Re: [ATM] convex secondary

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

You actually don't want to have both ROCs the same otherwise you won't know
which you are testing.  A few percent different ROC is what you want to
have.  The back surface only needs to be 1/4 wave spherical in order to test
through without any problems with the error beiing in the sphericity rather
than in random surface shape - i.e. no lumpy surface.
When doing the Foucault test, you will have a minor shading from the front
surface which needs to be taken note of.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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