[Laser] RS-232 comms via laser

[Kerry Banke]

 From my experience with modulating the cheap laser pointer which contain 
only a diode and resistor, the response is good up to hundreds of MHz if 
high frequency construction techniques are used. The same goes for the 
small area PIN  detectors.  I'm sending channel 3 audio/video modulated RF 
(50 + MHz) for our demos.  I think the distance is probably limited mostly 
by optics to transfer essentially all of the laser pointer power to the 
detector at some distance. My ATV system should be good for  at least 
several hundred yards if not more with the Tx  beam expander I'm using and 
4" receive optics. I  really should run some tests to estimate the maximum 
distance for this simple  system.
  - Kerry N6IZW -

At 08:18 AM 2/16/2006, you wrote:
>Folks:
>
>Heard about this system today ...
>
>http://www.geocities.com/SiliconValley/Lakes/7156/laser.htm
>
>Has anyone tried this setup?
>Going beyond the 100m the article specifies?
>"High" data rates?
>
>Serial data rates to 128000 bps are available to most of us with a
>reasonably modern
>computer. The thing that worries me is as the "switching rate" increases, the
>laser response will degrade at some point (internal capacitance of the
>diode + driver ccts being one of the issues).
>
>What's the data rate / distance we can reasonably expect out of a
>laser system like this?
>
>I'll be trying this out in the next few months of spare time but I
>would like to
>know if anyone else has tried pushing this type of system hard (and fast).
>
>BTW I do know about Ronja but this is a bit different (and "lower tech"). 
>Better
>for a starter project in data over lasers.
>
>Brian VY1BB
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