Welcome, from sunny Australia!

Listening Spy Device
... welcome to Amsterdam, Mr Bond!

With all the other devices on these pages, I fully realise that there's pretty much zero chance of any of them ever being made. This one is different, because I know that it's already been done! The only reason I'm writing about it is because I thought it up without outside influence, and perhaps there are some (paranoid!) people and/or companies out there that may need to protect their secrets ...
It was said in the 60's that the newly invented laser was "a solution looking for a problem."  Well, I found a different sort of use for one. It's dead simple - If you can point a laser at a window at 90°, or to be more accurate slightly off 90° so that the reflected beam comes back to the side. I guess that if you could work the angles accurately enough, you could use pretty much angle you like. Certainly more handy if you could do that, as it could be quite difficult to get a 90° angle all the time.
All that need be done is to know very accurately the frequency of the laser beam on the way out, and then measure the frequency again when it bounces back off the window.
The reason for measuring the frequency on the return is this - If anyone is talking in the room then the sound pressure made from them speaking will cause the window to vibrate ... slightly. This will make the laser beam's frequency change slightly, too, and so when worked backwards it would be possible to find out what people are saying in a room many hundreds of yards way, even on a pitch black night with the lights out.

I have read in a magazine somewhere that the CIA already had a device like this in operation. I don't know for how long, but at least I know such a toy is possible.

I also think that a more advanced system would be possible, ie, if you could get a sensitive enough telescope to look at the laser spot (Gotta be an infra-red laser, of course, so the human eye can't see it), then it should be possible to detect speech through solid walls. It would take a very sensitive system, but I think it may be possible.

With the other odd gadgets on these pages I have said it's just one of my crazy ideas, but at least I know that this one works!
So maybe there's hope for the others???

* Short update - I got an email from someone that has actually done it, and the details can be found here.
 
 

On to the -
- Geothermal power plant
- Laptop computer electronic circuit simulator
- Anti-aircraft missile system
- Horizontally opposed diesel aircraft engine
- Different electric car
- Super cooler device
- Radar Jammer
- Land speed record car contender
- Water speed record contender