How far can a 1W blue 450 nm laser go at night?

[Charlie3082]

I have never tested this myself since im not really a outdoors person

 

[Alaskan]

Point it at the sun, about 8 minutes and 20 seconds later the photons will get there, but you probably mean a visible beam, correct? That requires particles to reflect off of, as well as the beam to stay narrow enough to be able to see the light of the beam reflecting from them (side view) with your eyes. The divergence of the laser determines the beam width at distance and if narrow enough (as it should be for a common 1W 450 nm pointer) you should be able to see the beam from the side for a few miles. Go look on YouTube for videos of a laser from a distance.

Here's one:

The laser shown in this video probably doesn't have low divergence (just average), if it did, the beam would not spread to be so wide so quickly.