The events of September 11, 2001 changed the way business thought about perimeter security and access control. Rather than just a barrier to keep intruders out, fences and gates are installed with protection against potential terrorist attacks in mind. 

In the Norton Healthcare System in Louisville, Ky., there are behavioral patients who need round-the-clock monitoring. To do so, explains Stanley Helm, security director, the rooms are equipped with security cameras. But the cameras used for years required plenty of background light in order to get clear pictures, and that meant the lights were always turned on, even when the patients were trying to sleep.