[ATM] New? Idea for mirror support

[iss at pvtnetworks.net (Andy Saulietis)]

Doug asks, re supporing a mirror with a central rod:



>Has anybody tried something like this?  Is this just another crazy idea that
>won't work?

The mirror will be restrained radially as you suggest, but there will also
be a moment (torque) applied to the back of the mirror, the amount 
dependiong on the
elevation angle. This torque can deform the center of the mirror.

Re mirror supports in general..I've found that there are no such
things as 'rigid' materials..when trying to maintin geometries
meaured in fractions of wavelenghths of light or arc seconds,
*evrything* is made of jello..<g>

I've supported perforated mirrors of 24-36" size using a central
tube attached to the cell..the center support has to be located
near the middle of the central hole so there's an equal amount
of mirror weight both in front of and behind the support.

I'v thought about restraining a mirror radially by attaching (with RTV)
radial dovetail slots to the back of the mirror..these slots are trapped by
a radial mating bars, each mirror support point (9, 18, 27 etc) has
one such slot/bar. The idea is that the mirror is now free to
expand/contract relative to the cell structure. The slots/bars
would have to have low stiction, but each one only carries a fraction
of the total weight..thoughts? Probably an overkill but I'm beginning
design of a 37" f4.6 alt-az & want to avoid the sling issues with
this large & thin (2") mirror.




Andy Saulietis
ISS Enterprises
10 Milky Way
PO Box 19
Mayhill NM 88339


World's first astronomy land development:

http://www.pvtnetworks.net/~iss/starend1.htm

9 of 17 lots sold to astronomers as of 1/04

505-687-3067 voice/fax, call voice or e-mail to set up
e-mail: iss@pvtnetworks.net