Re: ATM Primary mirror support in the horizontal plane (Nastran plots)

[astro.electronic@t-online.de (Michael Koch)]

Hi Clive,

>  Richard has been kind enough to allow me to
> publish a few pictures of his work that model the in
> plane deformations you might expect to find in a
> primary optic (pointed at the horizon) with several
> different methods of mechanical support. 
>   For the record, the optic modeled was 500mm
> diameter, 40mm edge thickness, Pyrex.  Deformation
> contour is scaled in micro inches.
>    You can retrieve a copy of the Nastran plots from
> here;
> http://www.geocities.com/milnecd/20case1.jpg
> http://www.geocities.com/milnecd/20case3.jpg
> http://www.geocities.com/milnecd/20case6.jpg

These results are very interesting, and I have some remarks and questions about 
them:

1. Who is Richard?

2. Was the modeled mirror flat on both sides? If not, which focal length has it?

3. Same question as others had too: Are you sure the scale is in micro inches?

4. On the 3 pictures the "Total Translation" is shown. But this is not 
useful, because the optical performance will only be affected by the Z axis 
translation, which will be smaller. 
I think you did already 95% of a work that is very useful for us, but then you 
printed out the wrong pictures. The Z axis translations are the secret 
we would like to know.

5. The normal vertical support for a big mirror is either a sling (radial forces 
over the lower half circumference) or a styrofoam plate of the same thickness as 
the mirror (approximation: radial forces over the lower 120 degrees segment???). 
I'm sure results for these two cases would be **VERY INTERESTING** for many 
ATM's.

Michael

*******************************************
 ASTRO ELECTRONIC  Dipl.-Ing. Michael Koch
         www.astro-electronic.de
*******************************************