Hacker Samy Kamkar is debuting his own open source version of a laser microphone—a spy tool that can invisibly pick up the sounds inside your home through a window, and even the text you’re typing.
demonstrating that he can point a laser that’s invisible to the human eye at a faraway laptop, through a window, and detect the computer’s vibrations to reconstruct virtually every character typed on it
Make it a UV laser and it would be invisible.
Infrared is not visible