[ATM] ATM: FringeXP comparison to professional software

[mpeck1 at ix.netcom.com (Michael Peck)]

At 17:11 27-01-04 -0500, Aplanatic@aol.com wrote:

>I have compared accuracy statements of several software producers, 
>including also
>a [?] program "Intelli.Wave" .  All producers give approximately same 
>accuracy for interferometric analysis. It looks like with interferometry 
>with one fold accuracy of interferogram
>there is no warranty for better than lambda/30 surface ( lambda/15 
>wavefront) accuracy.
>Independent from additional errors introduced by testing procedure and others.
>

A couple quick remarks. If I read the web page correctly (with the help of 
Google and an online German<->English dictionary) FringeXP was being 
compared to results from phase shifting interferometry, which according to 
Malacara is at least an order of magnitude more precise than static fringe 
analysis. So this isn't just a software comparison but a comparison to a 
hardware platform and analysis approach that no ATM and very few pros 
manufacturing for the amateur market have access to. As long as the number 
crunching is done correctly - and as far as I can tell FringeXP does - the 
limitation is more due to hardware than the choice of software.

Also, from the point of view of someone who's forgotten a thing or two 
about statistics, that statement about "lambda/30 surface accuracy" seems 
so imprecise as to be virtually meaningless. If the reference is to errors 
in estimates of P-V I suspect an accuracy of +-.03 waves in a single 
interferogram is optimistic. It's also irrelevant. If the reference is to 
rms error estimates I'd say the author is being a bit pessimistic (by a 
factor of 2 or 3). In any case you can get back as much precision as you 
want by combining data from multiple interferograms. ATM's at least can 
afford to collect and analyze as much data as we want, since after all a 
hobby is all about wasting time. Some pros (Royce, Mulherin) recognize the 
desirability of combining data, but they can't spend unlimited amounts of 
time on analysis.

Mike Peck


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Michael Peck
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