When a high-performance infrared detector is connected to a monitor, it becomes an anti-theft alarm system. The adoption of SMT and dual shielding technology effectively improves the detector’s resistance to RFI and visible light interference; and the use of dynamic threshold comparator technology enhances the detector’s ability to identify real signals. This product, characterized by automatic temperature compensation, reliable detection performance and easy installation, are suitable for being used as the human body intrusion detectors of the anti-theft alarm systems in banks, shopping malls, warehouses, residential areas, etc.