KPAO system modeling

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KPAO system modeling

• Christopher Neyman Ralf Flicker
• for the KPAO team

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KPAO overview

• 2nd generation AO at KECK
• General Astronomy AO instrument
• Narrow field AO for near IR and visible
• Wavefront error goal of 120 nm RMS
• Multi LGS, single DM baseline architecture
• Conceptual design phase (05-06)

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KPAO ARCADIA

• Linear AO code, see Ellerbroek JOSA A1994
• single DM
• Only one on axis evaluation point
• 9m aperture
• 12 wfs apertures across pupil, actual KPAO needs
  2-3x
• Minimum variance reconstructor with knowledge of
  Cn2
• Indicates improved performance with
  focus/astigmatism sensing from the NGS
• Gains verified by our Monte Carlo simulations and
  others
• Is NGS focus sensing applicable to classical
  MCAO?
• Good performance with 3-5 LGS

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Single DM Tomography Error
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Monte Carlo simulation

• YAO simulation (Rigaut code)
• KPAO 140 configuration
• 5 LGS _at_ 90 km (32x32 SH WFS)
• 1 NGS (2x2 SH WFS)
• 1 DM _at_ 0 km, 33x33 actuators
• Virtual DM _at_ 8 km

LGS

• Virtual DM idea
• 2-DM tomography
• Projection vDM DM
• WFS correction term (for closed loop)

Virtual DM
DM
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YAO KPAO simulation contd.
KPAO 140 wavefront error budget
Focal Aniso.
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Future Design Work

• COW sparse matrix reconstructors (with SOY)
• Time filtering enhancements
• LGS propagation effects
• Wave optics effects
• Detailed AO design