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


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


5

How First Light Performance Requirements Drive AO Architecture Decisions


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


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


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


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


10

NFIRAOS on Nasmyth

Opto-mechanical layout

NFIRAOS Prototypes and Testbeds

96-channel DM drive electronics board

MCAO test bench


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


12

13

LGSF Optical Path Trade Study

• New OP• Baseline OP

TMT.AOS.PRE.13.081.DRF01


Work in Progress on Beam Duct Turbulence Modeling


14

Difference from mean interior air temperature

CAD model of Fold mirror array and relay lenses

AO Component Requirement Summary


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


16

DM Development

One-Quadrant Prototype LGS WFS CCDs


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


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


TIPC Nd:YAG SFG Guidestar Laser System


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


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


23

AO Performance

Estimate

(Zenith,median seeing,

50% sky coverage)


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


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)


26

• Median seeing

Median AO Performance vs. Galactic Latitude and Longitude (at Transit)


27

• Good (25%) seeing

High Precision Astrometry for Observations of the Galactic Center


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?


29

Progress in PSF Reconstruction


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.


32

adaptive optics for the thirty meter telescope brent ellerbroek thirty meter telescope observatory...

Documents

byrnes c

alexis hill c

matthias schoeck c

carlos correia c

jenny atwood c

spano paolo c

kei szeto c

malcolm smith c