UCOLick Laboratory for Adaptive Optics Developing Adaptive Optics for the Next Generation of Astrono

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UCO/Lick Laboratory for Adaptive
OpticsDeveloping Adaptive Optics for the Next
Generation of Astronomical Telescopes

• Donald Gavel, Daren Dillon, Renate Kupke, Marc
  Reinig, Scott Severson, Mark Ammons, Eddie Laag,
  Jess Johnson , Katie Morzinsky, Carlos Cabrera,
  Bautista Fernandez, Luke Johnson
• UCO/Lick Observatory Laboratory for Adaptive
  Optics
• University of California, Santa Cruz
• Brian Bauman, Bruce Macintosh, Dave Palmer, Julia
  Evans, Lisa Poyneer
• Lawrence Livermore National Laboratory
• Astro 205
• November 15, 2006

Lick Observatory, Mt Hamilton, CA
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UCO/Lick Observatory Pioneering Laser Guide Star
Adaptive Optics

• LGS AO facility at Lick 3-m telescope routine
  science observing since 2001
• LGS AO at Keck 10-m telescope science observing
  starting 2005A

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Why do astronomers need AO?
Three images of a bright star
Lick Observatory, 1 m telescope
With adaptive optics
Long exposure image
Short exposure image speckles
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The Atmospheric Blurs Astronomical Images

• Temperature fluctuations in small patches of air
  cause changes in index of refraction (like many
  little lenses)
• Light rays are refracted many times (by small
  amounts)
• When they reach telescope they are no longer
  parallel
• Hence rays cant be focused to a point

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Point focus
Light rays affected by turbulence
Parallel light rays
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Diffraction-Limited Image FormationMarechals
Condition

• If the wavefront phase is contained within
  confocal spheres l/2 apart everywhere where the
  intensity is significant
• The waves will add up at the focus

wavefront surface

focus
Dx lt l/2
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Diffraction angle

• Tip/Tilt allowed by Marechals condition

D
fl/D
Dx lt l/2
f
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How AO Works
Light from both guide star and astronomical
object is reflected from deformable mirror
distortions are removed
Measure the wavefront from a guide star near
the object you want to observe
Calculate on a computer the shape to apply to a
deformable mirror to correct blurring
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How Adaptive Optics WorksInvert the wavefront
aberration with an anti-atmosphere (deformable
mirror)
Feedback loop next cycle corrects the (small)
errors of the last cycle
or other astronomical instrument
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AO movie from Shane Telescope AO system
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If there is no nearby star, make your own star
using a laser
Implementation
Concept
Lick Obs.
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Anatomy of a Laser Guide Star
The Guide Star Fluorescent scattering by the
mesospheric Sodium layer at 95 km
Maximum altitude of (unwanted) backscatter from
the air 35 km
Back scatter from air molecules
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Laser system on the Shane Telescope Lick
Observatory, Mt Hamilton, CA
D. Whysong
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LICK LASER
M. Perrin
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Science with the Lick AO System
LGS AO
Graham/Perin AO LGS Polarimetry goes here
NGS AO
Herbig Ae/Be stars (J. Graham, UC Berkeley)
Uranus
Asteroids and asteroid moons (F. Marchis, UC
Berkeley)
Quasar host galaxies (M. Lacy, LLNL, E. Gates, UC
Santa Cruz)
Neptune
Planets (F. Marchis, UC Berkeley)
Star cluster (E. Steinbring, UC Santa Cruz)
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Science with the Keck AO System

• Solar system studies (I. De Pater, UCB)

Keck AO image of Uranus at near infrared
wavelengths showing details of the ring structure.

• Black hole at the center of our Galaxy (A. Ghez,
  UCLA)

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Keck Telescope
http//www2.keck.hawaii.edu/optics/ao/
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Dye Laser
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DM used on the Keck AO System
349 degrees of freedom
Back View
Front View
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Next Generation Adaptive OpticsMultiple
Guidestar Tomography Volume Correction MCAO
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AO correction of a star 30 meter telescope
Uncorrected
Corrected
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Limitations for AO systems with one guide star

• Isoplanatic Angle

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Limitations for AO systems with one guide star

• Isoplanatic Angle
• Limits the corrected field

r0
q0
h
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Limitations for AO systems with one guide star

• Cone effect

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Limitations for AO systems with one guide star

• Cone effect
• Missing turbulence outside cone
• Spherical wave stretching of wavefront
• Limits the telescope diameter

r0
D0
h
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How tomography works
kZ
kX
Fourier slice theorem in tomography (Kak,
Computer Aided Tomography, 1988)

• Each wavefront sensor measures the integral of
  index variation along the ray lines
• The line integral along z determines the kz0
  Fourier spatial frequency component
• Projections at several angles sample the kx,ky,kz
  volume

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Equivalent layer thickness
r0
Q
Q Dz lt r0
Altitude, z
Dz
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Tomography error for a 30 meter aperture and CP
profile
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MCAO correction of a field of stars30 meter
telescope
Uncorrected
Corrected
Simulation performed by Jose Milovich on the MCR
supercomputer cluster at Lawrence Livermore
National Laboratory
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Laboratory for Adaptive Optics
Claire Max, Principal Investigator Joseph Miller,
co-Investigator Jerry Nelson, co-Investigator Dona
ld Gavel, Laboratory Director

• A permanent facility within the UCO/Lick
  Observatory located at the UC Santa Cruz campus

• Presently funded by a grant from the Gordon and
  Betty Moore Foundation
• LAO Goals
• Develop Adaptive optics technology and methods
  for the next generation of extremely large
  ground-based telescopes
• Develop and build a planet finder instrument
  using extreme adaptive optics technology

3. Develop, test, and evaluate new components and
key technologies for adaptive optics 4. Provide a
laboratory where students and postdocs will be
trained in adaptive optics design, modeling, and
implementation
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LAO Facilityin Thimann Labs Building, UCSC
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MCAO / MOAO Testbed
Interferometer reference beam
Open loop WFS path
Ref Flat
SLM
NGS
LGS
Guide star fibers
Far Field Camera

• Up to 8 wavefront guide stars and 4 tip/tilt
  stars
• 10,000 DOF per DM (100x100 subaperture Hartmann
  sensors)
• Up to 3 DMs (MCAO) or 1 DM and open loop WFS path
  (MOAO)
• 5 Hz sample control rate
• Moving phase plates (wind)
• Moving LGS fibers in z to simulate LGS
  elongation, or laser pulse

Configurable guide star constellation
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MCAO/MOAO Testbed in Operation
Ammons, et. al., SPIE 6272-175
Testbed commissioning results
1 LGS (Anisoplanatic)
3 LGS Tomography
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Micro-electo-mechanical System (MEMS) Deformable
Mirror

• MEMS device in the lab now
• 32x32 array
• 360m actuator to actuator
• Goals
• 64x64 array planet finder for 8 m telescope
• 100x100 array 30 m telescope general use

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MEMS deformable mirror with electrostatic
actuators
Simplified actuator model
Linear Spring

Moveable plate electrode
V
Fixed plate electrode
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4k Element Mirror Straightforward Extension of
Proven 1k Mirror Fabrication Process

• 64x64 element device
• High density wiring achieved through buried
  poly layer
• Wirebonding to off-chip electronics
• 1 device/100mm wafer
• Packaged in custom ceramic PGA chip carrier

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Boston University Boston Micromachines
Corporation Design
To get the same AO fitting error (Kolmogorov
turbulence) Npiston/Ncontinuous
6.2 Ntip-tilt/Ncontinuous 1.8 (C. Max, CfAO
website)
Continuous
Piston
Tip-Tilt
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Low-Order (Woofer) MEMS DMs

• Silicon membrane 10m 37-61 dof
• Piezo-bimorph 25m 36-100 dof
• Magnetic 100m 50 dof

Membrane DM
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Extreme Adaptive OpticsImaging Extrasolar
Planets
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ExAO Development and Instrument Prototype at the
UCO/Lick Laboratory for Adaptive Optics
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Visible Light Laser Guidestar AO System
Experiments

• Designed for Nickel 1-m Telescope, Mt. Hamilton
• Proof of concept for MEMS deformable mirrors in
  astronomical AO instruments
• PoC of AO uplink correction of laser beam
• In construction phase experiments start mid 2007

Nickel Telescope 1 meter Primary Mirror
ViLLaGEs Optical Bench
CCD Dewar Controller
Electronics Cabinet
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Laboratory for Adaptive OpticsSingle Conjugate
AO DemonstratorUsing a Membrane Deformable Mirror
Agiloptics Clarifi system
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Pyramid-Lenslet Wavefront Sensor Development
Johnson, et. al., SPIE 6272-165
Pupil images
Unaberrated
Defocused
Direct Phase (Interferometric) Readout
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Prototype MCAO tomography reconstructor
Implementation with massive parallel processing
for ELT AO
Student-led design project won Best Senior
Engineering Project award
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Visit us on the web http//lao.ucolick.org/