Re: [ATM] [atm_free] Detecting Astig in Ronchi images

["Mel Bartels" <mbartels@bbastrodesigns.com>]

> Actually, I think that if you could comment briefly on specific
> features in each photo, those comments, if added to Dale's web page,
> would make an excellent reference document that many would appreciate
> and could learn from.
> 
> To me, the only real dead giveaway for something bad going on (other
> than a generally uneven, rough surface) is in the fourth photo, where
> the slightly off-center line has markedly different behavior on either
> side of line near the top of the mirror.
>    http://home.comcast.net/~doeason/DDavis/ronchi_scan.htm


Almost all the images show a twist or displacement to the left as you head
downward at the 50% zone.  If you plot the equivalent degree of
parabolization that yields 1/2 wave surface error and compare it to a
perfect ronchigram, the different is about the amount of the wiggle.

Mel Bartels


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