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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1990
Loc: Hockessin, De
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Re: flat mirror tests
07/03/09 01:23 PM
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It seems that the major hang up on the water test is making collimated light, especially if you want to test a big flats since you need a big lens. I had to dig around for a couple of months before I found 8" plano convex lens to use. I couldn't find a fresnel lens with a long enough focal length. I'm wondering if a simple solution is inexpensive spherical reflector, the type that is used in commerical and house hold lighting ? The quality of the collimated light doesn't need to be perfect. A small neon blub is placed at the focus it is hung above the water container and then one uses a simple 45 degree window glass beam splitter to view the test.
One thing I thought to try is to add a water soluble polymer to the water. The polymer would increase the vicosity of the water but won't change the refractive index by much. The higher viscosity would dampen vibration much quicker. I have an article on doing the test from the British Ast. Society in which they add Gum of Aerobic to the water which is doing the same thing but not as well as high molecular weight polymer would.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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