[ATM] Telescope design -- Linux software

[ArtfulBodger]

Can anyone recommend Linux software to help me design telescope 
optics?  I have a li'l project in mind, but it's a bit more complex 
than your basic Newtonian ... more of a Nasmyth-ish kind of thing ... 
and I need to work out the details.

I'll appreciate any help, but of course the more you can tell me 
about a given software app, the better.

Thanks, all.

Pete

-- 
Artful Bodger
http://www.artfulbodger.net