I've been figuring a Pyrex 8" primary for a few months now. I use DFTFringe for testing. (Plus Foucault  & Rochigrams)

My question is about the proper setting for the Gaussian blur when trying to determine the wavefront.

In my case, should I set it to 10% or 20% (or some other number) ???

I attach some pictures, including an R-gram (outside of R0C) for the mirror as it stands now.

https://www.dropbox.com/s/ss5d9jiege3mlwn/BABO%20AG%20202-1564-10pc%20385%20s883.wft?dl=0

Joe

Pictures:

I think even 5% is  more accurate for your case.  That is because using your .wft file I can adjust the Foucault image so I can see that weave pattern that shows up when many igrams with different fringe orientation are taken.   Meaning that you have averaged out most of the igram noise and are left with remnants of fringe print through.   Also because your igram looks very good with little noise.   Thus you can reduce the blur radius.       So because the surface is not as smooth as a very good mirror and with a high edge the higher blur values are artificially smoothing the surface too much at even 10%.

Your red colored ronchi I think is an actual ronchi and it too shows the surface defects well.  I think at 5% DFTFringe simulated ronchi matches your actual better.  You can see a little more noise in the 5% but it captures the edge better than the 20%.

Dale

Here it is in DFTFringe64 next release and 5%.  Yes, I'm about to release 5.1.

Extremely grateful for your analysis. Thanks,

Joe