Lasers - Possible use as a Distress Signal?

[hakzaw1]

https://www.youtube.com/watch?v=n6ejwtuOf-0

 

[Things]

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

 

[The Lightning Stalker]

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.

 

[EpicHam]

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.

they are charging $250 for a 50mW green laser.
Wut?
greatland laser

 

[The Lightning Stalker]

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.