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Registered Member #617
Joined: Fri Mar 30 2007, 07:29PM
Location: Buffalo NY
Posts: 49
Ive done a bit of research on the systems and I was wondering if anyone knows exactly how to record a reflection and translate it into sounds. I have only played with a simple red laser pointer but there is really a huge deflection and it would be cool if I could learn some more about this and possibly build a laser mic, or it might be one hell of a project for someone with experience with lasers.
Registered Member #1361
Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305
If you could find some sort of mic/amplifier in one circuit, then all youd need would be a audio transformer and laser, and a couple of batts. Search google for "laser transmitter".
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Use GOOGLE. There are plenty of resources out there showing how to do this.
Its actually an easy project as far as the electronics go. Just a simple demodulator circuit is required.
The hard part of course is aligning the laser and receiver which is extremely difficult.
This is definitely not something you just carry around with you and set-up at your convenience. It took me nearly two weeks to work out alignment issues using highly precision lab tripods to listen at a target 50 feet away.
Plus they really don't work that well at all. I was barely able to understand any sounds i was hearing. You really only see these things in the movies. The various intelligency agencies have experimented with these, but practically speaking, they found much easier ways to do their listening.
Registered Member #618
Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628
Besides, If your gonna easdrop on someone it might not be too successful if they spot a laser dot, and look your way, sure you could try and bluff out of it but for the most part youd be better of trying to make a small SMD mic transmitter and a wireless reciver disquised as a walkman or something.
Registered Member #617
Joined: Fri Mar 30 2007, 07:29PM
Location: Buffalo NY
Posts: 49
Im not actually going to use it against someone, I would just like to see if I could do it. And i think the laser from a cdrw drive could solve the problem of the red dot.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
The laser in a cdrw drive is (or at least damn should be) a single mode diode, so as long as you have some decent optics you should not have much trouble getting a nice beam out of it.
Of course getting the alignment corrent is going to be almost impossible...
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Ken M. wrote ...
Besides, If your gonna easdrop on someone it might not be too successful if they spot a laser dot, and look your way, sure you could try and bluff out of it but for the most part youd be better of trying to make a small SMD mic transmitter and a wireless reciver disquised as a walkman or something.
Thats why you use an infrared laser. Of course that makes alignment that much more difficult.
Registered Member #617
Joined: Fri Mar 30 2007, 07:29PM
Location: Buffalo NY
Posts: 49
I would like to see this working even 3 feet away from a window, just as a proof of concept thing. I found a good demodulator circuit and im going to see if that works next weekend i think. if i combine this: with possibly this: or would that do something nasty to the waveform and distort it to much? thanks.
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Laser Easdropping Systems
