Widening the Scope of Adaptive Optics

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Widening the Scope of Adaptive Optics

• Matthew Britton

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The Seeing Limit
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Atmospheric Turbulence
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Wavefront phase
Diffraction limited image
Seeing limited image
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Long Exposure PSFs
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Palomar Seeing on Aug 20, 2005
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Turbulence Profiles
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Diffraction Limited PSFs
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Seeing Limited PSFs
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Adaptive Optics
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Adaptive Optics
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NGC 7469 (CFHT)
NGC 3603(VLT)
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Anisoplanatism
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(No Transcript)
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Modeling the PSF
OTFoa OTFgs ATF
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An Experiment at Palomar
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Observations of a 21 Binary
Companion

• Guide Star

OTFgs ATF OTFoa
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Why is this experiment important?

• Establish consistency of DIMM/MASS measurements
  and AO PSFs
• Test theoretical formulation of anisoplanatism
• If successful, allows PSF predictions over wide
  fields.

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Observed and Predicted PSFs
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Strehl Ratios vs. Time
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Predicted vs. Measured Strehls
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Differential Photometry and Astrometry

• M(x,y) A P(xDx,yDy)

A - differential photometry Dx,Dy - differential
astrometry
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Fitting the Observation
I(r) OTFgs(r) d OTFoa(r) expi q r
d differential photometry q differential
astrometry
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Fit Residuals
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Differential Photometry
Relative Intensity
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Differential Astrometry
r
q
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Observations of a Quadruple
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Modelling the Observation
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LGS Adaptive Optics
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Laser Tilt Indeterminacy

• Pilkington 1987 (Nature)

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Adaptive Optics with Lasers
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LGS PSFs on a 10 m Aperture
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Keck LGS observation Of M5 (Courtesy of the CfAO
Treasury Survey)
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Advanced Wide Field Adaptive Optics
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A Preliminary Comment

• Field dependence of the AO system performance is
  a function of
• Aperture diameter
• Observing wavelength
• Guide star configuration
• How the adaptive mirrors are deployed
• Zenith angle
• Turbulence conditions (-gt time)

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Single Laser AO (SLGLAO)

• Poor to moderate performance over a modest field
• FOV 70 (D / 30 m)(90 km / h)

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Ground Layer AO (GLAO)

• Poor performance
• Field uniformity

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Tomography
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Laser Tomography AO (LTAO)

• Good performance on axis

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Multiconjugate AO (MCAO)

• Good performance over 30 field

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Multiobject AO (MOAO)

• Intermediate performance over 5 field

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Conclusions

• There are a number of ways to provide wide field
  AO compensation.
• Postprocessing using turbulence profiles
• XXAO
• At least one of them is likely to work for your
  observations