Re: [ATM] TraceXP, Ronchi Simulation, etc.

[Scott Rychnovsky <srychnov@chem.ps.uci.edu>]

Dave,

Can your program use data for an imperfect mirror in the simulation? 
It would be nice if we could feed in simulated imperfect mirrors to 
see what effect the imperfections would have on Ronchi and Foucault 
tests.  Zernike coefficients would make sense, and they come out of 
the very nice Fringe program directly!

Scott



>Greetings,
>Among other things, I've been working on a new ray tracing program called 
>TraceXP.  It works under the windows environment and is very easy to use  and
>understand (I hope).  I'm almost done with the first version and will  be
>looking for a few folks that would like to beta test it.
>Along with standard ray tracing and optimization, TraceXP performs several 
>physically-correct simulations including the point spread function and the 
>Ronchi-Foucault test. 
>I'd like to share with you something that I find interesting.  The  following
>JPG image shows a comparison between the simulated Ronchi test of a  mirror
>that Wolfgang Rohr is testing and an actual photograph of the Ronchi 
>pattern. 
>The test was performed in autocollimation on a 250 mm diameter  f/4.8 mirror.
>  The ray trace was set up to mimic as carefully as  possible the actual test
>system, and included the flat with its central  hole.
>There is one significant and obvious difference between the actual test and 
>the simulation.  In the simulation a point source was used, and in the  actual
>test an extended source was used.  The extended source tends to  (thankfully)
>smear and obscure some of the fine diffraction structure. 
>If you'd wondered in the past why your Ronchi test looks so  complicated and
>confusing, the answer lies in the very complicated diffraction  pattern that's
>formed by the grating, as shown in the simulation.  It gets  even more
>complicated when a paraboloidal mirror is tested at its center of  curvature.
>Here's the image:
>_http://members.aol.com/aplanatic/Ronchi_test.jpg_
>(http://members.aol.com/aplanatic/Ronchi_test.jpg)
>The image on the right is the photograph that Wolfgang took of the Ronchi 
>test.  The two images on the left are the full physical-optic 
>simulation of  the
>Ronchi test of a perfect mirror of the same size and fratio using a grating 
>with the same pitch.  One simulation is inside of focus and the other is 
>outside of focus.
>There are many interesting extensions of this work.  Perhaps the most 
>interesting at this time is the full diffraction simulation of the 
>Foucault test 
>using masks.
>Your comments are welcome.
>Dave Rowe
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>ATM mailing list http://www.atmlist.net/


-- 
Scott Rychnovsky
srychnov@chem.ps.uci.edu
ATM Page: http://tlepage.home.mindspring.com/
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