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A comment on Fingers can detect nano-scale wrinkles even on a seemingly smooth surface. Parent comment

Re:Fingers can detect nano-scale wrinkles even on a seemingl... by Florin_Andrei on Tuesday January 14, 2014 @02:14PM (#7059043)
It's almost certainly all about the pattern.

I make telescope mirrors. The error I'm allowed is 100 nm. I would love to just drag my fingers over the glass and tell if something is not quite right with the optical surface. In reality, I need a pretty elaborate optical setup to amplify the errors about 1/2 million times, in order to see them.

I'm guessing the spatial frequency of the pattern in that experiment is on the same size scale like the vertical amplitude of it.

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Re:Fingers can detect nano-scale wrinkles even on a seemingl... by taavi013 on Tuesday January 14, 2014 @06:18PM (#7060491)
It is rumoured that Bernhard Schmidt had so sensitive touch, that he could physically feel polishing results by his (only) left hand.

http://en.wikipedia.org/wiki/Bernhard_Schmidt#Mittweida_year...

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Re:Fingers can detect nano-scale wrinkles even on a seemingl... by Florin_Andrei on Wednesday January 15, 2014 @03:13PM (#7065829)
If this is about the early stages of polishing, I believe it (and I can do it myself).
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