Note: This page is taken from n.wikia.com.
(As written in the N in-game help)
Sluggish but deadly, these guys need a second or so of charging before firing; use it to run for cover.Laser drones are by far the slowest enemies in the game. They can see any location in a room that isn't blocked by a wall or door. Once they see the player, they'll shine a small, harmless ray at them. It's recommended to get out of the way quickly, because that little ray turns into a deadly laser in just about a second. Neither beam moves from the place where the ninja was seen. Laser drones aren't too dangerous in open spaces without steep slopes like in 94-3: neural net. But if there are other enemies teaming up against the player, things can get hard really fast. And in places where jumping is made harder by extremely steep slopes or curves, they become troublesome. These drones are both hardest and usually found in places with steep slopes or curves and several other enemies in the same areas that the laser drone often fires, like in 1.4's 27-3: suicide mission.
Mapmaking tactics Edit
Laser drones are also used numerous times in DDAs to create close calls. In these, the ninja is usually seen flying through the drone's laser a millisecond before it becomes lethal enough to kill.