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A comment on Ask HN: What problem are you close to solving and how can we help?. Parent comment

Re:Ask HN: What problem are you close to solving and how can... by marcosdumay on Sunday August 29, 2021 @05:00PM (#28350434)
Adding another step (not a problem, just maybe a solution), a quick estimate says that if I place a few kHz signal at the sample, it will induce enough current at the tip to be detected by the preamp when the distance reaches the micrometers. That's the same range you want to stop the approximation, so it may be a nice proximity signal.

I've got to try this on my next attempt.

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Re:Ask HN: What problem are you close to solving and how can... by minhmeoke on Sunday August 29, 2021 @06:16PM (#28350974)
Sounds good!

In the future, if you'd like even more precise measurements, theoretically you could use 2 different frequencies or a reflected source, and look at the interference or superposition of the waves.

I'm by no means an expert in this, but I've heard that optical measurement (eg: laser + Michelson interferometer) could theoretically take you down to the nanometer range.

But it's easy to go overboard with this, haha.

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-20-5-56...

https://iopscience.iop.org/article/10.1088/0957-0233/9/7/004

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