Can a Laser and Reflective Material Create a High-Frequency Microphone?

  • Thread starter Thread starter Raven Luni
  • Start date Start date
  • Tags Tags
    Acoustic Design
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
3 replies · 4K views
Raven Luni
Messages
6
Reaction score
0
Greetings,

I've been looking for a way to create a microphone capable of picking up high frequencies (up to about 100kHz). Electrets don't 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 don't 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?
 
Engineering news on Phys.org
Raven Luni, Welcome to Physics Forums! 

You may see this patent, which detects acoustic frequencies up to 100 kHz:
http://www.google.com/patents/US5146083

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
 
Last edited by a moderator:
Excellent information - thanks :)