[ATM] Secondary questions

[Alexis Cousein]

Larry Kruzan wrote:
> Hi All,
> 
>  
> 
> I am soon going to mate the secondary flat to the spreader and would like to
> ask if I am doing this right.  My plan is to mount ¼” plywood that is the
> size and shape of the mirror to the spreader then adhere the mirror to the
> plywood with RTV. 

Don't forget to use a maximum of three blobs, to make them at least 1-2mm thick,
and to make them no wider than around 8mm. I had a secondary causing quite some
astigmatism because it conformed to the holder it was glued on (which is what
you get with more than 3 attachment points or blobs that are too thin), and
wide blobs can actually (because the centre cures later than the edge) also
warp the mirror by pulling on it.

I blackened the edge of my mirror with Tamiya XF1 flat black paint.



-- 
Alexis Cousein                                  al at sgi.com
Senior Systems Engineer/Solutions Architect     SGI/Silicon Graphics
--
<If I have seen further, it is by standing on reference manuals>