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range of laser pen


Most of us are familiar with laser pen (laser pointer) which work on 3 button cells.

Can you estimate the average distance the red beam can travel from earth to sky?

I think it can't pass out of the earth's atmosphere.

Arrow What you think about its average range of LASER PEN Question

No, the average laser pointer cannot reach out of the Earth's atmosphere with any appreciable power.

The actual range depends greatly on ambient light and atmospheric conditions. It also varies between lasers. Most lasers you can find are 5mw or less; higher output power means more range. Also, different lasers have different beam spreads (the beam spreading out over distance) the tighter the beam, the more range.

The laser sight for my rifle is a 35mw green laser. I don't know exactly how far it can reach, but the dot is visible at 500 yards, even in daylight. (and in low light, the beam itself is clearly visible)
I agree with ocalhoun.

However, if you're talking about mild red lasers, the most common laser, it's probably more than 5 meters, but less than 30.
it may nice to check this experiment 1mW laser can go > 20 km.
I echo everyone else's comments. Distance has many variables, but in referring to the dirt cheap 5mw red beams, they can hardly be seen a km away.

I've bought a few different power laser modules from China over the years for different projects. It still amazes me how far down in price they continue to go. You can get a 50 mw green for around $20 these days, and even 50mw violet beams for less than that!
It depends on the color, too. Red doesn't do much, blue and green works better. I found a commercially available 2W (!) blue laser with a range of 55km,

Actually I'd like to know if a laser exists that can put a spot on the moon Razz

Ok.. there isn't any.. but suppose there would be a really big one.. and every person in Asia would aquire the device and point it to the dark side of the moon simultaneously, would that help ?

There's a very funny web page about that,
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