Eddy current/metal proximity sensors (sensitive)

Hi everyone, first post here
I am building a project for finding the modal deflection of a spinning shaft, for that i will need some sensitive proximity sensors (or anything that can turn deflection into voltage etc.)
I was wondering if there are any good eddy current sensors for use with arduino, or any other sensitive enough sensors, i can only seem to find hall effect sensors (good for sensing magnets....) and ultrasonic sensors (resolution of 1cm, way too much)

I also did an extensive search of the forum without finding something fitting. Can anyone tell me if such a thing exists, or where i should search?
It would be better of course if anyone has experience with such sensors.
*If possible, i would like to avoid using accelerometers, there are various reasons for this.

Every answer would be much appreciated, thanks!

Pika007:
Hi everyone, first post here
I am building a project for finding the modal deflection of a spinning shaft, for that i will need some sensitive proximity sensors (or anything that can turn deflection into voltage etc.)
I was wondering if there are any good eddy current sensors for use with arduino, or any other sensitive enough sensors, i can only seem to find hall effect sensors (good for sensing magnets....) and ultrasonic sensors (resolution of 1cm, way too much)

I also did an extensive search of the forum without finding something fitting. Can anyone tell me if such a thing exists, or where i should search?
It would be better of course if anyone has experience with such sensors.
*If possible, i would like to avoid using accelerometers, there are various reasons for this.

Every answer would be much appreciated, thanks!

Strange to come to an Arduino forum with such questions. Seems more appropriate for an engineering forum.

But, the shaft must be metal for you to suggest eddy currents. How much deflection range are you wanting to detect?

How much access space do you have to the shaft? Both sides?

If you can polish the shaft for light reflection, a reflection may contain modulation data from the shaft deflection.

If you can magnetize a portion of the shaft from one side, a magnetic pickup on the opposite side might also contain modulation form the deflection.

Is the shaft short enough so harmonics of the deflection cannot occur?

Are there bearings on the shaft that may allow sound sensors that would pick up deflection modulation?

All I can think of right now!

Paul

I might have explained myself wrong, this project is going to be in arduino and i was wondering if there are compatible parts, like there are lidars, laser proximity sensors etc. which are meant for these types of projects.

Anyways, the answers as listed:

-Shaft is metal. I don't need to detect more than 4mm overall range, can probably do with 3. the shaft will of course deflect in both ways (when it's not hitting standing wave rotation frequencies)

-The only thing obstructing access to the shaft are discs in the middle of it, i have around 30cm or more on each side of the discs. I'll edit this message to upload a picture in a while.

-Polishing might be an option, magnetizing not really.

-Shaft is about 0.5m, harmonics are going to occur, and the deflection on that point is what i essentially want to measure (not longitudal modes though, the sensors are going to be located parallel to the lengthwise dimension of the shaft)

-There are bearings that might be able to allow that. I'll look into it.

Thank you very much for the help!