A Light barrier (also called a Security System and a Door System) is a hatch that appears in the Metroid Prime 2: Echoes Bonus Disc. It is a white-colored force field with an elaborate design on it consisting of black circle outlines surrounding whole circles, each connected by lines. A larger circular black border surrounds a crimson circle. It is vulnerable to the Dark Beam; once hit, it fades away. There is another one that is completely invulnerable and black in color at the end of the Command Center Access.
In the final game, they are absent. This is because Samus does not have the Dark Beam at that time of her exploration.
"Security Systems active. Dark Beam weapon system required for door access. Energize door with this weapon to open it."
"Door System access denied. Unable to bypass security codes. Seek an alternate exit."