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Acoustic Diaphragm Design

  1. Jun 19, 2012 #1

    I've been looking for a way to create a microphone capable of picking up high frequencies (up to about 100kHz). Electrets dont tend to go that high and piezo crystals even detuned will only give a limited band.

    I had the idea of bouncing a laser off a sheet of reflective material. The light can either be picked up directly, by pulsing the beam with a square wave and taking the phase shift as a form of pulse width modulation, or with a sine wave and using the doppler shift (I'll have fun experimenting with all these methods).

    What I dont have any clue about is the material and what properties it should have. What kind of thickness, surface area, tension etc. would I need? Would there be a resonant frequency? Is it even possible for the frequency range in question?
  2. jcsd
  3. Jun 19, 2012 #2


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    Raven Luni, Welcome to Physics Forums! 

    You may see this patent, which detects acoustic frequencies up to 100 kHz:

    Here is a ready-made acoustic sensor you may learn from:
    http://www.digikey.com/us/en/techzone/sensors/resources/articles/ultrasonic-mems-sensor-spm0404ud5.html [Broken]
    Last edited by a moderator: May 6, 2017
  4. Jun 20, 2012 #3
    Excellent information - thanks :)
  5. Jun 22, 2012 #4


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    Last edited by a moderator: May 6, 2017
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