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Lasers - Possible use as a Distress Signal?


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My cousins from over 5km away have often remarked to me how they can clearly see the beam of my 445nm laser when I point it into the night sky.
Dunno about you, but I wouldn't call 5km "far". Could just yell someone down at that distance ;)

Sure given enough power it might be visible from a good distance away, but we're talking about pointers, not 40W laserscopes :)
 
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There are special lasers for survival signaling.
They have a narrow angle fan pattern to
make it easier to get the light where it has
to go. With a regular laser it is very difficult
to keep the dot on something that is so
many miles away.
 
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  1. They are 7.5mW, not 50mW
  2. They are most likely high quality and IR
    filtered
  3. I suspect they use a Powell lens, which
    are very expensive.
 




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