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Originally Posted by bird
I've thought about it, mainly because I could separate the cooling stage (refrigerator) from the main body of the scope and save some weight. I would probably use a jacket that enclosed the rear and side of the mirror with a gasket of some sort to seal around the edge near the front surface.
Wasn't sure what coolant I would try, some light oil or water + antifreeze. Need to be sure that it doesn't affect the mirror chemically.
The down side is that it is not as portable as the current setup, and anything with liquids is messy...
cheers, Bird
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Hi Bird,
Correct me if I'm wrong, but from the look of the scope it's using an alloy/metal tube? Have you thought about wacking a Peltier cooler on the tube?
A few thoughts based on the cooling systems I used on the camera.
The use of formed copper or stainless steel tubing (thin wall) works extremely well. A coil that spirals round the back of the tube beind the mirror cell (like your current cooling plate) and then around the edge of the mirror. Gasket using thin neoprene and use swaged connectors.
For the cooling pump, a double or triple peltier pump running on to a copper (best) or aluminium cylinder with copper pipe coiled around it (10~20 turns works well), lag well with insulation. A windscreen wiper or heavy duty fishtank pump with good quality silicon tube would be ideal for the interconnections between the refrigeration unit and cooling coil. One thing that is needed is a trap/reservoir to remove air from the lines, this only needs to be a 1L bottle with an inlet and outlet pipe brought the top lid with the pipes immersed at unequal lengths in to the coolant. The outlet pipe should be at a lower level.
For coolant, I used a silicon based industrial coolant which is probably overkill, something like Dynalene HC50 or possibly Paratherm HC etc would do the trick. Avoiding water based products unless they have a good corrosion inhibitor in them for obvious reasons!
Of course the ideal way to dispose of the internal temperature gradient of a mirror would be to fit coolant lines inside the mirror, something that would not be impossble to do with a mirror blank and some of the current hole drilling technologies.
Cheers,
Ian