Active Occulter

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Active Occulter

• Roy Coulter
• Institute for Astronomy/ UH

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Design Parameters

• Near limb observations with minimal scattered
  light
• Moving edge centered on optical axis for good
  occulting
• Radial motion and rotating assembly
• Must fit within 13mm field stop volume
• Radial slit sensing with offset bias for limb
  position adjustment
• Motion requirement a few arc seconds, 100 hz
• Thermal control via heat pipe technology
• Manual switching between observing modes

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Active Occulter Concept
PI piezo electric bender, 60 V 200 Hz _at_ 5
arc-sec Thermal control 3mm heat pipes
copper strap for occulting edge Permanent drive
system, insert bolted in place and stored on heat
stop Single photo sensor Rotation and limb
position set visually by observer
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Active Occulter Concept (cont.)
5mm x 5mm stop FOV 128 x 128 Irradiance
2.5 W/mm2 .375 W/mm2 _at_ 85 refl. Thermal
loads Limb image - 24 W 0.1 mm gap - 1
W Occulter - 0.7 W ave. Tracker slit - 100 mW
max