Re: [ATM] Testing Tunnel

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

Hmm. Thanks for the observations. I guess it will be necessary to isolate the testing stand from the mirror stand, rather than have them all on the same support.
Vladimir G wants me to invite Dale E to come and give a demo/talk on interferometery. Sounds like a winner. Dale?
Guy

G Gagne <gagne41@clearwire.net> wrote: Living in Florida means no cellar for testing mirrors so it had to be 
done in my garage. For testing my 12 inch mirror I purchased a 14 inch 
inside diam., 12 foot long "sonotube" used for pouring concrete columns. 
Cost was less than $50, delivered. I cut the tube to proper length and 
layed it across sawhorses, mounting the mirror at one end and the 
Foucault tester at the other. Being thick rolled paper and closed at the 
end by the mirror, it is extremely rigid, insulated,  and was completely 
devoid of air currents. Never any sign of  vibrations either.
I recently needed to test a 16 inch mirror for a friend but  the 
sonotube was too small. Instead, I set a 14 foot long, 4x6 wood beam 
across the sawhorses to support the mirror stand and Foucault tester. 
The slightest movement of the Foucault tester resulted in the most 
annoying vibrations in the images. The worst vibrations occured with 
Ronchi testing at the center of curvature with just one band showing. 
Some of the vibrations may have been air currents as they continued long 
after the apparatus should have been at rest.

Gil Gagne
Port Orange, FL

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"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."
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Guy Brandenburg, Washington, DC
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