Optex’s patented "Multifocus Optics" technology has been used to create "Quad Zone Logic" for accurate detection of humans. Using this logic, the RX-40PT has been designed to give extremely high false alarm protection with tolerance to spot temperature changes from curtains or small to medium size animals. Optex's Optical Quad Technology user taller detection zones divided into upper and lower areas. It detects IR energy changes in both areas and then couples them for extremely accurate detections. Offering very high reliability in hostile areas. Quad Zone Logic provides multi segmented detection zones over the detection area. An alarm signal is created by the cumulated total IR energy of each zone. It is designed so that a human size target will normally fill 4 to 8 zones, and this will cause an alarm to be generated.