[Laser] Optical comms at 100 + miles in Australia

[Karel Kulhavy]

> A very handy source of fresnels is the 3dLens company in Taiwan. They make 
> a 39.5 cm square (about 15.5 inches square) fesnel with 33 cm focal length, 
> thickness 2 mm, and offer it on Net for $28.60 American dollars. That would 
> give you terrific collection area for receiving, and a transmit beam spread 

Yes that would be Ronja 10M Brutal Armageddon ;-) Wouldn't you like to
develop plans and building guides and let it merge into Ronja? :)

> The remaining problem, of course, is to reduce the fresnel's field of view 
> so that your transceiver doesn't burst into flames when sunlight gets 
> '"down the chute""! A series of parallel tubes or a box structure in front 

Why? Just a fancy effect as a bonus ;-) There could be even an "insert
egg here" slot for making pancakes ;-)

> of the lens would probably do the trick in limiting the FOV - but we've 
> been doing most of our DX tests at night so that's not such a worry to us.

Ronja solves this by metal case. I know it could glow red-hot with your
proposal, but then it could be solved by internal baffles and thermal
shield from copper tin. However if the sun hit the receiver, it would
REALLY get out of luck ;-) Possibly a coil-operated metal shutting door
that would be triggered by photodiode overcurrent?

I think it's definitely worth merging because current number of
registered installations in 90 on Ronja:
http://ronja.twibright.com/installations.php

And many people could exploit such wonderful optical head series (and
it's a free technology :) )

Cl<