[ATM] SEC: UNCLASSIFIED:-Primary Mirror Retainers

[jlerch1 at tampabay.rr.com (James Lerch)]

----- Original Message ----- 
From: "Bob May" <bobmay@nethere.com>


> Put any stress on the bolt in the center and you are flexing the mirror and
> it will show a trefoil shape to the stars as a result.
> Without the stress, stars at the horizon (with a thin mirror) will tend to
> get a wierd shape as the center will tend to tilt a bit causing a trail in
> the shape of the star although that shape won't be too strong.

Hi Bob,

The obvious answer is to drill a hole in the center of the mirror.  (I smile
while I say that, but there is a bit of honesty in the statement..)

If the hole is made large enough to accept a rather large sturdy rod with some
type of linear bearing (like Teflon or bronze sleeve), we can support the mirror
so it won't slide off the cell, but leave 4 degrees of freedom (tip, tilt,
piston, and rotation).  Ron is seriously considering this option on his 22" 3/4"
edge thick plate glass primary.  Ron's currently using (and cursing) a sling
support..


James