1. Roy Coulter Institute for Astronomy/ UH
Active Occulter
Roy Coulter
Institute for Astronomy/ UH

2. 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

3. Active Occulter Concept
PI piezo electric bender, 60 V
200+ ±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

4. Active Occulter Concept (cont.)
5mm x 5mm stop
FOV = 128” x 128”
Irradiance = 2.5 W/mm2
% refl.
Thermal loads:
Limb image - 24 W
0.1 mm gap - 1 W
Occulter W ave.
Tracker slit - ~100 mW max