NAOS audit: March 96- December 96
NAOS contract signed with ONERA et al.: March 97
CONICA FDR: mid 98
NAOS PDR - FDR: Oct. 98 - June 99
~5 years
NAOS-CONICA PAE: Sept. 2001
NAOS-CONICA first light: Nov. 2001
NACO open to the community: Oct 2002
2
NAOS in figures
4 Institutes :
ONERA, LAOG, ODP, ESO






5-year project
~5 Meuros
60 FTEs
Tests in France in 2001
First light 25/11/2001

ESO, 27/11/2009
NAOS: 2.3 tons
CONICA: 0.9 tons
(attached to Nasmyth rotator)
3
NAOS main features (1/2)…
Two Shack-Hartmann Wavefront Sensors,
each including 2 pupil samplings:
14x14 (144 valid subap.) and 7x7 (36)
VWFS :
• Spectral range: 0.45 - 1 mm
• 2 interchangeable lenslet arrays
(0.29 and 0.58 arcsec/pixel)
• EEV CCD 128x128 pixels, 16 outputs (ESO)
frame rate from 444 to 15 Hz
binning, windowing
noise : 2.9e- to 5.4e• 48 configurations!!!
IR WFS :
• Spectral range: 0.8 - 2.5 mm
• 14x14 array + 2 arrays of 7x7 on 3 fixed detector areas
(0.8 and 0.4 arcsec/pix)
ESO, 27/11/2009
• Rockwell Hawaii 1024x1024 pixels
frame rate from 180 to 15 Hz
noise : from 10 to 20 e-
• 36 configurations !!!
4
NAOS main features (2/2)
Deformable mirror (Cilas)
• 185 actuators (piezo-stacked), 10 m stroke
2-axis Tip/Tilt Mirror: 2.1 mas resolution
Real time Computer (Shakti):
• 0dB Error BW: 27 Hz (V) and 22 Hz (IR)
• modal optimization (every 2 mn)
• on-line performance and seeing
Dichroic Wheel:
• 2 neutral and 3 dichroic BS
WFS Field Selector:
• NGS in 2 arcmin FOV
• Tracking (refraction, flexures, moving object)
Observation software:
ESO, 27/11/2009
• NAOS configuration, control of Field Selector
• Aberration pre-compensation, chopping
Off-line preparation software
5
Mechanical structure
PM 2
V-WFS
IR WFS



Diameter: 2m
Max Length: 3m
Thickness: 0.7m
TTM
DM
Output
ESO, 27/11/2009
input
PM 1
6
Pupil sampling
Telescope pupil
185 useful
actuators
144 useful subapertures
ESO, 27/11/2009
Central obscuration
7
CONICA
1-5 microns (1Kx1K)
34 filters
4 grisms
7 cameras
3 slits
Polarimetry
Coronography
Fabry-Perot Imaging
ESO, 27/11/2009








8
ESO, 27/11/2009
Flange to “rotate” CONICA
Imaging: 1-5 µm
Polarisation
Coronography
Spectro 1-5 µm: max 2500
Fabry Perot: R=1800
9
… and NAOS-CONICA became NACO …
They lived happy everafter … and they had plenty of photons …
NAOS
CONICA
Cable twist
ESO, 27/11/2009
VLT-UT4: F/15
VLT Nasmyth Platform
10
NACO challenges
• High order correction in near IR (Sr(K)=70%)
• Faint limiting magnitude star in V (Mv>17)
• IR wavefront sensing for embedded objects
• Compatibility with LGS operation
• Minimization of instrument thermal and sky bkg effects
•
ESO, 27/11/2009
Minimise the number of optical surfaces
no derotator  direct rotation of NACO
• AO with Chopping and Counter chopping
• Very low flexure requirements (NAOS & CONICA)
• “background limiter” to reduce dichroic background
• High image quality for CONICA (Sr(K)>90%)
• Low Instrumental background <1e
• One detector for 1-5 m!
• Many CONICA observing modes: Imaging, coronagraphy, Low resolution
spectroscopy, FP, polarimetry
And now … let’s go on sky … with a pit-stop in lab 
11
First laboratory results
Turbulent image
Image without
turbulence
SR = 69%
90%
ESO, 27/11/2009
Seeing 0.6 arcsec
AO corrected image
Result: SR 65 % @ 0.93 arcsec seeing (specification 70 %) 12
Paranal re-integration
YESSSSSSSS !
I’m gonna observe in
J, H, K, L, M …
I’m gonna detect exoplanets
The instrumentalist
(use to be an astronomer )
ESO, 27/11/2009
The astronomer
NOOOOOOOO !
Oh my god …
I have to make it work !
13
Let’s go on the telescope
Well …
maybe ...
Is this going to work??
ESO, 27/11/2009
Of course it will
!!!!!!!!!!
14
And yes … it worked and it is still working
ESO, 27/11/2009
High Strehl (K)
50%
15
ESO, 27/11/2009
Faint star correction
Strehl (K)=17%
16
ESO, 27/11/2009
The Galactic Centre
The Galactic Centre with and without AO in L'-band seen by NAOS
(Clénet et al. 2004)
17
ESO, 27/11/2009
Thetis
Differential tracking
Composite image H-K
20.6 arcsec diameter
resolution 70 mas or 410 km
~10 sec exposure time
18
ESO, 27/11/2009
Io with NAOS-CONICA
Long wavelengths
capabilities
Brg-L’
230/4.2 s exposure
68mas or 210 km
1.2 arcsec diameter
19
On-sky SR behavior versus magnitude
ESO, 27/11/2009
Visible WFS
IR WFS
Stars: seeing  0.7 ’ ’, crosses:  1.1 ’ ’, diamonds: > 1.1 ’ ’ ;
14x14 arrays: large symbols, 7x7 arrays: small symbols
• Bright NGS : SR loss of 20-30 %
• Faint NGS : significant correction
20
ESO, 27/11/2009
Exoplanet detection with NACO
21
SR loss sources (1/2)
Vibrations detected on WFS data:
On-sky
• 16 - 18 Hz : 3000 -10000 nm²
• 48 - 55 Hz : 2000 - 5000 nm²
• 68 - 70 Hz : 500 - 1000 nm²
No vibration on Comas
Variations in amplitude and
Vibration lines
No vibration
occurence
ESO, 27/11/2009
Laboratory
No vibration in laboratory
Nothing on internal source: telescope vibrations
22
SR loss sources (2/2)
Telescope vibrations:
Main influence on Tip-Tilt modes but
other excitations detected on high
order modes
ESO, 27/11/2009
Vibrations not compensated for:
out of the NAOS temporal bandwidth
Strehl loss estimated to 10 %
23
Differential aberrations in CONICA and dichroics
SR= 56%
At 2.15 m
SR = 89 %
ESO, 27/11/2009
SR =66%
With pre-compensation by NAOS
deformable mirror
No compensation
At 1.09 m
SR = 93 %
Without turbulence, SR ~ 93 % in K with pre-compensation
24
Conclusion
 In median seeing conditions:
SR ~ 50% at K band; best Sr(K)=64% on sky
 Substantial compensation with very faint NGS:
Mv=17.6, SR=6% (gain of 7)
 Fully automated operation (VLT software)
 Many features available in NAOS for specific astronomical
observations:



ESO, 27/11/2009

IR WFS
differential refraction, pointing model
tracking on moving object,
chopping, counter-chopping
 241 scientific papers so far
=> 34.5 papers per year => Good scientific return !
25