To: atm{at}shore.net,"Vladimir Galogaza" 
From: Jim Burrows 
Reply-To: Jim Burrows 


Thanks to Vladimir Galogaza for suggesting it, I've added a
"Star" source to Diffract.  Since the FFT stuff is already in
there, the programming was done in a couple of hours.  I haven't done much
testing of the changes, so I welcome comments from any beta testers out
there.

You can duplicate quite a few of the pictures in Suiter's star-test book,
except it's hard to get enough image magnification.  Image magnification
will probably have to be handled differently than I'm doing here - the
quick and easy, but limited, FFT way is to decrease the apparent size of
the mirror (increase the size of the mirror's "box").  The
star-test images for primary astigmatism (A22 in Diffract) match Suiter's
quite nicely.  If you put in more than a passing amount of A22s (45 deg
astigmatism axis) and turn on the Ronchi test, the lines are still straight
for an otherwise parabolic mirror, but they're gently slanted, like you had
given the grating a little turn.

Download as usual:

         http://home.earthlink.net/~burrjaw/public/diffract.zip
(2003-03-01, Win32, 401k)

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

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