Is laser beam visible in vacuum?

[Rigel84]

This is what I understand about light.
Light is electromagnetic wave, it comes from the source, bounces from the objects and we see reflected light.
Let's imagine next situation. We are in a dark room and we got only one light source, a toy laser. When we turn it on, we can clearly see beam coming out of our toy and point on the wall where beam hits the wall.
My guess is that we see that beam only because it interacts with air and dust.
Is laser beam visible in vacuum?

 

[.Scott]

You are correct. Often, the laser beam is invisible as it passes through the air. When it is visible, it is because of dust and perhaps fog.

I believe that, in theory, it is possible for a laser to be so powerful that it interacts with a vacuum, but that would be a very exceptional experiment.