Build your own laser listening device

This is one of those “it works, and it’s scary” hacking projects. Build your own laser listening device for about $3. Video after the jump.Via Funditor

“In a microphone, sound waves (differences in the pressure of air) cause a diaphragm to vibrate back and forth, altering its resistance to an electric current. When an electric current passes through said diaphragm, the output forms a complex signal that can then be reinterpreted by speakers or a recording device as sound. The device shown here works in a very similar way. Sound bounces off of a window, causing minuscule vibrations (acting like the microphone’s diaphragm). When a laser is trained on the window, its reflection will vibrate with the sound. The laser’s reflection, if converted to an electrical signal can now be recorded as sound. I will outline how I made my own (cost me $3, hope yours is the same or less) – the technically savvy among you will spot the countless variations possible on this basic idea.”

Frank's the editor in chief of tech.nocr.at. He can be found surfing the internet and playing with gadgets. Follow him on twitter @franklinhares