Laser based listening devices work by bouncing the beam off of a window. Sounds in the room cause minute vibrations in the window. These vibrations modulate the laser beam. The laser beam is then converted back into sound at the receiver. Hack-A-Day reader [Aaron v] decided to build one of these devices. It worked, but needs some improvement. He followed plans found here (Coral CDN cache). I’ve also got a local copy of the receiver schematic since there doesn’t seem to be too many of these projects with decent hosting. Williamson Labs has a good discussion of the problems these systems can run into and more advanced setups like interferometry.

i recieved an email from owen the other day:

fellow hackologists may be interested in a year and half long project of mine to build a computer controlled sheet metal cutting system. It uses a 100 watt CO2 industrial laser.

there are some videos on his site showing the co2 laser milling machine in action. it’s absolutely fantastic. just the control system itself is pretty intense. if you are interested in doing something like this, you should also check out his blog that chronicled the whole contruction.

i’m pretty sure i need one of these.

update: apparently i can’t spell (thanks pedant). i was thinking it was z for zippy.