Why can we see the path of lasers/flashlight in videos, but IRL we need a medium to reflect them like smoke/vapor

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[https://www.youtube.com/watch?v=a0H0vOWUjbY](https://www.youtube.com/watch?v=a0H0vOWUjbY)
Was recently watching the new Allen Pan video on making a laser grid lawn mower, and I was just confused by why we can see the lasers on the video, when it seems him and his friends couldn’t. At 6:45 it seems clear that Backyard Scientist uses his camera to see the lasers themselves because they wouldn’t be visible unless they shined the light into their eyes, but the camera can pick up the path of the lasers?

In: Physics

3 Answers

Anonymous 0 Comments

The light is scattering off of particles of dust and other stuff in the air. Only a small fraction is getting scattered but it’s enough to make the beam visible (especially once things start smoking).

The guys in the video can’t see it very well because they’re wearing goggles that are designed to block most of the light at that wavelength. You don’t want even a small accidental reflection to get in your eye with the amount of power.

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