laser sight

A device used to aid target acquisition, which when on, projects a colored beam onto the target. This includes detachable firearm modules as well as targeting lasers integrated directly into weapons, helmets, or robots. Also see laser pointer projection, which can be used when the beam and/or dot are visible.

Not to be confused with laser pointer, a small cylindrical tool used to direct attention to one spot during meetings and lectures.

Also please don't confuse with eye beam, where lasers may shoot from a character's eyes.