[ATM] testing tunnel

[Dale Eason]

I use long aluminum poles that telescope into each
other.  The ends are held by old photographic light
stands that telescope and fold up like a camera
tripod.  I place 3M indoor window insulation film over
them as a shroud.  All is very light weight and
portable.  It does not do anything for the vibration
but I don't have the problem with Foucault.  For
interferometry I handle the vibration with a fast
shutter speed and some dampening under the mirror
table legs.

Mine is only 15 feet long.

Dale Eason
--- Guy Brandenburg <gfbrandenburg at yahoo.com> wrote:

> Has anybody ever put pencil to paper (or mouse to
> screen) and described their ideal testing tunnel?
> 
> I'm somewhat frustrated by the environment I
> currently have to do ronchi and foucault and
> what-have-you testing. There is too much floor
> vibration, and also too many air currents, and you
> have to open a large gate, and so on. One of our
> regulars brought in a very large 120VAC muffin fan
> to experiment with, in order to see whether a blast
> of air from the side on the mirror would improve
> things; it definitely made it WORSE, even when held
> in someone's hands so that vibration of the stand
> wouldn't be an issue. We tried numerous different
> angles.
> 
> I'm thinking of using surplus 2 by 8s to make a
> long, heavy table about 24 feet long and roughly 28
> inches wide, set along one wall of our workshop,
> with space underneath for storage of stuff. Why 24
> feet? Because we have defnitely had some projects
> that required a ROC of 20 feet, and it's proably
> best to arrange for even longer than that. On top
> would be some PVC or copper or galvanized plumbing
> pipe arranged in such a way as to hold a shroud. The
> shroud would probably start off being black roll
> plastic, but might eventually graduage to some sort
> of cloth, using loops designed to hold shower
> curtains in place. This would of course require
> moving massive amounts of stuff around in the
> basement of the center where we hold classes. And
> I'm worried that some of the cabinets and so on that
> I would have to put in front of the 24-foot table
> would inevitably block access to some places we
> would want to put mirrors in.
> 
> Any suggesionts would be more than welcome.
> 
> Guy Brandenburg
> 
> 
> "Thus, from the war of nature, from famine and
> death, the most exalted object which we are capable
> of conceiving, namely, the production of the higher
> animals, directly follows. There is grandeur in this
> view of life, with its several powers, having been
> originally breathed into a few forms or into one;
> and that, whilst this planet has gone cycling on
> according to the fixed law of gravity, from so
> simple a beginning endless forms most beautiful and
> most wonderful have been, and are being, evolved."
> - wrote Charles Darwin.
> Guy Brandenburg, Washington, DC
> My home page on astronomy, mathematics, education:
>
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
> or else 
> http://tinyurl.com/r6fh2
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 



 
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