Precision DIY calipers? That’s a moiré

[jhncls]

https://hackaday.com/2018/03/07/0-05-mm-precision-thats-a-moire/

[djmips]

That's interesting. Big Clive explored a set of inexpensive calipers that seemed to work on an interference pattern but sensed with two PCBs passing over each other. He mentions in his theory of operation moire pattern measuring devices. It's a fascinating device.

https://youtu.be/fKSSY1gzCEs

[mikewarot]

I'm amazed at how well the results work, and how easy he makes it look. This is a classic example of how something can seem obvious in retrospect, yet wasn't.

This could easily be scaled up or down to any size desired. It might even be able to work on a protractor.

[Valgrim]

I guess one could use this technique to create any sort of very precise measurement or calculation tools, like slide rules or sextants.