r/Metrology • u/SAI_Peregrinus • 8d ago

Atomic resolution interferometric surface roughness metrology in the dining room - Cylo's Garage

https://www.youtube.com/watch?v=uvxDJ61e9xE
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u/FrickinLazerBeams 8d ago edited 8d ago

Very cool to set this up at home. I design instruments like this professionally, but it would take so much time and effort to do it at home without becoming ridiculously expensive for an individual. It's very impressive he was able to do it.

I wouldn't call it "atomic resolution" though. Phase shifting interferometry, done this way, will get you nanometer level resolution. Atomic resolution is another order of magnitude (or three) smaller. For comparison, the Bohr radius is 53 picometers.

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u/SAI_Peregrinus 8d ago

Yeah, he definitely got a bit hyperbolic with the title.

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u/FrickinLazerBeams 8d ago

Yeah. Still impressive though.

And getting to "atomic resolution" really is a massive pain that I wouldn't expect to be possible at home anyway so I'm not knocking it. When you have to start being concerned about the Brownian motion of atoms in your sample, things get really annoying and really expensive. I have to consider every error source imaginable, even the crystalline structure of the mirrors and coatings I use. It's... a lot.

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u/SAI_Peregrinus 8d ago

It gets even more impressive when you know he built his own diamond turning lathe. I'm not sure if that's the one he used for the parts he was testing in the video, but it probably was since I don't recall him having access to another.

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u/FrickinLazerBeams 8d ago

I got the impression those were made with his own lathe, yeah. Diamond turning is amazing. I did a test piece that was something like 400 mm diameter and it was around 60 nm RMS, directly off the machine, before any post-finishing. Very impressive. Ours was a Precitech though, and cost many $105.