I would like to have an image (in any kind of space), where I see the path of a "light" source. In my understanding the most common, directed source would be a laser pointer.
a) Is this correct? If not, what would be an other option?
As far as I know, to be able to "see" the path of the light, the material through the light passes should reflect some of it into my "camera", like smoke.
b) Is this correct? Do I always need this "material"? Does the air reflect any of it?