ATM Aplanats II via troublesome Juno X-mailer

[kwhitefire@juno.com]

>Aplanats are telescopes with flat focal planes.  This is a difficult 
>situation with mirrors.  Add mirror #3 and the focal plane becomes 
>flattened more easily than with two mirrors.

THE Bible (Born & Wolf, "Principles of Optics") says an aplanatic system is 
one which is free of spherical aberration and coma - nothing about 
curvature of field.  The Ritchey-Chrétien cass is aplanatic, but has plenty 
of field curvature.

Now, if I can plot a mirror design that eliminates all three to a reasonably small quantity, this would be Something Good, right?

How close to zero coma, zero astig, and zero focal plane curvature must I get for a design to be effectively aplanatic?

So I seek perfection in the physical world!  It's my right!

Kevin of Eastern Iowa
Seeker of the Darkness




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