Projecting them to lasers which are already attached in the room.
My (non-technical) understanding of this sort of laser security system is that it functions by detecting when a beam is interrupted and tripping an alarm.
On one end of the room is a laser projector, directly across from that is a sensor. If the sensor ever fails to detect the beam that should be pointed at it, the alarm is sounded.
Robert sets up his own laser beam projectors and points them at the receiving sensors, so that even if the real beam gets interrupted, the sensor won't realize it (because it's still sensing light from the "fake beam.")