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
It is visible to security cameras
Infrared doesn’t pass through windows.
To humans
It’s already infrared. Also, UV is partially visible to humans in some scenarios.