That sounds like it could be in the range of a digital read-out (dro) as they are used for milling machines and lathes. my mechanics had video just the other day about replacing one, and the old one had 5 microns accuracy.
Does the interval you're measuring move around much?
Can the measurement system touch or be affixed to it?
Sounds like a pair of nice calipers might work. So depending on your precision needs, you might get away with the same approach: sliding grid of capacitive cells that slide over the measurement cells. Microcontroller measures them as it slides through. Atan2() for the final result. The meter only part of this is called a DRO(Digital ReadOut)
We had a similar issue at one point, and had to build something custom that cost way more than I'd like to admit. Thus, I would recommend just looking at DRO kits for CNC milling machines.
If your project is not budget constrained, than there are complete closed-loop stage solutions around:
Thanks for sharing this video, I am also interested in this exact thing. However from my understanding with an approach like this you are limited by the size of the image sensor, meaning if my surface has a bump that is larger than the size of the image sensor it would not get measured. Any idea on how to make something like this work if the goal was to measure slightly larger topographical changes at a less granular resolution like in the 100mm range?
Note those 532nm green DPSS lasers are repeatable within +-1nm across their normal operating temperature. Adding a 20nm wide OD6 narrow band-pass filter to a $5 5mW DPSS laser module is the cheapest precision money can buy these days.
Really depends what one can get away with in the mechanism being built. Note, many machines will fall under export restriction, and as a company people have to decide whether that encumbrance is worth the hassle.
Really cool man, will need to spend some time to fully wrap my head around this. Wonder if this is going to provide maybe too much granularity, as I am measuring slopes variation of say 2cm/100cm like a golf green. Trying out just using basic ToF sensor as of now.
Yea I have some ideas, but I haven't found an easy way to implement it yet.
The term of art that I'm exploring is called "Holographic Interferometry".
Sibling poster gave you a link to regular interferometry.
But basically, if you split the laser beam, one goes straight into the camera sensor, and the other off your object, you can do some pretty amazing things. Depending on a lot of little details (The devil is hiding here).
I found 3Blue1Brown's explanation to be the best, but less "ready to use".
Very very cool. I think what I am looking to do is much more simpler, which is trying to create precise mappings of golf greens. Starting out just using a simple ToF sensor and running it over the surface.
