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Defining Reference Turbulence Profiles for E-ELT AO P erformance Simulations

Defining Reference Turbulence Profiles for E-ELT AO P erformance Simulations. M. Sarazin, J. Ascenso, M. Le Louarn, G. Lombardi, J. Navarrete ESO. AO requirements Full Range Profilers Surface Layer Profilers Surface Layer and Enclosure. Cn2 profile. Has impact on 2 aspects:

december
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Defining Reference Turbulence Profiles for E-ELT AO P erformance Simulations

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  1. Defining Reference Turbulence Profiles for E-ELT AO Performance Simulations M. Sarazin, J. Ascenso, M. Le Louarn, G. Lombardi, J. Navarrete ESO AO4ELT3 - Florence, May 2013

  2. AO requirements • Full Range Profilers • Surface Layer Profilers • Surface Layer and Enclosure AO4ELT3 - Florence, May 2013

  3. Cn2 profile • Has impact on 2 aspects: • Simulation accuracy: we have to model enough layers to be representative of the “real atmosphere” • Have to reconstruct (in the RTC) the wavefront on enough layers to maximize performance (but not make a too big RTC) • Number of layers to model depends on the field of view and the position of the lasers. More layers for wider fields. • ~30-40 simulated layers would be needed for ATLAS(LTAO) / MAORY (MCAO) • To maximize performance, it seems that ~10 layers need to be reconstructed in RTC AO4ELT3 - Florence, May 2013

  4. Reconstructed Cn2 layers 42m case Tomographic NGS-based AO system simulated, with on-axis optimization. Size of the NGS constellation is variable. 26 simulated layers Simulated performance stabilizes after ~25-30 layers for LTAO 9 layers reconstructed out of 26 simulated: ~ same performance as 26 reconstructed  9 enough for reconstructed. AO4ELT3 - Florence, May 2013

  5. Used at ESO in red: • Ct2 Microthermal sensors on balloons (no SL) • SCIDAR • SLODAR • SLIDAR • MASS (no GL) • PBL (moon) Full range Cn2 profilers AO4ELT3 - Florence, May 2013

  6. MASS –Multi Aperture Scintillation Sensor • MASS is the perfect tool for site testing to assess: • the contribution of the high atmosphere to the seeing • the short term characteristics of the turbulence • and its seasonal trends AO4ELT3 - Florence, May 2013

  7. MASS weighting function km MASS algorithm response to a thin turbulent layer J=5.10-14m+1/3 real including scintillation noise in 6 layer mode (top) and in HD mode (bottom) See Kornilov, V., & Kornilov, M. 2011, Exp. Astron., 29,155 AO4ELT3 - Florence, May 2013

  8. E-ELT Environmental Specifications E-ELT Armazones: from LuSCI (blue) and MASS (white) profiles AO4ELT3 - Florence, May 2013

  9. Reconstructed Cn2 layers 6.4 arcmin 1.6 arcmin 3.2 arcmin Impact of split of the highest layer onto 2 independent layers (same energy per layer). Log-lin scale T. Fusco, Private communication AO4ELT3 - Florence, May 2013

  10. PARSCA: Paranal Seeing Campaign (1993-1994) 22 km A. Fuchs thesis, Nice University AO4ELT3 - Florence, May 2013

  11. PARSCA: Paranal Seeing Campaign (1993) All records from the 20 balloons launched from the foot of Paranal in March 1993 are merged into a single vertical profile AO4ELT3 - Florence, May 2013

  12. PARSCA: Paranal Seeing Campaign (1993) The single vertical profile after binning with 100m (200 layers) and 1000m (20 layers) AO4ELT3 - Florence, May 2013

  13. Balloon vs. MASS Profiles Comparison of balloon profiles from Paranal (red&black) to E-ELT Armazones MASS measurements (green) AO4ELT3 - Florence, May 2013

  14. Balloon vs. MASS Profiles Comparison of balloon profiles from Paranal (red&black) to E-ELT Armazones MASS measurements (green) – Log-log scale AO4ELT3 - Florence, May 2013

  15. SCIDAR vs. MASS Profiles MASS and SCIDAR agree well only in the high atmosphere Optical turbulence profiles at Mauna Kea measured by MASS & SCIDARTokovinin et al, PASP 2005 AO4ELT3 - Florence, May 2013

  16. Paranal multi-instrument Campaign (2007) W. Dali Ali et al, A&A 524, A73 (2010) AO4ELT3 - Florence, May 2013

  17. Proposal Create the required number (40? TBD) of simulated layers on the basis of an Hufnagel-Valley profile while respecting the fractions given in the E-ELT environmental specifications. We need to know from which height above ground to start AO4ELT3 - Florence, May 2013

  18. LUSCI (SHABAR) @Paranal&Armazones • SL-SLODAR @Paranal Surface layer profilers AO4ELT3 - Florence, May 2013

  19. LUNAR SCINTILLOMETER (Poster G. Lombardi et al) LuSci consists of a linear array of photo-detectors MEASURING THEFast MOONLIGHT fluctuations The optical turbulence profile is determined by using models of the turbulence spectrum and of the Lunar shape (Tokovinin et al. 2010). the profile is restored starting from fixed pivot points at 3, 12, 48, 192 and 768 m above the instrument.

  20. SLOPE DETECTION AND RANGING (Poster G. Lombardi et al) The SL-SLODAR uses an optical triangulation method observing wide separation binaries (> 100”). The profile is determined from the spatial covariance of the slope of the wavefront phase aberration at the ground for the two different paths through the atmosphere defined by a double star target (Butterley et al. 2006). Cn2(h) for 8 layers starting from the telescope pupil are provided with a resolution Δh that varies between ∼6 and ∼16 m depending on the binary separation (θ) and its zenithal distance.

  21. ΔJ VS WIND SPEED (Poster G. Lombardi et al) ΔJ = JSL-SLODAR − JLuSci simultaneous SL-SLODAR and LuSci integrals in the same range of altitudes ΔJ is more significant when the wind speed is < 3 m s−1.

  22. Surface Layer and Enclosure Does the turbulence come inside or flows around? AO4ELT3 - Florence, May 2013

  23. Surface Layer and Enclosure Does the turbulence comes inside or flows around? AO4ELT3 - Florence, May 2013

  24. Surface Layer and EnclosureWhat would be the image quality of the E-ELT at Paranal? AO4ELT3 - Florence, May 2013

  25. Surface Layer and EnclosureVLT-UT-SH vs. DIMM (any line of sight) UT1-SH seeing (10m-30m) versus DIMM seeing (6m) AO4ELT3 - Florence, May 2013

  26. Surface Layer and EnclosureVLT-UT-SH & MASS-DIMM Surface Layer (UT1-SH minus DIMM) vs. ground layer (DIMM minus MASS) AO4ELT3 - Florence, May 2013

  27. Surface Layer and EnclosureVST vs. DIMM (any line of sight) VST-OMEGACAM seeing (10m-20m) versus DIMM seeing (6m) AO4ELT3 - Florence, May 2013

  28. Surface Layer and EnclosureVST OMEGACAM & MASS-DIMM VST predicted image quality after removal from DIMM of surface layer estimated contribution AO4ELT3 - Florence, May 2013

  29. Work in Progress! Thank you AO4ELT3 - Florence, May 2013

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