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laser listening device?

D

disma

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Sep 23, 2007
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If you used a laser, and reflect a beam off of a window pane, you should be able to pick up sound from the beam, and if you did it right, you could use interference to create an extremely sensitive listening device! I would think the higher the frequency of the laser the more sensitive this could be made. This would be a cool project to try with a bluray diode.


Max
 





Unfortunately the actual site seems down, but there was an article on Hack-a-Day about it; I can't post the link, but it is on hackaday.com, posted march 22nd, 2006.

There is a discussion there in the comments, and the williamson-labs link has good information still.
 
This has been done before.All you need is a laser, a photodiode and a microfone jack.Of course this would turn out very choppy , but you can improve on it. :P
 
Switch said:
This has been done before.All you need is a laser, a photodiode and a microfone jack.Of course this would turn out very choppy , but you can improve on it. :P
Click to expand...

it's very, VERY annoying.

i wonder if you could add like a vocoder and turn the sound into music or a sample :p

(farts into music, anyone?)
 
[link=http://www.hackaday.com/2006/03/22/laser-listening-device/]http://www.hackaday.com/2006/03/22/laser-listening-device/[/link]

here's the original post from hackaday
 
that's the post I was talking about; thanks for posting it (I need 10 posts before I can submit links)
 
Why did you resurrect a 3-year-old thread just to type some inane "wow that is very cool" message?

These old threads should auto-lock after a year.
 
Two things;

1. Don't necropost. The last reply on this thread prior to you was in 2008... it's been over three years.

2. Learn to use the EDIT button instead of posting twice.
 
Bionic-Badger said:
Why did you resurrect a 3-year-old thread just to type some inane "wow that is very cool" message?

These old threads should auto-lock after a year.
Click to expand...

I agree....
That would stop a lot of NecroPosting by new members...


Jerry
 
Since this has been necroposted I'll post some actual relavent info!

A tv show called "Penn and Teller tell a lie" recently did a segment about this exact scenario and claim that it works. They used about $20 worth of parts to do it.

Note. Yes in the vid you see Teller (guy on the right) shine a green laser into his eye...... yeah no comment. Hope it was <5mw?

Penn & Teller Tell A Lie - Laser Pointer Listener? - YouTube
 
I've seen that too, but already knew it works from other websites etc describing the system.

Downside is that it works only when you are looking straight onto the window, or you would need different locations for the laser and the receiver.
 
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