Re: [ATM] Re:Tees instead of triangles

[Ken Hunter <atm_ken_hunter@yahoo.com>]

With a 3 inch thick blank, thermal equilibrium is
going to be a much worse thing to worry about than
cell induced deformations... Ensure that the blank has
either a controlled environment (cooled to expected
nighttime temps) or active cooling that tracks the
current temp. 

We had 16 inch scopes on Kitt Peak that were unearly
unusable (except by ATM's and visiting guests that
didn't know any better) that are the same dimension as
your blank. You might consider splitting the blank
into 2 but that would require refiguring of the
surface if it is a finished optic already.

Ken Hunter


--- Mark Holm <mdholm@telerama.com> wrote:
> > I received an email suggesting that my mirror is
> so thick that a 6-point cell will suffice.
> 
> Yes.  Sorry, I didn't have much time, and didn't
> look at your mirror 
> dimensions.
> 
> 6-points is plenty.  The number to watch is the RMS.
>  Anything less than 
> 1/200 is in safe territory.  Actually, the 16x3 has
> lots of safety. 
> Your slightly larger diameter won't be a problem.
> 
> Run Plop for the 6-point design with your
> dimensions, and you will be fine.
> 
> -- 
> Mark Holm
> mdholm@telerama.com
> 
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> 


		
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