One way you can do this without another light source is to bounce a laser beam off a window or other things that are reflective.
In fact, the same principle can be achieved with radio. The Russians once planted a device in a wooden seal they gave to a US ambassador as a gift which, when a focused radio beam was aimed at it, would reflect and oscillate that beam due to vibrations in the air.
In fact, the same principle can be achieved with radio. The Russians once planted a device in a wooden seal they gave to a US ambassador as a gift which, when a focused radio beam was aimed at it, would reflect and oscillate that beam due to vibrations in the air.
https://en.wikipedia.org/wiki/The_Thing_%28listening_device%...