Path: utzoo!attcan!uunet!microsoft!w-colinp
From: w-colinp@microsoft.UUCP (Colin Plumb)
Newsgroups: sci.electronics
Subject: Re: Correct Terminology
Message-ID: <743@microsoft.UUCP>
Date: 25 Feb 89 01:47:47 GMT
References: <603@icus.islp.ny.us> <7944@netnews.upenn.edu> <5632@homxc.ATT.COM> <55@enuxha.eas.asu.edu> <1310@ccnysci.UUCP>
Reply-To: w-colinp@microsoft.uucp (Colin Plumb)
Organization: very little
Lines: 20

sukenick@ccnysci.UUCP (SYG) wrote:
> Collimated: the output is directional, and there is no such thing as perfectly
> 	collimated... (Dr. Heisenberg wouldn't let you get them perfectly
> 	straight and even if you did your best, the photons'll feud
> 	amongst themselves and spread out)

Um.. don't I remember someone cracked this problem?  Instead of a (statistical)
normal distribution of intensity as you get away from the axis, someone used
a Bessel function or something.  Less than 10% efficiency, but then you can
send it literally forever.

If the light from the laser has a cross-sectional intensity distribution D,
and 1m further out it has diffused to f(D), they solved f(X) = X.

Doing it along the axis of beam propagation produces solitons - very useful
for transatlantic fibres!
-- 
	-Colin (uunet!microsoft!w-colinp)

"Don't listen to me.  I never do."