If a laser’s light travels in only one direction how can I see the beam?

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https://imgur.com/a/sIqUcl1

If the laser’s light travels straight in one direction out from the laser pointer, then how come I can see the beam? How does that light even get to my eyes?

Comments

  1. Rannasha Avatar

    If you see the laser beam, then part of the light of the beam is deflected by particles in the air. Smoke, dust, water vapor, you name it. That’s why a laser light show will often make use of things like smoke machines to make the beams more visible.

  2. drawliphant Avatar

    Raylegh scattering. The gas itself can reflect a tiny portion of a laser beam in all directions. The gas molecules will start to move with the light wave just a little bit, their magnetic field oscillates with the light waves and they’ll re-emit the light that excited the gas but only a very small amount.

    This is what causes the sky to be blue and the sunset to be red, because blue light scatters first, and red makes it through a thick atmosphere.