A couple of nights ago, it was real foggy when I got home at 6AM. I took the laser (not the whole rifle) outside and shot it through the fog. I could see the entire beam for at least a quarter mile. It may have gone even farther, but it was getting faint.
I was also able to light up water droplets on leaves even further away. Of course, this was still with an eye-safe .5mW beam. It's just that the human eye is six times more sensitive to green than to red, making the green easier to see, and so appear brighter.
A web site shows how to use the laser from a DVD burner to make a 10mW red beam. That's downright dangerous, and also eats up batteries like crazy.
I bought one.
Why? Well, I had to go speak at one of the Nat'l Labs (DOE) and thought, "Hey, a green laser, being the affordable cutting edge, would give my presentation a little edge." It's always good to have an edge when you're wading into the pure science pool with the PhDs.
I was the last briefer of the day. And wouldn't you know it? *Every* presenter in front of me had a green laser. So much for my edge. (I cain't quite justify $400+ for a spiffy blue one just yet...)
Then week before last, I had to brief the extremely senior chief muckety muck of my organization. And I thought, "Duh - he's a PhD! I can distract him from the not-so-great news on slide 3 with the green laser! He'll say, "ooooh! Green!"'
Well, I couldn't find it. It's lost! So I did without. And wouldn't you know it? I was last again and the presenter in front of me had a green laser. And the PhD said, "Ooooh! Green!" I wanted so much to go beat my forehead on a brick wall.
I need another green laser. (I'm watching those blue prices like a hawk, tho. And yellow, too!)