How are professional laser shows done How are professional laser shows done ? I need an explanation of the phenomenon of a laser visible in mid air ,(NOT THE APPARATUS USED which means I don't want the engineering aspect of it,I only want the phenomenon occurring in the air .) How are we able to create a hollow object in mid air . Check this link --https://m.youtube.com/watch?v=F03HeVAa9jY , where you can see hollow object in mid air. What are the physical phenomenon that enables us to see it?
 A: What you are seeing there is the scattering of laser light off of particles in the air that the shows creators are using to allow you to see the image.  They usually have some kind of smoke machine which puts a mist of particles in the air that allow the light to scatter off of it.  The lasers that form the image are focused (in the sense that many lasers converge at that location, or the lasers spend more time illuminating that path, not actual optical focusing) to a particular region in space so that more scattering off of the smoke particles occurs at that physical location.  This is how you end up seeing the images projected in space.
Edit: As was pointed out by lemon, in the example you provided a link to, the laser show here could be projecting everything on to a screen (it seems that if it is, they are doing other things to give it the sense of projection in space, although there are certain elements that seem convincing, without viewing from another angle, its hard to tell in this video).  For the effect that you are curious about though, projecting images with lasers in "mid-air", fog screens are certainly used in other instances, and create the effect that you mentioned.
