Article View: sci.electronics
Article #7205Re: Lasers for communication
From: Paul A. Houle
Date: Thu, 13 Sep 1990 02:03
Date: Thu, 13 Sep 1990 02:03
21 lines
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1694 bytes
Making an optical link with a laser is very possible, and actually
can be very easy if you've got the right kind of laser. It only takes
two technological tricks to pull it off - one is that you have to be
able to modulate the laser beam, and the other one is to detect the
modulations. Number 2 is exactly the same as if you did it with LED's.
The same circuits work, and HeNe lasers don't produce enough power to
ruin photocells or CdS cells. Some lasers have a modulation jack that
you can plug your audio/data (or even video with some models!) source
into that will automatically modulate the beam. Most of these lasers use
a stable cavity but have a modulator in the beam path -- something that
gets dark when you apply electricity through it. There are many physical
properties that you can use to get this effect - best known is the
"Kerr Cell" which works like a LCD. Controlling power input to the
laser is also possible, but tends to add more noise and, for most models,
you'll have to considerably modify the power supply. A final trick is to
use a bit of mirror that you can vibrate to move the beam on and off the
detector.
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!maverick.ksu.ksu.edu!unmvax!nmt.edu!pahsnsr From: pahsnsr@nmt.edu (Paul A. Houle) Newsgroups: sci.electronics,sci.physics Subject: Re: Lasers for communication Message-ID: <1990Sep13.020325.10622@nmt.edu> Date: 13 Sep 90 02:03:25 GMT References: <1064.26E59478@ofa123.fidonet.org> <1872@oucsace.cs.OHIOU.EDU> <153DAVE@ORION> Organization: New Mexico Institute of Mining and Technology Lines: 21