NIO GSMT Overview
S. Strom, L. Stepp
23 August, 2001
AURA NIO: Mission
•
In response to AASC call for a GSMT, AURA
formed a New Initiatives Office (NIO)
–
•
collaborative effort between NOAO and Gemini to
explore design concepts for a GSMT
NIO mission
“ to ensure broad astronomy community access to a
30m telescope contemporary in time with ALMA and
NGST, by playing a key role in scientific and technical
studies leading to the creation of a GSMT.”
Goals of the NIO
•
•
•
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Foster community interaction re GSMT
Develop point design
Conduct studies of key technical issues and
relationship to science drivers
Optimize community resources:
– emphasize studies that benefit multiple programs,
– collaborate to ensure complementary efforts,
– give preference to technical approaches that are
extensible to even more ambitious projects.
•
Develop a partnership to build GSMT
AURA New Initiatives Office
Management Board
Matt Mountain
Jeremy Mould
William Smith
Engineering Oversight
Jim Oschmann
Project Scientist
Steve Strom
Program Manager
Larry Stepp
Contracted Studies
studies
Contracted
TBD
Systems Scientist
Brooke Gregory
Part time support
NOAO & Gemini
Administrative assistant
Jennifer Purcell
Optics
Opto-mechanics
Larry
Stepp
Myung
Cho
Controls
Controls
George
Angeli
(NOAO)
George
Angeli
Adaptive Optics
Adaptive
Optics
Brent Ellerbroek (Gemini)
Ellerbroek/Rigaut
(Gemini)
Mechanical Designer
Rick Robles
Structures
Paul Gillett
Site Testing
Alistair Walker (NOAO)
Instruments
Sam Barden (NOAO)
Objectives: Next 2 years
•
•
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Develop point design for GSMT & instruments
Develop key technical solutions
– Adaptive optics
– Active compensation of wind buffeting
– Mirror segment fabrication
Investigate design-to-cost considerations
Involve the community in defining GSMT science and
engineering requirements
Involve the community in defining instrumentation
options; technology paths
Carry out conceptual design activities that support and
complement other efforts
Develop a partnership to build GSMT
Resources: 2001-2002
• NIO activities: $3.6M
– Support core NIO staff (‘skunk works team’)
–
–
• Analyze point design
• Develop instrument and subsystem concepts
Support Gemini and NOAO staff to
• Explore science and instrument requirements
• Develop systems engineering framework
Support community studies:
• Enable community efforts: science; instruments
• Enable key external engineering studies
• Support alternative concept studies
Objectives: Next Decade
•
•
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Complete GSMT preliminary design (2Q 2005)
Complete final design (Q4 2007)
Serve as locus for
– community interaction with GSMT partnership
– ongoing operations
– defining; providing O/IR support capabilities
– defining interactions with NGST
Resources: Next Decade
• $15M in CY 2003-2006 from NOAO base
– Enables start of Preliminary Design with partner
• $25M in CY 2007-2011 from NOAO base
• Create a ‘wedge’ of ~$10M/yr by 2010
– Enables NOAO funding of
• Major subsystem
• Instruments
• Operations
Key Milestones
2Q01: Establish initial science requirements
• 3Q01: Complete initial instrument concepts
• 3Q01: Complete initial point design analysis
• 1Q02: Identify and fund alternate concept studies
• 2Q02: Identify and fund key technology studies
• 2Q02: Identify potential US and/or international partners
•1Q03: Complete concept trade studies
• 2Q03: Develop MOUs with partner(s)
• 2Q03: Establish final science requirements
• 4Q03: Initiate Preliminary Design
• 2Q05: Complete Preliminary Design
• 4Q05: Complete next stage proposal
FIRST STEP:
UNDERSTAND SCIENCE REQUIREMENTS
Developing Science Cases
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Two community workshops (1998-1999)
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Tucson task group meetings (SEP 2000)
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NIO working groups (MAR 01 – SEP 01)
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NIO-funded community task groups (CY 2002)
NIO-funded community workshop (CY 2002)
– Broad participation; wide-ranging input
– Large-scale structure; galaxy assembly
– Stellar populations
– Star and planet formation
– Develop quantitative cases; simulations
– Refine performance goals and requirements
Tomography of the Universe
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Goals:
Map out large scale structure for z > 3
Link emerging distribution of gas; galaxies to CMB
Measurements:
Spectra for 106 galaxies (R ~ 2000)
Spectra of 105 QSOs (R ~15000)
Key requirements:
20’ FOV; >1000 fibers
Time to complete study with GSMT: 3 years
Issues
– Refine understanding of sample size requirements
– Spectrograph design
Mass Tomography of the Universe
Existing Surveys + Sloan
Hints of Structure at z=3
(small area)
z~0.5
z~3
100Mpc (5Ox5O), 27AB mag (L* z=9), dense sampling
GSMT
1.5 yr
Gemini
50 yr
NGST
140 yr
Tomography of Galaxies and
Pre-Galactic Fragments
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•
•
•
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Goals:
Determine gas and stellar kinematics
Quantify SFR and chemical composition
Measurements:
Spectroscopy of H II complexes and underlying stars
Key requirements:
Deployable IFUs feeding R ~ 10000 spectrograph
Wide FOV to efficiently sample multiple systems
Time to complete study with GSMT: ~1 year
Issues
– Modeling surface brightness distribution
– Understanding optimal IFU ‘pixel’ size
Tomography of Individual Galaxies
out to z ~3
• Determine the gas and
stellar dynamics within
individual galaxies
• Quantify variations in
star formation rate
– Tool: IFU spectra
[R ~ 5,000 – 10,000]
GSMT 3 hour, 3s limit
at R=5,000
0.1”x0.1” IFU pixel
(sub-kpc scale structures)
J
26.5
H
25.5
K
24.0
Origins of Planetary Systems
•
Goals:
•
Measurements:
•
Key requirements:
•
•
– Understand where and when planets form
– Infer planetary architectures via observation of ‘gaps’
Spectra of 103 accreting PMS stars (R~105; l ~ 5m)
On axis, high Strehl AO; low emissivity
Time to complete study with GSMT:
2 years
Issues
Understand efficacy of molecular ‘tracers’
Trades among emissivity; sites; telescope & AO design
Probing Planet Formation with High
Resolution Infrared Spectroscopy
Planet formation studies in the infrared (5-30µm):




Probe forming planets in inner disk regions
Residual gas in cleared region
low t emission
Rotation separates disk radii in velocity
High spectral resolution
high spatial resolution
S/N=100, R=100,000, l>4mm
Gemini
GSMT
NGST
out to 0.2kpc sample ~ 10s
1.5kpc
~100s
X

8-10m telescopes with high resolution
(R~100,000) spectrographs can detect
the formation of Jupiter-mass planets in
disks around nearby stars (d~100pc).
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Stellar Populations
Goals:
Quantify IMF in different environments
Quantify ages; [Fe/H]; for stars in nearby galaxies
Develop understanding of galaxy assembly process
Measurements:
Spectra of ~ 105 stars in rich, forming clusters (R ~ 1000)
CMDs for selected areas in local group galaxies
Key requirements:
MCAO delivering 2’ FOV; MCAO-fed NIR spectrograph
Time to complete study with GSMT: 3 years
Issues
– MCAO performance in crowded fields
Derived Top Level Requirements
Narrow field AO
1 2
Field of View
10 arcsec + Principle wavelegths
1.0 - 2.5 microns
PSF
Resolution Diffraction limited + +
Stability
1%
+
Strehl
80%
Photom. accuracy(derived)
1%
Astrometric accuracy
10^-4 arcsec
+
Stability timescale
3,600 s
Emissivity
<20%
Maintenance/Ops
<15%
Reliability
90%
Science Efficiency
90%
3 MCAO
1 2 3 Low order AO
1 2 3 Seeing limited (PF) 1 2 3
+
2 arcmin + +
2 arcmin +
20 arcmin
1.0 - 2.5 microns
1.0 - 20 microns
0.4 - 2.5 microns
Diffraction limited +
5% - 50%
5% - +
10^-3 arcsec
3,600s
<20%
<15%
90%
90%
How to r ead this table:
Four telescope “Operating regimes” are defined and the specs for the
telesc ope (not the instrument) in each regime are cited. There are columns at
the right of each regime labeled 1,2,3 for the th ree science programs
discussed in the NO AO panel W orkshop. In these columns the spe cs are
assessed in term s of the adequacy for each sc ience program .
0.1-0.2 arcsec +
2%
<10%
2%
10^-2 arcsec
3,600s
10%
<15%
90%
90%
Matt:
0.4-0.7 arcsec +
2%
0%
1%
0.05 arcsec
10,000 s
15%
<15%
90%
90%
I think this mode is
important, its our only
"thermal IR" mode, and
we may find some
spectroscopy modes are
so photon starved they
1 Galaxy Evolution and LS Structure
2 Stellar Populations
3 Star and Planet Formation
Key:
+ meets needs
- does not meet needs
irrelevant or not critical
NIO Approach
Parallel efforts
– Address challenges common to all ELTs
• Wind-loading
• Adaptive optics
• Site
– Explore “point design”
• Start from a strawman motivated by science
• Understand key technical issues through analysis
– NB: Point design is simply a starting point!
• NIO will explore alternate approaches
Enemies Common to all ELTs
• Wind…..
• The Atmosphere……
Wind Loading
•
•
Primary challenge may be wind buffeting
– More critical than for existing telescopes
• Structural resonances closer to peak wind power
• Wind may limit performance more than local seeing
Solutions include:
– Site selection for low wind speed
– Optimizing enclosure design
– Dynamic compensation
• Adaptive Optics
• Active structural damping
Gemini South Wind Test
Performed during integration of Gemini
Telescope on Cerro Pachon
– Enclosure has large vent gates – permits testing a
range of enclosure conditions
– Dummy mirror has properties equivalent to the
real primary mirror, but can be instrumented
– M1 is above the EL axis - open to the wind flow
(similar to concepts for future larger telescopes)
Instrumentation
3-axis anemometers
Pressure sensors, 32 places
Sensor Locations
Ultrasonic anemometer
Ultrasonic anemometer
Pressure sensors
AVERAGE Pressure (C00030oo)
1.5
AVERAGE Pressure (C00030oo)
7
10
1
6
10
0.5
5
0
magnitude
pressure (N/m2)
10
-0.5
4
10
3
10
2
-1
10
-1.5
10
1
0
-2
0
50
100
150
200
Time History: time (second)
250
300
10
-3
10
SUM = -226
-2
-1
0
10
10
10
Frequency Response Function: frequency (Hz)
1
10
Animation
Wind pressure: C00030oo
test_2, day_2, Azimuth angle=00, Zenith angle=30, wind_gate:open, open; wind speed=11 m/s
Wind Pressure Structure Function
C00030oo
Average Structural Function for C00030oo
4
RMS pressure, Prms (N/m2)
3.5
3
2.5
2
1.5
1
0.5
0
Prms = 0.076124 d ** 0.4389
0
1000
2000
3000
4000
5000
sensor spacing, d (mm)
6000
7000
8000
RMS pressure difference (pascals)
Extrapolation to 30 Meters
0.25
Pressure variation on 30-m mirror about twice 8-m
0.2
0.15
0.1
Prms = 0.04d^0.5
0.05
0
0
5
10
15
20
Sensor separation (meters)
25
30
Summary and Conclusions
• Wind loading on M1 is strongly dependent on vent gate openings
• Wind loading on M2 is not strongly dependent on vent gate
openings
• Control algorithm will maintain wind speed at M1 < 3 m/sec
• With vent gates closed, M1 deformations remain within error
budget even in high winds
• Pressure variations on M1 are larger than average pressure
• M1 wind deformations are dominated by astigmatism
• M1 deformations are proportional to RMS pressure variations on
surface
• M1 deformations ~ proportional to (wind velocity at mirror)²
• Pressure structure functions fit 0.5 power law
• Structure functions allow extrapolation to larger telescopes –
pressure range for 30m twice that of 8m
AO Technology Constraints:
DMs and Computing power
(50m telescope; on axis)
Actuator pitch
r0(550 nm) = 10cm
S(550nm) S(1.65mm)
No. of
actuators
Computer
power
(Gflops)
CCD pixel
rate/sensor
(M pixel/s)
10cm
74%
97%
200,000
9 x 105
800
25cm
25%
86%
30,000
2 x 104
125
50cm
2%
SOR (achieved)
61%
8,000
789
1,500
~2
31
4 x 4.5
Early 21st Century technology will keep AO confined to l > 1.0 mm
for telescopes with D ~ 30m – 50m
AO Technology Constraints:
Guide stars and optical quality
MCAO system analysis by Rigaut & Ellerbroek (2000):
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30 m telescope
2 arcmin field
9 Sodium laser constellation 10 watts each
4 tip/tilt stars (1 x 17, 3 x 20 Rmag)
Telescope residual errors
~ 100 nm rms
Instrument residual errors ~ 70 nm rms
System performance:
l(mm)
1.25
1.65
2.20
Delivered Strehl
0.2 ~ 0.4
0.4 ~ 0.6
0.6 ~ 0.8
PSF variations < 1% across FOV
Site Evaluation
• ELT site evaluation more demanding
• Evaluation criteria include
– surface and high altitude winds
– turbulence profiles
– transmission
– available clear nights (long-term averages)
– cirrus cover (artificial guide star performance)
– light pollution
– accessibility
– available local infrastructure
– land ownership issues
Site Evaluation
• NIO gathering uniform data for sites in:
– Northern Chile
– Mexico and Southwest US
– Hawaii
• Effort led by NIO staff
• Parallel effort in Mexico, aligned with NIOdeveloped criteria
POINT DESIGN APPROACH
GSMT System Considerations
Science
Mission
Instruments
Adaptive Optics
Active Optics
(aO)
Full System
Analysis
Site
Characteristics
Enclosure
protection
Support &
Fabrication
Issues
GSMT
Concept
(Phase A)
Point Design: Philosophy
• Select plausible design
– must address key science requirements
• Identify key technical challenges
• Focus analysis on key challenges
• Evaluate strengths and weaknesses
– guide initial cost-performance evaluation
– inform concept design trades
• Point design is only a strawman!
Point Design: Motivations
• Enable high-Strehl performance over several
arc-minute fields
– Stellar populations; galactic kinematics; chemistry
• Provide a practical basis for wide-field, native
seeing-limited instruments
– Origin of large-scale structure
• Enable high sensitivity mid-IR spectroscopy
– Detection of forming planetary systems
Choices for NIO Point Design
• Explore prime focus option
– attractive enabler for wide-field science
– cost-saving in instrument design
• Assume adaptive M2
– compensate for wind-buffeting
– reduce thermal background
– deliver enhanced-seeing images
• Explore a radio telescope approach
– possible structural advantages
– possible advantages in accommodating large
instruments
Point Design: End-to End Approach
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•
•
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Science Requirements (including instruments)
Error Budget
Control systems
Enclosure concept
– Interaction with site, telescope and budget
• Telescope structure
– Interaction with wind, optics and instruments
• Optics
•
– Interaction with telescope, aO/AO systems and instruments
AO/MCAO
– Interaction with telescope, optics, and instruments
• Instruments
– Interaction with AO and Observing Model
30m Giant Segmented Mirror Telescope
Point Design Concept
Typical 'raft', 7 mirrors per raft
GEMINI
1.152 m mirror
across flats
Special raft - 6 places, 4
mirrors per raft
30m F/1 primary, 2m adaptive secondary
Circle, 30m dia.
Key Point-Design Features
• Paraboloidal primary
– Advantage: Good image quality over 20 arcmin
field with only 2 reflections
• Seeing-limited observations in visible
• Mid-IR
– Disadvantage: Higher segment fabrication cost
Key Point-Design Features
• F/1 primary mirror
– Advantages:
• Reduces size of enclosure
• Reduces flexure of optical support structure
• Reduces counterweights required
– Disadvantages:
• Increased sensitivity to misalignment
• Increased asphericity of segments
Key Point-Design Features
• Radio telescope structure
– Advantages:
• Cass focus can be located just behind M1
• Allows small secondary mirror – can be adaptive
• Allows MCAO system ahead of Nasmyth focus
– Disadvantage:
• Requires counterweight
• Sweeps out larger volume in enclosure
GSMT Control Concept
Deformable M2 : First
stage MCAO, wide field
seeing improvement
and M1 shape control
Active M1 (0.1 ~ 1Hz)
619 segments on 91 rafts
LGSs provide full sky
coverage
 M2: rather slow, large stroke
DM to compensate ground layer
and telescope figure,
or to use as single DM at
l>3 mm. (~8000 actuators)
 Dedicated, small field
(1-2’) MCAO system (~4-6DMs).
10-20’ field at
0.2-0.3” seeing
1-2’ field fed to the
MCAO module
Focal plane
Enabling Techniques
Active and Adaptive Optics
– Active Optics already integrated into Keck, VLT,
Gemini, Subaru, Magellan, …
– Adaptive Optics “added” to CFHT, Keck, Gemini,
VLT, …
Active and Adaptive Optics will have to be
integrated into GSMT Telescope and
Instrument concepts from the start
30m GSMT
Initial Point-Design Structural Model
Z
X
Y
Output Set: Mode 1, 2.156537 Hz, Deformed(0.0673): Total Translation
Horizon Pointing - Mode 1 = 2.16 Hz
Response to Wind
Need to quantify wind effects, and develop control system
responses to correct pointing, focus, and optical aberrations
Modeling of Active Corrections
We are considering two approaches:
– Partition mode shapes + line-of sight equations
– Ray-tracing mode shapes
Structural Mode Shapes
M1 Surface
Modal Partitioning
•
For each vibration mode shape
– Separate group of nodes representing M1
– Determine Zernike polynomials for M1 mode shape by leastsquares fit
– Determine rigid-body motions of M2, calculate effect on
image motion and aberrations

Combine participation of all modes in random
vibration analysis based on a defined wind input, to
calculate the PSD, and RMS amplitude of:
–
–
–
–
image motion
piston and focus
astigmatism
coma
Ray Tracing of Mode Shapes
•
For each vibration mode shape
– Determine rigid-body motions of M1 and M2
– Develop an “interferogram” phase map from the residual
aberrations on M1
– Input information to an optical analysis program (i.e., Code V)
– Determine image motion and Zernike polynomials that
describe the wavefront at the focal surface

Combine participation of all modes in random vibration
analysis based on a defined wind input, to calculate
the PSD, and RMS amplitude of:
–
–
–
–
image motion
piston and focus
astigmatism
coma
Controls Approach:
Offloading Decentralized Controllers
LGS MCAO
~100
spatial & temporal avg
~50
AO (M2)
spatial & temporal avg
~20
spatial avg
aO (M1)
temporal avg
~10
spatial avg
Secondary
rigid body
2
spatial & temporal avg
Main Axes
0.001
0.01
0.1
1
10
100
Enclosure studies
Initial enclosure studies will focus on:
– Ability to protect telescope from wind
– Understanding cost issues
Some Possible Enclosure Designs
AO Systems
• Adaptive secondary mirror
• Adaptive mirror in prime focus corrector
• Multi-conjugate wide-field AO
• High-order narrow-field conventional AO
Adaptive M2 Intrinsic to Point Design
Options: low- to high-order
• Compensate for winddriven M1 distortions
• Deliver high Strehl, mid-IR
images with low emissivity
• Deliver high-Strehl, near-IR
images
Goal: 8000 actuators
30cm spacing on M1
Key Point-Design Features
• 2m diameter adaptive secondary mirror
– Advantages:
•
•
•
•
Correction of low-order M1 modes
Enhanced native seeing
Good performance in mid-IR
First stage in high-order AO system
– Disadvantages:
• Increased difficulty (i.e., cost)
Optical “seeing improvement”
using low order AO correction
Image profiles
are Lorenzian
16 consecutive nights of
adaptive optics at CFHT
Boundary Layer Compensation
Median natural seeing (upper
solid line) and median
compensated seeing at V
band for a single deformable
mirror with actuator pitches
of 25 cm (solid), 50 cm
(dotted) and 1-m (dashed).
(From Rigaut, 2001)
MCAO/AO foci and instruments
Oschmann et al (2001)
MCAO optics
moves with telescope
elevation axis
Narrow field AO or
narrow field seeing
limited port
MCAO Imager
at vertical
Nasmyth
4m
MCAO System
Instruments
•
•
Telescope, AO and instruments must be
developed as an integrated system
NIO team developing design concepts
– Multi-Object, Multi-Fiber, Optical Spectrograph
– Near IR Deployable Integral Field Spectrograph
– MCAO-fed near-IR imager
– Mid-IR, High Dispersion, AO Spectrograph
•
•
•
Build on extant concepts where possible
Define major design challenges
Identify needed technologies
Multi-Object Multi-Fiber Optical
Spectrograph (MOMFOS)
•20 arc-minute field
• 60-meter fiber cable
• 700 0.7” fibers
• 3 spectrographs, ~230 fibers each
• VPH gratings
• Articulated collimator for different resolution regimes
Resolution
Example ranges with single grating
• R= 1,000
350nm – 650nm
• R= 5,000
470nm – 530nm
• R= 20,000
491nm – 508nm
• Detects 13% - 23% of photons hitting the 30m primary
Prime Focus MOMFOS
Barden et al (2001)
Key Point-Design Features
(MOMFOS)
• MOMFOS located at prime focus
– Advantages
• Fast focal ratio leads to reasonably-sized instrument
• Adaptive prime focus corrector allows enhanced seeing
performance
– Disadvantages
• Issues of interchange with M2
MOMFOS
with Prime
Focus
Corrector
Conceptual design
fits in a 3m dia by
5m long cylinder
MOMFOS Spectrograph
Micro-Lens Relay
500 mm diameter
fiber fed by two
micro-lenses with
spherical surfaces
Field stop limits
light to 0.72” aperture
100% of light couples into fiber.
MOMFOS Spectrograph
R=20000
mode
R=5000
mode
R=1000
mode
500mm pupil; all spherical optics
350 nm
440 nm
500 nm
560 nm
650 nm
On-axis
Spot Diagrams for
MOMFOS
Spectrograph
R=1000 case with 540 l/mm
grating.
470 nm
Circle is 85 microns equal to
size of imaged fiber.
On-axis
R=5000 case with 2250 l/mm
grating.
Barden et al (2001)
485 nm
500 nm
515 nm
530 nm
MOMFOS Spectrograph
Predicted Efficiency
Near Infra-Red Deployable Integral
Field Spectrograph (NIRDIF)
• MCAO fed
• 1.5 to 2.0 arc-minute FOV
• 1 – 2.5 mm wavelength coverage
• Deployable IFU units
• 1.5 arc-second FOV per IFU probe
• 31 slices per IFU probe (0.048” per slice)
• ~26 deployable units
Near Infra-Red Deployable Integral
Field Spectrograph (NIRDIF)
Relay optics contained in deployable arm.
1.5 by 1.5 arc-second field of view.
f/38 to f/128 converter from MCAO field to image
slicer.
Telecentric input and output.
Cold stop located within relay.
Near Infra-Red Deployable Integral
Field Spectrograph (NIRDIF)
f/128 image slicer with 31 slices converted to f/11.5 for
the spectrograph.
Side view showing
top, middle, and
bottom slices.
Top view showing
top, middle, and
bottom slices.
Near Infra-Red Deployable Integral
Field Spectrograph (NIRDIF)
Spectrographs
• 2 IFU’s per spectrograph
• ~13 spectrographs
• R = 1000 to 10,000
• Z, J, H, and K spectral coverage (not simultaneous)
• 2 K detector format assumed
Mid-Infrared High Dispersion AO
Spectrograph (MIHDAS)
• Adaptive Secondary AO feed
• On-Axis, Narrow Field/Point Source
• R=120,000
• 3 spectrographs
• 2-5 mm (small beamed, x-dispersed), 0.2 arc-second
slit length
• 10-14 mm (x-dispersed), 1 arc-second slit
• 16-20 mm (x-dispersed), 1 arc-second slit
• 10-14 mm spectrograph likely to utilize same collimator as
16-20 mm instrument. Different Gratings and Camera.
• 2-5 mm spectrograph may require additional AO mirrors.
Mid-Infrared High Dispersion AO
Spectrograph (MIHDAS)
16-20 mm spectrograph will be large. Diffraction limit
at 20 microns is about ¼ arc-second, comparable to
native seeing limit.
Echelle grating is 1.5 meters in length! Overall
instrument is expected to take up a volume of
about 3 by 3 by 3 meters!
All of which needs to be cryogenically cooled.
Instrument to be located at Cass location and move
with the telescope.
Mid-Infrared High Dispersion AO
Spectrograph (MIHDAS)
45 l/mm X-disperser
26.5° blaze
~360 mm
R10 Echelle (84°)
7 mm/line
150 by 1500 mm\
m = 696 - 804
16 to 20 mm
1” slit length
.28” slit width
1024 by 1024 Si:As detector
MCAO Near-IR Imager
(1:1 Unfolded)
40 mm
Pupil
~2 arc minute field
MCAO Near-IR Imager
• f/38 input with 1:1 reimaging optics
• 1.5 to 2 arc-minute field of view
Monolithic imager  5.5 mm/arc-second plate scale!
 685 mm sized detector array for 2 arc-min field!
 28K by 28K detector!
 7 by 7 mosaic of 4K arrays
 0.004 arc-second per pixel sampling
Alternative approach is to have deployable capability
for imaging over a subset of the total field.
Instrument
Locations on
Telescope
• Prime Focus
• Co-moving Cass
• Fixed Gravity Cass
• Direct-fed Naysmyth
• Fiber-fed Naysmyth
View showing Fixed Gravity Cass
instrument
Instrument
Locations on
Telescope
View showing Co-moving Cass
instrument
Instrument Locations on Telescope
Fiber-fed
MOMFOS
MCAO-fed
NIRDIF
or
MCAO Imager
Cass-fed
MIHDAS
Information on AURA NIO activities is
available at:
www.aura-nio.noao.edu