RE: ATM "Frozen" liquid mirrors

[Kurt Hillig <khillig@Chem.LSA.UMich.Edu>]

On Fri, 21 Feb 1997, Murray Foster wrote:

>       :       :       :       :       :       :       :       :
> Environment: A lot of attention is focused on creating vibration free
> environments when capturing holograms. There is a book that I have at home
> about do-it-yourself holograms. I think its called the "Hologram Making
> Handbook" (I'll get the correct title to you in the future). The basic
> method is to build a big sandbox and support it on partially inflated inner
> tubes (the small trailer sized ones). Sand is used because it provides a
> medium for positioning mirrors, lenses and film holders. For our purposes a
> good sized chunk of concrete would create a nice source of inertia for a
> stable platform that would dampen vibrations.

Sand is used in part because its high internal friction makes it effective
at damping vibrations; concrete, on the other hand, is *not* good at this!
We had a big cast concrete optical table in the basement here, made on the
assumption that a really massive structure would be very stable.  But when
you tapped it, it rang like a bell, and the folks who had it built went
through a lot of trouble trying to get it to work.  Ultimately it was
jackhammered apart and replaced with a conventional optical table.

A sandbox on inner tubes - even a couple sheets of plywood laminated
together - would be better than concrete!

                            Dr. Kurt Hillig
   Dept. of Chemistry      I always tell the    fax (313)647-4865
 University of Michigan     absolute truth     phone (313)647-2867
Ann Arbor, MI  48109-1055    as I see it.    X.500 khillig@umich.edu
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