i-hacked.com — Using a simple laser pen pointer, a few misc parts, and about 15 minutes, you can make a simple laser communicator that converts a sound source into light that travels across a room, and back into sound with very little quality loss.
May 11, 2005 View in Crawl 4
nuggetMay 12, 2005
Very cool.
thecolor11May 12, 2005
Why not save yourself and use an IR LED. Their response is more linear, so AM comes out cleaner. Laser diodes are better with digital signals, because you can turn them on past the knee voltage and back off quickly.
jibberishMay 12, 2005
ocontinuum: People do not user lasers for communications because it is faster, they use lasers through Fiber Optics because you do not get any Electromagnetic interference of the signal (Visible Light is immune to 60Hz hum, transformers, lightning spikes, etc…), less attenuation of the signal characteristics over distance (signal goes further) compared to copper transmission media, and because the bandwidth offered by a single Fiber Optic cable is dramatically larger than that of it's copper predecessor. Last time I checked, Laser light and Radio waves are all forms of light constituting parts of the electromagnetic spectrum. All forms of light travel at 3x10^8 m/s through a vacuum. Fiber optics are a form of glass, when light hits a more dense material like glass it slows down and refracts the light (bends) so actually Radio signals propagate (move) faster than lasers through Fiber Optics because they propagate through a less dense medium like air.
hax0rMay 12, 2005
How can this be modified to bounce the laser off of a window to hear the sound from inside the room? I imagine you'd have to hit it at a very acute angle so you could catch the reflected beam.
eddimondNov 14, 2006
I know this is over a year old, but I just wanna say that Ocontinuum is wrong. Laser isn't faster than radio waves. Infact, all waves in the electro magnetic spectrum travle at the speed of light (300 000 000m/s).
eddimondNov 14, 2006
also, Hax0r, to make the laser bounce off windows the angle of the laser, from the normal, has to be greater than the critical (usually between 40 and 50 in glass, it's dependant on the density of the glass), causing total internal reflection(this is how fibre optics work). Hope that helps.