[Laser] Big IR LEDs

[Chris L]

   Dear Andrew,

   No,  they  don't seem to make them. Even the red 1 watt is NOT made in
   the  3 watt or 5 watt rating, and it's on 630 nM, not 660 nM like most
   other  super  brite  red  LEDs  - probably to make better usage of the
   eye's wavelength response curve.

   If  it was a 930 nM IR LED it wouldn't be much use - that hits a major
   H2O absorbtion band. If it were 830 nM that might help. But only a red
   light can be focussed by eye and seen in a rifle sight - and if you've
   ever stood on a mountaintop and TRIED to line up an IR beam you'd soon
   give it away.

   As  I  mentioned  in a previous posting, in 1991 I tried a high output
   830  nM  LED against a 3000 mCd 5mm LED (660 nM) and the difference in
   transmitted  flux  was  not that great - only a few dB in the IR LED's
   favour   -  and  that  was  hard  to  even  notice  as  the  beam  was
   scintillating  up  and  down  about  a  5 Hz rate some 7 dB or so! Red
   Luxeons  leave  both for dead, particularly as the source size matches
   the focal spot of many of the better fresnels.

   If  only someone DID make an IR Luxeon, or even one out around 700 nM,
   the  beam might not attract quite so much attention, but believe me, a
   VISIBLE beam is so much easier to align.

   All the best to all,

   Chris Long.
   >From: "Andrew T. Flowers, K0SM" <aflowers at frontiernet.net>
   >Reply-To: Free Space LASER Communications <laser at mailman.qth.net>
   >To: laser at mailman.qth.net
   >Subject: [Laser] Big IR LEDs
   >Date: Fri, 01 Apr 2005 23:54:14 -0500
   >
   >Does anyone know of a large IR LED on the order of the Luxeon
   >devices?  I imagine the market isn't quite as large for such an
   >item, but I wonder if such a thing is obtainable.
   >
   >Andy
   >K0SM/2
   >
   >
   >
   >
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