MotionProtect Curtain is a curtain type detector for indoor use, it creates an invisible veil protecting windows, doors and valued goods from burglars. To create MotionProtect Curtain we have developed an optical system consisting of two infrared sensors and a segmented mirror. This system allows the detector to receive twice as much information about the events in the protected zone than provided by regular curtain detectors. It helps to determine reliably the cause of triggering: a stream of hot air, an animal or an intruder and it reacts only to the real threats.