I am creating a laser microphone in labs at the moment, and was wondering if anyone could help explain how/ why it works.
We are shining a laser a a reflective surface and using a photo-diode and some basic op amp electronics to detect the reflected beam and produce a voltage output.
Everything works and we are picking up an audible sound signal. However I'm trying to work out the physics behind it. Is it because the vibrations of the reflective surface are causing the reflected laser beam to travel by different amounts, therefore causing interference, causing the intensity to vary? Or is it something else all together.