eli5 On projectors, why does the screen show only on the wall, rather than being carried out like a laser?
In: Technology
If you mean why do projectors not work on far away things like lasers and need a wall to be clear? It is because the light coming from a laser is very focused and uniform, which helps it keep together and not get scattered over long distances.
Light coming from a projector on the other hand is spread out wide by the projector to show a whole imagine on the wall/screen it is designed to be used with. Removing that wall/screen the projector light continues traveling and spreading out and getting scattered by dust or the air to the point where when it does hit something you cant make it out as the image.
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