Transcript Canary Phase A FDR

The on-sky NGS/LGS MOAO
demonstrator for EAGLE
Tim Morris
Durham University
Talk overview
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MOAO with EAGLE
CANARY concept
Optomechanical design
Subsystem performance
System performance
System calibration tasks
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
MOAO with EAGLE
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With the current baseline design, EAGLE will:
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E-ELT has a deformable ‘secondary’ that will be used as
a closed-loop woofer (GLAO-like DM)
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use 6 LGS and up to 5 NGS to map the turbulence above the EELT
correct up to 20 x ~2” diameter science fields anywhere within
the central 5’ diameter field using open-loop AO
250Hz frame rate
EAGLE is both a closed and open-loop system
30% ensquared energy with 75mas (H-band) required
performance
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
MOAO with EAGLE: big questions
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Can we achieve tomographic reconstruction to the required
accuracy over such wide fields?
Can we reliably control a DM in open-loop?
How do we calibrate the system?
How accurately do we need to measure the Cn2 profile to optimise performance?
What is the impact of running the system with both open and closed loop DMs?
How do we compensate for LGS specific effects that can impact MOAO
performance?
What are the principle performance drivers required when designing an MOAO
system?
What is the best way to combine both NGS and LGS WFS signals to measure
tomography?
Answer as many of these questions as possible as soon as possible
to feed into the EAGLE design
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Some can be (and have been) answered in simulation or using a lab
system such as SESAME
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
CANARY concept
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
CANARY Aims
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Perform NGS then LGS based tomographic WFSing
Perform open-loop AO correction on-sky
Develop calibration and alignment techniques
Fully characterise system and subsystem performance
Create a single MOAO channel EAGLE as closely as
possibly using the 4.2m William Herschel Telescope
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Effectively a 1/10th scale model of E-ELT using a 10km Rayleigh
LGS
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
CANARY phased development
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Based around a set of reconfigurable optical
modules to allow ‘easy’ changes between three
CANARY phases
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Phase A: Low-order NGS-only MOAO (2010)
Phase B: Low-order LGS MOAO (2011)
Phase C: High-order LGS + NGS MOAO (2012)
All phases will include an extensive calibration
and diagnostics package
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Diagnostics and Performance monitoring
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On-axis NGS WFS behind AO corrected focal plane
(Truth Sensor)
 On-axis NIR imaging camera (Science Verification
Camera)
 High-order high-bandwidth DM figure sensor
 SLODAR analysis performed using open-loop WFSs
 External turbulence profilers
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SLODAR
MASS-DIMM
Telescope simulator
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Turbulent phase screens
NGS and LGS alignment and calibration sources
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Phase A : NGS MOAO
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Components:
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Low-order 8x8 DM
3 x L3CCD open-loop NGS WFSs
Open-loop optimised Fast Steering
Mirror
Hardware accelerated Real Time
control system
NGS MOAO Calibration Unit
10" Truth sensor
& IR camera FOV
NGS WFS
NGS WFS
NGS WFS
Phase A: NGS MOAO
WHT
Nasmyth
Science
Verification
GHRIL
Derotator
NGS
Pickoffs
Calibration
Unit
3 x NGS
WFS
AO4ELTs, Paris 2009
NGS
FSM
Low-order
DM
Truth
Sensor
Figure
Sensor
CANARY: NGS/LGS MOAO demonstrator
2.5’
Derotated
WHT field
Tim Morris et al
Phase B: Low-order LGS MOAO
GLAS
BLT
WHT
Nasmyth
Diffractive
Optic
GHRIL
Derotator
Calibration
Unit
Phase B: Low-order
LGS MOAO
LGS
Rotator
LGS
Dichroic
LGS
Pickoffs
GLAS
Laser
Figure
Sensor
3 x NGS
WFS
NGS
FSM
Low-order
DM
NGS
Pickoffs
Science
Verification
Truth
Sensor
LGS
FSM
1.5’ Diameter
LGS asterism
4 x LGS
WFS
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New modules include:
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Electronically shuttered LGS WFS CCD
Modified GLAS launch system
LGS dichroic and relay system
LGS MOAO Calibration Unit
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
LGS
WFS
Tim
Morris et al
Phase C: High-order LGS MOAO
GLAS
BLT
WHT
Nasmyth
Diffractive
Optic
GHRIL
Derotator
LGS
Rotator
NGS
FSM
Figure
Sensor
GLAS
Laser
Low-order
DM
Calibration
Unit
Phase C: High-order woofer-tweeter
LGS MOAO (woofer closed loop)
LGS
Dichroic
NGS
Pickoffs
LGS
Pickoffs
3 x NGS
WFS
LGS
FSM
MEMS
DM
Science
Verification
Truth
Sensor
4 x LGS
WFS
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Closest resemblance to proposed EAGLE MOAO implementation
Largest upgrade here is to the RTCS. From Phase B we have:
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~ 2 times increase in pixel bandwidth
~ 5 times increase in slope bandwidth
~ 17 times increase in actuator bandwidth
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Optomechanical design
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Phase A optical design
Output focal plane
Input Focal Plane
AO4ELTs, Paris 2009
Truth Sensor focal plane
Science Verification Camera focal plane
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Phase B optical design
LGS TT mirror
Acquisition camera moved to
input focal plane
AO4ELTs, Paris 2009
NGS WFS placed at
corrected focal plane
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Phase C optical design concept
LGS WFS(s) moved behind
closed-loop DM
AO4ELTs, Paris 2009
Possible locations of
MEMS MOAO DM
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
NGS WFS Assembly
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Telescope Simulator
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Subsystem performance
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Open-loop DM Control
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4% open-loop error with hard PZT DM demonstrated in
laboratory with SESAME
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Figure sensor could be used to control any long term
drifts in DM surface shape
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40nm RMS error if a 1000nm RMS DM surface is requested
Will introduce some additional latency
Has been used with a Xinetics DM and produces a similar
surface error to the hard PZT DM
Open loop control of a DM doesn’t seem to be a problem
for CANARY low-order DM
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High-order MEMS DM open-loop control has already been
demonstrated
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Subsystem performance: LGS Launch
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Test system installed on WHT and tested in May
Uses DOE in GLAS launch system to create a 4 star asterism (MMT
approach)
 Several possible asterisms available by changing DOE
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80% of light into 4 diffracted LGS beams but altitude is lowered c.f. GLAS
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10 to 90” diameter asterisms (takes about 15 minutes)
Still want an upgraded laser to increase WFS SNR
Software problem with LGS detector meant range gated images couldn’t be
obtained
Non-gated image of ~40” LGS
radius asterism at 6.7km
AO4ELTs, Paris 2009
DOE mounted in rotation stage at
GLAS BLT entrance
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
RTCS
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Hybrid FPGA-CPU Realtime Control System
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Currently runs at Phase A/B at 300-400Hz using a single
threaded reconstructor pipeline
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FPGA pixel processing developed for HOT and SPARTA
Reconstructor in CPU
DM control in CPU
Latency and jitter to be measured
Upgrade required to cope with high-order LGS WFSs
and DM in Phase C
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Parallelise reconstructor
GPU acceleration
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
RTCS overview
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
System performance
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Phase A Performance
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Monte-Carlo simulations performed using independent codes in Durham
and Paris
 Single open-loop DM
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3 x NGS WFSs
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Off-axis (30” to 90”)
7 x 7 subapertures
0.1e- read noise
Mv = 8 to 14
250Hz frame rate
Representative summer La Palma turbulence profile used1
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8x8 actuators
DM (and science path) on-axis
r0 = 12cm
45% @ 0km
15% @ 2.5km
30% @ 4km
10% @ 13.5km
Fuensalida et al, RevMexAA, 31, 84-90 (2007)
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Simulated Performance
Source of error
WFE (nm rms)
WFS open-loop estimation
63 (from YAO)
WFS noise (quantum + readout)
40 at mR=10
80 at mR=12
190 at mR=14
Tomographic reconstruction (30’’ radius)
260 (GLAO least-square)
220 (tomographic least square)
170 (L&A MMSE) (Vidal et al)
DM fitting
140
DM open-loop error
48
Tip-tilt open-loop error
26
Temporal and aliasing
113
Residual high-orders from optics
50
TOTAL
mR=12 : 285 to 340
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Error terms
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Principle term is tomographic reconstruction
error
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Have identified several suitable targets within a
2.5’ diameter FOV observable between JuneOctober
Will be even worse with the 10km Rayleigh LGS
at Phases B and C
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30” radius means metapupils at highest turbulent
layer are almost completely separated
30” is still pretty small to find a 4-star mv = 12
asterism
Requires the external turbulence profiling to
determine how much of the turbulence is above
the LGS
The Truth Sensor will be used as the principle
system diagnostic
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Science camera can be used when the
turbulence cooperates
>60% turbulence in the ground layer is often
observed at the WHT
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
System Calibration
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Phase A calibration
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Interaction matrix measurement using a
reverse path calibration source
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NGS WFS pickoff prism
From reverse path
calibration source
Or use TS to measure DM influence functions
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On-axis point source pointing backwards at
output focal plane can be observed by each
NGS WFS in turn
Requires stable pupil image at lenslet array
across full FOV
Or measure matrices on-sky
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To
WFS
Observe ground-layer only turbulent sources
within the telescope simulator with NGS WFSs
and TS
Translate TS measure influence functions to
each DM
From telescope
Learn and Apply method from Fabrice Vidal first
thing this morning
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Other calibration tasks
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Field dependent aberrations
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Non-common path error compensation
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Confirm with full field acquisition camera
Detector calibration
At Phase B/C:
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Use sources in NGS focal plane
NGS pickoff positioning accuracy
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Deployable point sources in most focal planes
Some pointing backwards for reverse path calibration
WFS linearity/gain optimisation (for WCOG etc.)
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Pupil image stability is <1/100th pupil diameter
Monitoring and compensation changing field aberrations
LGS WFS offsets/centroid gain
Range gate setting and optimisation
LGS WFS interaction matrix
To be developed further during the Integration and Testing phase
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Runs from October 09 – April 10
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
Conclusions
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Already answered some of the big questions that MOAO
with EAGLE raises
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Open-loop DM control
Several calibration schemes proposed
CANARY will have the capability to answer the
remaining ones by demonstrating and testing wide-field
LGS tomographic AO
Critical subsystems are being testing and the initial
integration phase is about to begin
We’re on track to go on-sky mid 2010 with the Phase A
NGS tomography experiment
Phase B design to be reviewed at the end of this year
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
The CANARY team
Durham
Richard Myers, Gordon Talbot, Nigel Dipper, Deli Geng, Eddy
Younger, Alastair Basden, Colin Dunlop, Nik Looker, Jonny
Taylor, Mark Harrison, Tim Butterley, Dani Guzman, Laura
Young, Simon Blake, Sofia Dimoudi
Obs. Paris
Zoltán Hubert, Gerard Rousset, Eric Gendron, Fabrice Vidal,
Damien Gratadour, Aglae Kellerer, Michel Marteaud, Fanny
Chemla, Phillipe Laporte
UKATC
Andy Longmore, David Henry, Stephen Todd, Colin Dickson,
Brian Stobie
ONERA
Thierry Fusco, Clelia Robert, Nicolas Vedrenne
ING
Jure Skvarc
PUC Santiago
Andres Guesalaga
Herriott-Watt
Alan Greenaway, Heather Dalgarno
Engineering and
Project Solutions Ltd
Kevin Dee
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al
CANARY capabilities
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CANARY can:
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Perform, calibrate and characterise accuracy of open-loop LGS
tomography on-sky
Measure/monitor everything to make sure we understand performance
of each component as well as the system as a whole
Develop alignment and calibration techniques
Combine several off-axis NGS and LGS WFSs to map the turbulence
Eventually use a closed-loop woofer and open-loop tweeter
Emulate arbitrary LGS intensity profiles and elongation
CANARY cannot:
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Reach EAGLE performance goal
Match the total number of subapertures/actuators within EAGLE
Match the exactly LGS/NGS FOV afforded by the E-ELT
Take advantage of the multiplex normally afforded by MOAO – only a
single channel
AO4ELTs, Paris 2009
CANARY: NGS/LGS MOAO demonstrator
Tim Morris et al