Re: [ATM] Ronchi Movie of the ultra thin mirror and other ramblings.

["Stephen Koehler" <s.c.koehler@gmail.com>]

Dale,

The movie is very useful, in that you can move the slider back and
forth as if you are controlling the platform yourself.  I must say
that the kink, or s-curve in the line is very subtle in the movie.  I
can see it, but I think it would be easy to miss.

Here's a demonstration of the undercorrection visible in the Ronchi
image.  Go to the movie and pull the slider until the figure starts to
look like the greek letter phi (a vertical line going through a
circle).  Here's another link to the movie:

http://home.comcast.net/~doeason/DDavis/ronchi_100lpi.mpg

Expand the circle until it is overlapping the edge of the mirror. 
That is the position at which you have "nulled" the mirror's outer
zone.  If you look at my simulation from the interferometry, this
corresponds to a little beyond the frame marked 4.000.

http://www.visi.com/~mkoehler/eason_davis_misc/davis_ronchi_sim.png

Next, look at the simulation from a fully corrected f/3.5 in my
reference simulation:

http://www.visi.com/~mkoehler/eason_davis_misc/davis_ronchi_ref.png

Notice how the phi pattern keeps expanding all the way to the frame
marked 7.000.  When it finally reaches the edge in the reference
figure, there are two prominent circles nestled in the two halves of
the phi.  The lack of these circles demonstrates the undercorrection.

--
Steve Koehler
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