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[ATM] Eyepiece testing.

The recent discussion of eyepiece correction prompted an idea for eyepiece 
testing.  If I ever get my RC cass secondary refigured, a possible use of 
the Hindle sphere is to test eyepieces.  With a mask on the sphere and a 
point source slightly displaced laterally from the sphere's ROC, position 
the eyepiece and a webcam with its lens removed in the return cone of light 
to get an image.  The image could be processed with good ol' FFTs to find 
the eyepiece aperture's transmission function.  Then a neat problem to be 
solved:  given the functions for a collection of eyepieces, what is the 
optimum profile of an objective mirror to be used with that eyepiece 
collection?  Somewhat the same mess that I'm in - figure a secondary to 
make an RC match with a given primary.

         -- Jim Burrows
         -- mailto://burrjaw@earthlink.net
         -- http://home.earthlink.net/~burrjaw
         -- Seattle N47.4723 W122.3662 (WGS84) 

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