Adaptive Optics for the Thirty Meter Telescope Brent Ellerbroek Thirty Meter Telescope Observatory...
-
Upload
edwin-haynes -
Category
Documents
-
view
216 -
download
0
Transcript of Adaptive Optics for the Thirty Meter Telescope Brent Ellerbroek Thirty Meter Telescope Observatory...
Adaptive Optics for the Thirty Meter Telescope
Brent Ellerbroek
Thirty Meter Telescope Observatory Corporation
AO4ELT3
Florence, Italy
May 27, 2013
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
1
Brent Ellerbroeka, Sean Adkinsb, David Andersenc, Jenny Atwoodc, Arnaud Bastardd, Yong Boe, Marc-André Boucherc, Corinne Boyera, Dmitri Budkerf, Peter W. G. Byrnesc, Kris Caputac, Jeffrey Cavacog, Shanqiu Chenh, Carlos
Correiac, Raphael Coustyd, Joeleff Fitzsimmonsc ,Luc Gillesa, James Gregoryi, Glen Herriotc, Paul Hicksonj, Alexis Hillc, Zuo Junweie, Zoran Ljusicc, N. Marchetd, Angel Otarolaa, Dan O’Marai, Leo Myerk, Benoit Neichell, John Pazderc, Hubert Pagesd, Spano Paoloc, Robert Priorc,
Vladimir Reshetovc, Simon Rochesterf, Jean-Christophe Sinquing, Matthias Schoeckc, Malcolm Smithc, Kei Szetoc, Jinlong Tangh, Jean-Pierre Veranc,
Lianqi Wanga, Kai Weih, Ivan Weversc, and Sylvana Yeldak
aTMT Observatory Corporation, bW. M. Keck Observatory, cNRC Herzberg, dCILAS, eTechnical Institute of Physics and Chemistry, fRochester Scientific, gAOA Xinetics,
hInstitute of Optics and Electronics, iMIT Lincoln Laboratory, jUniversity of British Columbia, kUniversity of California at Los Angeles, lGemini Observatory
Contributors
2TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
Presentation Outline
TMT Project highlights
First light AO requirements review
Derived architecture and technology choices
Subsystem status report– NFIRAOS; LGSF
Component development– Deformable mirrors; wavefront sensing detectors; guidestar
lasers; real time controller
Modeling and algorithm development
Related papers at AO4ELT3
Acknowledgements
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
3
TMT Project Highlights
Site permit approved by the Hawaiian BLNR– Geotechnical studies and ground preparation to begin this year– Construction start date slated for April 2014
Construction Phase funding proposals under review in Canada, India, and Japan, and China
Yale University has committed to joining the Project
NSF Cooperative Agreement signed
Instrument design work progressing well– IRIS Preliminary Design Phase initiated May 2013– IRMS delta Design Review (from MOSFIRE) held April 2013– MOBIE Conceptual Design Review in September 2013
First light scheduled for 2022TMT.AOS.PRE.13.081.DRF01
AO4ELT3, Florence, Italy, 05/27/20134
First Light AO Requirements Review
3 science ports at f/15 with 2 arc min unvignetted field
High throughput (85% in J, H, K, and I bands)
Low thermal emission (15% of sky + telescope)
Diffraction-limited IR image quality on a moderate FoV– [187, 191, 208] nm wavefront error over a [0,17,30] arc sec field
High sky coverage (50% at galactic pole)
High photometric accuracy– 2% over 30 arc sec at l=1 mm for a 10 minute observation
High astrometric accuracy– 50 mas over 30 arc sec in H band for a 100 second observation
High observing efficiency
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
5
How First Light Performance Requirements Drive AO Architecture Decisions
6TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
High throughput Minimize surface count
Low thermal emission -30C operating temperature
Diffraction limited performance in J, H, K bands
Order 60x60 wavefront sensing and correction
30”corrected science field Atmospheric tomography + MCAO
High Sky coverage Laser guide star (LGS) wavefront sensing
NGS tip/tilt/focus sensing in the near IR
MCAO to “sharpen” NGS images
High precision astrometry and photometry on 30” fields
Distortion-free optical design form
MCAO for uniform, stable PSF
AO telemetry for PSF reconstruction
Available at TMT first light with low risk and acceptable cost
Utilize existing and near term components and system concepts whenever possible
High-order LGS MCAO with
NGS tip/tilt/focus sensing in the Near IR
First Light AO System Architecture and Technology Choices
7TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
Laser Guide Star Facility (LGSF)– Nd:YAG or Raman
fiber laser tech-nology
– Lasers mounted on telescope elevation journal
– Conventional beam transport (mirrors)
– Center-launch laser projection
Laser Systems
Beam Transfer Optics
Laser Launch
Telescope
First Light AO System Architecture and Technology Choices
8TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
Narrow Field IR AO System (NFIRAOS)– Piezostack
deformable mirrors and tip/tilt stage
– “Polar coordinate” CCD array for the LGS WFS
– HgCdTe CMOS arrays for low order, infra-red NGS WFSs (in client instruments)
NFIRAOS facility AO
Project Participants
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
9
CILAS, Orleans
(Wavefront Correctors)
TOPTICA, Munich
(Laser Systems)
TIPC, Beijing
(Laser Systems)
IOE, Chengdu (Laser Guide Star Facility)
TMT, Pasadena
(Management and SE)
Keck Observatory, Waimea (WFS readout electronics)
DRAO, Penticton
(RTC)
MIT/LL, Lexington
(WFS CCDs)
UBC, Vancouver
(Sodium LIDAR)
HIA, Victoria
(NFIRAOS)
Also Rochester Scientific (Berkeley, Sodium Atomic Physics)
AOA/Xinetics, Devens (Wavefront Correctors)
NFIRAOS Status Update
“Pre-Final” Design Phase is now underway
Prototyping/test activities include:– DM drive electronics development– DM breadboard testing– WFS lenslet testing– Instrument rotator interface– Component testing at -30C– MCAO lab bench development
Design work will include:– NGS WFS optics bench– LGS WFS zoom optics– NFIRAOS instrument support tower– FEA for vibration/thermal/seismic effects
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
10
NFIRAOS on Nasmyth
Opto-mechanical layout
NFIRAOS Prototypes and Testbeds
96-channel DM drive electronics board
MCAO test bench
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
11
Source simulators
LGS WFS Path
“Science” Path
Phase Screen
Location
DM’s
Recent LGSF Design Activities
Design updated for new MELCO telescope structure:– (Yet another) optical path trade study– 2-axis launch telescope flexure compensation system– Laser system and laser bench layout on telescope elevation
journal– Details of beam tube diameter, relay lens design, and top end
layout
Beam tube turbulence modeling underway
LGSF Preliminary Design phase scheduled to begin November 2013
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
12
13
LGSF Optical Path Trade Study
• New OP• Baseline OP
TMT.AOS.PRE.13.081.DRF01
AO4ELT3, Florence, Italy, 05/27/2013
Work in Progress on Beam Duct Turbulence Modeling
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
14
Difference from mean interior air temperature
CAD model of Fold mirror array and relay lenses
AO Component Requirement Summary
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
15
Deformable mirrors
63x63 and 76x76 actuators at 5 mm spacing
10 mm stroke and 5-10 % hysteresis at -30C
Tip/tilt stage 500 mrad stroke with 0.05 mrad noise
80 Hz bandwidth
NGS WFS detector
240x240 pixels, 4x4 pixels per subaperture
~0.8 quantum efficiency,~1 electron at 10-800 Hz
LGS WFS detectors
60x60 subapertures with 6x6 to 6x15 pixels each
~0.9 quantum efficiency, 3 electrons at 800 Hz
Low-order IR NGS WFS detectors
1024x1024 pixels (subarray readout on ~8x8 windows)
~0.6 quantum efficiency, 3 electrons at 10-200 Hz
Sodium guidestar lasers
25W (20W with backpumping), M2 < 1.17
Coupling efficiency of 130 photons-m2/s/W/atom
Real time controller
Solve 35k x 7k reconstruction problem at 800 Hz
Initial testing of the CILAS 6x60 actuator breadboard has been completed in early 2013– Good actuator-level performance at ambient and low
temperature (-30C)– Not all requirements met at the full breadboard level– New round of development underway
New study initiated at AOA Xinetics– Evaluate actuator performance at -30C– Develop DM conceptual designs meeting TMT performance and
interface requirements
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
16
DM Development
One-Quadrant Prototype LGS WFS CCDs
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
17
Front- and back-illuminated devices now tested– Meet specs for QE and CTE– Read noise of 2.7 to 3.7 e- at
3.5 MHz (3 e- requirement)– Dark current sufficiently low
for 800 Hz frame rate
BI devices have good yield – 3 of 8 probed CCDs show
very good performance– 99% of outputs functional,
99% low noise Black: QE spec and allowed nonuniformity
Red: Measuremented QE
(Courtesy Keck Observatory)
NGS WFS CCDs for NFIRAOS
MIT/LL CCID-74– 256x256 pixels– 64 planar JFET amplifiers
Testing of back-illuminated engineering devices now in progress at Keck– High QE as above (for Polar CCD)– Dark current of 26
electrons/pixel/second– Read noise approaches 1 electron
at 100 FPS– Candidate science grade CCDs
will be packaged for testing and potential use as the deliverable NGS WFS CCD for NFIRAOS
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
18
Engineering Grade Device in Test Station
Measured read noise at -15C with 32 Amplifiers
Guidestar Laser Systems
TMT continues to follow two laser development efforts:
Toptica/MPB frequency-doubled Raman fiber laser meets all TMT requirements for output power, line width, beam quality, volume, and power dissipation– some TMT interfaces will require development
Work on TIPC prototype SFG Nd:YAG laser is continuing:– Currently 18W@800Hz power for 100μs pulse– M2 ~ 1.5– Line width of 0.6 GHz, with 0.2 GHz wavelength stability
On-sky tests in early 2013 confirm high sodium coupling efficiency for a large spot size without repumping
Further on-sky tests (with repumping) planned later this yearTMT.AOS.PRE.13.081.DRF01
AO4ELT3, Florence, Italy, 05/27/201319
TIPC Nd:YAG SFG Guidestar Laser System
20TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
Laser System and Optical Schematic Lijiang Observatory, February 2013
Laser Coupling Efficiency (Sce) vs. IrradianceResults from Lijiang, China, February-March 2013
TMT.AOS.PRE.12.073.DRF01 21
Results were obtained for:
– Various Power Levels– 800 Hz or 600 Hz Pulse
Repetition Rate– Pulse lengths 95 to 100
micro-secs
Results, as expected, show the effect of optical saturation
TMT Specification: 120 Photos/W/s/(atoms/m2)
Sce at higher Irradiance levels can be improved with D2b repumping and may reach the TMT Specification
More tests with repumping and smaller spot sizes planned
Real Time Controller (RTC) Architectures
RTC architecture study now underway at NRC Herzberg and TMT to update RTC conceptual designs from 2008-09
Benchmarking and design of a GPU-based architecture is currently most advanced– 2 GPUs per WFS implement
gradient computation and matrix-vector-multiply (MVM) wavefront reconstruction
– Matrix updated at 0.1 Hz
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
22
Benchmark results: 0.95ms mean latency, 1.05 ms peak
Timing includes gradient computation, MVM computation, data transfer over 10 Gig ethernet
Recent Work in AO Modeling and Control Algorithm Development
AO Error budget maintenance and sky coverage analysis– Incorporates improved modes for optical surface errors and sodium range
tracking
Performance trade studies for OIWFS passband and detector choices
High precision astrometry
High contrast imaging
PSF reconstruction lab tests with GeMS
Analysis of LGS Fratricide amplitude for GeMS
On-instrument WFS guidestar acquisition
Distributed (computationally efficient) Kalman Filter tomography
LGS SLODAR for Cn2 _and wind velocity_ profile estimation
MCAO Lab Bench development at NRC-Herzberg also continuing
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
23
AO Performance
Estimate
(Zenith,median seeing,
50% sky coverage)
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
24
Term WFE, nm RMS
Delivered Performance 191
Higher-order error (LGS modes) 163
First-order turbulence compensation 132
Generalized fitting error 106
Noise-free estimation error 59
Servo lag 17
WFS noise and nonlinearity 52
Opto-mechanical implementation errors 71
TMT pupil misregistration 12
Telescope/enclosure wavefront 37
NFIRAOS wavefront 53
Science instrument wavefront 30
AO components and higher-order effects 66
Deformable mirrors 49
LGS WFS and sodium layer 39
Control algorithm implementation 21
Tip/tilt and plate scale (NGS controlled modes) 58
Telescope windshake 17
Telescope vibration and tracking error 20
Turbulence and measurement noise 52
Contingency 80
AO Sky Coverage vs. OIWFS Detector Option and Spectral Passband
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
25
Median seeing
Galactic pole guidestar densities
Zenith angles from 0 to 50 degrees
Widening the spectral passband from JH to JHKs improves sky coverage by ~10%
Switching from the H2RG detector to SELEX APDs would yield another ~5% improvement
191
Median AO Performance vs. Galactic Latitude and Longitude (at Transit)
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
26
• Median seeing
Median AO Performance vs. Galactic Latitude and Longitude (at Transit)
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
27
• Good (25%) seeing
High Precision Astrometry for Observations of the Galactic Center
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
28
Many sources of error have been investigated:– Photon, detector, thermal noise– Differential tip/tilt jitter– Distortions:
Probe arm positioning error
Geometric (static)– PSF estimation– Confusion
Single-epoch error budget:– Bright stars (K < 15): distortion
dominates (~8 μas)– Faint stars (K > 15): confusion
dominates (> 8 μas)
High Contrast Imaging
IRIS imager optics now included in modeling
NFIRAOS+IRIS equivalent to ~1h of Gemini/Keck in 30 s
Approaches GPI performance in 1-2 h, assuming 50x of SSDI speckle suppression (hard)– Better astrometry and higher
SNR for high res. spectroscopy– Fainter and more distant
targets?
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
29
Progress in PSF Reconstruction
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
30
• GEMs (Canopus) references sources and ground-conjugate DM used to generate long-exposure PSFs and simultaneous WFS telemetry
• PSFs with Strehls of ~40% estimated to within 1-2% relative error• Next step: Wide-field PSF reconstruction for MCAO using both DMs
Related Papers at AO4ELT3Schoeck 1010 Monday High precision astrometry
Hickson 0830 Tuesday Mesospheric sodium layer
Marois 1120 Tuesday High contrast Imaging
Ellerbroek 1140 Tuesday High precision astrometry
Gilles 1200 Tuesday LGS Fourier Tomography
Veran 1810 Tuesday RTC architecture study
Veran 1130 Wednesday Improved tilt sensing
Yelda 1700 Wednesday Galactic center astrometry
Thompson 1720 Thursday Vibration requirements
Simard 0830 Friday TMT Science
Lu 0950 Friday Astrometry with MCAO
Wang 1120 Friday GPU-based RTC
Wang Poster NFIRAOS sky coverage
Herriot Poster T/T/F NGS Acquisition
Herriot Poster RTC timing jitter specifications
Otarola Poster GeMS fratricide analysis
Gilles Poster PSF reconstruction 31
Acknowledgements
The TMT Project gratefully acknowledges the support of the TMT partner institutions.
They are– the Association of Canadian Universities for Research in Astronomy (ACURA),– the California Institute of Technology– the University of California– the National Astronomical Observatory of Japan– the National Astronomical Observatories and their consortium partners– And the Department of Science and Technology of India and their supported institutes.
This work was supported as well by– the Gordon and Betty Moore Foundation– the Canada Foundation for Innovation– the Ontario Ministry of Research and Innovation– the National Research Council of Canada– the Natural Sciences and Engineering Research Council of Canada– the British Columbia Knowledge Development Fund– the Association of Universities for Research in Astronomy (AURA)– and the U.S. National Science Foundation.
TMT.AOS.PRE.13.081.DRF01AO4ELT3, Florence, Italy, 05/27/2013
32