In the mission Science Center Interior, you will come to a point where you have to climb out of an elevator shaft. Once you climb out, kill the enemies that come towards you, the enemies to your right around the corner, and the enemies to your left around the corner. Once you kill them all, go down the stairs to the left of where you exited the elevator shaft. Kill the enemies that are on the ground floor and then look up. Against the walls to your left and right in the middle of the room will be metal bars holding lights, two on the left and two on the right. Shoot them and they will fall down. Once you shoot all 4 the achievement should unlock.