Metrology - the science of measurement

Some notes of interesting techniques, sites and people concerning this topic.

On YouTube there are some very interesting video clips on prototyping and machine metrology which are a must see by Dan Gelbart. He shares a measurement technique, which he refers to as reversal technique. In essence two unknown surfaces can be mapped, and compared if a common reference surface also of unknown dimension is used.
https://makezine.com/2015/03/20/18-lessons-smart-prototyping-self-made-billionaire/

Airy and Bessel Points effects explained.
https://www.mitutoyo.co.jp/eng/pdf/E4329_QuickGuide.pdf

31/03/2018 - Recently I browsed  through Stefan Gotteswinter web site, wealth of knowledge! Here he shared a link to 50 tidbits for precision work, #47 references Donaldson Reversal, still need to read up more on this, but I believe this is what Dan Gelbart refers to.