Cited as a reference · for some experience
$3 laser transmits audio over 100m (arduino)
Why people recommend it
Demonstrates sending audio across roughly a hundred metres with a cheap laser diode and Arduino, cited as proof of range for optical data links.
Watch for: a demo more than a build guide
In their words
We're trying something like the setup in this YouTube video $3 laser transmits audio over 100m (Arduino)
Carl on arduino.stackexchange.com, Mar 2017. CC BY-SA.