Re: ATM Cass secondary ronchi test

[Atparke@aol.com]

Hi Peter,

I don't think I'm up for a second set of curves on my secondaries, but thanks 
for the offer of calculating them.

My thought on using the ronchi was as a quick visual comparison to a computer 
generated image to augment interference and star testing.  This test helped 
me a lot on my first (newtonion) mirror.  It was intuitive and gave me 
something to visualize while doing figuring strokes.  And it was very fast, 
allowing me to quickly see the effect of different figuring strokes.

But after reading your note its clear to me now that the problem is the 
flatness and homogeneity of the mirror material.  

So if the flatness and homogeneity of the secondary was acceptable, how could 
the ronchi test be applied? Do you think this test might be worth while? 
i.e., modify ronchi  computer program to accept thickness, k, index, ROC, and 
output images with offsets?

-A. Parker