[ATM] Foucault test errors due to source and knife edge separation

[burrjaw at earthlink.net (Jim Burrows)]

At 2004-02-20 11:42 +0000, Jerry wrote:

>         has anyone calculated the errors in the Foucault test as a function
>of the mirror radius and separation of the source and knife edge?
>Typical figures are a mirror radius of 3000mm, separation of 30mm, mirror
>diameter 250mm
>As far as I could see it's about X^2/r^4*x^2/4, where X is half the
>separation between the knife edge and source, r the radius, and x the
>distance from the mirror centre

Cute question - big waste of scrap paper <g>.  Assuming moving-source with 
the source and KE on a perpendicular to the optical axis, a parabolic 
mirror, and geometric optics, I think it's true that the only way the 
returning rays exactly hit the KE is X=0 and x = the usual R + y?/2R, y = 
zone radius.

         -- Jim Burrows
         -- mailto://burrjaw@earthlink.net
         -- http://home.earthlink.net/~burrjaw
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