How far can a 100mw laser travel?

Answer 1

There is no maximum theoretical distance; a laser generates light, and light can go on essentially forever. If you are asking what the maximum distance is at which you could SEE the laser, then that would depend on the power output of the laser. It's not yet technically possible to build a laser that could be seen from another planet, but that day probably isn't too far off.

Answer 2

It depends on the size and weight of the individual laser. Those little laser pointers that are used to put a red dot on the screen during a presentation can be carried around on a key-ring, and can go wherever the owner of the keys goes, whereas the multi-megawatt lasers used for astronomical probes are permanent fixtures in observatories, and can't travel at all once they're installed. If you're asking about the beam of light emitted by a laser, that's a different question. That keeps going until it runs into something that it can't penetrate. The real question is: How far away from the laser can its light go and still be detected ? That depends on the laser's power. One impressive example is the way that a laser is routinely used to measure the distance to the moon. A laser pulse is transmitted toward the moon through an astronomical telescope, reflected from a small reflector that the Apollo astronauts left on the moon's surface, and detected back at the observatory on earth, after a round-trip of almost a half-million miles.

Answer 3

Technically speaking light never stops travelling. It's also invisible until it is reflected off a medium into your retina. The laser light you see is the light reflecting off dust particles, so more particles the brighter the beam appears but the less distance the light travels as it expands and is attenuated.

It's visibility and brightness is constant but reduced by the medium through which it travels. So firing a laser upward starts a beam of photons which continues travelling until they hit something.

That's the technical answer. In reality, if you fire a 100mW laser light it will be easily visible for 20 miles or so by the person who looks along the beam, but less so by persons at a tangent to the beam. Whether it produces a spot at the other end depends how dirty your air pollution is.

Answer 4

The range of a LASER depends mostly on the quality of the collimation of the beam, not its power or color. Without more information than the question provides I would not want to attempt to give a numeric value.

Answer 5

There is no specific limit; until it runs into something solid, or a thick gas cloud that absorbs it. But reflected light, like moonlight or the light of Jupiter, can never be anywhere as intense as direct light, like the light of the Sun. And because of that, it dissipates into near-invisibility relatively nearby.

For example, we can see the the direct light of bright stars thousands of light years away, and galaxies a million times farther - but we cannot see the reflected light of asteroids or cometary bodies in the Oort cloud less than a half-light year away.

Answer 6

Light (elctromagnetic radiation) travels a indeterminate distance (read infinite - limited by the size of the universe) unless it is absorbed by matter.

Answer 7

It will go on in a straight line (which is realy a curve) forever unles the light is interfered with in some way in the mean time until it gets back to its stating point.