Laser listener DIY
Laser microphone:
“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 which can then be reinterpeted 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 savy among you will spot the countless variations possible on this basic idea.”
My thoughs on this: a red laser pointer is probably no good - if you’re messing with some bad guys out there, you will lose your life in minutes after the red dot is on the wall of their room… But - if you use an IR beamer or IR laser… think about it.