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Help with laser sound project

  1. Jul 29, 2010 #1
    ok, so ive seen the movie
    where they aline a HEnE laser with a photodiode to hear the modulations in the photon stream.
    i been trying to re-do it, and i just cant get it to work. im NOT using a HeNe laser, im using a normal laser from a pen, as i was sure the concept of the laseres "resonance" is the same, but as its not working im beginning to doubt. im not sure im using a silicon diode either(got it from a friend,so cant check it, but its a very reflective diode, so again in theory, it should work.

    can anyone explain me why its not working? is it the laser? is it the diode?
    i really need this to work as its part of my bachelor project.

    Best regards
    please reply here
    thanks :)
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Jul 29, 2010 #2


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    Staff: Mentor

    I'm at work, so I'm not able to watch YouTube videos. What is providing the modulation for your laser? Can you at least pick up ON/OFF changes with your PIN photodiode circuit?
    Last edited by a moderator: Sep 25, 2014
  4. Jul 29, 2010 #3
    the modulations is coursed by small vibrations in the ground, as the laser and photodiode is alined, and the diode is abit reflective coursing the photon stream to bounce back in to the lasers mirror and back to the diode several times. making the smallest vibration or movement of the laser or diode to become amplified and audible as the diode is hooked up to a speaker.

    i already build a box with laser and a photodiode making it possible to transfer sound over laser using AM modulation.
    now i want to combine the two, to make it as a interactive music installation.

    so the magic here is the resonance from the diode and back in to the laser and so on.
    am i right when i think this is not only doable with a HeNe laser? but also with a "regular" laser as the concept with mirrors is the same, its only the medium thats different?
  5. Aug 3, 2010 #4
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