Hello,
I'm trying to determine which sensor may be best to measure the oscillatory frequency of a remote object. For example, I would like to measure the pitch produced by an organ pipe at a 1 m distance based on a light determination of vibration, rather than sound produced. Thanks for your help!
It is possible, but technically difficult to use variations in the intensity of reflected light to measure object vibrational frequency.
A laser and photodiode with bandpass filter and focusing optics could be a basis for the device.
Why not use a microphone? Sounds like the most sensible solution to this problem. Does need good data processing of course.
What you want to do sounds hard. Very hard.
You have to aim the beam perfectly; make sure your measurement setup does not vibrate at all (or you will measure BOTH vibrations superimposed); make sure that the object you're trying to measure is actually reflecting your signal reliably; no reflections from other vibrating objects, and probably a few more caveats.
I have seen this done but with DSP (Digital Signal Processing) computers. The Arduino will not have enough computing power to process all the filters etc required in any reasonable time. You would need a calibrated Reference Microphone, here is a link that may help: https://www.sweetwater.com/store/search?s=Reference+Microphone You will also need a clean amplifier to amplify the signal to a usable level.
The air column in the pipe is doing the vibration. IF there is coupling to the pipe, itself, what mode of vibration is it? Is the pipe enlarging and shrinking? Might be easier to use a laser to discover the pulses of the air column at the exit of the pipe.
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