MMT RealTimeReconstructor

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MMT Real-Time-Reconstructor
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Hardware

• CPU Quad-core Xeon X5355 _at_ 2.66 GHz
• RAM 2GB
• OS CentOS with RTAI real-time extensions
• Frame Grabber EDT PCI-DV
• Serial link to tip/tilt computer

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Requirements

• NGS
• 216 subaperture slopes
• R matrix 216 45
• Up to 1kHz
• LGS
• 600 subaperture slopes (averaged by 5 in GLAO)
• R matrix 120 55
• Up to 600 Hz

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Operation AO system

• Initialization by separate control computer
• AO loop turned on but left open (no commands to
  DM)
• Loop closed System gain automatically set to
  zero
• User updated gain increased to finite number

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Inside RTR during closed loop

• Read frame from WFS camera
• A look up table (LUT) maps pixels to subapertures
  
• Background subtraction of subapertures
• Calculation of slopes via center of mass
• Linearization using LUT 1024 element vector
• Read tip/tilt signal from tilt computer
• Concatenate slopes from WFS and T/T

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Inside RTR cont.

• Matrix multiply slopes by R to get DM delta
  commands
• Read in DM position
• Final commands sent to mirror
• Delta command user gain 0.1 modal filter
  DM position
• (modal filter is 1 control space of R)

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• Old RTR layout