[Laser] Re : NLOS contact

[Garnier Yves]

Hi Stuart
Direct forward scatter via Rayleigh scattering seems to me very difficult with a red or an infrared laser in clear air conditions.
We never succeed with it.
It's quite possible with an hazy sky and a very flat TX RX aiming axes angle via the Mie scattering effect.
In fact that is very similar the cloud bounce way ! 
Rayleigh scattering could be very strong by clear sky with a blue laser.
A blue sensitive photomultiplier tube at the RX side could be a good choice.
But...this link could be under the 10 Km range because the blue diffusing air effect will produce also a strong propagation loss in the laser beam.
Many experiments to do...?  
73
Yves F1AVY
http://f1avyopto.wifeo.com


--- En date de : Ven 4.2.11, I <stuart.wisher at talktalk.net> a écrit :

> De: I <stuart.wisher at talktalk.net>
> Objet: [Laser] NLOS contact
> À: laser at mailman.qth.net
> Date: Vendredi 4 février 2011, 13h47
> 
> Thanks for the links Yves,
> 
> 
> 
> All your contacts seem to be by reflection, whether off
> mountains, clouds or meadows. My modest contact was by
> forward scatter since we could not find a reflecting site
> between us.
> Have you tried contacts by scatter? I could not get all
> your info to load and translate so I am unaware if you have
> tried this mode.
> Maybe we will try this again by cloudbounce after reading
> of your excellent results using that mode.
> As I mentioned, I have a 200mW red laser so we will try for
> a contact with a coherent signal next
> 
> 
> Regards,
> 
> 
> Stuart G8CYW
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