I really appreciated reading a lot of interesting threads here the past few weeks. However, now I have signed up since I can't figure out what's the best way to measure very small distances with an arduino and what type of sensor would be the best.
I'd like to measure distances in range of at least 0-5mm with a resolution of 10µm or less. I actually think that a capacitive sensor could do this job pretty well (like in calipers or many scientific testing devices) but I could not find any supplier for this or a DIY instruction. I'm not sure if a caliper would work because as far as I know communication is very slow and it should be adjustable.
Another idea was to build a small gear and get the revolution by a stepper motor.
Last but not least, I'm not sure if a IR proximity sensor could do the job.
I would be very thankful for any input, also for other ideas. Of course it should be affordable (so less 100$).
Thanks for your reply.
It is a linear movement. A tip shall be lowered until it reaches a surface and I would like to measure the distance between the initial position and the surface position.
Sure, it's the encoder... I think you got what I meant...
Yeah, there will be rotation involved, it will be a simple rack and pinion unit, where the rotation comes from a stepper motor.
Not sure about the backlash yet. I think it wouldn't be a problem to add a linear encoder rail.
There will be a load cell to detect when the surface is reached.