How to Acquire
This is a relatively simple achievement/trophy to collect. Find a rewire tool and attach it to a wall of light's circuitry - this will reset it so that guards, tallboys, and other enemies will not be able to pass through safely. To get an enemy to approach the wall of light, Corvo Attano simply has to make enough noise. An enemy will approach, and be disintegrated by the wall of light, unlocking the achievement.
It is also possible to earn this achievement by carrying an unconscious guard through a wall of light, although it will kill Corvo in the process.