[ATM] Re: Second Thoughts on Mirror Support

[tkrajci at san.osd.mil (Tom Krajci)]

>From: Jeff Anderson-Lee <jonah@eecs.berkeley.edu>

>The plate doesn't simulate it -- the RTV does.  

I disagree.  Pivots allow the mirror or support plate to flex...and at
the end of it all...the same support forces exist...assuming there is no
stiction in the pivots.  With a single plate, RTV'd to the mirror...as
the mirror or plate flexes...the forces at the support points change.  I
don't like the sound of that.  With a relatively non-thin mirror that
may work, but for thinner and thinner mirrors I think you are setting
yourself up for trouble.

>Make the plate thick 
>enough that it doesn't bend significantly and the RTV can probably make

>up the difference: a compliant cell!

I don't argue that the cell is compliant...but I have problems with "
the RTV can probably make up the difference"...especially the word
"probably."  Again, with thicker/smaller mirrors you are not pushing the
envelope.  Thinner/larger mirrors are probably outside the envelope for
this support scheme.

What other evidence is out there that this support scheme (single rigid
plate, RTV'd to mirror) works for various size/thickness mirrors?

Tom Krajci
Tashkent, Uzbekistan


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