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[kwhitefire@juno.com]

I have a couple of questions regarding aplanatic reflactors.

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.

I have devised several instruments of moderate size that have focal planes in excess of 10,000 inches.  Is this flatness close enough to aplanatic to count?

One instrument I have designed has a field curvature of over 250 miles and coma/astig near that of a Newtonian.

Another instrument I designed has a field curvature in excess of 86,000 inches.  The coma and astig are -.000020 and +.000046.

How flat a field do I need before I can call it an aplanat?  These two designs are both difficult-looking on the computer.  The tolerances are difficult at best.  How difficult is it to work to a b of +/- .0005?

Kevin of Eastern Iowa
Seeker of the Darkness




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