[Laser] Atmosphere turbulence bubbles

[Chris L]

Dear Jim et al,

Thanks for that info on the tutorials - we'll follow those up.

Some of these Internet refs may be of interest:

A paper indicating that one approach to the reduction of laser fading 
through atmospheric turbulence lies in placing a controlled diffusion filter 
in front of the transmitting laser to remove some of its coherence prior to 
transmission, so that the fades don't go too deep... this confirms our 
statements on the undesirability of coherent beams through a turbulent 
atmosphere:

http://pegasus.cc.ucf.edu/~okorotko/OptEng43.pdf

Here's a particularly interesting paper on free space optical comms and the 
effect of atmospheric turbulence, by Zhu and Kahn:

http://www-ee.stanford.edu/~jmk/pubs/trans.com.ml.det.turb.pdf

A paper on coding schemes to avoid optical turbulence disruption:

http://www-ee.stanford.edu/~jmk/pubs/trans.com.smc.turb.pdf

A paper on similar atmospheric turbulence effects affecting higher frequency 
microwave transmission channels:

http://ipnpr.jpl.nasa.gov/tmo/progress_report/42-158/158E.pdf

In view of what we've said about the greater simplicity of Luxeon 
transmission systems, I think these papers will add a little confirmation to 
all that... perhaps it IS better to begin with a non-coherent source, after 
all.

And we repeat, those ARRL 'coherency requisites' are just plain Goddam 
stupid.

Chris Long (Melbourne, Australia) and Mike Groth VK7MJ (Hobart, Tasmania).