[ATM] SEC: UNCLASSIFIED:-Primary Mirror Retainers

[Andrew.Martyn at defence.gov.au (Andrew.Martyn@defence.gov.au)]

Was thinking last night about mirror cell design and all the various
comments made recently about the pros and cons of RTVing mirrors to the
cell. I have always RTVed my mirrors using 3 or 4 point cells as they have
been full thickness mirrors of 10" or less and this has meant I have not
had to worry about retaining clips and I have not seen any mirror
distortion problems. However I was thinking of designs for a larger thinner
mirror and thinking of the benefits of a non RTV design mainly in terms of
the mirror not being distorted due to temperature changes changing the
shape and size of the mirror cell relative to the mirror. However, I do
like the idea of RTV in terms of mirror security.

So I though why not use RTV a nut to the centre of the mirror back. Then
through a hole in the mirror support pass a screw which locates into the
RTVed nut. The hole through the mirror support would be big enough to let
the mirror move around a bit but not big enough to let the screw head pass
through. This arrangement would stop the mirror from falling out of the
cell but not unduly restrain or apply a force on the mirror itself. Normal
non RTVed supports would then be used for the bottom and side of the
mirror.

I am probably reinventing the wheel, but does anyone see any problems with
this approach?

Andy