Re: ATM Secondaries by Replication?

["Bob May" <bobmay@nethere.com>]

I think that you will find that the amount of the secondary's surface that
contributes to the focus point will be above 3/4 of the diameter of the
secondary.  You will want to have the accuracy of that much of the secondary
to be at least as good as the primary so that sets the standard to which you
need to have on the secondary otherwise the errors in the secondary will be
the biggest error source in the image.  I might add that small area errors
(hills and valleys) will produce less error than a general overall curvature
will as the general curvature will produce astigmitism while little
hills/valleys will merely spread out the Airy disk slightly, the amount
depending upon the amount of the p/v of the hills.  The type of error does
make a difference!
Bob May
http://nav.to/bobmay
bobmay@nethere.com