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An Adaptive Optics Road Map
Presentation to the AURA Board
7 February 2001
A Renaissance in Groundbased
IR (even Optical) Astronomy?
Based on presentation to the NSF
by Steve Strom
Adaptive Optics Road Map
HISTORICAL CONTEXT
Adaptive optics: one of the major advances in
telescope technology of the 20th century
“comparable to the invention of the telescope”


AO systems to date demonstrate its potential
to:
– Deliver high fidelity, diffraction-limited images
– Enable large gains in sensitivity
– Reduce the size of instruments

Science enabled by AO is impressive
–
–
–
–
Imaging lava flows on Io; storms on Neptune;
Imaging accretion disks; precessing jets in YSOs
Resolving Dense galactic and globular clusters
Measuring stellar fluxes; colors in nearby galactic
nuclei
Adaptive Optics Road Map
However…..
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Only 1% – 3% of the sky is accessible to current
AO systems
Laser systems are still VERY expensive (and
immature technologies)
Detector technologies are still limiting
performance
Data reduction techniques need to be better
understood (or more widely disseminated)
The full scientific potential of AO has yet to be
realized – need 1 – 2 arcminute corrected FOV’s
AO is the enabling technology for the “next
generation” of (extremely) large groundbased
telescopes
Adaptive Optics Road Map
Progress to “second generation”
Adaptive Optics
ALFA AO
System
Sodium Laser
result S ~ 0.2,
within a factor
of 2 of the
predicted
result (S= 0.4)
And now Lick is
Getting S ~ 0.7
Adaptive Optics Road Map
Unfortunately Sodium Lasers are
not a mature technology
Adaptive Optics Road Map
State-of-the-art is still complex
- Keck’s laser room (one wall)
Adaptive Optics Road Map
Conclusions (circa 2001)

We are entering a decade of unparalleled growth in the
competitiveness of ground-based O/IR astronomy

Adaptive Optics will be largely responsible for growth

The US and Gemini communities have a unique lead in Adaptive
Optics

However the lack of a mature Sodium Laser technology
represents an effective “log-jam” in the further development of
Adaptive Optics

The problem Gemini faces, in common with other AO programs,
is that the non-recurring costs of developing viable, facility
class lasers for such systems are currently beyond the
resources of any of the major adaptive optics programs

A focused, community wide effort (Gemini, CfAO, USAF) will
lead to “turn-key” affordable Sodium Lasers for all grounbased
telescopes

This will enable MCAO and the ‘Next Generation’ 30m - 100m
telescopes
Adaptive Optics Road Map
Some drawbacks of “classical” AO

Simulation on
an 8m
telescope, H
Band
(1.6 um)

Atmospheric
spatial
decorrelation
limits effective
FOV

AO correction
requires a
bright star

Sky coverage
limited to
0.1% - 1% of
sky
Adaptive Optics Road Map
Some drawbacks of “classical” AO

Variation in
Point Spread
Function (PSF)
across the field
of view
complicates
the
quantitative
interpretation
of observations
in dense fields
or spatially
complex objects
Adaptive Optics Road Map
Adaptive Optics Road Map
Effectiveness of MCAO
Numerical
simulations:
 5 Natural
guide stars
 5 Wavefront
sensors
 2 mirrors
 8 turbulence
layers
 MK
turbulence
profile
 Field of view
~ 1.2’
 H band
Adaptive Optics Road Map
Modeling verses Data
GEMINI AO Data
20 arcsec
2.5 arc min.
M15: PSF variations
and stability
measured as
predicted
Adaptive Optics Road Map
Quantitative AO Corrected Data
• AO performance can
be well modeled
• Quantitative predictions
confirmed by observations
• AO is now a valuable
scientific tool:
• predicted S/N gains
now being realized
• measured
photometric errors
in crowded fields ~ 2%
Rigaut et al 2001
Adaptive Optics Road Map
The Realm of MCAO

MCAO vs CAO:
– Field of view, gain in area:
J20-80 x, K10-20 x,
depending on criteria and
conditions.
– Photometric performance:
photometric accuracy prop to
Strehl variations in the field.
MCAO ~ CAO / 10, i.e. for
accuracy of 5% for CAO,
MCAO gets to 0.5% -> 0.01
mag on a CMD.
MCAO
1/2 FoV
1/2 FoV
AO
0
10
20
30
40
50
60
[arcsec]
Adaptive Optics Road Map
Realms of MCAO/CAO
100
Distant
GSAO
Milky WayMCAO
Galaxies
programs
PUEO
HK
Keck
ESO
Field of view 
[arcseconds]
10
1
Nearby
Galaxies
Keck
CAO
0.1
0.05
0.01
0.005
Photometric accuracy [mag]
First test of tomographic
technique
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Ragazzoni et al, 2000,
Nature 403, 54
Collected optical data on a
constellation of 4 stars
Used tomographic
analysis from outer three
to predict phase errors of
the central star
Tomographic calculations
correctly estimated the
atmospheric phases errors
to an accuracy of 92%
–
–
better than classical AO
MCAO can be made to
work
Adaptive Optics Road Map
Sodium Laser at
Chile
Adaptive Optics Road Map
The Southern Sodium Layer Preliminary results
February 11,
2001
Adaptive Optics Road Map
Laser Development timescales in context
2000
2010
Keck I&II Keck-Inter.
UT1-UT4 VLT-I
HET
LBT
ALTAIR+LGS
ALTAIR
Gemini-N Hokupa’a
Gemini-S
Hokupa’a-II
ALMA NGST
Unchallenged
‘03 MCAO “NGST class” science
Adaptive Optics Road Map
Laser Development timescales in
context
2000
2010
Keck I&II Keck-Inter.
UT1-UT4 VLT-I
HET
LBT
ALMA NGST
ALTAIR+LGS
Gemini-N Hokupa’a
‘03 GAOS MCAO
Gemini-S
Hokupa’a-II
2nd Generation Telescopes
2000
CELT
GSMT
2010
MAXAT
OWL
2015
Adaptive Optics Road Map
The Groundbased Scientific Impact
- Relative S/N Gain of groundbased diffraction limited
20m,30m, 50m and 100m telescopes compared to NGST
100m
50m
30m
20m
Adaptive Optics Road Map
NGST advantage
S/N x 10
Groundbased
advantage
Spectroscopy, vres = 30 kms/s
ADAPTIVE OPTICS:
A ROADMAP FOR THE NEXT DECADE
Based on presentation by CfAO and
NOAO/NIO on behalf of the US AO
community
27 APR 2000
Adaptive Optics Road Map
CHALLENGES

Develop new systems approaches
– Increase sky coverage/Strehl through use of LGS
– Enable wider fields through use of MCAO
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Develop key components
– Reliable, high power lasers
– Advanced wavefront sensors and deformable mirrors
– Fast detectors
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Advance understanding of atmospheric
turbulence
– Understand turbulence; Sodium layer excitation
NB: AO advances required for d >> 10m telescopes
Adaptive Optics Road Map
TOWARD AN AO ROADMAP
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Community workshop held on 13/14 DEC in
Tucson
– Co-sponsored by CfAO and NOAO
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Goals:
– Prepare a 10 year roadmap for NSF investment in AO
• new systems approaches
• systems design issues
• technology investments
• subsystem developments
• software issues
• key investment areas and associated milestones
– Define a process for implementing/updating the
roadmap
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– Concept studies for next generation telescopes
• identify the role of AO
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Expected Return:
– Deeper understanding of the relative priorities of
roadmap investments as the decade unfolds
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– develop reliable, affordable sodium lasers (10-50 W)
– support R&D on Rayleigh beacons
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Expected Return:
– greatly accelerated implementation of laser beacons on
extant telescopes
– wider field correction through use of MCAO
– all sky coverage at increased Strehl
– extension of AO correction to shorter wavelengths
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– prototyping and testing of wavefront correction elements
• curved optics
• adaptive secondaries and primaries
• transmissive optics
• higher order deformable mirrors
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Expected Return:
–
–
–
–
improved optical simplicity and efficiency
reduced thermal background
simplified control systems
enhanced wavefront quality
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– faster, lower noise detectors with more pixels and
broader wavelength coverage for wavefront sensing
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Expected Return:
– improved AO performance with both natural and laser
reference beacons
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– advanced numerical methods for computing optimum
corrections for inferred wavefront distortions
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Expected Return:
– enhanced corrected field of view
– improved uniformity of image quality over large FOV
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– site-specific monitoring campaigns
– instrument packages for real-time support of AO systems
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Expected Return:
– site characterization for design of optimum AO systems
– site selection for next generation telescope(s)
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– model AO system performance
– evaluate/validate competitive approaches to modeling
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Expected Return:
– confidence in predictions from modeling
– improved systems approaches
Adaptive Optics Road Map
KEY TECHNOLOGIES
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Proposed Investment:
– support of concept studies and workshops to explore
instrumentation design in the AO era
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Expected Return:
– instrument design and performance matched to
opportunities provided by AO
Adaptive Optics Road Map
SCHEDULE FOR KEY ACTIVITIES
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Site Monitoring
– 2001: Begin 3 year program of site testing to provide a
database for AO system modeling
– 2002: Deploy instruments for Na-layer monitoring
– 2003: Deploy initial instruments for monitoring turbulence
in real time
– 2004: Develop second-generation turbulence monitoring
instruments
– 2004: Deploy instrumentation for long-term studies at
several promising sites for next generation telescopes
Adaptive Optics Road Map
SCHEDULE FOR KEY ACTIVITIES
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Systems Designs
– 2001-2003: Solicit candidate designs for AO systems on
30-m class telescopes
– 2004-2006: Test at least two design concepts in the lab or
on extant telescopes
– 2006-2010: Build one full-up AO system to test advanced
concepts on 8-10m telescopes in service of
implementation on a 30-m telescopes
– 2009-2010: Develop merged design of 30-100m telescope
and advanced AO system
Adaptive Optics Road Map
SCHEDULE FOR KEY ACTIVITIES
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Deformable Mirrors
– 2001: Draft plan for developing deformable mirror
technologies (~10,000 degrees of freedom)
– 2002-2004: Construct modest-sized prototypes
– 2005-2007: Build two or three deformable mirrors using
scalable technologies
Adaptive Optics Road Map
SCHEDULE FOR KEY ACTIVITIES
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Wavefront-sensing detectors
– 2001: Facilitate foundry runs for fast, low-noise detectors
for wavefront sensing in the visible and near-IR
– 2002-2003: Take delivery and test in existing AO systems
– 2004-2006: Fund and test the most promising technology
for 512x512 detectors (for 30-100m application)
Adaptive Optics Road Map
Investment Required
10 year plan required 2002 - 2012
AO Systems for GSMT will cost ~ $100M
Adaptive Optics Road Map