
Great project on i-hacked.com. Using a simple laser pen pointer, a few misc parts, and about 15 minutes, you can make a simple laser communicator that converts a sound source into light that travels across a room, and back into sound with very little quality loss. Link.
Hmm. the setting, a huge college classroom with many students. Small earphones. receiver. big cheating possibilities-
There’s another (lower-tech) way to go about sending audio data with light. Using a sheet of mylar, taped in front of a small speaker, a laser pointer, and a solar cell connected to headphones or amp just as in the original experiment. You can bounce the laser off of the mylar and onto the solar cell, and the visual waveform contains enough sound information to be replayed with remarkable clarity, considering the low-tech setup.
I used this build inside a science fair project that used different types of light emitters. I was trying to find the one that had the best energy efficiency for transmitting data. Unfortunately, te laser pen didnt work at all for me, so I replaced it with an LED and got some results. It sort of worked although the quality of sound was terrible and your couldn’t exactly transmit the sound across a room. A small solar cell was used for the project.