Re: [ATM] Lateral mirror support test cases measured with interferometer

["Tom Krajci" <tom_krajci@tularosa.net>]

Note:  This is from Dale Eason.  I am forwarding it to the list at his
request.

Tom Krajci

-----Original Message-----
From: Dale Eason [mailto:atmpob@yahoo.com]
Sent: Saturday, 2006-December-02 23:26
To: Tom Krajci
Subject: Re: [ATM] Lateral mirror support test cases measured with
interferometer


Tom,
>From the other images you should be able to see that
the mirror is sitting on the support and that almost
all of the mirrors weight is supported by that
support.

The nylon support is very slippery on the polished
glass edge.  So much so that the 20 lb mirror will
slide on them with about 2 onces of out of face plane
force applied.  You can be assured that most of the
force is directed toward the center of the mirror
otherwise the mirror would slide off.  They were
picked for that exact reason and the stand tilted back
a little for that reason.

Another prof of little out of mirror plane force is
given since I state that the stand was tilted back
about 5 degress and yet when the support is close to
the back edge of the mirror it deforms the mirror face
back toward the test stand.  If there were friction
forces with the edge it would be more likely to deform
the edge away from the test stand as the mirror tries
to force its way through the back pads to the test
stand.

Yes there are two ways latteral supports can deform
the mirror, forces out of mirror plane due to friction
and forces not applied to the center of mass.

To clarify the study only measures the center of mass
problem.  So keep that sling, chain, or whatever on
the center of mass.


Dale Eason

--- Tom Krajci <tom_krajci@tularosa.net> wrote:

> Thanks for the photos in this document!  They show
> where the lateral support
> is placed relative to the mirror's edge (center of
> mass) in various tests.
> But they don't show the forces being applied by the
> lateral support(s).  I
> can assume that the force applied is
> normal/perpendicular to the mirror's
> edge...but I can't be certain because this support
> setup probably can apply
> force that is not normal to the mirror's
> edge...thanks to the shape of the
> support, and the presence of friction between the
> support and the mirror
> edge.
>

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