RE: [ATM] Use of bearings in (static) mirror cells

["Koehler, Steve" <Steve_Koehler@securecomputing.com>]

Jerry,

> Personally, I like the idea of a cylinder surrounding the mirror with
> silicone inside between the mirror and the cylinder.

One thing I haven't seen mentioned in this discussion is the need to keep edge
supports from acting perpendicular to the mirror face.  I'm not sure your
silicone edge support would do this very well.

For example, if you collimate by raising or lowering one or more of the back
support pads (or pad groups), then the mirror must slide against the edge
supports without being held back.  (An alternative would be for the edge support
and back support to be part of a solid unit that is adjusted together in
collimation.  However, then it is necessary to make sure that stresses don't
build up within the unit due to varying expansion factors of different
materials, etc.)

A sling does well at avoiding forces perpendicular to the mirror face, as long
as it is kept parallel to the edge of the mirror all the way back to the support
bolts.  Various alternatives exist for two-point edges supports, such as using
roller bearings, or flexible piano wire studs.  Making the contact points
slippery with something like Teflon also helps.

-- Steve Koehler
   steve_koehler@securecomputing.com


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