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.001" is 0.0254 millimeters 
That is extremely small.
You can start by reading about the VL53L0X : https://www.st.com/en/imaging-and-photonics-solutions/vl53l0x.html.
That is a "normal" Time-of-Flight laser distance sensor.
I think it is not even close to what you want.
There are papers on this subject: MIT team boosts resolution of Time-of-Flight depth sensors 1,000-fold; cascaded Time of Flight - Green Car Congress.
You could go to mouser.com and try to find such a sensor with such a high accuracy. I can't find them 
This sounds like you are trying to measure something (distance) to actually calculate something else (eg rpm). What is it you are cactually trying to achieve, you've given a method, not the problem.
I think a diagram is needed.
That's no far off the speeds/stresses in a turbine engine, I calculate each gram of material on
the edge of the disc is pulling 100kgf (1000N) from the axis, so clearly there's no way to mount
anything on the rotating parts, so an optical method is the way to go.
Perhaps high speed macro-photography with a stroboscope matched to the spin?
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More study seems to be in your future. Movement measured with light uses PULSES of light. The time from the beginning of the pulse to the time the reflected pulse is received will allow you to compute distance and find the difference between this measurement and the previous measurement which is the movment.
Paul
ardunoob2021:
Sorry for the delay in responding. Holidays=more work, less time to do the fun stuff.
I've been looking at lasers which can be used to measure distance. I guess my real question (since I'm a noob), is that since light travels much faster that sound waves, it should be ideal for my application, correct? The concept is pretty simple: Rotating disk with a piece that moves farther toward the edge of the disk as rpm increases. Since the speed of light is 299,792,458 meters per second, it should be easy to sense this, as long as the sensing rate is fast enough, even with the Baud Rate at 9600. Maybe it's that I don't understand. If I need to measure an object from 50-500cm away as it moves in and out with acceleration/deceleration, if a laser sensor is sensing the light returned (just a a packet of photons), why does it have to have a (example) 1cm resolution? Couldn't we just change the code (cm / 393.701) to make it give that reading in thousandths? Even at 9600 samples per second, it seems plausible. Maybe I'm way off base. Just trying to understand. I appreciate the help
Please post a photo or a sketch. In your approach it seams (besides the well presented problem of centrifugal force posted by MarkT) that your circuit will rotate as well (mounted near the axis?). In such a case you have to make something wireless, battery operating. Extraordinary requirements (2.5um distance measurement going with about 90Km/hour) need extraordinary details level of SYSTEM description or pitfalls are all around...
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Well, it's obvious you will need to sync the laser pulse to when the weight is exactly 90 degrees with the laser beam. Can you do that?
Paul
The VL53L0X as mentioned above is doing no better than mm resolution, and needs way longer than it gets at 15000 rpm to do its measurement. At that speed a single rotation takes a mere 4 ms (15000 rpm is 250 Hz), so the time that the weight is in position for taking a measurement is a mere fraction of that. That alone is going to complicate the measurement big time.
Looking at the image two questions.
- what are the dimensions we're talking about here?
- how do you prevent that thing from shaking itself to bits? There's a weight on one side, that's causing imbalance as it moves outwards.
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aren't there lasers which emit a constant beam, not intermittent pulses?
Of course. But the methods usually used with CW lasers to measure distance are inaccurate and limited to short ranges.
You can buy laser rangefinders with the sort of accuracy you would like. Last I looked they run several $K. But I imagine that they are far too slow for your project.
With a reflective edge on the moving part and some expert machining and high quality optics, one could conceivably cobble together an interference-based ranging device. To get absolute distances, you will need to count interference fringes from a reference. (The author of the video you linked is a bit confused about how interference works for a reflected path to produce peaks and nulls). That would be difficult to impossible for something visible only during a narrow window of time, and moving at a linear velocity of up to 140 m/s.
Paul, aren't there lasers which emit a constant beam, not intermittent pulses?
Can you please explain how you conceive of computing distance with a constant beam?
When you make comments like that, I am tempted to just go find something more productive.
Paul
Things can be simplified by using sensors that rotate with the thing being measured.
For 0.001 inch resolution simply attach the weight to the movable part of a cheap digital caliper mounted on the disk.
For an optical system place the laser diode on the axis of the rotating disk and fire at the back of the sliding weight. This will allow continuous fringe measurements throughout the rotation.
Just out of curiosity how do you plan to deal with the violent vibrations generated by of an out of balance high speed spinning thing? The signal you are looking for will likely be buried in this noise.
It would be helpful if you, the OP, answer the question in post #2, which is, essentially... "WHY" do you...
ardunoob2021:
...need to be able to measure the distance to the plate as rpm increases...
?
And, what are you going to do with that distance information?
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ardunoob2021:
Paul, my apologies if I offended you. My intent is not to offend, rather to understand.
Well, not offended at all. Just trying to follow your thought process, but that seemed to end with just a statement and no followup as to how it is done. We are trying to find a workable way to do the measurement you asked about and wonder if your research has discovered some other way.
Paul
Paul
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You have been told several time how to measure the distance, but seem to be ignoring that.
Paul