0
High-contrast AO for imaging extrasolar planets (formerly known as Extreme AO) Bruce Macintosh (LLNL)
Outline <ul><li>Science motivation for Extreme AO: Imaging extrasolar planets </li></ul><ul><li>Fourier optics with perfec...
 
Formation history is encoded in distributions Core acceretion + migration predictions (Ida&Lin 2004)
Orbital scattering in 3 body systems; Chatterjee et al. astro-ph/0703166 5 AU 50 AU
Disk fragmentation efficient at 10-20 AU Mayer et al. 2002  20 AU Q min =1.7 Q min =1.4 160 yr 350 yr
Doppler
Direct detection & spectroscopy of brown dwarfs Mclean et al 2003
Lafrienere et al 2007 (Gemini Planet Survey) etc.  GDPS
Uncertainty in luminosity of young planets Marley et al 2006 astro-ph/0609739 Previous models Low-entropy core accretion m...
Voyager “family portrait”
Conventional AO limited by scattered light Strehl ratio S Halo intensity 1-S
“ Extreme” AO (ExAO) gain > S/(1-S)
High-contrast AO PSF <ul><li>Fraunhoffer regime: focal plane and pupil plane are connected by Fourier transforms </li></ul...
Pupil electric field from aperture and phase Pupil plane Focal plane E(x,y) e     A = aperture    = phase a,   = fo...
Simple case: uniform phase Pupil plane Focal plane E(x,y) e     A = aperture    = phase a,   = fourier transforms o...
For small phase errors: Taylor expansion (Sivaramakrishnan et al 2002, Perrin et al 2003) Pupil plane Focal plane
PSF expansion
PSF terms <ul><li>Diffraction pattern term </li></ul>Airy pattern
aa *=|FT(A)| 2  is the diffraction term
Two-d Airy patterns
Coronagraphs <ul><li>Invented by Bernard Lyot in 1930 for studying the  corona  of the sun without waiting for an eclipse ...
How can we control diffraction? PSF =aa *=|FT(A)| 2 A PSF
Coronagraph 1: Gaussian apodization
Coronagraph 101: Blackman or Kaiser apodization <ul><li>A =0.42-0.05 cos[2  ( r +0.5)] +0.08 cos[4  ( r +0.5)] </li></ul...
Apodization in 2d
Shaped-pupil coronagraphs (Kasdin et al. 2003) Pupil PSF
Lyot coronagraph (Lyot, 1933) Starlight
Lyot coronagraph (Lyot, 1933) Planet Sivaramakrishnan et al 2001 has a nice 1-d analysis of how this works
Many new coronagraphs in recent years <ul><li>Explosion of coronagraph concepts in recent years </li></ul><ul><li>Lyot fam...
PSF terms <ul><li>Diffraction pattern term </li></ul><ul><li>Pinned speckle term </li></ul><ul><ul><li>Antisymmetric </li>...
d  /d
 
White noise White noise
AO architecture and terms D = primary mirror diameter DM conjugate  to telescope primary d=actuator spacing d WFS conjugat...
Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
AO architecture and terms D = primary mirror diameter DM conjugate  to telescope primary d=actuator spacing d WFS conjugat...
Phase Power spectra
Phase Power spectra
Band-limiting for anti-aliasing: spatial filter PSF intensity Position (arcsec)  /d ap
Spatial filter (Poyneer and Macintosh 2004) implementation Science Camera+Coronagraph Focal stop spatial filter   /d=0.9”...
Phase Power spectra
AO Timelag WFS measurement Inner working distance  ~3-5   /D Fitting error Outer working distance  ~N   /D
Random intensity of all the Fourier components produces speckles
(ExAO PSF movie goes here)
As speckles average out (  ~D/v wind ) planets can be detected
AO architecture and terms D = primary mirror diameter DM conjugate  to telescope primary d=actuator spacing d WFS conjugat...
ExAO 0 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
ExAO 1 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
ExAO 2 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
ExAO 5 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
ExAO and the Gemini Planet Imager <ul><li>2003: Basic ExAO feasibility study and Keck strawman </li></ul><ul><li>2004: Gem...
Calibration Module LOWFS Reference arm shutter LO pickoff Phasing Mirror Apodizer Wheel Woofer  DM & Tip/Tilt Linear ADC F...
High order high-speed AO (LLNL) <ul><li>MEMS deformable mirror </li></ul>Woofer DM Calibration/ Alignment Unit Spatially F...
Apodized-pupil Lyot coronagraph  (Soummer 2005) Apodizer Hard-Edged Mask Lyot Mask  Soummer 2005
Integral field spectrograph (James Larkin, UCLA) Detector Lenslet Array Collimator Optics Camera Optics Focal Plane Pupil ...
Spectrograph format <ul><li>Each spectrum is 16 pixels long, one of  YJHK ,   =50 </li></ul><ul><li>68,000 spectra on ...
Broad-band ExAO snapshot
ExAO spectral data cube James Larkin, UCLA
Fresnel optics effects (more complicated than simple Fraunhoffer model) cause speckles from aberrations near focus not to ...
GPI mechanical design  GPI enclosure Electronics Gemini Cassegrain support structure Optics structure Gort
GPI optical structure
VLT Planetfinder: SPHERE
Monte Carlo models of science performance (Graham&Macintosh)
Monte Carlo models of science performance (Graham&Macintosh)
ExAO can detect a significant population of planets Radial velocity detections GPI detections
Extrasolar planets H =8-11 mag H =5-8 mag H =4-6 mag
Space AO: Terrestrial Planet Finder <ul><li>Terrestrial Planet Finder Coronagraph (was 2020, now deferred) </li></ul><ul><...
Extrasolar planets H =8-11 mag H =5-8 mag H =4-6 mag TPF space coronagraph
Extrasolar planets H =8-11 mag H =5-8 mag H =4-6 mag Small TPF
A very large coronagraph
TPF Occultor (Webster Cash et al)
References <ul><li>Angel, R, “Ground based imaging of extrasolar planets using adaptive optics’, 1994 Nature 368, 203 (Ori...
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  • Until less than a decage ago all our knowledge of planet formation came form the solar system Comparison of the solar systems with exoplanetary systems is a reminder that we can’t learn about planet formation from samples of N=1
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    1. 1. High-contrast AO for imaging extrasolar planets (formerly known as Extreme AO) Bruce Macintosh (LLNL)
    2. 2. Outline <ul><li>Science motivation for Extreme AO: Imaging extrasolar planets </li></ul><ul><li>Fourier optics with perfect wavefronts – coronagraphs </li></ul><ul><li>Fourier optics with phase errors – High-contrast AO PSFs </li></ul><ul><li>ExAO system design: the Gemini Planet Imager </li></ul>
    3. 4. Formation history is encoded in distributions Core acceretion + migration predictions (Ida&Lin 2004)
    4. 5. Orbital scattering in 3 body systems; Chatterjee et al. astro-ph/0703166 5 AU 50 AU
    5. 6. Disk fragmentation efficient at 10-20 AU Mayer et al. 2002 20 AU Q min =1.7 Q min =1.4 160 yr 350 yr
    6. 7. Doppler
    7. 8. Direct detection & spectroscopy of brown dwarfs Mclean et al 2003
    8. 9. Lafrienere et al 2007 (Gemini Planet Survey) etc. GDPS
    9. 10. Uncertainty in luminosity of young planets Marley et al 2006 astro-ph/0609739 Previous models Low-entropy core accretion models Extreme AO regime Current AO surveys
    10. 11. Voyager “family portrait”
    11. 12. Conventional AO limited by scattered light Strehl ratio S Halo intensity 1-S
    12. 13. “ Extreme” AO (ExAO) gain > S/(1-S)
    13. 14. High-contrast AO PSF <ul><li>Fraunhoffer regime: focal plane and pupil plane are connected by Fourier transforms </li></ul><ul><li>(x,y) = pupil plane coordinates </li></ul><ul><ul><li>Natural coordinate system is in units of telescope diameter </li></ul></ul><ul><ul><li>x=x [m] /D </li></ul></ul><ul><li>(  = focal plane coordinates </li></ul><ul><ul><li>Natural coordinate system is in units of  /D </li></ul></ul><ul><ul><li> X  D  </li></ul></ul><ul><li>Spatial frequency 1/a <=> angular scale  /a </li></ul><ul><li>Upper case / lower case = fourier transform pairs </li></ul><ul><ul><li>Upper case for pupil plane </li></ul></ul><ul><li>e(  ) = FT[E (x,y)] </li></ul><ul><li>P,p = PSF (intensity) </li></ul>E e FT
    14. 15. Pupil electric field from aperture and phase Pupil plane Focal plane E(x,y) e  A = aperture  = phase a,  = fourier transforms of above
    15. 16. Simple case: uniform phase Pupil plane Focal plane E(x,y) e  A = aperture  = phase a,  = fourier transforms of above A |a| 2
    16. 17. For small phase errors: Taylor expansion (Sivaramakrishnan et al 2002, Perrin et al 2003) Pupil plane Focal plane
    17. 18. PSF expansion
    18. 19. PSF terms <ul><li>Diffraction pattern term </li></ul>Airy pattern
    19. 20. aa *=|FT(A)| 2 is the diffraction term
    20. 21. Two-d Airy patterns
    21. 22. Coronagraphs <ul><li>Invented by Bernard Lyot in 1930 for studying the corona of the sun without waiting for an eclipse </li></ul>
    22. 23. How can we control diffraction? PSF =aa *=|FT(A)| 2 A PSF
    23. 24. Coronagraph 1: Gaussian apodization
    24. 25. Coronagraph 101: Blackman or Kaiser apodization <ul><li>A =0.42-0.05 cos[2  ( r +0.5)] +0.08 cos[4  ( r +0.5)] </li></ul><ul><li>More complex functions can have higher contrast or better throughput </li></ul><ul><li>Apodizers in general are hard (impossible) to manufacture </li></ul>
    25. 26. Apodization in 2d
    26. 27. Shaped-pupil coronagraphs (Kasdin et al. 2003) Pupil PSF
    27. 28. Lyot coronagraph (Lyot, 1933) Starlight
    28. 29. Lyot coronagraph (Lyot, 1933) Planet Sivaramakrishnan et al 2001 has a nice 1-d analysis of how this works
    29. 30. Many new coronagraphs in recent years <ul><li>Explosion of coronagraph concepts in recent years </li></ul><ul><li>Lyot family: </li></ul><ul><ul><li>Basic: Lyot 1939 MNRAS 99, 538; Sivaramakrishnan et al 2001 </li></ul></ul><ul><ul><li>Band-limited: Kuchner & Traub 2003 </li></ul></ul><ul><ul><li>Apodized: Soummer 2005 Ap.J. 618, L161 </li></ul></ul><ul><li>Apodizers: </li></ul><ul><ul><li>Shaped-pupil: Kasdin et al 2003, Kasdin et al 2005 Applied Optics 44 1177, etc. </li></ul></ul><ul><ul><li>Phase-induced apodizer: Guyon et al 2005 Ap.J. 622, 744 </li></ul></ul><ul><li>Interference / wave-optics </li></ul><ul><ul><li>4-quadrant phase mask: Rouan et al 2000 PASP 777 1479 </li></ul></ul><ul><ul><li>Nulling interferometer/coronagraphs: Mennesson et al. 2004 Proc. SPIE 4860, 32 </li></ul></ul><ul><li>Optical vortices, many others… </li></ul><ul><li>Most practical coronagraphs only work at > 3-5  /D </li></ul><ul><li>Control of phase errors has been neglected </li></ul>
    30. 31. PSF terms <ul><li>Diffraction pattern term </li></ul><ul><li>Pinned speckle term </li></ul><ul><ul><li>Antisymmetric </li></ul></ul><ul><ul><li>Traces the diffraction pattern; vanishes when diffraction is negligible </li></ul></ul><ul><ul><li>See Bloemhof 2003, Perrin et al 2003 </li></ul></ul><ul><li>Halo term </li></ul><ul><ul><li>~=|  | 2 (power spectrum of  </li></ul></ul><ul><ul><li>Symmetric </li></ul></ul><ul><ul><li>Dominant source of scattered light in high-contrast AO! </li></ul></ul><ul><li>Strehl term </li></ul><ul><ul><li>Removes power from PSF core </li></ul></ul>
    31. 32. d  /d
    32. 34. White noise White noise
    33. 35. AO architecture and terms D = primary mirror diameter DM conjugate to telescope primary d=actuator spacing d WFS conjugate to DM & primary Atmosphere parameters: Coherence length r 0 Wind velocity v Deformable Mirror Collimating Lens Tip/Tilt Mirror Wavefront Sensor Dichroic Science Camera
    34. 36. Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
    35. 37. Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
    36. 38. Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
    37. 39. Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
    38. 40. Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
    39. 41. Phase Spatial frequency Power spectrum Spatial frequency Spatial frequency
    40. 42. AO architecture and terms D = primary mirror diameter DM conjugate to telescope primary d=actuator spacing d WFS conjugate to DM & primary Atmosphere parameters: Coherence length r 0 Wind velocity v Deformable Mirror Collimating Lens Tip/Tilt Mirror Wavefront Sensor Dichroic Science Camera
    41. 43. Phase Power spectra
    42. 44. Phase Power spectra
    43. 45. Band-limiting for anti-aliasing: spatial filter PSF intensity Position (arcsec)  /d ap
    44. 46. Spatial filter (Poyneer and Macintosh 2004) implementation Science Camera+Coronagraph Focal stop spatial filter  /d=0.9” Wavefront Sensor Deformable Mirror Dichroic
    45. 47. Phase Power spectra
    46. 48. AO Timelag WFS measurement Inner working distance ~3-5  /D Fitting error Outer working distance ~N  /D
    47. 49. Random intensity of all the Fourier components produces speckles
    48. 50. (ExAO PSF movie goes here)
    49. 51. As speckles average out (  ~D/v wind ) planets can be detected
    50. 52. AO architecture and terms D = primary mirror diameter DM conjugate to telescope primary d=actuator spacing d WFS conjugate to DM & primary Atmosphere parameters: Coherence length r 0 Wind velocity v Deformable Mirror Collimating Lens Tip/Tilt Mirror Wavefront Sensor Dichroic Science Camera
    51. 53. ExAO 0 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
    52. 54. ExAO 1 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
    53. 55. ExAO 2 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
    54. 56. ExAO 5 nm static errors, 5 MJ/500 MYr planet, 15 minute integration
    55. 57. ExAO and the Gemini Planet Imager <ul><li>2003: Basic ExAO feasibility study and Keck strawman </li></ul><ul><li>2004: Gemini “Extreme AO Coronagraph” Conceptual design begins </li></ul><ul><li>2005: CfAO team selected </li></ul><ul><li>2006: (June): Project start </li></ul><ul><li>First light: 2010 </li></ul>Team LLNL: Project lead + AO AMNH: Coronagraph masks&design HIA: Optomechanical + software JPL: Interferometer WFS UCB: Science modeling UCLA: IR spectrograph UdM: Data pipeline UCSC: Final integration&test
    56. 58. Calibration Module LOWFS Reference arm shutter LO pickoff Phasing Mirror Apodizer Wheel Woofer DM & Tip/Tilt Linear ADC F/64 focusing ellipse Dichroic Focal Plane Occultor Wheel IR spectrograph Collimator Beamsplitter Polarization modulator Lyot wheel Lenslet Stage Pupil Camera Zoom Optics Prism HAWAII II RG Pupil viewing mirror WFS Lenslet WFS P&C & focus SF Filter Wheel CCD Filter Wheel Entrance Window IR Self-calibration interferometer Artificial sources Pinhole IR CAL WFS CAL-IFS P&C & focus WFS collimator Dewar Window Filter Wheel Polarizing beamsplitter and anti-prism Gemini f/16 focus MEMS DM AO Coronagraph
    57. 59. High order high-speed AO (LLNL) <ul><li>MEMS deformable mirror </li></ul>Woofer DM Calibration/ Alignment Unit Spatially Filtered WFS 0.7-0.9  m GPI Window Focal stop spatial filter  / d =0.9” Commercial computer Fourier (predictive) control Superpolished optics (2 nm RMS) 18 cm 56 cm Subaperture I<9 mag. (V<11 aux.) R <13 mag. Guide star mag >0.9 0.4 Strehl @ 1.65  m Spatially-filtered SH 700-900 nm Shack-Hartmann 400 – 1000 nm Wavefront sensor 2000 Hz 670 Hz Control rate 4096 actuators (1809 active) 349 actuators (240 active) Deformable mirror GPI (2010) Keck AO (1999)
    58. 60. Apodized-pupil Lyot coronagraph (Soummer 2005) Apodizer Hard-Edged Mask Lyot Mask Soummer 2005
    59. 61. Integral field spectrograph (James Larkin, UCLA) Detector Lenslet Array Collimator Optics Camera Optics Focal Plane Pupil Plane Rotating Cold Pupil Stop Filters R.I. Telephoto Camera Lenslet Spectrograph Collimated light from Coronagraph Prism Window Low spectral resolution (R~50) High spatial resolution (0.014 arcsec) Wide field of view (3x3 arcsec) Minimal scattered light
    60. 62. Spectrograph format <ul><li>Each spectrum is 16 pixels long, one of YJHK ,  =50 </li></ul><ul><li>68,000 spectra on a 2048x2048 detector 4.5 pixel spacing </li></ul><ul><li>2.8 x 2.8 arcsecond field of view, 0.014 arcsecond pixels </li></ul>Single Spectrum
    61. 63. Broad-band ExAO snapshot
    62. 64. ExAO spectral data cube James Larkin, UCLA
    63. 65. Fresnel optics effects (more complicated than simple Fraunhoffer model) cause speckles from aberrations near focus not to subtract as well Marois et al. 2006, Spie O1 O2 O3 O4
    64. 66. GPI mechanical design GPI enclosure Electronics Gemini Cassegrain support structure Optics structure Gort
    65. 67. GPI optical structure
    66. 68. VLT Planetfinder: SPHERE
    67. 69. Monte Carlo models of science performance (Graham&Macintosh)
    68. 70. Monte Carlo models of science performance (Graham&Macintosh)
    69. 71. ExAO can detect a significant population of planets Radial velocity detections GPI detections
    70. 72. Extrasolar planets H =8-11 mag H =5-8 mag H =4-6 mag
    71. 73. Space AO: Terrestrial Planet Finder <ul><li>Terrestrial Planet Finder Coronagraph (was 2020, now deferred) </li></ul><ul><li>Original baseline: 8x3m mirror with advanced AO to correct internal errors </li></ul><ul><li>Coronagraph works at 4  /D -> 0.08 arcseconds for 8-m telescope </li></ul><ul><ul><li>Earth at 10 pc = 0.1 arcsec </li></ul></ul><ul><li>Various interim 2-4 m class missions proposed with more advanced coronagraphs </li></ul><ul><ul><li>2-3  /D coronagraph allows smaller telescope </li></ul></ul><ul><li>Some visible-light spectroscopy of Earthlike planets </li></ul>
    72. 74. Extrasolar planets H =8-11 mag H =5-8 mag H =4-6 mag TPF space coronagraph
    73. 75. Extrasolar planets H =8-11 mag H =5-8 mag H =4-6 mag Small TPF
    74. 76. A very large coronagraph
    75. 77. TPF Occultor (Webster Cash et al)
    76. 78. References <ul><li>Angel, R, “Ground based imaging of extrasolar planets using adaptive optics’, 1994 Nature 368, 203 (Original exoplanet paper) </li></ul><ul><li>Burrows, A., et al., “A nongray theory of extrasolar planets and brown dwarfs”, 1997 Ap.J 491, 856 (Planet models) </li></ul><ul><li>Sivaramakrishnan, A., et al., “Ground-based coronagraphy with High-Order Adaptive optics”, 2001 Ap.J. 552, 397 (Lyot coronagraphs) </li></ul><ul><li>Kasdin, N.J., et al, 2003, “Extrasolar planet finding via optimized apodized pupil and shaped pupil coronagraphs”, Ap.J. 582, 1147 </li></ul><ul><li>Kuchner, M, and Traub, W., “A Coronagraph with a Band-limited Mask for Finding Terrestrial Planets” 2002 Ap.J. 570, 200 (improved Lyot coronagraph) </li></ul><ul><li>Sivaramakrishnan, A., et al, “Speckle decorrelation and dynamic range in speckle noise limited imaging”, 2002 Ap.J. 581, L59 (2 nd -order PSF expansion) </li></ul><ul><li>Perrin, M., et al. “The structure of the High Strehl Ratio Point-Spread Functions”, 2003, Ap.J. 596, 702 (high-order PSF expansion) </li></ul><ul><li>Poyneer, L, and Macintosh, B., “Spatially-filtered wavefront sensor for high-order adaptive optics”, 2004, JOSA A 21, 810 (aliasing + WFS) </li></ul><ul><li>Guyon, O., et al. “Theoretical Limits on Extrasolar Terrestrial Planet Detection with Coronagraphs”, 2006 Ap.J.S. 167, 81 </li></ul><ul><li>Cash, W., et al, “The New Worlds Observer: using occulters to directly observe planets”, 2006 Proc. SPIE 2625 </li></ul>
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