Light baffling
This included:
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coating the mirror box with fiber-impregnated flat black paint (Rosco "velour black" ultra flat theater set paint, mixed with coarse sawdust), |
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using this same paint on aluminum flashing baffle material mounted behind the mirror, |
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using this paint to liberally coat the inside of the secondary cage |
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putting Protostar flocking paper on the part of the secondary cage opposite the focuser |
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using spare flocking paper to cover the part of each truss tube most likely to "bounce" light onto the primary, |
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adding PVC "triangles" to fill the gap between the shroud and the corners of the mirror box, |
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and adding hardware to ensure that the Astrosystems shroud overlapped with the mirror box sides. |
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Since the exhaust vents for the four 80mm side fans were located on the side of the mirror box that would face the most incoming light (from above), baffling was critical. I opted to make a hinged vent that could be opened to provide excellent blocking of any light leakage through this area, but which can also be closed when the scope is not in use to avoid allowing dust an easy path to the mirror. |
The result? A light-tight optical path!
This view of the upside down mirro box shows the black paint and the underside of the fan vent, with its sides folded in.
Daytime (worst case) view down OTA past the primary mirror-- needs baffling!
Baffle pieces-- the left two show their black side (which will face the mirror), the right two their blue enameled backs
The completed baffles in place. (The gap in the center is the intake area for the 120mm fan. The fourth strip of baffling that runs the width of the mirror box below the lower collimation "star" is not visible in this image.)
Same daytime view with baffles installed
Daytime glare off the taped truss tubes.
Flocked vs. Unflocked truss tubes-- the one on the left has a ~1" wide strip of Protostar flocking paper on it, facing the mirror. Makes a big difference, eh?!
Plastic triangles used to seal top corners of mirror box-- which shroud does not cover--against stray light
Side fan vent closed
Side fan vent open
View up through the opened fan vent. For light from above to reach this angle, the scope would have to be pointed near horizontally!
