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Widening the Scope of Adaptive Optics

Widening the Scope of Adaptive Optics. Matthew Britton. The Seeing Limit. Atmospheric Turbulence. Wavefront phase. Diffraction limited image. Seeing limited image. Diffraction limit. Seeing limit. Seeing limit (x40). Point source Sensitivity. Point source Sensitivity. Angular

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Widening the Scope of Adaptive Optics

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  1. Widening the Scope of Adaptive Optics Matthew Britton

  2. The Seeing Limit

  3. Atmospheric Turbulence

  4. Wavefront phase Diffraction limited image Seeing limited image

  5. Diffraction limit Seeing limit Seeing limit (x40) Point source Sensitivity Point source Sensitivity Angular Resolution Angular Resolution ~ D2 ~ D4 ~ D0 ~ D Long Exposure PSFs

  6. Palomar Seeing on Aug 20, 2005

  7. Turbulence Profiles

  8. Seeing Limited PSFs

  9. Adaptive Optics

  10. Adaptive Optics

  11. Neptune (Keck) NGC 7469 (CFHT) NGC 3603(VLT)

  12. Anisoplanatism

  13. Modeling the PSF OTFoa=OTFgs* ATF

  14. An Experiment at Palomar

  15. Turbulence theory Cn2 profile measurements Observations of a 21” Binary Guide Star Companion OTFgs * ATF= OTFoa

  16. Observed and Predicted PSFs

  17. Strehl Ratios vs. Time

  18. Predicted vs. Measured Strehls

  19. Fitting the Observation I(r) = OTFgs(r) + d * OTFoa(r) * exp{i q * r} d = differential photometry q = differential astrometry

  20. Differential Photometry Relative Intensity

  21. Differential Astrometry r q

  22. Observations of a Quadruple

  23. Modelling the Observation

  24. LGS Adaptive Optics

  25. Laser Tilt Indeterminacy Pilkington 1987 (Nature)

  26. Adaptive Optics with Lasers

  27. LGS PSFs on a 10 m Aperture

  28. Keck LGS observation Of M5 (Courtesy of the CfAO Treasury Survey)

  29. Advanced Wide Field Adaptive Optics

  30. 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 (-> time)

  31. Single Laser AO (SLGLAO) Poor to moderate performance over a modest field FOV = 70” (D / 30 m)(90 km / h)

  32. Ground Layer AO (GLAO) Poor performance Field uniformity

  33. Tomography

  34. Laser Tomography AO (LTAO) Good performance on axis

  35. Multiconjugate AO (MCAO) Good performance over 30” field

  36. Multiobject AO (MOAO) Intermediate performance over 5’ field

  37. 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…

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