Re: [ATM] Ultra-ThinEdgeSupportIdea-RE:[atm_free]ULTRA-THIN30"mirror from Hong Kong

[Jarvis Krumbein <jkoptic@juno.com>]

Arjan, take a look at the support system used on the 200" at Mt. Palomar.
 This is probably the best known example of a large astatic mounting for
a mirror.  Russel Porter did some very detailed drawings of the
arrangement which have been published in "The Glass Giant of Palomar" as
well as other publications.

Jarvis Krumbein

On Tue, 31 Jan 2006 09:42:45 +0100 "Arjan te Marvelde"
<arjan.te.marvelde@hetnet.nl> writes:
> Hi Nils Olof,
> 
> > Sorry, I don't see the mis-understanding here. Surely they work 
> (just
> > as "floating" supports do) by supporting the mirror's weight in 
> such a
> > way as to - if not prevent, at least minimize - mirror 
> deformation.
> 
> Of course the mirror weight has to be supported by the cell, but 
> what Mel
> points at is that the mechanism is essentially different.
> 
> Each astatic support asserts a force to the mirror, which is only 
> determined
> by the lever and its counterweight, and not by the mirrors' weight. 
> If you
> would have astatic supports only, they'd have to be tuned so that 
> the sum of
> their forces cancels the force caused by the mirror weight. 
> Otherwise the
> force imbalance will make the mirror move until it hits some 
> non-linearity.
> This is obviously hard to realize, so usually there will be three 
> fixed
> supports that take the residual mirror weight and hence also fix the
> mirrors' position.
> 
> Arjan
> 
> 
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