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Transfer Data with Lasers?

S

simplysped

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Hi Guys,
Been away for a long time. I just thought of something, so I thought I would ask you guys if this idea is completely stupid.

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Let's say that you had a red & a green laser, both with a decent amount of power, pointed at a sensor across town. Assuming it can reach the sensor with no problems, how fast do you think it could transfer data?
 





Depends on what type of "method" you are using. You could do a digital setup were you could only transmit data in binary ( 1's and 0's ) On and Off. Then have the sensor with the micro-controller or computer decode the information. You could also do an analog setup like using a photodiode as the sensor and then have the laser dim and brighten up, kinda like they do sending radio throught lasers. ( Teachers do demos like those )

I would think that if you get the code all figured out and get all the bugs worked out, i would say you will be able to send/recieve as fast as your program will encode and decode the information!
 
gotwake424 said:
I would think that if you get the code all figured out and get all the bugs worked out, i would say you will be able to send/recieve as fast as your program will encode and decode the information!
Click to expand...
I'll get right on that!

Hehe, I know it's very far fetched. But it would be neat if you could make a little laser network with your neighbor to transfer files and whatnot. :D
 
Amateur radio operators have been doing that for some time. With lasers. I ran across an article awhile back about a couple guys who used $3.00 cat toy pointers and transmitted data approx. 5 miles at 10MHz data rate.. I can't seem to find it now, though.
 
CD/DVD/blu ray are based on that. I guess the limitation in this data transfer system wouldn't be the laser. A cable can transfer data way faster than they do nowadays, but that's because the devices we use to read and write the data can process it faster.

It would be the same with lasers. If a bluray disc can actually be read at 400Mbps, I guess if no disk is involved even higher.

Yours,
Albert
 
haven't seen it used outside of fiber optics.. personally

however, the technology to code and decode signals using a laser is already and has been out there for quite some time.. so.. it's not surprising that FSO is already being used for applications.
 
So this have alredy been released :o

As you can read there, it's not the laser that limits the speed, it's the device using it ;)
 
it is the same as with current fiber optic data transmissions. so far we are no where near limited by the by the medium near as much as what is on each end. right now we only able to power that laser diode off and on only so fast. as well only able to detect that being off so fast. and that is the main limiting factor. that is what you can upgrade your fiber connection alot of times just by changing out the media converter. your media converter is what transfers your regular copper signal to light. (well I suppose charge time of the diode would have something to do with it but as of right now I don't think it does.
 
laser diodes can be modulated into the 100s of MHz at least (if not much higher), so it would depend more on the detector than the source.
 
I currently own a labby which modulates at a max of 30kHz. While this is not extraordinarily fast I guess it would be enough.
The 412mW burst of green should be plenty to communicate with someone several miles away.
I prefer the interwebz or mobile phones though.

Seb
 
Jaseth said:
I currently own a labby which modulates at a max of 30kHz. While this is not extraordinarily fast I guess it would be enough.
The 412mW burst of green should be plenty to communicate with someone several miles away.
I prefer the interwebz or mobile phones though.

Seb
Click to expand...

He is talking about sending data, it would be faster than the interwebz. It would also be safer, if you encoded the data using an algorithm. But thats getting complicated!
 
Its an interesting idea, and has been done in various forms before.

In normal operation a dvd drive is able to read or write several megabytes a second, so the diode and sensor can obviously handle this speed.

There is, however, a limitation to the speed caused by the signal/noise ratio in the optical path. This also involves any ambient light you pick up as noise, so factors like directivity and monochromatic sensitivity become important.

I suppose links like these are rarely used because of their practical drawbacks - you do need a perfect line of sight, and your system will fail during fog, smog, rainfall and even when a bird flies through the beam.
 
Benm said:
Its an interesting idea, and has been done in various forms before.

In normal operation a dvd drive is able to read or write several megabytes a second, so the diode and sensor can obviously handle this speed.

There is, however, a limitation to the speed caused by the signal/noise ratio in the optical path. This also involves any ambient light you pick up as noise, so factors like directivity and monochromatic sensitivity become important.

I suppose links like these are rarely used because of their practical drawbacks - you do need a perfect line of sight, and your system will fail during fog, smog, rainfall and even when a bird flies through the beam.
Click to expand...

You do bring up a very good point, "any ambient light you pick up as noise, so factors like directivity and monochromatic sensitivity become important" The only way that i would see this having a big effect would be if the laser was not very bright. If the beam is still intense enough at the sensor i would think it would be easy over come with harder were modifications.

I think that this project will get harder the greater of a distance between the laser and sensor.
 
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