If a laser beam is a focused beam of light, then how does some of it find its way into my eyes? On the other hand, if I’m seeing it the way I see everything else, does that mean photons are bouncing off of it into my eyes? Do photons bounce off photons?
In: Technology
Hi /u/UnadvisedOpinion!
If someone used a laser-pointer in a boundless vacuum, you wouldn’t be able to see it (unless it was shining directly into your eyes).
The reason why you can follow a laser pointer pointing at a wall is, that the photons are reflected *by the wall* into all directions. Therefore, some of the photons originally emitted by the laser get reflected into your eye which makes it possible for you to see it.
>Do photons bounce off photons?
No, photons do not interact with each other except in [very specific circumstances](https://en.wikipedia.org/wiki/Pair_production).
Light reflects off of stuff, if it was in space you won’t see it
If it’s in earth atmosphere you’ll see laser due to air particles getting in the way of light and bouncing it to your eyes
You can only see a laser beam if it passes through a medium with stuff in it, like dust or fog.
Some of the laser light will then bounce off the small particles of dust, or the water droplets in fog, and end up in your eye which is why you can see the beam.
A laser beam that’s passing through a vacuum is invisble until it hits something.
Most laser beams are actually invisible, and those that are visible are usually made deliberately visible for show. Generally speaking beams are visible when they’re shot through a non clean medium with many particulates for the beam to bounce into and off of. It can be anything from dust particles to the humidity in the air, smoke and whatever else may be floating in the air. You’re seeing the light bounced off of those particles that finds its way into your eyes.
This is also one of the biggest problems with lasers. They lose a lot of energy over distance very fast when they’re shot out in the open for this exact reason. A lot of their energy is lost by bouncing into floating stuff.
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